sensation and perception experiments

4 Sensation and Perception

Imagine standing on a city street corner. You might be struck by movement everywhere as cars and people go about their business, by the sound of a street musician’s melody or a horn honking in the distance, by the smell of exhaust fumes or of food being sold by a nearby vendor, and by the sensation of hard pavement under your feet.

We rely on our sensory systems to provide important information about our surroundings. We use this information to successfully navigate and interact with our environment so that we can find nourishment, seek shelter, maintain social relationships, and avoid potentially dangerous situations.

This chapter will provide an overview of how sensory information is received and processed by the nervous system and how that affects our conscious experience of the world. We begin by learning the distinction between sensation and perception. Then we consider the physical properties of light and sound stimuli, along with an overview of the basic structure and function of the major sensory systems. The chapter will close with a discussion of a historically important theory of perception called Gestalt.

Learning Objectives

By the end of this section, you will be able to:

• Distinguish between sensation and perception
• Describe the concepts of absolute threshold and difference threshold
• Discuss the roles attention, motivation, and sensory adaptation play in perception

What does it mean to sense something? Sensory receptors are specialized neurons that respond to specific types of stimuli. When sensory information is detected by a sensory receptor,  sensation  has occurred. For example, light that enters the eye causes chemical changes in cells that line the back of the eye. These cells relay messages, in the form of action potentials (as you learned when studying biopsychology), to the central nervous system. The conversion from sensory stimulus energy to action potential is known as  transduction .

You have probably known since elementary school that we have five senses: vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). It turns out that this notion of five senses is oversimplified. We also have sensory systems that provide information about balance (the vestibular sense), body position and movement (proprioception and kinesthesia), pain (nociception), and temperature (thermoception).

The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold.  Absolute threshold  refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time. The sensitivity of our sensory receptors can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away (Okawa & Sampath, 2007). Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962).

It is also possible for us to get messages that are presented below the threshold for conscious awareness—these are called  subliminal messages . A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain: This is an absolute threshold. A message below that threshold is said to be subliminal: We receive it, but we are not consciously aware of it. Over the years there has been a great deal of speculation about the use of subliminal messages in advertising, rock music, and self-help audio programs. Research evidence shows that in laboratory settings, people can process and respond to information outside of awareness. But this does not mean that we obey these messages like zombies; in fact, hidden messages have little effect on behavior outside the laboratory (Kunst-Wilson & Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel, Sarrazin, Legrain, & Gobancé, 2009; Loersch, Durso, & Petty, 2013).

Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them. This is known as the  just noticeable difference (jnd)  or  difference threshold . Unlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. As an example, imagine yourself in a very dark movie theater. If an audience member were to receive a text message that caused the cell phone screen to light up, chances are that many people would notice the change in illumination in the theater. However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice. The cell phone brightness does not change, but its ability to be detected as a change in illumination varies dramatically between the two contexts. Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has become known as Weber’s law: The difference threshold is a constant fraction of the original stimulus, as the example illustrates.

While our sensory receptors are constantly collecting information from the environment, it is ultimately how we interpret that information that affects how we interact with the world.  Perception  refers to the way sensory information is organized, interpreted, and consciously experienced. Perception involves both bottom-up and top-down processing.  Bottom-up processing  refers to sensory information from a stimulus in the environment driving a process, and  top-down processing  refers to knowledge and expectancy driving a process, as shown in  Figure 5.2  (Egeth & Yantis, 1997; Fine & Minnery, 2009; Yantis & Egeth, 1999).

Imagine that you and some friends are sitting in a crowded restaurant eating lunch and talking. It is very noisy, and you are concentrating on your friend’s face to hear what she is saying, then the sound of breaking glass and the clang of metal pans hitting the floor rings out. The server dropped a large tray of food. Although you were attending to your meal and conversation, that crashing sound would likely get through your attentional filters and capture your attention. You would have no choice but to notice it. That attentional capture would be caused by the sound from the environment: it would be bottom-up.

Alternatively, top-down processes are generally goal-directed, slow, deliberate, effortful, and under your control (Fine & Minnery, 2009; Miller & Cohen, 2001; Miller & D’Esposito, 2005). For instance, if you misplaced your keys, how would you look for them? If you had a yellow key fob, you would probably look for the yellowness of a certain size in specific locations, such as on the counter, coffee table, and other similar places. You would not look for yellowness on your ceiling fan, because you know keys are not normally lying on top of a ceiling fan. That act of searching for a certain size of yellowness in some locations and not others would be top-down—under your control and based on your experience.

One way to think of this concept is that sensation is a physical process, whereas perception is psychological. For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the  sensation  is the scent receptors detecting the odor of cinnamon, but the  perception  may be “Mmm, this smells like the bread Grandma used to bake when the family gathered for holidays.”

Although our perceptions are built from sensations, not all sensations result in perception. In fact, we often don’t perceive stimuli that remain relatively constant over prolonged periods of time. This is known as  sensory adaptation . Imagine going to a city that you have never visited. You check in to the hotel, but when you get to your room, there is a road construction sign with a bright flashing light outside your window. Unfortunately, there are no other rooms available, so you are stuck with a flashing light. You decide to watch television to unwind. The flashing light was extremely annoying when you first entered your room. It was as if someone was continually turning a bright yellow spotlight on and off in your room, but after watching television for a short while, you no longer notice the light flashing. The light is still flashing and filling your room with yellow light every few seconds, and the photoreceptors in your eyes still sense the light, but you no longer perceive the rapid changes in lighting conditions. That you no longer perceive the flashing light demonstrates sensory adaptation and shows that while closely associated, sensation and perception are different.

There is another factor that affects sensation and perception: attention. Attention plays a significant role in determining what is sensed versus what is perceived. Imagine you are at a party full of music, chatter, and laughter. You get involved in an interesting conversation with a friend, and you tune out all the background noise. If someone interrupted you to ask what song had just finished playing, you would probably be unable to answer that question.

One of the most interesting demonstrations of how important attention is in determining our perception of the environment occurred in a famous study conducted by Daniel Simons and Christopher Chabris (1999). In this study, participants watched a video of people dressed in black and white passing basketballs. Participants were asked to count the number of times the team dressed in white passed the ball. During the video, a person dressed in a black gorilla costume walks among the two teams. You would think that someone would notice the gorilla, right? Nearly half of the people who watched the video didn’t notice the gorilla at all, despite the fact that he was clearly visible for nine seconds. Because participants were so focused on the number of times the team dressed in white was passing the ball, they completely tuned out other visual information.  Inattentional blindness  is the failure to notice something that is completely visible because the person was actively attending to something else and did not pay attention to other things (Mack & Rock, 1998; Simons & Chabris, 1999).

In a similar experiment, researchers tested inattentional blindness by asking participants to observe images moving across a computer screen. They were instructed to focus on either white or black objects, disregarding the other color. When a red cross passed across the screen, about one-third of subjects did not notice it ( Figure 5.3 ) (Most, Simons, Scholl, & Chabris, 2000).

Motivation can also affect perception. Have you ever been expecting a really important phone call and, while taking a shower, you think you hear the phone ringing, only to discover that it is not? If so, then you have experienced how motivation to detect a meaningful stimulus can shift our ability to discriminate between a true sensory stimulus and background noise. The ability to identify a stimulus when it is embedded in a distracting background is called  signal detection theory . This might also explain why a mother is awakened by a quiet murmur from her baby but not by other sounds that occur while she is asleep. Signal detection theory has practical applications, such as increasing air traffic controller accuracy. Controllers need to be able to detect planes among many signals (blips) that appear on the radar screen and follow those planes as they move through the sky. In fact, the original work of the researcher who developed signal detection theory was focused on improving the sensitivity of air traffic controllers to plane blips (Swets, 1964).

Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life experiences. As you will see later in this chapter, individuals who are deprived of the experience of binocular vision during critical periods of development have trouble perceiving depth (Fawcett, Wang, & Birch, 2005). The shared experiences of people within a given cultural context can have pronounced effects on perception. For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963) published the results of a multinational study in which they demonstrated that individuals from Western  cultures  were more prone to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa. One such illusion that Westerners were more likely to experience was the  Müller-Lyer  illusion ( Figure 5.4 ): The lines appear to be different lengths, but they are actually the same length.

These perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context. People in Western cultures, for example, have a perceptual context of buildings with straight lines, what Segall’s study called a carpentered world (Segall et al., 1966). In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion (Segall et al., 1999). It is not just vision that is affected by cultural factors. Indeed, research has demonstrated that the ability to identify an odor and rate its pleasantness and its intensity, varies cross-culturally (Ayabe-Kanamura, Saito, Distel, Martínez-Gómez, & Hudson, 1998).

Children described as thrill-seekers are more likely to show taste preferences for intense sour flavors (Liem, Westerbeek, Wolterink, Kok, & de Graaf, 2004), which suggests that basic aspects of personality might affect perception. Furthermore, individuals who hold positive attitudes toward reduced-fat foods are more likely to rate foods labeled as reduced-fat as tasting better than people who have less positive attitudes about these products (Aaron, Mela, & Evans, 1994).

• Describe important physical features of wave forms
• Show how physical properties of light waves are associated with perceptual experience
• Show how physical properties of sound waves are associated with perceptual experience

Amplitude and Wavelength

Two physical characteristics of a wave are amplitude and wavelength ( Figure 5.5 ). The  amplitude  of a wave is the distance from the center line to the top point of the crest or the bottom point of the trough.  Wavelength  refers to the length of a wave from one peak to the next.

Wavelength is directly related to the frequency of a given wave form.  Frequency  refers to the number of waves that pass a given point in a given time period and is often expressed in terms of  hertz (Hz) , or cycles per second. Longer wavelengths will have lower frequencies, and shorter wavelengths will have higher frequencies ( Figure 5.6 ).

Light Waves

The  visible spectrum  is the portion of the larger  electromagnetic spectrum  that we can see. As  Figure 5.7 shows, the electromagnetic spectrum encompasses all of the electromagnetic radiation that occurs in our environment and includes gamma rays, x-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves. The visible spectrum in humans is associated with wavelengths that range from 380 to 740 nm—a very small distance since a nanometer (nm) is one-billionth of a meter. Other species can detect other portions of the electromagnetic spectrum. For instance, honeybees can see light in the ultraviolet range (Wakakuwa, Stavenga, & Arikawa, 2007), and some snakes can detect infrared radiation in addition to more traditional visual light cues (Chen, Deng, Brauth, Ding, & Tang, 2012; Hartline, Kass, & Loop, 1978).

In humans, light wavelength is associated with the perception of color ( Figure 5.8 ). Within the visible spectrum, our experience of red is associated with longer wavelengths, greens are intermediate, and blues and violets are shorter in wavelength. (An easy way to remember this is the mnemonic ROYGBIV:  r ed,  o range,  y ellow,  g reen,  b lue,  i ndigo,  v iolet.) The amplitude of light waves is associated with our experience of brightness or intensity of color, with larger amplitudes appearing brighter.

Sound Waves

Like light waves, the physical properties of sound waves are associated with various aspects of our perception of sound. The frequency of a sound wave is associated with our perception of that sound’s  pitch . High-frequency sound waves are perceived as high-pitched sounds, while low-frequency sound waves are perceived as low-pitched sounds. The audible range of sound frequencies is between 20 and 20000 Hz, with the greatest sensitivity to those frequencies that fall in the middle of this range.

As was the case with the visible spectrum, other species show differences in their audible ranges. For instance, chickens have a very limited audible range, from 125 to 2000 Hz. Mice have an audible range from 1000 to 91000 Hz, and the beluga whale’s audible range is from 1000 to 123000 Hz. Our pet dogs and cats have audible ranges of about 70–45000 Hz and 45–64000 Hz, respectively (Strain, 2003).

The loudness of a given sound is closely associated with the amplitude of the sound wave. Higher amplitudes are associated with louder sounds. Loudness is measured in terms of  decibels (dB) , a logarithmic unit of sound intensity. A typical conversation would correlate with 60 dB; a rock concert might check-in at 120 dB ( Figure 5.9 ). A whisper 5 feet away or rustling leaves are at the low end of our hearing range; sounds like a window air conditioner, a normal conversation, and even heavy traffic or a vacuum cleaner are within a tolerable range. However, there is the potential for hearing damage from about 80 dB to 130 dB: These are sounds of a food processor, power lawnmower, heavy truck (25 feet away), subway train (20 feet away), live rock music, and a jackhammer. About one-third of all hearing loss is due to noise exposure, and the louder the sound, the shorter the exposure needed to cause hearing damage (Le, Straatman, Lea, & Westerberg, 2017). Listening to music through earbuds at maximum volume (around 100–105 decibels) can cause noise-induced hearing loss after 15 minutes of exposure. Although listening to music at maximum volume may not seem to cause damage, it increases the risk of age-related hearing loss (Kujawa & Liberman, 2006). The threshold for pain is about 130 dB, a jet plane taking off, or a revolver firing at close range (Dunkle, 1982).

Although wave amplitude is generally associated with loudness, there is some interaction between frequency and amplitude in our perception of loudness within the audible range. For example, a 10 Hz sound wave is inaudible no matter the amplitude of the wave. A 1000 Hz sound wave, on the other hand, would vary dramatically in terms of perceived loudness as the amplitude of the wave increased.

Of course, different musical instruments can play the same musical note at the same level of loudness, yet they still sound quite different. This is known as the timbre of a sound.  Timbre  refers to a sound’s purity, and it is affected by the complex interplay of frequency, amplitude, and timing of sound waves.

• Describe the basic anatomy of the visual system
• Discuss how rods and cones contribute to different aspects of vision
• Describe how monocular and binocular cues are used in the perception of depth

The visual system constructs a mental representation of the world around us ( Figure 5.10 ). This contributes to our ability to successfully navigate through physical space and interact with important individuals and objects in our environments. This section will provide an overview of the basic anatomy and function of the visual system. In addition, we will explore our ability to perceive color and depth.

Anatomy of the Visual System

The eye is the major sensory organ involved in  vision  ( Figure 5.11 ). Light waves are transmitted across the cornea and enter the eye through the pupil. The  cornea  is the transparent covering over the eye. It serves as a barrier between the inner eye and the outside world, and it is involved in focusing light waves that enter the eye. The  pupil  is the small opening in the eye through which light passes, and the size of the pupil can change as a function of light levels as well as emotional arousal. When light levels are low, the pupil will become dilated, or expanded, to allow more light to enter the eye. When light levels are high, the pupil will constrict, or become smaller, to reduce the amount of light that enters the eye. The pupil’s size is controlled by muscles that are connected to the  iris , which is the colored portion of the eye.

After passing through the pupil, light crosses the  lens , a curved, transparent structure that serves to provide additional focus. The lens is attached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects. In a normal-sighted individual, the lens will focus images perfectly on a small indentation in the back of the eye known as the  fovea , which is part of the  retina , the light-sensitive lining of the eye. The fovea contains densely packed specialized photoreceptor cells ( Figure 5.12 ). These  photoreceptor  cells, known as cones, are light-detecting cells. The  cones  are specialized types of photoreceptors that work best in bright light conditions. Cones are very sensitive to acute detail and provide tremendous spatial resolution. They also are directly involved in our ability to perceive color.

While cones are concentrated in the fovea, where images tend to be focused, rods, another type of photoreceptor, are located throughout the remainder of the retina.  Rods  are specialized photoreceptors that work well in low light conditions, and while they lack the spatial resolution and color function of the cones, they are involved in our vision in dimly lit environments as well as in our perception of movement on the periphery of our visual field.

We have all experienced the different sensitivities of rods and cones when making the transition from a brightly lit environment to a dimly lit environment. Imagine going to see a blockbuster movie on a clear summer day. As you walk from the brightly lit lobby into the dark theater, you notice that you immediately have difficulty seeing much of anything. After a few minutes, you begin to adjust to the darkness and can see the interior of the theater. In the bright environment, your vision was dominated primarily by cone activity. As you move to the dark environment, rod activity dominates, but there is a delay in transitioning between the phases. If your rods do not transform light into nerve impulses as easily and efficiently as they should, you will have difficulty seeing in dim light, a condition known as night blindness.

Rods and cones are connected (via several interneurons) to retinal ganglion cells. Axons from the retinal ganglion cells converge and exit through the back of the eye to form the  optic nerve . The optic nerve carries visual information from the retina to the brain. There is a point in the visual field called the  blind spot : Even when light from a small object is focused on the blind spot, we do not see it. We are not consciously aware of our blind spots for two reasons: First, each eye gets a slightly different view of the visual field; therefore, the blind spots do not overlap. Second, our visual system fills in the blind spot so that although we cannot respond to visual information that occurs in that portion of the visual field, we are also not aware that information is missing.

The optic nerve from each eye merges just below the brain at a point called the  optic chiasm . As  Figure 5.13  shows, the optic chiasm is an X-shaped structure that sits just below the cerebral cortex at the front of the brain. At the point of the optic chiasm, information from the right visual field (which comes from both eyes) is sent to the left side of the brain, and information from the left visual field is sent to the right side of the brain.

Once inside the brain, visual information is sent via a number of structures to the occipital lobe at the back of the brain for processing. Visual information might be processed in parallel pathways which can generally be described as the “what pathway” and the “where/how” pathway. The “what pathway” is involved in object recognition and identification, while the “where/how pathway” is involved with location in space and how one might interact with a particular visual stimulus (Milner & Goodale, 2008; Ungerleider & Haxby, 1994). For example, when you see a ball rolling down the street, the “what pathway” identifies what the object is, and the “where/how pathway” identifies its location or movement in space.

WHAT DO YOU THINK? The Ethics of Research Using Animals

David Hubel and Torsten Wiesel were awarded the Nobel Prize in Medicine in 1981 for their research on the visual system. They collaborated for more than twenty years and made significant discoveries about the neurology of visual perception (Hubel & Wiesel, 1959, 1962, 1963, 1970; Wiesel & Hubel, 1963). They studied animals, mostly cats and monkeys. Although they used several techniques, they did considerable single-unit recordings, during which tiny electrodes were inserted in the animal’s brain to determine when a single cell was activated. Among their many discoveries, they found that specific brain cells respond to lines with specific orientations (called ocular dominance), and they mapped the way those cells are arranged in areas of the visual cortex known as columns and hypercolumns.

In some of their research, they sutured one eye of newborn kittens closed and followed the development of the kittens’ vision. They discovered there was a critical period of development for vision. If kittens were deprived of input from one eye, other areas of their visual cortex filled in the area that was normally used by the eye that was sewn closed. In other words, neural connections that exist at birth can be lost if they are deprived of sensory input.

What do you think about sewing a kitten’s eye closed for research? To many animal advocates, this would seem brutal, abusive, and unethical. What if you could do research that would help ensure babies and children born with certain conditions could develop normal vision instead of becoming blind? Would you want that research done? Would you conduct that research, even if it meant causing some harm to cats? Would you think the same way if you were the parent of such a child? What if you worked at the animal shelter?

Like virtually every other industrialized nation, the United States permits medical experimentation on animals, with few limitations (assuming sufficient scientific justification). The goal of any laws that exist is not to ban such tests but rather to limit unnecessary animal suffering by establishing standards for the humane treatment and housing of animals in laboratories.

As explained by Stephen Latham, the director of the Interdisciplinary Center for Bioethics at Yale (2012), possible legal and regulatory approaches to animal testing vary on a continuum from strong government regulation and monitoring of all experimentation at one end, to a self-regulated approach that depends on the ethics of the researchers at the other end. The United Kingdom has the most significant regulatory scheme, whereas Japan uses the self-regulation approach. The U.S. approach is somewhere in the middle, the result of a gradual blending of the two approaches.

There is no question that medical research is a valuable and important practice. The question is whether the use of animals is a necessary or even best practice for producing the most reliable results. Alternatives include the use of patient-drug databases, virtual drug trials, computer models and simulations, and noninvasive imaging techniques such as magnetic resonance imaging and computed tomography scans (“Animals in Science/Alternatives,” n.d.). Other techniques, such as microdosing, use humans not as test animals but as a means to improve the accuracy and reliability of test results. In vitro methods based on human cell and tissue cultures, stem cells, and genetic testing methods are also increasingly available.

Today, at the local level, any facility that uses animals and receives federal funding must have an Institutional Animal Care and Use Committee (IACUC) that ensures that the NIH guidelines are being followed. The IACUC must include researchers, administrators, a veterinarian, and at least one person with no ties to the institution: that is, a concerned citizen. This committee also performs inspections of laboratories and protocols.

Color and Depth Perception

We do not see the world in black and white; neither do we see it as two-dimensional (2-D) or flat (just height and width, no depth). Let’s look at how color vision works and how we perceive three dimensions (height, width, and depth).

Color Vision

Normal-sighted individuals have three different types of cones that mediate  color vision . Each of these cone types is maximally sensitive to a slightly different wavelength of light. According to the  trichromatic theory of color vision , shown in  Figure 5.14 , all colors in the spectrum can be produced by combining red, green, and blue. The three types of cones are each receptive to one of the colors.

CONNECT THE CONCEPTS

Colorblindness: a personal story.

Several years ago, I dressed to go to a public function and walked into the kitchen where my 7-year-old daughter sat. She looked up at me, and in her most stern voice, said, “You can’t wear that.” I asked, “Why not?” and she informed me the colors of my clothes did not match. She had complained frequently that I was bad at matching my shirts, pants, and ties, but this time, she sounded especially alarmed. As a single father with no one else to ask at home, I drove us to the nearest convenience store and asked the store clerk if my clothes matched. She said my pants were a bright green color, my shirt was a reddish-orange, and my tie was brown. She looked at me quizzically and said, “No way do your clothes match.” Over the next few days, I started asking my coworkers and friends if my clothes matched. After several days of being told that my coworkers just thought I had “a really unique style,” I made an appointment with an eye doctor and was tested ( Figure 5.15 ). It was then that I found out that I was colorblind. I cannot differentiate between most greens, browns, and reds. Fortunately, other than unknowingly being badly dressed, my colorblindness rarely harms my day-to-day life.

Some forms of color deficiency are rare. Seeing in grayscale (only shades of black and white) is extremely rare, and people who do so only have rods, which means they have very low visual acuity and cannot see very well. The most common X-linked inherited abnormality is red-green color blindness (Birch, 2012). Approximately 8% of males of European Caucasian descent, 5% of Asian males, 4% of African males, and less than 2% of indigenous American males, Australian males, and Polynesian males have red-green color deficiency (Birch, 2012). Comparatively, only about 0.4% of females of European Caucasian descent have red-green color deficiency (Birch, 2012).

The trichromatic theory of color vision is not the only theory—another major theory of color vision is known as the  opponent-process theory . According to this theory, color is coded in opponent pairs: black-white, yellow-blue, and green-red. The basic idea is that some cells of the visual system are excited by one of the opponent colors and inhibited by the other. So, a cell that was excited by wavelengths associated with green would be inhibited by wavelengths associated with red, and vice versa. One of the implications of opponent processing is that we do not experience greenish-reds or yellowish-blues as colors. Another implication is that this leads to the experience of negative afterimages. An  afterimage describes the continuation of a visual sensation after the removal of the stimulus. For example, when you stare briefly at the sun and then look away from it, you may still perceive a spot of light although the stimulus (the sun) has been removed. When color is involved in the stimulus, the color pairings identified in the opponent-process theory lead to a negative afterimage. You can test this concept using the flag in  Figure 5.16 .

But these two theories—the trichromatic theory of color vision and the opponent-process theory—are not mutually exclusive. Research has shown that they just apply to different levels of the nervous system. For visual processing on the retina, the trichromatic theory applies: the cones are responsive to three different wavelengths that represent red, blue, and green. But once the signal moves past the retina on its way to the brain, the cells respond in a way consistent with opponent-process theory (Land, 1959; Kaiser, 1997).

Depth Perception

Our ability to perceive spatial relationships in three-dimensional (3-D) space is known as  depth perception . With depth perception, we can describe things as being in front, behind, above, below, or to the side of other things.

Our world is three-dimensional, so it makes sense that our mental representation of the world has three-dimensional properties. We use a variety of cues in a visual scene to establish our sense of depth. Some of these are  binocular   cues , which means that they rely on the use of both eyes. One example of a binocular depth cue is  binocular disparity , the slightly different view of the world that each of our eyes receives. To experience this slightly different view, do this simple exercise: extend your arm fully and extend one of your fingers and focus on that finger. Now, close your left eye without moving your head, then open your left eye and close your right eye without moving your head. You will notice that your finger seems to shift as you alternate between the two eyes because of the slightly different view each eye has of your finger.

A 3-D movie works on the same principle: the special glasses you wear allow the two slightly different images projected onto the screen to be seen separately by your left and your right eye. As your brain processes these images, you have the illusion that the leaping animal or running person is coming right toward you.

Although we rely on binocular cues to experience depth in our 3-D world, we can also perceive depth in 2-D arrays. Think about all the paintings and photographs you have seen. Generally, you pick up on depth in these images even though the visual stimulus is 2-D. When we do this, we are relying on a number of  monocular cues , or cues that require only one eye. If you think you can’t see depth with one eye, note that you don’t bump into things when using only one eye while walking—and, in fact, we have more monocular cues than binocular cues.

An example of a monocular cue would be what is known as linear perspective.  Linear perspective  refers to the fact that we perceive depth when we see two parallel lines that seem to converge in an image ( Figure 5.17 ). Some other monocular depth cues are interposition, the partial overlap of objects, and the relative size and closeness of images to the horizon.

DIG DEEPER: Stereoblindness

Bruce Bridgeman was born with an extreme case of lazy eye that resulted in him being stereoblind, or unable to respond to binocular cues of depth. He relied heavily on monocular depth cues, but he never had a true appreciation of the 3-D nature of the world around him. This all changed one night in 2012 while Bruce was seeing a movie with his wife.

The movie the couple was going to see was shot in 3-D, and even though he thought it was a waste of money, Bruce paid for the 3-D glasses when he purchased his ticket. As soon as the film began, Bruce put on the glasses and experienced something completely new. For the first time in his life, he appreciated the true depth of the world around him. Remarkably, his ability to perceive depth persisted outside of the movie theater.

There are cells in the nervous system that respond to binocular depth cues. Normally, these cells require activation during early development in order to persist, so experts familiar with Bruce’s case (and others like his) assume that at some point in his development, Bruce must have experienced at least a fleeting moment of binocular vision. It was enough to ensure the survival of the cells in the visual system tuned to binocular cues. The mystery now is why it took Bruce nearly 70 years to have these cells activated (Peck, 2012).

• Describe the basic anatomy and function of the auditory system
• Explain how we encode and perceive pitch
• Discuss how we localize sound

Our auditory system converts pressure waves into meaningful sounds. This translates into our ability to hear the sounds of nature, to appreciate the beauty of music, and to communicate with one another through spoken language. This section will provide an overview of the basic anatomy and function of the auditory system. It will include a discussion of how the sensory stimulus is translated into neural impulses, where in the brain that information is processed, how we perceive pitch, and how we know where sound is coming from.

Anatomy of the Auditory System

The ear can be separated into multiple sections. The outer ear includes the  pinna , which is the visible part of the ear that protrudes from our heads, the auditory canal, and the  tympanic membrane , or eardrum. The middle ear contains three tiny bones known as the  ossicles , which are named the  malleus  (or hammer),  incus  (or anvil), and the  stapes  (or stirrup). The inner ear contains the semi-circular canals, which are involved in balance and movement (the vestibular sense), and the cochlea. The  cochlea  is a fluid-filled, snail-shaped structure that contains the sensory receptor cells (hair cells) of the auditory system ( Figure 5.18 ).

Sound waves travel along the auditory canal and strike the tympanic membrane, causing it to vibrate. This vibration results in the movement of the three ossicles. As the ossicles move, the stapes presses into a thin membrane of the cochlea known as the oval window. As the stapes presses into the oval window, the fluid inside the cochlea begins to move, which in turn stimulates hair cells , which are auditory receptor cells of the inner ear embedded in the basilar membrane. The  basilar membrane  is a thin strip of tissue within the cochlea.

The activation of hair cells is a mechanical process: the stimulation of the hair cell ultimately leads to activation of the cell. As hair cells become activated, they generate neural impulses that travel along the auditory nerve to the brain. Auditory information is shuttled to the inferior colliculus, the medial geniculate nucleus of the thalamus, and finally to the auditory cortex in the temporal lobe of the brain for processing. Like the visual system, there is also evidence suggesting that information about auditory recognition and localization is processed in parallel streams (Rauschecker & Tian, 2000; Renier et al., 2009).

Pitch Perception

Different frequencies of sound waves are associated with differences in our perception of the pitch of those sounds. Low-frequency sounds are lower-pitched, and high-frequency sounds are higher pitched. How does the auditory system differentiate among various pitches?

Several theories have been proposed to account for pitch perception. We’ll discuss two of them here: temporal theory and place theory. The  temporal theory  of pitch perception asserts that frequency is coded by the activity level of a sensory neuron. This would mean that a given hair cell would fire action potentials related to the frequency of the sound wave. While this is a very intuitive explanation, we detect such a broad range of frequencies (20–20,000 Hz) that the frequency of action potentials fired by hair cells cannot account for the entire range. Because of properties related to sodium channels on the neuronal membrane that are involved in action potentials, there is a point at which a cell cannot fire any faster (Shamma, 2001).

The  place theory of pitch perception suggests that different portions of the basilar membrane are sensitive to sounds of different frequencies. More specifically, the base of the basilar membrane responds best to high frequencies and the tip of the basilar membrane responds best to low frequencies. Therefore, hair cells that are in the base portion would be labeled as high-pitch receptors, while those in the tip of the basilar membrane would be labeled as low-pitch receptors (Shamma, 2001).

In reality, both theories explain different aspects of pitch perception. At frequencies up to about 4000 Hz, it is clear that both the rate of action potentials and place contribute to our perception of pitch. However, much higher frequency sounds can only be encoded using place cues (Shamma, 2001).

Sound Localization

The ability to locate sound in our environments is an important part of  hearing . Localizing sound could be considered similar to the way that we perceive depth in our visual fields. Like the monocular and binocular cues that provided information about depth, the auditory system uses both  monaural  (one-eared) and  binaural  (two-eared) cues to localize sound.

Each pinna interacts with incoming sound waves differently, depending on the sound’s source relative to our bodies. This interaction provides a monaural cue that is helpful in locating sounds that occur above or below and in front of or behind us. The sound waves received by your two ears from sounds that come from directly above, below, in front, or behind you would be identical; therefore, monaural cues are essential (Grothe, Pecka, & McAlpine, 2010).

Binaural cues, on the other hand, provide information on the location of a sound along a horizontal axis by relying on differences in patterns of vibration of the eardrum between our two ears. If a sound comes from an off-center location, it creates two types of binaural cues: interaural level differences and interaural timing differences.  Interaural level difference  refers to the fact that a sound coming from the right side of your body is more intense at your right ear than at your left ear because of the attenuation of the sound wave as it passes through your head.  Interaural timing difference  refers to the small difference in the time at which a given sound wave arrives at each ear ( Figure 5.19 ). Certain brain areas monitor these differences to construct where along a horizontal axis a sound originates (Grothe et al., 2010).

Hearing Loss

Deafness  is the partial or complete inability to hear. Some people are born without hearing, which is known as  congenital deafness . Other people suffer from  conductive hearing loss , which is due to a problem delivering sound energy to the cochlea. Causes for conductive hearing loss include blockage of the ear canal, a hole in the tympanic membrane, problems with the ossicles, or fluid in the space between the eardrum and cochlea. Another group of people suffer from sensorineural hearing loss, which is the most common form of hearing loss. Sensorineural hearing loss can be caused by many factors, such as aging, head or acoustic trauma, infections and diseases (such as measles or mumps), medications, environmental effects such as noise exposure (noise-induced hearing loss, as shown in  Figure 5.20 ), tumors, and toxins (such as those found in certain solvents and metals).

Given the mechanical nature by which the sound wave stimulus is transmitted from the eardrum through the ossicles to the oval window of the cochlea, some degree of hearing loss is inevitable. With conductive hearing loss, hearing problems are associated with a failure in the vibration of the eardrum and/or movement of the ossicles. These problems are often dealt with through devices like hearing aids that amplify incoming sound waves to make the vibration of the eardrum and movement of the ossicles more likely to occur.

When the hearing problem is associated with a failure to transmit neural signals from the cochlea to the brain, it is called  sensorineural hearing loss . One disease that results in sensorineural hearing loss is  Ménière’s disease . Although not well understood, Ménière’s disease results in a degeneration of inner ear structures that can lead to hearing loss, tinnitus (constant ringing or buzzing),  vertigo  (a sense of spinning), and an increase in pressure within the inner ear (Semaan & Megerian, 2011). This kind of loss cannot be treated with hearing aids, but some individuals might be candidates for a cochlear implant as a treatment option.  Cochlear implants  are electronic devices that consist of a microphone, a speech processor, and an electrode array. The device receives incoming sound information and directly stimulates the auditory nerve to transmit information to the brain.

WHAT DO YOU THINK? Deaf Culture

In the United States and other places around the world, deaf people have their own language, schools, and customs. This is called  deaf culture . In the United States, deaf individuals often communicate using American Sign Language (ASL); ASL has no verbal component and is based entirely on visual signs and gestures. The primary mode of communication is signing. One of the values of deaf culture is to continue traditions like using sign language rather than teaching deaf children to try to speak, read lips, or have cochlear implant surgery.

When a child is diagnosed as deaf, parents have difficult decisions to make. Should the child be enrolled in mainstream schools and taught to verbalize and read lips? Or should the child be sent to a school for deaf children to learn ASL and have significant exposure to deaf culture? Do you think there might be differences in the way that parents approach these decisions depending on whether or not they are also deaf?

• Describe the basic functions of the chemical senses
• Explain the basic functions of the somatosensory, nociceptive, and thermoceptive sensory systems
• Describe the basic functions of the vestibular, proprioceptive, and kinesthetic sensory systems

Vision and hearing have received an incredible amount of attention from researchers over the years. While there is still much to be learned about how these sensory systems work, we have a much better understanding of them than our other sensory modalities. In this section, we will explore our chemical senses (taste and smell) and our body senses (touch, temperature, pain, balance, and body position).

The Chemical Senses

Taste (gustation) and  smell  (olfaction) are called chemical senses because both have sensory receptors that respond to molecules in the food we eat or in the air we breathe. There is a pronounced interaction between our chemical senses. For example, when we describe the flavor of a given food, we are really referring to both gustatory and olfactory properties of the food working in combination.

Taste (Gustation)

You have learned since elementary school that there are four basic groupings of taste: sweet, salty, sour, and bitter. Research demonstrates, however, that we have at least six  taste  groupings. Umami is our fifth taste.  Umami  is actually a Japanese word that roughly translates to yummy, and it is associated with a taste for monosodium glutamate (Kinnamon & Vandenbeuch, 2009). There is also a growing body of experimental evidence suggesting that we possess a taste for the fatty content of a given food (Mizushige, Inoue, & Fushiki, 2007).

Molecules from the food and beverages we consume dissolve in our saliva and interact with taste receptors on our tongue and in our mouth and throat.  Taste buds  are formed by groupings of taste receptor cells with hair-like extensions that protrude into the central pore of the taste bud ( Figure 5.21 ). Taste buds have a life cycle of ten days to two weeks, so even destroying some by burning your tongue won’t have any long-term effect; they just grow right back. Taste molecules bind to receptors on this extension and cause chemical changes within the sensory cell that result in neural impulses being transmitted to the brain via different nerves, depending on where the receptor is located. Taste information is transmitted to the medulla, thalamus, and limbic system, and to the gustatory cortex, which is tucked underneath the overlap between the frontal and temporal lobes (Maffei, Haley, & Fontanini, 2012; Roper, 2013).

Smell (Olfaction)

Olfactory receptor  cells are located in a mucous membrane at the top of the nose. Small hair-like extensions from these receptors serve as the sites for odor molecules dissolved in the mucus to interact with chemical receptors located on these extensions ( Figure 5.22 ). Once an odor molecule has bound a given receptor, chemical changes within the cell result in signals being sent to the  olfactory bulb : a bulb-like structure at the tip of the frontal lobe where the olfactory nerves begin. From the olfactory bulb, information is sent to regions of the limbic system and to the primary olfactory cortex, which is located very near the gustatory cortex (Lodovichi & Belluscio, 2012; Spors et al., 2013).

There is tremendous variation in the sensitivity of the olfactory systems of different species. We often think of dogs as having far superior olfactory systems than our own, and indeed, dogs can do some remarkable things with their noses. There is some evidence to suggest that dogs can “smell” dangerous drops in blood glucose levels as well as cancerous tumors (Wells, 2010). Dogs’ extraordinary olfactory abilities may be due to the increased number of functional genes for olfactory receptors (between 800 and 1200), compared to the fewer than 400 observed in humans and other primates (Niimura & Nei, 2007).

Many species respond to chemical messages, known as  pheromones , sent by another individual (Wysocki & Preti, 2004). Pheromonal communication often involves providing information about the reproductive status of a potential mate. So, for example, when a female rat is ready to mate, she secretes pheromonal signals that draw attention from nearby male rats. Pheromonal activation is actually an important component in eliciting sexual behavior in the male rat (Furlow, 1996, 2012; Purvis & Haynes, 1972; Sachs, 1997). There has also been a good deal of research (and controversy) about pheromones in humans (Comfort, 1971; Russell, 1976; Wolfgang-Kimball, 1992; Weller, 1998).

Touch, Thermoception, and Nociception

A number of receptors are distributed throughout the skin to respond to various touch-related stimuli ( Figure 5.23 ). These receptors include Meissner’s corpuscles, Pacinian corpuscles, Merkel’s disks, and Ruffini corpuscles.  Meissner’s corpuscles  respond to pressure and lower frequency vibrations, and  Pacinian corpuscles  detect transient pressure and higher frequency vibrations.  Merkel’s disks  respond to light pressure, while  Ruffini corpuscles  detect stretch (Abraira & Ginty, 2013).

In addition to the receptors located in the skin, there are also a number of free nerve endings that serve sensory functions. These nerve endings respond to a variety of different types of touch-related stimuli and serve as sensory receptors for both  thermoception  (temperature perception) and  nociception (a signal indicating potential harm and maybe pain) (Garland, 2012; Petho & Reeh, 2012; Spray, 1986). Sensory information collected from the receptors and free nerve endings travels up the spinal cord and is transmitted to regions of the medulla, thalamus, and ultimately to the somatosensory cortex, which is located in the postcentral gyrus of the parietal lobe.

Pain Perception

Pain is an unpleasant experience that involves both physical and psychological components. Feeling pain is quite adaptive because it makes us aware of an injury, and it motivates us to remove ourselves from the cause of that injury. In addition, pain also makes us less likely to suffer additional injury because we will be gentler with our injured body parts.

Generally speaking, pain can be considered to be neuropathic or inflammatory in nature. Pain that signals some type of tissue damage is known as  inflammatory pain . In some situations, pain results from damage to neurons of either the peripheral or central nervous system. As a result, pain signals that are sent to the brain get exaggerated. This type of pain is known as  neuropathic pain . Multiple treatment options for pain relief range from relaxation therapy to the use of analgesic medications to deep brain stimulation. The most effective treatment option for a given individual will depend on a number of considerations, including the severity and persistence of the pain and any medical/psychological conditions.

Some individuals are born without the ability to feel pain. This very rare genetic disorder is known as  congenital insensitivity to pain  (or  congenital analgesia ). While those with congenital analgesia can detect differences in temperature and pressure, they cannot experience pain. As a result, they often suffer significant injuries. Young children have serious mouth and tongue injuries because they have bitten themselves repeatedly. Not surprisingly, individuals suffering from this disorder have much shorter life expectancies due to their injuries and secondary infections of injured sites (U.S. National Library of Medicine, 2013).

The Vestibular Sense, Proprioception, and Kinesthesia

The  vestibular sense  contributes to our ability to maintain balance and body posture. As  Figure 5.24 shows, the major sensory organs (utricle, saccule, and the three semicircular canals) of this system are located next to the cochlea in the inner ear. The vestibular organs are fluid-filled and have hair cells, similar to the ones found in the auditory system, which respond to the movement of the head and gravitational forces. When these hair cells are stimulated, they send signals to the brain via the vestibular nerve. Although we may not be consciously aware of our vestibular system’s sensory information under normal circumstances, its importance is apparent when we experience motion sickness and/or dizziness related to infections of the inner ear (Khan & Chang, 2013).

In addition to maintaining balance, the vestibular system collects information critical for controlling movement and the reflexes that move various parts of our bodies to compensate for changes in body position. Therefore, both  proprioception  (perception of body position) and  kinesthesia  (perception of the body’s movement through space) interact with information provided by the vestibular system.

These sensory systems also gather information from receptors that respond to stretch and tension in muscles, joints, skin, and tendons (Lackner & DiZio, 2005; Proske, 2006; Proske & Gandevia, 2012). Proprioceptive and kinesthetic information travels to the brain via the spinal column. Several cortical regions in addition to the cerebellum receive information from and send information to the sensory organs of the proprioceptive and kinesthetic systems.

• Explain the figure-ground relationship
• Define Gestalt principles of grouping
• Describe how perceptual set is influenced by an individual’s characteristics and mental state

In the early part of the 20th century, Max Wertheimer published a paper demonstrating that individuals perceived motion in rapidly flickering static images—an insight that came to him as he used a child’s toy tachistoscope. Wertheimer, and his assistants Wolfgang Köhler and Kurt Koffka, who later became his partners, believed that perception involved more than simply combining sensory stimuli. This belief led to a new movement within the field of psychology known as  Gestalt psychology . The word  gestalt  literally means form or pattern, but its use reflects the idea that the whole is different from the sum of its parts. In other words, the brain creates a perception that is more than simply the sum of available sensory inputs, and it does so in predictable ways. Gestalt psychologists translated these predictable ways into principles by which we organize sensory information. As a result, Gestalt psychology has been extremely influential in the area of sensation and perception (Rock & Palmer, 1990).

One Gestalt principle is the  figure-ground relationship . According to this principle, we tend to segment our visual world into figure and ground. Figure is the object or person that is the focus of the visual field, while the ground is the background. As  Figure 5.25  shows, our perception can vary tremendously, depending on what is perceived as figure and what is perceived as ground. Presumably, our ability to interpret sensory information depends on what we label as figure and what we label as ground in any particular case, although this assumption has been called into question (Peterson & Gibson, 1994; Vecera & O’Reilly, 1998).

Another Gestalt principle for organizing sensory stimuli into meaningful perception is  proximity . This principle asserts that things that are close to one another tend to be grouped together, as  Figure 5.26  illustrates.

How we read something provides another illustration of the proximity concept. For example, we read this sentence like this, notl iket hiso rt hat. We group the letters of a given word together because there are no spaces between the letters, and we perceive words because there are spaces between each word. Here are some more examples: Cany oum akes enseo ft hiss entence? What doth es e wor dsmea n?

We might also use the principle of  similarity  to group things in our visual fields. According to this principle, things that are alike tend to be grouped together ( Figure 5.27 ). For example, when watching a football game, we tend to group individuals based on the colors of their uniforms. When watching an offensive drive, we can get a sense of the two teams simply by grouping along this dimension.

Two additional Gestalt principles are the law of  continuity  (or  good continuation ) and  closure . The law of continuity suggests that we are more likely to perceive continuous, smooth flowing lines rather than jagged, broken lines ( Figure 5.28 ). The  principle of closure  states that we organize our perceptions into complete objects rather than as a series of parts ( Figure 5.29 ).

According to Gestalt theorists,  pattern perception , or our ability to discriminate among different figures and shapes, occurs by following the principles described above. You probably feel fairly certain that your perception accurately matches the real world, but this is not always the case. Our perceptions are based on  perceptual hypotheses : educated guesses that we make while interpreting sensory information. These hypotheses are informed by a number of factors, including our personalities, experiences, and expectations. We use these hypotheses to generate our perceptual set. For instance, research has demonstrated that those who are given verbal priming produce a biased interpretation of complex ambiguous figures (Goolkasian & Woodbury, 2010).

Case Study in Sensation and Perception

In 2011, the  New York Times  published a feature story on Krista and Tatiana Hogan, Canadian twin girls. These particular twins are unique because Krista and Tatiana are conjoined twins, connected at the head. There is evidence that the two girls are connected in a part of the brain called the thalamus, which is a major sensory relay center. Most incoming sensory information is sent through the thalamus before reaching higher regions of the cerebral cortex for processing.

The implications of this potential connection mean that it might be possible for one twin to experience the sensations of the other twin. For instance, if Krista is watching a particularly funny television program, Tatiana might smile or laugh even if she is not watching the program. This particular possibility has piqued the interest of many neuroscientists who seek to understand how the brain uses sensory information.

These twins represent an enormous resource in the study of the brain, and since their condition is very rare, it is likely that as long as their family agrees, scientists will follow these girls very closely throughout their lives to gain as much information as possible (Dominus, 2011).

Over time, it has become clear that while Krista and Tatiana share some sensory experiences and motor control, they remain two distinct individuals, which provides tremendous insight into researchers interested in the mind and the brain (Egnor, 2017).

In observational research, scientists are conducting a  clinical  or  case study  when they focus on one person or just a few individuals. Indeed, some scientists spend their entire careers studying just 10–20 individuals. Why would they do this? Obviously, when they focus their attention on a very small number of people, they can gain a tremendous amount of insight into those cases. The richness of information that is collected in clinical or case studies is unmatched by any other single research method. This allows the researcher to have a very deep understanding of the individuals and the particular phenomenon being studied.

If clinical or case studies provide so much information, why are they not more frequent among researchers? As it turns out, the major benefit of this particular approach is also a weakness. As mentioned earlier, this approach is often used when studying individuals who are interesting to researchers because they have a rare characteristic. Therefore, the individuals who serve as the focus of case studies are not like most other people. If scientists ultimately want to explain all behavior, focusing attention on such a special group of people can make it difficult to generalize any observations to the larger population as a whole.  Generalizing  refers to the ability to apply the findings of a particular research project to larger segments of society. Again, case studies provide enormous amounts of information, but since the cases are so specific, the potential to apply what’s learned to the average person may be very limited.

Additional Supplemental Resources

• Users can explore various aspects of motion detection.
• Is seeing believing?  This page illustrates through several illusions that our visual perception cannot always be trusted.
• The International Association for the Study of Pain brings together scientists, clinicians, health-care providers, and policymakers to stimulate and support the study of pain and translate that knowledge into improved pain relief worldwide.
• Watch this video very closely it is a great example of change blindness and selective attention. Closed captioning available.
• Description of a famous ambiguous figure. Closed captioning available.
• Video footage of classic change blindness research. Closed captioning available.
• Animated demonstration of a famous ambiguous figure.
• How does color work? In this Ted-Ed video, you’ll learn about the properties of color, and how frequency plays a role in our perception of color.  A variety of discussion and assessment questions are included with the video (free registration is required to access the questions). Closed captioning available.
• Watch this Ted-Ed video to learn more about the ways in which our eyes and brain are tricked by optical illusions.  What does this tell us about the inner-workings of our brains?  A variety of discussion and assessment questions are included with the video (free registration is required to access the questions). Closed captioning available.
• How does the ear work? In this short video clip, you’ll learn about the inner workings of the human ear. Closed captioning available.

The mysterious science of pain – Joshua W. Pate  

• Explore the biological and psychological factors that influence how we experience pain and how our nervous system reactions to harmful stimuli.  Joshua W. Pate investigates the experience of pain.
• This video on the sensation and perception covers topics including absolute threshold, Weber’s Law, signal detection theory, and vision. Closed captioning available.
• This video on the homunculus covers the senses of hearing, taste, smell, and touch. Closed captioning available.
• This video on perceiving includes information on form perception, depth perception, and monocular cues. Closed captioning available.

Access for free at  https://openstax.org/books/psychology-2e/pages/1-introduction

Introduction to Psychology Copyright © 2020 by Julie Lazzara is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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Senses Experiments

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 Here are some senses experiments and activities that we have tried and some others that we have on the list to complete.

Sense Of Hearing

We hear because sound waves travel through the air until they hit the ear drum. The sound waves vibrate the eardrum, which in turn, vibrates the bones of the middle ear. These vibrations are transferred to the cochlea, located in the inner ear. The cochlea translates those vibrations into stimuli that the ocular nerve can send to the brain.

It all starts with sound waves and the eardrum. To demonstrate how sound can actually be a physical force, you can do this simple experiment.

Eardrum Experiment

You’ll need:

• plastic wrap
• 20 or so uncooked rice grains
• cookie sheet or metal baking pan

Stretch the plastic wrap over the bowl tightly. This is your eardrum. Place 20 or so rice grains on the tightened plastic wrap. Hold the pan or cookie sheet close to the blow, but not touching. Bang on the pan with your hand or large spoon making a loud noise. Watch the rice. It should jump each time you bang on the pan. The sound waves created should vibrate the plastic wrap making the rice move. Sound can be a physical force.

More on Hearing

The Science of Hearing   Video

How the Ears Work   Video

Operation Ouch- The Eardrum   Video

Journey of Sound to the Brain   Video

Sense Of Touch

The sense of touch can be used all over the body. We have touch receptors just under our skin that give us lots of information. If you want to test someone’s sense of touch, make a touch box . Get a box with a lid and cut a hole in the side just large enough to fit your hand. Choose various, safe objects of various textures that will fit easily into the box. (cotton ball, rock, rubber ball, tree bark, a sponge, an apple…) Place one object in the box at a time, but don’t let the other person see. Allow the person to put their hand through the hole and try and guess what they are feeling.

More on Touch

Touch Experiments

How your Skin Senses

Sense of Touch Experiments

Sense of Touch Video

Sensation (Touch, Pain, and Temperature) Video

Sense Of Sight

Our eyes work together to allow us to see. To test how they work together you will need:

• a paper cup

Set the paper cup on a table about 2 feet in front of your subject who should be sitting in a chair at the table. Have the person cover one eye. Hold a penny in your hand about 1.5 feet above the table. Slowly move your hand in front of, in back of and to the sides of the paper cup. When, the person thinks you are above the cup, have them say “Drop”.

Drop the penny. Do this again with one eye covered and then with both eyes open. Which way is easier? Your eyes work together for proper depth perception. Using both eyes should be easier to determine when the penny was above the cup.

Related Post: Sense of sight lesson and free printable

More on Sight

Sense of Sight Activities

Depth Perception Activity

20/20 Vision Activity

Sense of Sight- How it Works Video

Human Eye Video

What is Color Blindness Video

Vision: Crash Course A&P Video

How We See Color Video

The Visual System Video

Visual Perception   Video

Sense Of Taste

The sense of taste comes from taste receptors on your tongue. However, your taste is, also, influenced by your sense of smell. To test this you will need lifesaver candies of various flavors and a partner. Have your partner hold his or her nose. Give the lifesavers one at a time to your partner. Don’t let them see what color it is. Have them try to guess the flavor. Record the answers. Do the experiment again but with the nose unplugged. Which way made it easier to determine the flavor?

More On Taste

Sense of Taste Experiment

Test Your Taste

Test Your Taste Buds

Taste Testing Without Your Sense of Smell

The Sense of Taste   Video

Operation Ouch: The Tongue   Video

Taste Video

2-Minute Neuroscience: Taste   Video

Sense Of Smell

We had fun testing our sense of smell this week. Using small bowls with various odor-producing substances in our house and a blindfold, we conducted our smell test.

The bowls were held under the blindfolded subject’s nose. The subject tried to guess what they were smelling. We used hand soap, hot sauce, pickle juice and an orange.

More on Smell

Smell Experiments

Sense of Smell Experiments

Sniffing Out the Science of Smell

How Good is Your Sense of Smell?

The Sense of Smell   Video

How Your Nose Works   Video

How to Master Your Sense of Smell Video

Olfactory: Neuroanatomy Video Lab – Brain Dissections    Video

2-Minute Neuroscience: Olfaction Video

More Science Saturday

Don’t miss Science Saturday at MeetPenny.com . Get lots more sense study inspiration and ideas!

▲ Interactive Sensation Laboratory Exercises (ISLE) John H. Krantz & Bennett L. Schwartz

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Exploring Sensory Neuroscience Through Experience and Experiment

Many phenomena that we take for granted are illusions — color and motion on a TV or computer monitor, for example, or the impression of space in a stereo music recording. Even the stable image that we perceive when looking directly at the real world is illusory. One of the important lessons from sensory neuroscience is that our perception of the world is constructed rather than received. Sensory illusions effectively capture student interest, but how do you then move on to substantive discussion of neuroscience? This article illustrates several illusions, attempts to connect them to neuroscience, and shows how students can explore and experiment with them. Even when (as is often the case) there is no agreed-upon mechanistic explanation for an illusion, students can form hypotheses and test them by manipulating stimuli and measuring their effects. In effect, students can experiment with illusions using themselves as subjects.

In addition to their immediate aesthetic appeal, illusions have historically been used to investigate mechanisms of perception. While the success of this approach has been mixed — many illusions do not have accepted explanations or turn out to be more complex than initially thought — illusions are still powerful teaching tools. Not only do they engage student interest, they provide an accessible study subject. Students can alter illusions to determine their salient features, can often measure their strength, can form and test their own hypotheses, and analyze data collected by an entire class. Such activities can be done as in-class demonstrations or as student projects. For the rest of this article, I present several illusions and suggest ways in which they might be used in a class.

Examples shown here and used in the FUN workshop at Pomona came from the PsyCog CD ( Wyttenbach 2006 ; http://www.sinauer.com/detail.php?id=9504 ). However, free versions of these illusions can be found online or created by an instructor with basic graphic skills. Many can even be created using only the drawing tools and animation options found in PowerPoint™.

NEGATIVE AFTERIMAGE

Nearly everyone has seen negative afterimage illusions, and most textbooks discuss them in the context of trichromatic vision and opponent cells. This illusion is a good place to start because it introduces adaptation and opponent processes, which have bearing beyond color vision, and is tied to a simple model from which students can make straightforward predictions. Figure 1 shows an adapting stimulus, after which a white screen is presented. Students set the color and duration of adaptation and can time the duration of the afterimage.

Adapting Stimulus. Students set the color and duration of adaptation and can measure duration of the afterimage.

Questions: (1) What color of afterimage do you get with each of the adaptation colors? (2) What color do you expect to see when viewing cyan after adapting to blue? (3) Do you predict an afterimage from adaptation to a black image? (4) Does closing your eyes after adaptation make the afterimage last longer? (5) What do you see if, after adaptation, you move your head closer to or further from the white screen or look at the sky? (6) If you adapt one eye with the other eye closed and then switch eyes, is there an afterimage?

Interpretations: (1) Students should be able to predict the afterimage of any color by using the opponent model. (2) The opponent model also predicts biasing perception of another color; after adaptation to blue, any color should appear less blue (cyan becoming greenish, or magenta becoming redder). (3) The opponent model applies to black and white as well as to colors; it is also interesting to see a whiter-than-white afterimage on even the brightest background, which seems dingy in contrast. This also makes the point (reinforced by the contrast illusions) that perception of brightness depends on relative rather than absolute values. (4) Eye closing extends the afterimage duration, while blinking may restore a faded afterimage; I have not yet found a good explanation of this. (5) When the head moves closer to the screen, the afterimage appears to shrink, while it appears larger when the head is further from the screen or one looks at the sky. The adapted part of the visual field remains the same size (visual angle), but we interpret that size differently depending on distance cues; a given visual angle indicates a larger size when its source is distant than when it is near. (6) In my experience, the negative afterimage does not transfer from one eye to the other. While color is handled at many levels in the visual system, the first color-opponent cells are found in the lateral geniculate nucleus (LGN), before significant binocular processing.

In addition to these questions, students could do experiments testing the duration of the afterimage under different conditions such as very short or long adaptation periods, different levels of color saturation and so on.

MOTION AFTEREFFECT

The motion aftereffect, also known as the waterfall illusion, was first described by Aristotle. After one watches motion in one direction, stationary objects appear to move in the opposite direction. Like negative afterimages, this effect is due to an opponent process system. It poses a rich set of questions but is also just plain fun for students. (Project inward-moving concentric circles and then listen for reactions when students look at their hands.) Figure 2 shows an adapting stimulus, after which a mottled or blank screen is presented. Students set the duration, direction, speed, color, contrast, and size of the moving stimulus, and can time the duration of the aftereffect.

Motion Aftereffect Stimuli. Left: Inward-moving concentric circles. Students set the direction, speed, colors, contrast, duration, and size of the moving stimulus. Right: After adaptation, a mottled or blank screen is shown. Students can measure the duration of the aftereffect.

Questions: (1) How can you demonstrate the existence of detectors tuned to different directions of motion in the same part of the visual field? (2) Adapt to downward motion and then view horizontal motion. What do you predict? (3) Adapt to downward motion and then switch to upward motion; what do you predict? (4) How can you test whether motion detectors are present throughout the entire visual field? (5) How could you determine whether motion detection is primarily peripheral (retina to LGN) or central (V1 and up)? (6) What do you see if you adapt to motion and then view a blank surface? (7) How do the color and contrast of the adapting stimulus affect the aftereffect? (8) How do the speed of movement and size of the stripes affect the strength of aftereffect?

Interpretations: (1) The same part of the visual field can respond to, and have aftereffects from, motion in any direction. In principle, we could detect any direction from the vector sum of four detectors (right, left, up, down). (2) With downward motion detectors adapted, horizontally moving stripes appear to move diagonally upward. This supports the idea that direction is determined as a vector sum. (3) After adapting to downward motion, upward motion appears faster. This suggests that perceived motion is due to the ratio of responses of opposing detectors rather than to the absolute value of any one detector’s response. (4) The aftereffect is strongest at the periphery, with little motion in the center. This suggests that motion detectors are unevenly distributed. Peripheral vision may be specialized to direct attention to moving objects while central vision is specialized for detailed form. (5) Adapt one eye with the other closed, then check for the aftereffect with the adapted eye closed and the rested eye open. The aftereffect transfers across eyes (albeit more weakly), suggesting that it is due to neurons with binaural input (primary visual cortex or later). Human fMRI studies implicate motion-sensitive areas of visual cortex (area MT) in the aftereffect ( Huk et al., 2001 ). However, this does not rule out a peripheral role. A simple experiment suggests that adaptation also occurs at earlier stages. Simultaneously present upward movement to the left eye and downward movement to the right eye; each eye will have an independent negative aftereffect. (This can be done easily in PsyCog; use a piece of cardboard or pair of tubes to prevent each eye from seeing the display intended for the other.) (6) The motion aftereffect can be seen even on a blank surface. This is interesting because one sees motion without any objects to move. It may reflect the processing of motion and form by different pathways in visual cortex. (7) Color has no effect on the strength of the aftereffect, suggesting that motion detection relies on edges defined by luminance. Contrast also has little effect, and even the lowest-contrast moving stripes can give a robust aftereffect. I have not found a good explanation for this; perhaps motion detectors only require that contrast exceed some low threshold. (8) Strength of the aftereffect is affected not by stripe width and speed per se, but by the number of edge crossings. Thus wide stripes require faster movement or longer movement duration to achieve the same aftereffect as narrow stripes.

As with the negative afterimage, students can measure the duration of aftereffect under various conditions, such as short or long adaptation periods and varying sizes, speeds, contrasts, or colors of adapting stimuli.

ILLUSORY MOTION

In the last two decades, several new motion illusions have been invented. Some of them translate one type of motion into another (e.g., expansion into rotation), while others appear to move when completely stationary. Figure 3 is one of the latter, designed by Akiyoshi Kitaoka. These illusions are not as easily explained as the aftereffect, but students can still benefit from studying them.

Peripheral Drift. Students can set the colors of the image pieces to determine which stimulus features are essential.

Questions: (1) Is motion equally strong across the visual field? (2) Can you start and stop the motion by looking at the image in different ways? (3) Are all four colors needed? Can you change the strength or direction of motion by altering the color scheme? (4) Can adaptation to illusory motion cause a motion aftereffect?

Interpretations: (1) Most people see little or no motion at the point of fixation, with movement being most apparent in the peripheral visual field. (2) If one makes an effort to stare fixedly at one point without eye movements, motion is reduced or stopped. (3) Only three colors are needed (motion survives replacement of red with black in Figure 3 ). Motion is usually in the direction of the darker of the two ovals that surround a dark hourglass shape, but exceptions can be found, including some that appear to move weakly and in an ambiguous direction (make all shapes black but one white hourglass). Reducing contrast between light and dark areas reduces the strength of the illusion. (4) After adapting to one large disc, one may get a weak aftereffect.

Although these exercises seem to reveal little about the mechanisms behind this illusion, they reflect the ways in which scientists approach the subject. Observations about weakness in the central visual field, the effect of contrast, and eye movements led to the current explanations of this illusion ( Conway et al., 2005 ; Murakami et al., 2006 ).

There are many illusions of contrast, both in luminance and color. Despite straightforward explanations invoking lateral inhibition or other local mechanisms, full understanding of these illusions remains elusive. Figure 4 shows two cases in which gray blocks of equal density appear darker or lighter because of their surroundings and one case in which identically colored crosses appear quite different. In PsyCog and many online demonstrations, one can drag blocks together to see that they are in fact equal.

Contrast Illusions. Top: All small gray squares are the same density. Center: All gray rectangles are the same density. Bottom: Both crosses are the same color.

Questions: (1) Can you predict the outcome of a variety of contrast illusions? How are they usually explained? (2) How do assimilation illusions (e.g., the Munker-White illusion, Figure 4 center) challenge those explanations? (3) How would you measure the strength of a contrast illusion or test whether everyone is “fooled” by the same amount? (4) Can contrast illusions occur in negative afterimages? What would this tell us?

Interpretations: (1) It is not always easy to predict how a patch of color will appear based on its surroundings, since surroundings sometimes enhance contrast (top and bottom panels of Figure 4 ) and sometimes reduce it (center panel). (2) Explanations invoking contrast or edge enhancement make the wrong predictions in assimilation illusions. In the Munker-White illusion ( Figure 4 center panel), gray areas on the right border more white than black and thus “should” darken, while the reverse applies to gray areas on the left. However, our perception is the opposite. That does not mean that the usual explanations are wrong, only that they cannot be applied to all aspects of a scene. They may still apply to other aspects (for example, Mach bands appear in the Munker-White illusion). (3) To measure a contrast illusion, adjust two areas until they are subjectively equal and then measure their difference. Figure 5 illustrates this for a contrast enhancement illusion and an assimilation illusion. As a class project, student could measure their own contrast adjustments and do a statistical analysis of the pooled data. (4) Look at Figure 1 again; its negative afterimage is magenta, but the center of the afterimage is green. Since the original stimulus had no obvious magenta tint in the center, greenness in the afterimage is not itself an afterimage, but contrast enhancement occurring within the afterimage. Thus contrast enhancement is taking place after color-opponent cells, in V1 or later.

Measuring Contrast Illusions. Top: The basic contrast enhancement illusion with gray squares adjusted to subjective equality by the author and then brought together to show the amount of adjustment. One could then vary parameters such as the contrast between the dark and light surrounding areas and the size of the squares to determine how those affect illusion strength. Bottom: The Bezold effect, an assimilation illusion, with gray squares adjusted to subjective equality by the author. Interestingly, I can never make the gray squares look truly equal. They always seem a bit off and cannot be fixed by lightening or darkening.

These are just a few of the contrast illusions. I have omitted some very striking ones such as the scintillating grid ( Schrauf et al., 1995 ) because of their complexity. They still have use in teaching, both to excite interest and as fodder for mechanistic speculation. For further discussion of contrast illusions, particularly those resistant to easy explanation, see Purves and Lotto (2003) .

SIZE AND ORIENTATION

Explanations of size and orientation illusions are still very much in dispute, but they have the advantage of being easy to measure. Nearly everyone has seen the Müller-Lyer illusion ( Figure 6 ), so I use it as an example. The questions it raises apply equally to the Ponzo, Poggendorf, Vertical-Horizontal, Bisection, Lipps, Ebbinghaus-Delboef, Zollner, and Hering illusions and many others.

Measuring a Size Illusion. Top: The basic Müller-Lyer illusion with red lines adjusted to subjective equality by the author and measured to show the amount of adjustment. Bottom: A variant of the illusion, again with lines adjusted to subjective equality by the author and then measured.

Questions: (1) How would you measure the strength of a size illusion or test whether everyone is off by the same amount? (2) What experimental controls would you need to show that people misperceive size? (3) How could you test the hypothesis that misjudgment of length results from use of perspective cues? (4) Can you train yourself to make accurate size judgments in the Müller-Lyer illusion? If so, do the two lines actually look equal, or are you just compensating to make them equal?

Interpretations: (1) Rather than showing two equal lines that appear unequal, have the observer make the lines subjectively equal. The amount by which they differ is a measure of the illusion’s strength. This turns out to be fairly consistent. Data from a large class (along with controls) could be used for practice in statistical analysis. (2) At a minimum, we should check that people are able to adjust simple lines to equality (we do so easily). (3) If the Müller-Lyer illusion is due to perspective cues, then it should occur when the ends are arrowheads but not when they are circles, brackets, or other shapes that make no sense in the context of depth. As Figure 6 shows, this is not the case. (4) Most people can set the lines equal with practice but still see them as unequal.

Several competing theories attempt to explain illusions of size and orientation. Gregory (1998) and Gillam (1998) argue that the slants and angles in illusions are interpreted as perspective cues. Rock (1995) proposes that the size and orientation of an object are perceived in contrast with those of its local background. Prinzmetal and Beck (2001) attribute several illusions to mechanisms that correct for head tilt. Purves and Lotto (2003) propose that perception is determined by the “statistical relationship between the retinal image and all its possible sources”. None of these theories are mechanistic or based on neural data.

It is interesting that, after years of study, there are still no generally accepted explanations for these ubiquitous illusions. Although disappointing at some level, this makes such illusions ripe for student projects that test competing hypotheses.

There are so many good (and bad) web sites with visual illusions that it is difficult to keep track of them. These four sites offer explanations along with good graphics:

Wolfe et al.’s Sensation and Perception companion site has demonstrations and explanations keyed to the text but available to all.

Michael Bach’s site lets one manipulate many illusions; also includes explanations and references.

Akiyoshi Kitaoka’s site has many illusions, including his novel illusory motion ones, with links to his research papers on illusions.

The Vision Sciences Society has an annual contest for new illusions; the site links to published explanations.

CONCLUSIONS

As even these simple examples show, illusions are often complex and contradictory, with results that are hard to explain with basic textbook-level knowledge. While this can be frustrating at times, it is also exciting. It shows students that science is not simply a recitation of facts, but a process of testing hypotheses about the unknown. Better still, this process is open to students through their own perception of stimuli that they can design and manipulate.

Illusions can be used in introductory classes to stimulate interest and illustrate basic concepts (at the risk of over-simplification). Beyond that, in-class demonstrations can identify critical aspects of stimuli, show the importance of controls, and possibly analyze class-generated data.

More advanced classes might focus on mechanisms and the complexity of an apparently simple illusion. Most illusions combine several effects at once, and a class could work on identifying all features or simplifying an illusion to isolate one mechanism. Students could modify existing illusions or design their own to test specific hypotheses. Term papers and projects could gather data and delve into the extensive literature on illusions.

For instructors, going beyond the usual demonstration and simple explanation poses challenges. How much can we get out of an illusion? How can we present it in an engaging and scientifically valid way? Meeting these challenges should make teaching more fun for instructors as well as their students.

Acknowledgments

Development of PsyCog was supported by NSF award DUE-0088829. The author appreciates feedback from participants in his workshop at the 2011 FUN-PKAL meeting at Pomona College.

• Conway BR, Kitaoka A, Yazdanbakhsh A, Pack CC, Livingstone MS. Neural basis for a powerful static motion illusion. J Neurosci. 2005; 25 :5651–5656. [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Gillam B. Illusions at century’s end. In: Hochberg J, editor. Handbook of perception and cognition. 2nd ed. San Diego: Academic Press; 1998. [ Google Scholar ]
• Gregory RL. Eye and brain: the psychology of seeing. 5th ed. Oxford: Oxford University Press; 1998. [ Google Scholar ]
• Huk AC, Ress D, Heeger DJ. Neuronal basis of the motion aftereffect reconsidered. Neuron. 2001; 32 :161–172. [ PubMed ] [ Google Scholar ]
• Murakami I, Kitaoka A, Ashida H. A positive correlation between fixation instability and the strength of illusory motion in a static display. Vision Res. 2006; 46 :2421–2431. [ PubMed ] [ Google Scholar ]
• Prinzmetal W, Beck DM. The tilt-constancy theory of visual illusions. J Exp Psych. 2001; 27 :206–217. [ PubMed ] [ Google Scholar ]
• Purves D, Lotto RB. Why we see what we do: an empirical theory of vision. Sunderland, MA: Sinauer Assoc; 2003. [ Google Scholar ]
• Rock I. Perception. New York: WH Freeman; 1995. [ Google Scholar ]
• Schrauf M, Lingelbach B, Lingelbach E, Wist ER. The Hermann grid and the scintillation effect. Perception. 1995; 24 :88–89. [ Google Scholar ]
• Wyttenbach RA. PsyCog: explorations in perception and cognition. (CD-ROM) Sunderland, MA: Sinauer Assoc; 2006. [ Google Scholar ]

Chapter 4: Sensation and Perception

Sensation and perception.

Sensation and perception are two separate processes that are very closely related. Sensation is input about the physical world obtained by our sensory receptors, and perception is the process by which the brain selects, organizes, and interprets these sensations. In other words, senses are the physiological basis of perception. Perception of the same senses may vary from one person to another because each person’s brain interprets stimuli differently based on that individual’s learning, memory, emotions, and expectations.

Video 1. Sensation and Perception explains the differences between these two processes.

What does it mean to sense something? Sensory receptors are specialized neurons that respond to specific types of stimuli. When sensory information is detected by a sensory receptor, sensation has occurred. For example, light that enters the eye causes chemical changes in cells that line the back of the eye. These cells relay messages, in the form of action potentials (as you learned when studying biopsychology), to the central nervous system. The conversion from sensory stimulus energy to action potential is known as transduction .

You have probably known since elementary school that we have five senses: vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). It turns out that this notion of five senses is oversimplified. We also have sensory systems that provide information about balance (the vestibular sense), body position and movement (proprioception and kinesthesia), pain (nociception), and temperature (thermoception).

The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold. Absolute threshold refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time. The sensitivity of our sensory receptors can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away (Okawa & Sampath, 2007). Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962).

Video 2.  Absolute Threshold of Sensation

It is also possible for us to get messages that are presented below the threshold for conscious awareness—these are called subliminal messages . A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain: this is an absolute threshold. A message below that threshold is said to be subliminal: we receive it, but we are not consciously aware of it. Therefore, the message is sensed, but for whatever reason, it has not been selected for processing in working or short-term memory. Over the years there has been a great deal of speculation about the use of subliminal messages in advertising, rock music, and self-help audio programs. Research evidence shows that in laboratory settings, people can process and respond to information outside of awareness. But this does not mean that we obey these messages like zombies; in fact, hidden messages have little effect on behavior outside the laboratory (Kunst-Wilson & Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel, Sarrazin, Legrain, & Gobancé, 2009; Loersch, Durso, & Petty, 2013).

Dig Deeper: Unconscious Perception

Figure 2 . Priming can be used to improve intellectual test performance. Research subjects primed with the stereotype of a professor – a sort of intellectual role model – outperformed those primed with an anti-intellectual stereotype. [Photo: Jeremy Wilburn]

Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them. This is known as the just noticeable difference (jnd) or difference threshold . Unlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. As an example, imagine yourself in a very dark movie theater. If an audience member were to receive a text message on her cell phone which caused her screen to light up, chances are that many people would notice the change in illumination in the theater. However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice. The cell phone brightness does not change, but its ability to be detected as a change in illumination varies dramatically between the two contexts. Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has become known as Weber’s law : The difference threshold is a constant fraction of the original stimulus, as the example illustrates. It is the idea that bigger stimuli require larger differences to be noticed. For example, it will be much harder for your friend to reliably tell the difference between 10 and 11 lbs. (or 5 versus 5.5 kg) than it is for 1 and 2 lbs.

Video 3.  Weber’s Law and Thresholds 

While our sensory receptors are constantly collecting information from the environment, it is ultimately how we interpret that information that affects how we interact with the world. Perception refers to the way sensory information is organized, interpreted, and consciously experienced. Perception involves both bottom-up and top-down processing. Bottom-up processing refers to the fact that perceptions are built from sensory input. On the other hand, how we interpret those sensations is influenced by our available knowledge, our experiences, and our thoughts. This is called top-down processing .

Video 4.  Bottom-up versus Top-down Processing.

Look at the shape in Figure 3 below. Seen alone, your brain engages in bottom-up processing. There are two thick vertical lines and three thin horizontal lines. There is no context to give it a specific meaning, so there is no top-down processing involved.

Figure 3 . What is this image? Without any context, you must use bottom-up processing.

Now, look at the same shape in two different contexts. Surrounded by sequential letters, your brain expects the shape to be a letter and to complete the sequence. In that context, you perceive the lines to form the shape of the letter “B.”

Figure 4 . With top-down processing, you use context to give meaning to this image.

Surrounded by numbers, the same shape now looks like the number “13.”

Figure 5 . With top-down processing, you use context to give meaning to this image.

When given a context, your perception is driven by your cognitive expectations. Now you are processing the shape in a top-down fashion.

One way to think of this concept is that sensation is a physical process, whereas perception is psychological. For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the sensation is the scent receptors detecting the odor of cinnamon, but the perception may be “Mmm, this smells like the bread Grandma used to bake when the family gathered for holidays.”

Although our perceptions are built from sensations, not all sensations result in perception. In fact, we often don’t perceive stimuli that remain relatively constant over prolonged periods of time. This is known as sensory adaptation . Imagine entering a classroom with an old analog clock. Upon first entering the room, you can hear the ticking of the clock; as you begin to engage in conversation with classmates or listen to your professor greet the class, you are no longer aware of the ticking. The clock is still ticking, and that information is still affecting sensory receptors of the auditory system. The fact that you no longer perceive the sound demonstrates sensory adaptation and shows that while closely associated, sensation and perception are different.

Attention and Perception

There is another factor that affects sensation and perception: attention. Attention plays a significant role in determining what is sensed versus what is perceived. Imagine you are at a party full of music, chatter, and laughter. You get involved in an interesting conversation with a friend, and you tune out all the background noise. If someone interrupted you to ask what song had just finished playing, you would probably be unable to answer that question.

One experiment that demonstrates this phenomenon of inattentional blindness  asked participants to observe images moving across a computer screen. They were instructed to focus on either white or black objects, disregarding the other color. When a red cross passed across the screen, about one-third of subjects did not notice it (Most, Simons, Scholl, & Chabris, 2000).

Link to Learning

Video 5.  Test your perceptual abilities.

Figure 6 . Nearly one third of participants in a study did not notice that a red cross passed on the screen because their attention was focused on the black or white figures. (credit: Cory Zanker)

Motivations, Expectations, and Perception

Motivation can also affect perception. Have you ever been expecting a really important phone call and, while taking a shower, you think you hear the phone ringing, only to discover that it is not? If so, then you have experienced how motivation to detect a meaningful stimulus can shift our ability to discriminate between a true sensory stimulus and background noise. The ability to identify a stimulus when it is embedded in a distracting background is called signal detection theory . This might also explain why a mother is awakened by a quiet murmur from her baby but not by other sounds that occur while she is asleep. Signal detection theory has practical applications, such as increasing air traffic controller accuracy. Controllers need to be able to detect planes among many signals (blips) that appear on the radar screen and follow those planes as they move through the sky. In fact, the original work of the researcher who developed signal detection theory was focused on improving the sensitivity of air traffic controllers to plane blips (Swets, 1964).

Video 6.   Signal Detection Theory. 

Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life experiences. As you will see later in this module, individuals who are deprived of the experience of binocular vision during critical periods of development have trouble perceiving depth (Fawcett, Wang, & Birch, 2005). The shared experiences of people within a given cultural context can have pronounced effects on perception. For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963) published the results of a multinational study in which they demonstrated that individuals from Western cultures were more prone to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa. One such illusion that Westerners were more likely to experience was the Müller-Lyer illusion: the lines appear to be different lengths, but they are actually the same length.

Figure 7 . In the Müller-Lyer illusion, lines appear to be different lengths although they are identical. (a) Arrows at the ends of lines may make the line on the right appear longer, although the lines are the same length. (b) When applied to a three-dimensional image, the line on the right again may appear longer although both black lines are the same length.

These perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context. People in Western cultures, for example, have a perceptual context of buildings with straight lines, what Segall’s study called a carpentered world (Segall et al., 1966). In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion (Segall et al., 1999). It is not just vision that is affected by cultural factors. Indeed, research has demonstrated that the ability to identify an odor and rate its pleasantness and its intensity, varies cross-culturally (Ayabe-Kanamura, Saito, Distel, Martínez-Gómez, & Hudson, 1998).

Children described as thrill-seekers are more likely to show taste preferences for intense sour flavors (Liem, Westerbeek, Wolterink, Kok, & de Graaf, 2004), which suggests that basic aspects of personality might affect perception. Furthermore, individuals who hold positive attitudes toward reduced-fat foods are more likely to rate foods labeled as reduced-fat as tasting better than people who have less positive attitudes about these products (Aaron, Mela, & Evans, 1994).

Think It Over

Think about a time when you failed to notice something around you because your attention was focused elsewhere. If someone pointed it out, were you surprised that you hadn’t noticed it right away?

• North, A & Hargreaves, David & McKendrick, Jennifer. (1999). The Influence of In-Store Music on Wine Selections. Journal of Applied Psychology. 84. 271-276. 10.1037/0021-9010.84.2.271. ↵
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5.1 Sensation versus Perception

Learning objectives.

By the end of this section, you will be able to:

• Distinguish between sensation and perception
• Describe the concepts of absolute threshold and difference threshold
• Discuss the roles attention, motivation, and sensory adaptation play in perception

What does it mean to sense something? Sensory receptors are specialized neurons that respond to specific types of stimuli. When sensory information is detected by a sensory receptor, sensation has occurred. For example, light that enters the eye causes chemical changes in cells that line the back of the eye. These cells relay messages, in the form of action potentials (as you learned when studying biopsychology), to the central nervous system. The conversion from sensory stimulus energy to action potential is known as transduction .

You have probably known since elementary school that we have five senses: vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). It turns out that this notion of five senses is oversimplified. We also have sensory systems that provide information about balance (the vestibular sense), body position and movement (proprioception and kinesthesia), pain (nociception), and temperature (thermoception).

The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold. Absolute threshold refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time. The sensitivity of our sensory receptors can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away (Okawa & Sampath, 2007). Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962).

It is also possible for us to get messages that are presented below the threshold for conscious awareness—these are called subliminal messages . A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain: This is an absolute threshold. A message below that threshold is said to be subliminal: We receive it, but we are not consciously aware of it. Over the years there has been a great deal of speculation about the use of subliminal messages in advertising, rock music, and self-help audio programs. Research evidence shows that in laboratory settings, people can process and respond to information outside of awareness. But this does not mean that we obey these messages like zombies; in fact, hidden messages have little effect on behavior outside the laboratory (Kunst-Wilson & Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel, Sarrazin, Legrain, & Gobancé, 2009; Loersch, Durso, & Petty, 2013).

Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them. This is known as the just noticeable difference (jnd) or difference threshold . Unlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. As an example, imagine yourself in a very dark movie theater. If an audience member were to receive a text message that caused the cell phone screen to light up, chances are that many people would notice the change in illumination in the theater. However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice. The cell phone brightness does not change, but its ability to be detected as a change in illumination varies dramatically between the two contexts. Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has become known as Weber’s law: The difference threshold is a constant fraction of the original stimulus, as the example illustrates.

While our sensory receptors are constantly collecting information from the environment, it is ultimately how we interpret that information that affects how we interact with the world. Perception refers to the way sensory information is organized, interpreted, and consciously experienced. Perception involves both bottom-up and top-down processing. Bottom-up processing refers to sensory information from a stimulus in the environment driving a process, and top-down processing refers to knowledge and expectancy driving a process, as shown in Figure 5.2 (Egeth & Yantis, 1997; Fine & Minnery, 2009; Yantis & Egeth, 1999).

Imagine that you and some friends are sitting in a crowded restaurant eating lunch and talking. It is very noisy, and you are concentrating on your friend’s face to hear what they are saying, then the sound of breaking glass and clang of metal pans hitting the floor rings out. The server dropped a large tray of food. Although you were attending to your meal and conversation, that crashing sound would likely get through your attentional filters and capture your attention. You would have no choice but to notice it. That attentional capture would be caused by the sound from the environment: it would be bottom-up.

Alternatively, top-down processes are generally goal directed, slow, deliberate, effortful, and under your control (Fine & Minnery, 2009; Miller & Cohen, 2001; Miller & D'Esposito, 2005). For instance, if you misplaced your keys, how would you look for them? If you had a yellow key fob, you would probably look for yellowness of a certain size in specific locations, such as on the counter, coffee table, and other similar places. You would not look for yellowness on your ceiling fan, because you know keys are not normally lying on top of a ceiling fan. That act of searching for a certain size of yellowness in some locations and not others would be top-down—under your control and based on your experience.

One way to think of this concept is that sensation is a physical process, whereas perception is psychological. For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the sensation is the scent receptors detecting the odor of cinnamon, but the perception may be “Mmm, this smells like the bread Grandma used to bake when the family gathered for holidays.”

Although our perceptions are built from sensations, not all sensations result in perception. In fact, we often don’t perceive stimuli that remain relatively constant over prolonged periods of time. This is known as sensory adaptation . Imagine going to a city that you have never visited. You check in to the hotel, but when you get to your room, there is a road construction sign with a bright flashing light outside your window. Unfortunately, there are no other rooms available, so you are stuck with a flashing light. You decide to watch television to unwind. The flashing light was extremely annoying when you first entered your room. It was as if someone was continually turning a bright yellow spotlight on and off in your room, but after watching television for a short while, you no longer notice the light flashing. The light is still flashing and filling your room with yellow light every few seconds, and the photoreceptors in your eyes still sense the light, but you no longer perceive the rapid changes in lighting conditions. That you no longer perceive the flashing light demonstrates sensory adaptation and shows that while closely associated, sensation and perception are different.

There is another factor that affects sensation and perception: attention. Attention plays a significant role in determining what is sensed versus what is perceived. Imagine you are at a party full of music, chatter, and laughter. You get involved in an interesting conversation with a friend, and you tune out all the background noise. If someone interrupted you to ask what song had just finished playing, you would probably be unable to answer that question.

Link to Learning

See for yourself how inattentional blindness works by checking out this selective attention test from Simons and Chabris (1999).

One of the most interesting demonstrations of how important attention is in determining our perception of the environment occurred in a famous study conducted by Daniel Simons and Christopher Chabris (1999). In this study, participants watched a video of people dressed in black and white passing basketballs. Participants were asked to count the number of times the team dressed in white passed the ball. During the video, a person dressed in a black gorilla costume walks among the two teams. You would think that someone would notice the gorilla, right? Nearly half of the people who watched the video didn’t notice the gorilla at all, despite the fact that he was clearly visible for nine seconds. Because participants were so focused on the number of times the team dressed in white was passing the ball, they completely tuned out other visual information. Inattentional blindness is the failure to notice something that is completely visible because the person was actively attending to something else and did not pay attention to other things (Mack & Rock, 1998; Simons & Chabris, 1999).

In a similar experiment, researchers tested inattentional blindness by asking participants to observe images moving across a computer screen. They were instructed to focus on either white or black objects, disregarding the other color. When a red cross passed across the screen, about one third of subjects did not notice it ( Figure 5.3 ) (Most, Simons, Scholl, & Chabris, 2000).

Motivation can also affect perception. Have you ever been expecting a really important phone call and, while taking a shower, you think you hear the phone ringing, only to discover that it is not? If so, then you have experienced how motivation to detect a meaningful stimulus can shift our ability to discriminate between a true sensory stimulus and background noise. The ability to identify a stimulus when it is embedded in a distracting background is called signal detection theory . This might also explain why a mother is awakened by a quiet murmur from her baby but not by other sounds that occur while she is asleep. Signal detection theory has practical applications, such as increasing air traffic controller accuracy. Controllers need to be able to detect planes among many signals (blips) that appear on the radar screen and follow those planes as they move through the sky. In fact, the original work of the researcher who developed signal detection theory was focused on improving the sensitivity of air traffic controllers to plane blips (Swets, 1964).

Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life experiences. As you will see later in this chapter, individuals who are deprived of the experience of binocular vision during critical periods of development have trouble perceiving depth (Fawcett, Wang, & Birch, 2005). The shared experiences of people within a given cultural context can have pronounced effects on perception. For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963) published the results of a multinational study in which they demonstrated that individuals from Western cultures were more prone to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa. One such illusion that Westerners were more likely to experience was the Müller-Lyer illusion ( Figure 5.4 ): The lines appear to be different lengths, but they are actually the same length.

These perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context. People in Western cultures, for example, have a perceptual context of buildings with straight lines, what Segall’s study called a carpentered world (Segall et al., 1966). In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion (Segall et al., 1999). It is not just vision that is affected by cultural factors. Indeed, research has demonstrated that the ability to identify an odor, and rate its pleasantness and its intensity, varies cross-culturally (Ayabe-Kanamura, Saito, Distel, Martínez-Gómez, & Hudson, 1998).

Children described as thrill seekers are more likely to show taste preferences for intense sour flavors (Liem, Westerbeek, Wolterink, Kok, & de Graaf, 2004), which suggests that basic aspects of personality might affect perception. Furthermore, individuals who hold positive attitudes toward reduced-fat foods are more likely to rate foods labeled as reduced fat as tasting better than people who have less positive attitudes about these products (Aaron, Mela, & Evans, 1994).

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Journal of Experimental Psychology: Human Perception and Performance

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The Journal of Experimental Psychology: Human Perception and Performance ® publishes studies on perception, control of action, perceptual aspects of language processing, and related cognitive processes. All sensory modalities and motor systems are within its purview.

The journal also encourages studies with a neuroscientific perspective that contribute to the functional understanding of perception and performance. Authors are encouraged to consider and discuss the relevance and implications of their work for other areas of psychology, including those that are not typically featured in the journal.

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• Reports consist of empirical studies that increase theoretical understanding of human perception and performance. Studies will typically include human data, although machine and animal studies that reflect on human capabilities may also be published. Should an author submit a full report following an observation (or the other way around), the relationship between the two manuscripts must be acknowledged in an author footnote.
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Each issue of Journal of Experimental Psychology: Human Perception and Performance will highlight one article with the designation as an “Editor’s Choice” paper. Selection is based on the recommendations of the associate editors, who consider the following criteria: diversity of authors or participants; innovation; scientific rigor; and likely clinical or public significance or impact. Selected papers will appear in the APA Editor’s Choice newsletter .

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Related Journals of Experimental Psychology

For the other JEP journals, authors should submit manuscripts according to the instructions to authors for each individual journal:

• Journal of Experimental Psychology: Animal Learning and Cognition
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Alegria, M., Jackson, J. S., Kessler, R. C., & Takeuchi, D. (2016). Collaborative Psychiatric Epidemiology Surveys (CPES), 2001–2003 [Data set]. Inter-university Consortium for Political and Social Research. https://doi.org/10.3886/ICPSR20240.v8

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Authors must follow the APA Style Journal Article Reporting Standards (JARS) for quantitative, qualitative, and mixed methods. The standards offer ways to improve transparency in reporting to ensure that readers have the information necessary to evaluate the quality of the research and to facilitate collaboration and replication.

Transparency and openness

APA endorses the Transparency and Openness Promotion (TOP) Guidelines by a community working group in conjunction with the Center for Open Science ( Nosek et al. 2015 ). Effective July 1, 2021, empirical research, including meta-analyses, submitted to the  Journal of Experimental Psychology: Human Perception and Performance  must at least meet the “requirement” level for all eight aspects of research planning and reporting, except for replication. Authors should include a subsection in the method section titled “Transparency and openness.” This subsection should detail the efforts the authors have made to comply with the TOP guidelines. For example:

• We report how we determined our sample size, all data exclusions (if any), all manipulations, and all measures in the study, and we follow JARS (Appelbaum et al., 2018). All data, analysis code, and research materials are available at [stable link to repository]. Data were analyzed using R, version 4.0.0 (R Core Team, 2020) and the package ggplot , version 3.2.1 (Wickham, 2016). This study’s design and its analysis were not pre-registered.

In addition, the journal asks that authors report the year(s) of data collection in the method section.

Authors should also include a statement on the constraints of generality of their findings in the paper. This statement should describe and justify the target population for their work. The statement can appear anywhere in the paper, without any special format or heading.

Equity, Diversity, and Inclusion in Journal of Experimental Psychology: Human Perception and Performance

Journal of Experimental Psychology: Human Perception and Performance is committed to improving equity, diversity, and inclusion (EDI) in scientific research, in line with the APA Publishing EDI framework and APA’s trio of 2021 resolutions to address systemic racism in psychology.

To promote a more equitable research and publication process, Journal of Experimental Psychology: Human Perception and Performance has adopted the following standards for inclusive research reporting.

Author contribution statements using CRediT

The APA Publication Manual ( 7th ed. ) stipulates that "authorship encompasses…not only persons who do the writing but also those who have made substantial scientific contributions to a study." In the spirit of transparency and openness, Journal of Experimental Psychology: Human Perception and Performance has adopted the Contributor Roles Taxonomy (CRediT) to describe each author's individual contributions to the work. CRediT offers authors the opportunity to share an accurate and detailed description of their diverse contributions to a manuscript.

Submitting authors will be asked to identify the contributions of all authors at initial submission according to the CRediT taxonomy. If the manuscript is accepted for publication, the CRediT designations will be published as an author contributions statement in the author note of the final article. All authors should have reviewed and agreed to their individual contribution(s) before submission.

Authors can claim credit for more than one contributor role, and the same role can be attributed to more than one author. Not all roles will be applicable to a particular scholarly work.

Participant description, sample justification, and informed consent

Authors are required to include a detailed description of the study participants in the method section of each empirical report, including at least age and gender.

It is widely recognized that at least some psychological results are correlated with demographics. Thus, this journal follows APA position that basic demographics be provided in a manuscript because without this information the reader would have no basis for knowing to whom to generalize the findings. While researchers may firmly believe this information is not relevant, others may disagree, and future work can find new reasons for secondary exploratory analyses at a later point. Finally, not having this information makes it very difficult to perform and evaluate replications. For all these reasons, without special and strong justification, J ournal of Experimental Psychology: Human Perception and Performance will not accept manuscripts that do not report this information indeed, we make all efforts to catch this before a paper is sent for external review.

Authors are encouraged to include sex and other information such as:

• racial identity
• nativity or immigration history
• socioeconomic status
• clinical diagnoses and comorbidities (as appropriate)
• any other relevant demographics (e.g., disability status; sexual orientation)

In both the abstract and in the discussion section of the manuscript, authors must discuss the diversity of their study samples and the generalizability of their findings (see also the constraints on generality section below).

Authors are encouraged to justify their sample demographics in the discussion section. If Western, educated, industrialized, rich, and democratic (WEIRD) or all-White samples are used, authors should justify their samples and describe their sample inclusion efforts (see Roberts, et al., 2020 for more information on justifying sample demographics).

The method section also must include a statement describing how informed consent was obtained from the participants (or their parents/guardians), including for secondary use of data if applicable, and indicate that the study was conducted in compliance with an appropriate Internal Review Board.

Reporting year(s) of data collection

Authors must disclose the year(s) of data collection in both the abstract and in the method section in order to appropriately contextualize the study.

Inclusive reference lists

Research has shown that there is often a racial/ethnic and gender imbalance in article reference lists, and that Black women’s work is disproportionately not credited or cited as often as White authors’ work ( Kwon, 2022 ). Authors are encouraged to ensure their citations are fully representative by both gender and racial identity before submitting and during the manuscript revision process. Authors are encouraged to evaluate the race and gender of the authors in their reference lists (see this open-source code by Zhou, et al., 2020 , that authors can use to predict the gender and race of the authors in their reference lists) and to report the results in a citation diversity statement in the author note or discussion section of the manuscript.

See Dworkin, et al. (2020) ’s sample citation diversity statement:

“ Citation Diversity Statement . Recent work in neuroscience and other fields has identified a bias in citation practices such that papers from women and other minorities are under-cited relative to the number of such papers in the field (Caplar et al., 2017, Chakravartty et al., 2018, Dion et al., 2018, Dworkin et al., 2020, Maliniak et al., 2013, Thiem et al., 2018). Here, we sought to proactively consider choosing references that reflect the diversity of the field in thought, gender, race, geography, seniority, and other factors. We used automatic classification of gender based on the first names of the first and last authors (Dworkin et al., 2020, Zhou et al., 2020), with possible combinations including man/man, man/woman, woman/man, and woman/woman. Code for this classification is open source and available online (Zhou et al., 2020). We regret that our current methodology is limited to consideration of gender as a binary variable. Excluding self-citations to the first and last authors of our current paper, the references contain 12.5% man/man, 25% man/woman, 25% woman/man, 37.5% woman/woman, and 0% unknown categorization. We look forward to future work that could help us to better understand how to support equitable practices in science.”

Constraints on generality

In a subsection of the discussion titled "Constraints on generality," authors should include a detailed discussion of the limits on generality (see Simons, Shoda, & Lindsay, 2017 ). In this section, authors should detail grounds for concluding why the results are may or may not be specific to the characteristics of the participants. They should address limits on generality not only for participants but for materials, procedures, and context. Authors should also specify which methods they think could be varied without affecting the result and which should remain constant.

Public significance statements

Authors submitting manuscripts to the Journal of Experimental Psychology: Human Perception and Performance are required to provide 2–3 (between 120–150 words) brief sentences regarding the public significance of the study or meta-analysis described in their paper. This description should be included within the manuscript on the abstract/keywords page. It should be written in language that is easily understood by both professionals and members of the lay public.

• "We show that skin stretch affects tactile distance perception on the back of the hand with tactile distances being perceived as shorter on stretched than on non-stretched skin. "
• "These findings suggest that auditory training could help remediate difficulties with L2 speech learning in some individuals with auditory deficits, and that auditory testing could help predict which individuals are capable of proficient L2 learning."
• “The results provide evidence that the decision to switch to an alternative task depends not only on the accuracy of the previous trial, but also on the overall error history (i.e., the error probability) of the performed task, and the alternative task.”

To be maximally useful, these statements of public significance should not simply be sentences lifted directly out of the manuscript.

They are meant to be informative and useful to any reader. They should provide a bottom-line, take-home message that is accurate and easily understood. In addition, they should be able to be translated into media-appropriate statements for use in press releases and on social media.

Prior to final acceptance and publication, all public significance statements will be carefully reviewed to make sure they meet these standards. Authors will be expected to revise statements as necessary.

Please refer to the Guidance for Translational Abstracts and Public Significance Statements page to help you write this text.

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Authors must state whether data, code, and study materials are posted to a trusted repository and, if so, how to access them, including their location and any limitations on use. Trusted repositories adhere to policies that make data discoverable, accessible, usable, and preserved for the long term. Trusted repositories also assign unique and persistent identifiers. Recommended repositories include APA’s repository on the Open Science Framework (OSF), or authors can access a full list of other recommended repositories .

In a subsection titled "Transparency and Openness" at the end of the Method section, specify whether and where the data and material will be available or note the legal or ethical reasons for not doing so. For submissions with quantitative or simulation analytic methods, state whether the study analysis code is posted to a trusted repository, and, if so, how to access it (or the legal or ethical reason why it is not available).

For example:

• All data have been made publicly available at the [trusted repository name] and can be accessed at [persistent URL or DOI].
• Materials and analysis code for this study are not available.
• The code behind this analysis/simulation has been made publicly available at the [trusted repository name] and can be accessed at [persistent URL or DOI].

Preregistration of studies and analysis plans

Preregistration of studies and specific hypotheses can be a useful tool for making strong theoretical claims. Likewise, preregistration of analysis plans can be useful for distinguishing confirmatory and exploratory analyses. Investigators are encouraged to preregister their studies and analysis plans prior to conducting the research via a publicly accessible registry system (e.g., OSF , ClinicalTrials.gov, or other trial registries in the WHO Registry Network).

There are many available templates; for example, APA, the British Psychological Society, and the German Psychological Society partnered with the Leibniz Institute for Psychology and Center for Open Science to create Preregistration Standards for Quantitative Research in Psychology (Bosnjak et al., 2022).

Articles must state whether or not any work was preregistered and, if so, where to access the preregistration. Preregistrations must be available to reviewers; authors may submit a masked copy via stable link or supplemental material. Links in the method section should be replaced with an identifiable copy on acceptance.

• This study’s design was preregistered; see [STABLE LINK OR DOI].
• This study’s design and hypotheses were preregistered; see [STABLE LINK OR DOI].
• This study’s analysis plan was preregistered; see [STABLE LINK OR DOI].
• This study was not preregistered.

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In light of changing patterns of scientific knowledge dissemination, APA requires authors to provide information on prior dissemination of the data and narrative interpretations of the data/research appearing in the manuscript (e.g., if some or all were presented at a conference or meeting, posted on a listserv, shared on a website, including academic social networks like ResearchGate, etc.). This information (2–4 sentences) must be provided as part of the author note.

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In addition, APA Ethical Principles specify that "after research results are published, psychologists do not withhold the data on which their conclusions are based from other competent professionals who seek to verify the substantive claims through reanalysis and who intend to use such data only for that purpose, provided that the confidentiality of the participants can be protected and unless legal rights concerning proprietary data preclude their release" (Standard 8.14).

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The APA Ethics Office provides the full Ethical Principles of Psychologists and Code of Conduct electronically on its website in HTML, PDF, and Word format. You may also request a copy by emailing or calling the APA Ethics Office (202-336-5930). You may also read "Ethical Principles," December 1992, American Psychologist , Vol. 47, pp. 1597–1611.

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• Research specializations of the editor-in-chief and associate editors (PDF, 232KB)

Isabel Gauthier, PhD Vanderbilt University, United States

Associate editors

Anthony P. Atkinson, PhD Durham University, United Kingdom

Sang Chul Chong, PhD Yonsei University, Korea

Felipe De Brigard, PhD Duke University, United States

Paul E. Dux, PhD The University of Queensland, Australia

Chiara Gambi, PhD Cardiff University, United Kingdom

Nurit Gronau, PhD Open University of Israel, Israel

Ines Jentzsch, PhD University of St Andrews, United Kingdom

Damian Kelty-Stephen, PhD State University of New York at New Paltz, United States

Iring Koch, PhD RWTH Aachen University, Germany

Liuba Papeo, PhD CNRS, France

Athanassios Protopapas, PhD University of Oslo, Norway

Jelena Ristic, PhD McGill University, Canada

Joel S. Snyder, PhD University of Nevada, United States

Branka Spehar, PhD University of New South Wales, Australia

Ranxiao Frances Wang, PhD University of Illinois, Urbana-Champaign, United States

Intern junior editors

Ségolène Guérin, PhD Université Catholique de Louvain, Belgium

Aytaç Karabay, PhD New York University and Saadiyat Island, United Arab Emirates

Cynthia Tarlao, PhD McGill University, Canada

Consulting editors

Elkan G. Akyurek, PhD University of Groningen, Netherlands

Lara Bardi, PhD CNRS, France

Cristina Becchio, PhD University Medical Center Hamburg-Eppendorf, Germany

Melissa Beck, PhD Louisiana State University, United States

Stefanie Becker, PhD University of Queensland, Australia

Jason Bell, PhD University of Western Australia, Australia

Hazel I. Blythe, PhD University of Southampton, United Kingdom

Marc Brysbaert, PhD Ghent University, Belgium

Julie M. Bugg, PhD Washington University, St. Louis, United States

Nicolas Burra, PhD Université de Genève, Switzerland

Nancy Carlisle, PhD Lehigh University, United States

Caroline Catmur, PhD King's College, United Kingdom

Yang Seok Cho, PhD Korea University, Korea

Clara Colombatto, PhD University College London, United Kingdom

Joshua Correll, PhD University of Colorado Boulder, United States

Ruth Corps, PhD Max Planck Institute for Psycholinguistics, Netherlands

Mario Dalmaso, PhD Universita degli Studi di Padova, Italy

Carolin Dudschig, PhD Tübingen University, Germany

Susanne Ferber, PhD University of Toronto, Canada

Hannah L. Filmer, PhD University of Queensland, Australia

Jaclyn Ford, PhD Boston College, United States

Sophie Forster, PhD University of Sussex, United Kingdom

Christian Frings, PhD University of Trier, Germany

Miriam Gade, PhD Medical School Berlin, Germany

Nicholas Gaspelin, PhD University of Missouri, United States

Bradley S. Gibson, PhD University of Notre Dame, United States

Erin Goddard, PhD UNSW, Australia

Valerie Goffaux, PhD UC de Louvain, Belgium

Katie L. H. Gray, PhD University of Reading, United Kingdom

Lauren V. Hadley, PhD University of Nottingham, United Kingdom

Irina M. Harris, PhD University of Sydney, Australia

Jean-Rémy Hochmann, PhD Institut des Sciences Cognitives Marc Jeannerod, France

Bernhard Hommel, PhD Shandong Normal University, China

Timothy L. Hubbard, PhD Arizona State University, United States

Amelia R. Hunt, PhD University of Aberdeen, United Kingdom

Tina Iachini, PhD University of Campania Luigi Vanvitelli, Italy

Hee Yeon Im, PhD University of British Columbia, Canada

Aine Ito, PhD National University of Singapore, Singapore

Kevin Jarbo, PhD Carnegie Mellon University, United States

Luis Jimenez, PhD Universidad de Santiago de Compostela, Spain

Min-Suk Kang, PhD Sungkyunkwan University, South Korea

Sachiko Kinoshita, PhD Macquarie University, Australia

Maria Kozhevnikov, PhD National University of Singapore, Singapore

Gustav Kuhn, PhD Goldsmiths, University of London, United Kingdom

Oh-Sang Kwon, PhD UNIST, South Korea

Mike Le Pelley, PhD UNSW, Australia

Carly J. Leonard, PhD University of Colorado Denver, United States

Li Li, PhD New York University, Shanghai, China

Tobias Meilinger, PhD University of Tübingen, Germany

Hauke S. Meyerhoff, PhD University of Erfur, Germany

Jeff O. Miller, PhD University of Otago, Aotearoa

Jorge Morales, PhD Northeastern University, United States

Vishnu P. Murty, PhD Temple University, United States

Jonas Olofsson, PhD Stockholm University, Sweden

John W. Philbeck, PhD George Washington University, United States

Thomas S. Redick, PhD Purdue University, United States

Eva Reinisch, PhD Acoustics Research Institute, Austrian Academy of Sciences, Austria

Timothy J. Ricker, PhD College of Staten Island and City University of New York, United States

Amanda K. Robinson, PhD University of Queensland, Australia

Irene Ronga, PhD University of Turin, Italy

E. Glenn Schellenberg, PhD ISCTE-IUL, Portugal

Darryl W. Schneider, PhD Purdue University, United States

Lisa S. Scott, PhD University of Florida, United States

Mohinish Shukla, PhD Università di Padova, Italy

Heida Maria Sigurdardottir, PhD University of Iceland, Iceland

Marie Louise Smith, PhD Birkbeck College, United Kingdom

Alessandra S. Souza, PhD University of Zurich, Switzerland

James Strachan, PhD Center for Human Technologies, Italian Institute of Technology, Italy

Jie Sui, PhD University of Aberdeen, United Kingdom

Igor Utochkin, PhD University of Chicago, United States

Robrecht van der Wel, PhD Rutgers University, United States

Christina M. Vanden Bosch der Nederlanden, PhD University of Toronto Mississauga, Canada

Navin Viswanathan, PhD Pennsylvania State University, United States

Jeffrey B. Wagman, PhD UNSW Sydney, Australia

David White, PhD UNSW Sydney, Australia

Bo Yeong Won, PhD University of California, Riverside, United States

Geoffrey F. Woodman, PhD Vanderbilt University, United States

Brad Wyble, PhD Pennsylvania State University, United States

Naohide Yamamoto, PhD Queensland University of Technology, Australia

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Magen Speegle American Psychological Association, United States

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Special issue of APA's Journal of Experimental Psychology: Human Perception and Performance, Vol. 43, No. 10, October 2017. The articles demonstrate the links between classic game-changing research and contemporary works.

Transparency and Openness Promotion

APA endorses the Transparency and Openness Promotion (TOP) Guidelines by a community working group in conjunction with the Center for Open Science ( Nosek et al. 2015 ). The TOP Guidelines cover eight fundamental aspects of research planning and reporting that can be followed by journals and authors at three levels of compliance.

• Level 1: Disclosure—The article must disclose whether or not the materials are posted to a trusted repository.
• Level 2: Requirement—The article must share materials via a trusted repository when legally and ethically permitted (or disclose the legal and/or ethical restriction when not permitted).
• Level 3: Verification—A third party must verify that the standard is met.

Empirical research, including meta-analyses, submitted to the Journal of Experimental Psychology: Human Perception and Performance must, at a minimum, meet Level 2 (Requirement) for all eight aspects of research planning and reporting except for replication. Authors should include a subsection in their methods description titled “Transparency and openness.” This subsection should detail the efforts the authors have made to comply with the TOP guidelines.

The list below summarizes the minimal TOP requirements of the journal. Please refer to the Center for Open Science TOP guidelines for details, and  contact the editor  (Isabel Gauthier, PhD) with any further questions. Authors must share data, materials, and code via  trusted repositories (e.g.,  APA’s repository  on the Open Science Framework (OSF)). Trusted repositories adhere to policies that make data discoverable, accessible, usable, and preserved for the long term. Trusted repositories also assign unique and persistent identifiers.

We encourage investigators to preregister their studies and to share protocols and analysis plans prior to conducting the research. There are many available preregistration forms (e.g., the APA Preregistration for Quantitative Research in Psychology template, ClinicalTrials.gov , or other preregistration templates available via OSF ). Completed preregistration forms should be posted on a publicly accessible registry system (e.g., OSF , ClinicalTrials.gov, or other trial registries in the WHO Registry Network).

A list of participating journals is also available from APA.

The following list presents the eight fundamental aspects of research planning and reporting, the TOP level required by the  Journal of Experimental Psychology: Human Perception and Performance , and a brief description of the journal's policy.

• Citation: Level 2, Requirement—All data, program code, and other methods developed by others must be cited in the text and listed in the references section.
• Data Transparency: Level 2, Requirement—Article states whether the raw and/or processed data on which study conclusions are based are posted to a trusted repository and either how to access them or the legal or ethical reasons why they are not available.
• Analytic Methods (Code) Transparency: Level 2, Requirement—Article states whether computer code or syntax needed to reproduce analyses in an article is posted to a trusted repository and either how to access it or the legal or ethical reasons why it is not available.
• Research Materials Transparency: Level 2, Requirement—Article states whether materials described in the method section are available and either where to access them or the legal or ethical reasons why they are not available.
• Design and Analysis Transparency (Reporting Standards): Level 2, Requirement—Article must follow the APA Style Journal Article Reporting Standards (JARS-Quant, JARS-Qual, and/or MARS).
• Study Preregistration: Level 2, Requirement—Article states whether the study design and (if applicable) hypotheses of any of the work reported was preregistered and, if so, how to access it. Access to the preregistration must be available at submission. Authors opting for masked review should submit a masked copy via stable link or supplemental material.
• Analysis Plan Preregistration: Level 2, Requirement—Article states whether any of the work reported preregistered an analysis plan and, if so, how to access it. Access to the preregistration must be available at submission. Authors opting for masked review should submit a masked copy via stable link or supplemental material.
• Replication: Level 1, Disclosure—The journal publishes replications.

Other open science initiatives

• Open Science badges: Not offered
• Public significance statements: Offered
• Author contribution statements using CRediT: Required
• Registered Reports: Not published
• Replications: Published

Explore open science at APA .

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• Constraints on Generality (COG) statements (required)
• Inclusive reference lists (recommended)

More information on this journal’s reporting standards is listed under the submission guidelines tab .

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What Is Perception?

Recognizing Environmental Stimuli Through the Five Senses

Types of Perception

• How It Works

Perception Process

• Influential Factors
• Improvement Tips
• Potential Pitfalls

History of Perception

Perception refers to our sensory experience of the world. It is the process of using our senses to become aware of objects, relationships, and events. It is through this experience that we gain information about the environment around us.

Perception relies on the cognitive functions we use to process information, such as utilizing memory to recognize the face of a friend or detect a familiar scent. Through the perception process, we are able to both identify and respond to environmental stimuli.

Perception includes the five senses: touch, sight, sound, smell , and taste . It also includes what is known as proprioception , which is a set of senses that enable us to detect changes in body position and movement.

Many stimuli surround us at any given moment. Perception acts as a filter that allows us to exist within and interpret the world without becoming overwhelmed by this abundance of stimuli.

The different senses often separate the types of perception. These include visual, scent, touch, sound, and taste perception. We perceive our environment using each of these, often simultaneously.

There are also different types of perception in psychology, including:

• Person perception refers to the ability to identify and use social cues about people and relationships.
• Social perception is how we perceive certain societies and can be affected by things such as stereotypes and generalizations.

Another type of perception is selective perception. This involves paying attention to some parts of our environment while ignoring others.

The different types of perception allow us to experience our environment and interact with it in ways that are both appropriate and meaningful.

How Perception Works

Through perception, we become more aware of (and can respond to) our environment. We use perception in communication to identify how our loved ones may feel. We use perception in behavior to decide what we think about individuals and groups.

We perceive things continuously, even though we don't typically spend a great deal of time thinking about them. For example, the light that falls on our eye's retinas transforms into a visual image unconsciously and automatically. Subtle changes in pressure against our skin, allowing us to feel objects, also occur without a single thought.

Mindful Moment

Need a breather? Take this free 9-minute meditation focused on awakening your senses —or choose from our guided meditation library to find another one that will help you feel your best.

To better understand how we become aware of and respond to stimuli in the world around us, it can be helpful to look at the perception process. This varies somewhat for every sense.

In regard to our sense of sight, the perception process looks like this:

• Environmental stimulus: The world is full of stimuli that can attract attention. Environmental stimulus is everything in our surroundings that has the potential to be perceived.
• Attended stimulus: The attended stimulus is the specific object in the environment on which our attention is focused.
• Image on the retina: This part of the perception process involves light passing through the cornea and pupil onto the lens of the eye. The cornea helps focus the light as it enters, and the iris controls the size of the pupils to determine how much light to let in. The cornea and lens act together to project an inverted image onto the retina.
• Transduction: The image on the retina is then transformed into electrical signals through a process known as transduction. This allows the visual messages to be transmitted to the brain to be interpreted.
• Neural processing: After transduction, the electrical signals undergo neural processing. The path followed by a particular signal depends on what type of signal it is (for example, an auditory signal or a visual signal).
• Perception: In this step of the perception process, you perceive the stimulus object in the environment. It is at this point that you become consciously aware of the stimulus.
• Recognition: Perception doesn't just involve becoming consciously aware of the stimuli. It is also necessary for the brain to categorize and interpret what you are sensing. This next step, known as recognition, is the ability to interpret and give meaning to the object.
• Action: The action phase of the perception process involves some type of motor activity that occurs in response to the perceived stimulus. This might involve a significant action, like running toward a person in distress. It can also include doing something as subtle as blinking your eyes in response to a puff of dust blowing through the air.

Think of all the things you perceive on a daily basis. At any given moment, you might see familiar objects, feel a person's touch against your skin, smell the aroma of a home-cooked meal, or hear the sound of music playing in your neighbor's apartment. All of these help make up your conscious experience and allow you to interact with the people and objects around you.

Recap of the Perception Process

• Environmental stimulus
• Attended stimulus
• Image on the retina
• Transduction
• Neural processing
• Recognition

Factors Influencing Perception

What makes perception somewhat complex is that we don't all perceive things the same way. One person may perceive a dog jumping on them as a threat, while another person may perceive this action as the pup just being excited to see them.

Our perceptions of people and things are shaped by our prior experiences, our interests, and how carefully we process information. This can cause one person to perceive the exact same person or situation differently than someone else.

Perception can also be affected by our personality. For instance, research has found that four of the Big 5 personality traits —openness, conscientiousness, extraversion, and neuroticism—can impact our perception of organizational justice.

Conversely, our perceptions can also affect our personality. If you perceive that your boss is treating you unfairly, for example, you may show traits related to anger or frustration. If you perceive your spouse to be loving and caring, you may show similar traits in return.

Are Perception and Attitude the Same?

While they are similar, perception and attitude are two different things. Perception is how we interpret the world around us, while our attitudes (our emotions, beliefs, and behaviors) can impact these perceptions.

Tips to Improve Perception

If you want to improve your perception skills, there are some things that you can do. Actions you can take that may help you perceive more in the world around you—or at least focus on the things that are important—include:

• Pay attention. Actively notice the world around you, using all your senses. What do you see, hear, taste, smell, or touch? Using your sense of proprioception, notice the movements of your arms and legs or your changes in body position.
• Make meaning of what you perceive. The recognition stage of the perception process is essential since it allows you to make sense of the world around you. You place objects in meaningful categories so you can understand and react appropriately.
• Take action. The final step of the perception process involves taking some sort of action in response to your environmental stimulus. This could involve a variety of actions, such as stopping to smell the flower you see on the side of the road and incorporating more of your senses into your experiences.

Potential Pitfalls of Perception

The perception process does not always go smoothly, and there are a number of things that may interfere with our ability to interpret and respond to our environment. One is having a disorder that impacts perception.

Perceptual disorders are cognitive conditions marked by an impaired ability to perceive objects or concepts. Some disorders that may affect perception include:

• Spatial neglect syndromes , which involve not attending to stimuli on one side of the body
• Prosopagnosia , also called face blindness, is a disorder that makes it difficult to recognize faces
• Aphantasia , a condition characterized by an inability to visualize things in your mind
• Schizophrenia , a mental health condition that is marked by abnormal perceptions of reality

Some of these conditions may be influenced by genetics, while others result from stroke or brain injury.

Certain factors can also negatively affect perception. For instance, one study found that when people viewed images of others, they perceived individuals with nasal deformities as having less satisfactory personality traits. So, factors such as this can potentially affect personality perception in others.

Interest in perception dates back to ancient Greek philosophers who were interested in how people know the world and gain understanding. As psychology emerged as a science separate from philosophy, researchers became interested in understanding how different aspects of perception worked—particularly the perception of color.

In addition to understanding basic physiological processes, psychologists were also interested in understanding how the mind interprets and organizes these perceptions.

Gestalt psychologists proposed a holistic approach, suggesting that the whole is greater than the sum of its parts.  Cognitive psychologists have also worked to understand how motivations and expectations can play a role in the process of perception.

As time progresses, researchers continue to investigate perception on the neural level. They also look at how injury, conditions, and substances might affect perception.

American Psychological Association. Perception .

University of Minnesota. 3.4 Perception . Organizational Behavior .

Jhangiani R, Tarry H. 5.4 Individual differences in person perception . Principles of Social Psychology - 1st International H5P Edition . Published online January 26, 2022.

Aggarwal A, Nobi K, Mittal A, Rastogi S. Does personality affect the individual's perceptions of organizational justice? The mediating role of organizational politics . Benchmark Int J . 2022;29(3):997-1026. doi:10.1108/BIJ-08-2020-0414

Saylor Academy. Human relations: Perception's effect . Human Relations .

ICFAI Business School. Perception and attitude (ethics) . Personal Effectiveness Management Course .

King DJ, Hodgekins J, Chouinard PA, Chouinard VA, Sperandio I. A review of abnormalities in the perception of visual illusions in schizophrenia .  Psychon Bull Rev . 2017;24(3):734‐751. doi:10.3758/s13423-016-1168-5

van Schijndel O, Tasman AJ, Listschel R. The nose influences visual and personality perception . Facial Plast Surg . 2015;31(05):439-445. doi:10.1055/s-0035-1565009

Goldstein E. Sensation and Perception . Thomson Wadsworth; 2010.

Yantis S. Sensation and Perception . Worth Publishers; 2014.

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

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Sensation and Perception

Student resources, interactive sensation laboratory exercises (isle), isle activities.

Interactive Sensory Laboratory Exercises (ISLE)  is a set of activities, experiments, and illustrations that allow students to engage the concepts of  Sensation & Perception  by interacting with the phenomena discussed in the book, including anatomical diagrams, visual illusions, auditory illusions, and musical selections.

Access sample chapter-specific activities under each chapter, and access the full range of ISLE activities within the Interactive eBook.

Hands-On Experience

In working through these exercises, students have the opportunity to interact and see how different variables alter their experience. For example, students can:

• Try out Kuffler's experiment exploring center-surround receptive fields and other models of cells in the brain, with results generated in real time.
• See what a photograph looks like to people with different forms of dichromacy, and upload their own photographs to see what happens.
• Read about hue cancellation and then run an experiment that allows them to manipulate the stimulus and method settings.

Anaglyph glasses

Some of the photographic figures on ISLE are anaglyphic stereo­grams, and they will require special glasses to be seen properly. See Chapter 7 for more information about stereograms. While these glasses are not provided with the book, they are easy to make, or, if you prefer, cheap to buy, individually or in bulk. Please note that you will need Red/Cyan anaglyph glasses. Anaglyph glasses can be found in each new copy of Sensation and Perception , Second Edition. Consult ISLE P.1 for specific information about either making or ordering these glasses.

You can see the results of these experiments and collect the data in an Excel-ready format that is compatible with any statistical analysis package. In addition, there is a full set of quiz questions to be used to assess what students have gained from interaction with the exercises. See Chapter 3 for a sample.

Flexibility

The site is designed to work on most platforms, devices and browsers, and is optimized for display on tablets and mobile phones. Each exercise also includes its own set of specific instructions.

Acknowledgments

We gratefully acknowledge John Krantz, co-author of  Sensation & Perception , for creating and developing the Interactive Sensory Laboratory Exercises (ISLE). Special thanks are also due to  Hanover College  for hosting the site and to Sarah Blythe of Washington & Lee University for creating the ISLE assessments.

5.1 Sensation versus Perception

Learning objectives.

By the end of this section, you will be able to:

• Distinguish between sensation and perception
• Describe the concepts of absolute threshold and difference threshold
• Discuss the roles attention, motivation, and sensory adaptation play in perception

   What does it mean to sense something? Sensory receptors are specialized neurons that respond to specific types of stimuli. When sensory information is detected by a sensory receptor, sensation has occurred. For example, light that enters the eye causes chemical changes in cells that line the back of the eye. These cells relay messages, in the form of action potentials (as you learned when studying biopsychology), to the central nervous system. The conversion from sensory stimulus energy to action potential is known as transduction . Transduction represents the first step toward perception and is a translation process where different types of cells react to stimuli creating a signal processed by the central nervous system resulting in what we experience as a sensations. Sensations allow organisms to sense a face, and smell smoke when there is a fire.

Perceptions on the other hand, require organizing and understanding the incoming sensation information. In order for sensations to be useful, we must first add meaning to those sensations, which create our perceptions of those sensations. Sensations allow us to see a red burner, but perceptions entail the understanding and representation of the characteristic hot. Also, a sensation would be hearing a loud, shrill tone, whereas a perception would be the classification and understanding of that sounds as a fire alarm. Throughout this chapter sensations and perceptions will be discussed as separate events, whereas in reality, sensations and perceptions can be more accurately thought of as occurring along a continued where boundaries are more fluent between where a sensation ends and a perception begins.

You have probably known since elementary school that we have five senses: vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). It turns out that this notion of five senses is extremely oversimplified. We also have sensory systems that provide information about balance (the vestibular sense), body position and movement (proprioception and kinesthesia), pain (nociception), and temperature (thermoception), and each one of these sensory systems has different receptors tuned to transduce different stimuli. The vision system absorbs light using rod and cone receptors located at the back of the eyes, sound is translated via tiny hair like receptors known as cilia inside the inner ear, smell and taste work together most of the time to absorb chemicals found in airborne particles and food via chemically sensitive cilia in the nasal cavity and clusters of chemical receptors on the tongue. Touch is particularly interesting because it is made up of responses from many different types of receptors found within the skin that send signals to the central nervous system in response to temperature, pressure, vibration, and disruption of the skin such as stretching and tearing.

Free nerve endings embedded in the skin that allow humans to perceive the various differences in our immediate environment. Adapted from Pinel, 2009.

   The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold. Absolute threshold refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time. The sensitivity of our sensory receptors can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away (Okawa & Sampath, 2007). Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962). Additionally, one teaspoon of sugar can be tasted within two gallons of water, and the human olfactory system can detect the scent of one drop of perfume throughout a six room apartment.

It is also possible for us to get messages that are presented below the threshold for conscious awareness—these are called subliminal messages. A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain: This is an absolute threshold. A message below that threshold is said to be subliminal: The message is processed, but we are not consciously aware of it. Over the years, there has been a great deal of speculation about the use of subliminal messages in advertising, rock music, and self-help audio programs to influence consumer behavior. Research has demonstrated in laboratory settings, people can process and respond to information outside of awareness. But this does not mean that we obey these messages like zombies; in fact, hidden messages have little effect on behavior outside the laboratory (Kunst-Wilson & Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel, Sarrazin, Legrain, & Gobancé, 2009; Loersch, Durso, & Petty, 2013). Studies attempting to influence movie goers to purchase more popcorn, and reduced smoking habits demonstrated little to no success further suggesting subliminal messages are mostly ineffective in producing specific behavior (Karremans, Stroebe & Claus, 2006). However, neuroimaging studies have demonstrated clear neural activity related to the processing of subliminal stimuli stimuli (Koudier & Dehaene, 2007). Additionally, Krosnick, Betz, Jussim & Lynn (1992) found that participants who were presented images of dead bodies or buckets of snakes for several milliseconds (subliminal priming), were more likely to rate a neutral image of a woman with a neutral facial expression as more unlikable compared to participants who were shown more pleasant images (kittens and bridal couples). This demonstrates that although we may not be aware of the stimuli presented to us, we are processing it on a neural level, and also that although subliminal priming usually is not strong enough to force unwanted purchases, it may influence our perceptions of things we encounter in the environment following the subliminal priming.

Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them. This is known as the just noticeable difference (JND, mentioned briefly in the above study comparing color perceptions of Chinese and Dutch participants) or difference threshold. Unlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. As an example, imagine yourself in a very dark movie theater. If an audience member were to receive a text message on her cell phone which caused her screen to light up, chances are that many people would notice the change in illumination in the theater. However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice. The cell phone brightness does not change, but its ability to be detected as a change in illumination varies dramatically between the two contexts. Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has become known as Weber’s law.

Webers Law : Each of the various senses has its own constant ratios determining difference thresholds.

Webers ideas about difference thresholds influenced concepts of signal detection theory which state that our abilities to detect a stimulus depends on sensory factors (like the intensity of the stimulus, or the presences of other stimuli being processed) as well as our psychological state (you are sleepy because you stayed up studying the previous night). Human factors engineers who design control consoles for planes and cars use signal detection theory all the time in order to asses situations pilots or drivers may experience such as difficulty in seeing and interpreting controls on extremely bright days.

“ Although are perceptions are built from sensations, not all sensations result in perception .”

   While our sensory receptors are constantly collecting information from the environment, it is ultimately how we interpret that information that affects how we interact with the world. Perception refers to the way sensory information is organized, interpreted, and consciously experienced. Perception involves both bottom-up and top-down processing. Bottom-up processing refers to the fact that perceptions are built from sensory input, stimuli from the environment. On the other hand, how we interpret those sensations is influenced by our available knowledge, our experiences, and our thoughts related to the stimuli we are experiencing. This is called top-down processing.

One way to think of this concept is that sensation is a physical process, whereas perception is psychological. For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the sensation is the scent receptors detecting the odor of cinnamon, but the perception may be “Mmm, this smells like the bread Grandma used to bake when the family gathered for holidays.” Sensation is a signal from any of our six senses. Perception is the brain’s response to these signals. When we see our professor speaking in the front of the room, we sense the visual and auditory signals coming from them and we perceive that they are giving a lecture about our psychology class.

Although our perceptions are built from sensations, not all sensations result in perception. In fact, we often don’t perceive stimuli that remain relatively constant over prolonged periods of time. This is known as sensory adaptation. Imagine entering a classroom with an old analog clock. Upon first entering the room, you can hear the ticking of the clock; as you begin to engage in conversation with classmates or listen to your professor greet the class, you are no longer aware of the ticking. The clock is still ticking, and that information is still affecting sensory receptors of the auditory system. The fact that you no longer perceive the sound demonstrates sensory adaptation and shows that while closely associated, sensation and perception are different. Additionally, when you walk into a dark movie theater after being outside on a bright day you will notice it is initially extremely difficult to see. After a couple minutes you experience what is known as dark adaptation which tends to take about 8 minutes for cones (visual acuity and color), and about 30 minutes for the cones in your retina to adapt (light, dark, depth and distance) (Hecht & Mendelbaum, 1938; Klaver, Wolfs, Vingerling, Hoffman, & de Jong, 1998). If you are wondering why it takes so long to adapt to darkness, in order to change the sensitivity of rods and cones, they must first undergo a complex chemical change associated with protein molecules which does not happen immediately. Now that you have adapted to the darkens of the theater, you have survived marathon watching the entire Lord of the Rings series, and you are emerging from the theater a seemly short ten hours after entering the theater, you may experience the process of light adaptation, barring it is still light outside. During light adaptation, the pupils constrict to reduce the amount of light flooding onto the retina and sensitivity to light is reduced for both rods and cones which takes usually less than 10 minutes (Ludel, 1978). So why is the process of raising sensitivity to light to adapt to darkness more complex than lowering sensitivity to adapt to light? Caruso (2007) has suggested that a more gradual process is involved in darkness adaptation due to humans tendency over the course of evolution to slowly adjust to darkness as the sun sets over the horizon.

There is another factor that affects sensation and perception: attention. Attention plays a significant role in determining what is sensed versus what is perceived. Imagine you are at a party full of music, chatter, and laughter. You get involved in an interesting conversation with a friend, and you tune out all the background noise. If someone interrupted you to ask what song had just finished playing, you would probably be unable to answer that question.

   One of the most interesting demonstrations of how important attention is in determining our perception of the environment occurred in a famous study conducted by Daniel Simons and Christopher Chabris (1999). In this study, participants watched a video of people dressed in black and white passing basketballs. Participants were asked to count the number of times the team in white passed the ball. During the video, a person dressed in a black gorilla costume walks among the two teams. You would think that someone would notice the gorilla, right? Nearly half of the people who watched the video didn’t notice the gorilla at all, despite the fact that he was clearly visible for nine seconds. Because participants were so focused on the number of times the white team was passing the ball, they completely tuned out other visual information. Failure to notice something that is completely visible because of a lack of attention is called inattentional blindness. More recent work evaluated inattention blindness related to cellphone use. Hyman, Boss, Wise, McKenzie & Caggiano (2010) classified participants based on whether they were walking while talking on their cell phone, listening to an MP3 player, walking without any electronics or walking as a pair. Participants were not aware that while they walked through the square a unicycling clown would ride right in front of them. After the students reached the outside of the square they were stopped and asked if they noticed the unicycling clown that rode in front of them. Cell phone users were found to walk more slowly, change directions more often, pay less attention to others around them and were also the most frequent group to report they did not noticed the unicycling clown. David Strayer and Frank Drews additionally examined cell phone use in a series of driving simulators and found that even when participants looked directly at the objects in the driving environment, they were less likely to create a durable memory of those objects if they were talking on a cell phone. This pattern was obtained for objects of both high and low relevance for their driving safety suggesting little meaningful cognitive analysis of objects in the driving environment outside the restricted focus of attention while maintaining a cell phone conversation. Additionally, in-vehicle conversations did not interfere with driving as much as cell phone conversations as Strayer and Drews suggest, drivers are better able to synchronize the processing demands of driving with in-vehicle conversations compared to cell-phone conversations. Overall it is apparent that directing the focus of our attention can lead to sometimes serious impairments of other information, and it appears cell phones can have a particularly dramatic impact on information processing while performing other tasks.

In a similar experiment to the activity above, researchers tested inattentional blindness by asking participants to observe images moving across a computer screen. They were instructed to focus on either white or black objects, disregarding the other color. When a red cross passed across the screen, about one third of subjects did not notice it (figure below) (Most, Simons, Scholl, & Chabris, 2000).

Nearly one third of participants in a study did not notice that a red cross passed on the screen because their attention was focused on the black or white figures. (credit: Cory Zanker)

Motivation can also affect perception. Have you ever been expecting a really important phone call and, while taking a shower, you think you hear the phone ringing, only to discover that it is not? If so, then you have experienced how motivation to detect a meaningful stimulus can shift our ability to discriminate between a true sensory stimulus and background noise. This motivational aspect of expectation in conversation additionally may be why such strong inattentional blindness has been found in relation to cell phone use. The ability to identify a stimulus when it is embedded in a distracting background is called signal detection theory .

Signal detection theory:  A theory explaining explaining how various factors influence our ability to detect weak signals in our environment.

Signal detection theory also explains why a mother is awakened by a quiet murmur from her baby but not by other sounds that occur while she is asleep. This also applies to air traffic controller communication, pilot and driver control panels as discussed previously, and even the monitoring of patient vital information while a surgeon performs surgery. In the case of air traffic controllers, the controllers need to be able to detect planes among many signals (blips) that appear on the radar screen and follow those planes as they move through the sky. In fact, the original work of the researcher who developed signal detection theory was focused on improving the sensitivity of air traffic controllers to plane blips (Swets, 1964).

Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life experiences. As you will see later in this chapter, individuals who are deprived of the experience of binocular vision during critical periods of development have trouble perceiving depth (Fawcett, Wang, & Birch, 2005). The shared experiences of people within a given cultural context can have pronounced effects on perception. For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963) published the results of a multinational study in which they demonstrated that individuals from Western cultures were more prone to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa. One such illusion that Westerners were more likely to experience was the Müller-Lyer illusion (figure below): The lines appear to be different lengths, but they are actually the same length.

In the Müller-Lyer illusion, lines appear to be different lengths although they are identical. (a) Arrows at the ends of lines may make the line on the right appear longer, although the lines are the same length. (b) When applied to a three-dimensional image, the line on the right again may appear longer although both black lines are the same length.

   These perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context. People in Western cultures, for example, have a perceptual context of buildings with straight lines, what Segall’s study called a carpentered world (Segall et al., 1966). In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion (Segall et al., 1999). It is not just vision that is affected by cultural factors. Indeed, research has demonstrated that the ability to identify an odor, and rate its pleasantness and its intensity, varies cross-culturally (Ayabe-Kanamura, Saito, Distel, Martínez-Gómez, & Hudson, 1998). In terms of color vision across cultures, research has found derived color terms for brown, orange and pink hues do appear to be influenced by cultural differences (Zollinger, 1988).

Children described as thrill seekers are more likely to show taste preferences for intense sour flavors (Liem, Westerbeek, Wolterink, Kok, & de Graaf, 2004), which suggests that basic aspects of personality might affect perception. Furthermore, individuals who hold positive attitudes toward reduced-fat foods are more likely to rate foods labeled as reduced fat as tasting better than people who have less positive attitudes about these products (Aaron, Mela, & Evans, 1994).

   Sensation occurs when sensory receptors detect sensory stimuli. Perception involves the organization, interpretation, and conscious experience of those sensations. All sensory systems have both absolute and difference thresholds, which refer to the minimum amount of stimulus energy or the minimum amount of difference in stimulus energy required to be detected about 50% of the time, respectively. Sensory adaptation, selective attention, and signal detection theory can help explain what is perceived and what is not. In addition, our perceptions are affected by a number of factors, including beliefs, values, prejudices, culture, and life experiences.

References:

Openstax Psychology text by Kathryn Dumper, William Jenkins, Arlene Lacombe, Marilyn Lovett and Marion Perlmutter licensed under CC BY v4.0. https://openstax.org/details/books/psychology

Review Questions:

1. ________ refers to the minimum amount of stimulus energy required to be detected 50% of the time.

a. absolute threshold

b. difference threshold

c. just noticeable difference

d. transduction

2. Decreased sensitivity to an unchanging stimulus is known as ________.

a. transduction

c. sensory adaptation

d. inattentional blindness

3. ________ involves the conversion of sensory stimulus energy into neural impulses.

a. sensory adaptation

b. inattentional blindness

c. difference threshold

4. ________ occurs when sensory information is organized, interpreted, and consciously experienced.

a. sensation

b. perception

c. transduction

d. sensory adaptation

Critical Thinking Question:

1. Not everything that is sensed is perceived. Do you think there could ever be a case where something could be perceived without being sensed?

2. Please generate a novel example of how just noticeable difference can change as a function of stimulus intensity.

Personal Application Question :

1. Think about a time when you failed to notice something around you because your attention was focused elsewhere. If someone pointed it out, were you surprised that you hadn’t noticed it right away?

absolute threshold

bottom-up processing

inattentional blindness

just noticeable difference

sensory adaptation

signal detection theory

subliminal message

top-down processing

transduction

Answers to Exercises

1. This would be a good time for students to think about claims of extrasensory perception. Another interesting topic would be the phantom limb phenomenon experienced by amputees.

2. There are many potential examples. One example involves the detection of weight differences. If two people are holding standard envelopes and one contains a quarter while the other is empty, the difference in weight between the two is easy to detect. However, if those envelopes are placed inside two textbooks of equal weight, the ability to discriminate which is heavier is much more difficult.

absolute threshold:  minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time

bottom-up processing:  system in which perceptions are built from sensory input

inattentional blindness:  failure to notice something that is completely visible because of a lack of attention

just noticeable difference:  difference in stimuli required to detect a difference between the stimuli

perception:  way that sensory information is interpreted and consciously experienced

sensation:  what happens when sensory information is detected by a sensory receptor

sensory adaptation:  not perceiving stimuli that remain relatively constant over prolonged periods of time

signal detection theory:  change in stimulus detection as a function of current mental state

subliminal message:  message presented below the threshold of conscious awareness

top-down processing:  interpretation of sensations is influenced by available knowledge, experiences, and thoughts

transduction:  conversion from sensory stimulus energy to action potential

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Sensation and Perception

Introduction to Sensation and Perception

What you’ll learn to do: differentiate between sensation and perception.

Sensation and perception are two separate processes that are very closely related. Sensation is input about the physical world obtained by our sensory receptors, and perception is the process by which the brain selects, organizes, and interprets these sensations. In other words, senses are the physiological basis of perception. Perception of the same senses may vary from one person to another because each person’s brain interprets stimuli differently based on that individual’s learning, memory, emotions, and expectations.

LEARNING OBJECTIVES

• Define sensation and explain its connection to the concepts of absolute threshold, difference threshold, and subliminal messages
• Discuss the roles attention, motivation, and sensory adaptation play in perception

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• Introduction to Sensation. Provided by : Boundless. Located at : https://www.boundless.com/psychology/textbooks/boundless-psychology-textbook/sensation-and-perception-5/introduction-to-sensation-37/introduction-to-sensation-157-12692/ . Project : Boundless Psychology. License : CC BY-SA: Attribution-ShareAlike

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Basics: neuroscience and psychophysics

15 Psychophysical Methods

Learning Objectives

Be able to diagnose whether a given experiment measures an absolute threshold, a difference threshold, or is a magnitude estimation experiment

Be able to describe a couple of different methods of estimating a threshold

Know what a subliminal message is

Know Weber’s law (also called Weber-Fechner law)

The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold. Absolute threshold refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or how soft can a sound be to still be detected half of the time. The sensitivity of our sensory receptors can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away (Okawa & Sampath, 2007). Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962).

It is also possible for us to get messages that are presented below the threshold for conscious awareness—these are called subliminal messages. A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain: This is an absolute threshold. A message below that threshold is said to be subliminal—we receive it, but we are not consciously aware of it. Over the years there has been a great deal of speculation about the use of subliminal messages in advertising, rock music, and self-help audio programs. Research evidence shows that in laboratory settings, people can process and respond to information outside of awareness. But this does not mean that we obey these messages like zombies; in fact, hidden messages have little effect on behavior outside the laboratory (Kunst-Wilson & Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel, Sarrazin, Legrain, & Gobancé, 2009; Loersch, Durso, & Petty, 2013).

Subliminal messages exert diverse influences on our thoughts and our behavior ( van Gaal et al., 2012 ; Hassin, 2013 ). Subliminal stimuli can facilitate conscious processing of related information ( Van den Bussche et al., 2009 ), change our current mood ( Monahan et al., 2000 ), boost our motivation ( Aarts et al., 2008 ), and can even alter our political attitudes and voting intentions ( Hassin et al., 2007 ; Weinberger and Westen, 2008 ). With such a broad impact, subliminally planted information might have the potential to alter our decisions in everyday situations such as voting.

In order to influence decision-making in real-life situations, subliminal messages must be stored for long-term after only a few exposures, e.g. after a single confrontation with a subliminal TV advert. Furthermore, messages must be stored even if they contain complex relational information that requires semantic integration, such as “politician X will lower the taxes.” For subliminal manipulation to be effective, humans thus have to be able to semantically integrate and rapidly store unconscious pieces of novel information into long-lasting associative memories that can be retrieved if relevant to the context of a later decision.

Methods for estimating thresholds

When we design experiments, we have to decide how we’re going to approach a threshold estimation. Here are three common techniques

• Method of Limits . The experimenter can increase the stimulus intensity (or intensity difference) until the observer detects the stimulus (or the change). For example, turn up the volume until the observer first detects the sound. This is intuitive, but it is subject to bias — the estimated threshold is likely to be different, for example, if we start high and work down vs. start low and work up.
• Method of Adjustment. This is very much like the Method of Limits, except the experimenter gives the observer the knob: “adjust the stimulus until it’s very visible” or “adjust the color of the patch until it matches the test patch.”
• Method of Constant Stimuli . This is the most reliable, but most time-consuming. You decide ahead of time what levels you are going to measure, do each one a fixed number of times, and record % correct (or the number of detections) for each level. If you randomize the order, you can get rid of bias.

Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them. This is known as the just noticeable difference (JND) or difference threshold. Unlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. As an example, imagine yourself in a very dark movie theater. If an audience member were to receive a text message on her cell phone which caused her screen to light up, chances are that many people would notice the change in illumination in the theater. However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice. The cell phone brightness does not change, but its ability to be detected as a change in illumination varies dramatically between the two contexts. Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has become known as Weber’s law: the difference threshold is a constant fraction of the original stimulus, as the example illustrates.

Weber’s law is approximately true for many of our senses—for brightness perception, visual contrast perception, loudness perception, and visual distance estimation, our sensitivity to change decreases as the stimulus gets bigger or stronger. However, there are many senses for which the opposite is true: our sensitivity increases as the stimulus increases. With electric shock, for example, a small increase in the size of the shock is much more noticeable when the shock is large than when it is small. A psychophysical researcher named Stanley Smith Stevens asked people to estimate the magnitude of their sensations for many different kinds of stimuli at different intensities, and then tried to fit lines through the data to predict people’s sensory experiences (Stevens, 1967). What he discovered was that most senses could be described by a power law of the form P ∝S n where P is the perceived magnitude, ∝ means “is proportional to”, S is the physical stimulus magnitude, and n is a positive number. If n is greater than 1, then the slope (rate of change of perception) is getting larger as the stimulus gets larger, and sensitivity increases as stimulus intensity increases. A function like this is described as being expansive or supra-linear. If n is less than 1, then the slope decreases as the stimulus gets larger (the function “rolls over”). These sensations are described as being compressive. Weber’s Law is only (approximately) true for compressive (sublinear) functions; Stevens’ Power Law is useful for describing a wider range of senses.

Both Stevens’ Power Law and Weber’s Law are only approximately true. They are useful for describing, in broad strokes, how our perception of a stimulus depends on its intensity or size. They are rarely accurate for describing perception of stimuli that are near the absolute detection threshold. Still, they are useful for describing how people are going to react to normal everyday stimuli.

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OpenStax, Psychology Chapter 5.1 Sensation and Perception. Provided by: Rice University. Download for free at https://cnx.org/contents/[email protected]:K-DZ-03P@12/5-1-Sensation-versus-Perception. License: Creative Commons Attribution 4.0

Galanter, E. (1962). Contemporary Psychophysics. In R. Brown, E.Galanter, E. H. Hess, & G. Mandler (Eds.), New directions in psychology. New York, NY: Holt, Rinehart & Winston.

Kunst-Wilson, W. R., & Zajonc, R. B. (1980). Affective discrimination of stimuli that cannot be recognized. Science, 207, 557–558.

Nelson, M. R. (2008). The hidden persuaders: Then and now. Journal of Advertising, 37(1), 113–126.

Okawa, H., & Sampath, A. P. (2007). Optimization of single-photon response transmission at the rod-to-rod bipolar synapse. Physiology, 22, 279–286.

Radel, R., Sarrazin, P., Legrain, P., & Gobancé, L. (2009). Subliminal priming of motivational orientation in educational settings: Effect on academic performance moderated by mindfulness. Journal of Research in Personality, 43(4), 1–18.

Rensink, R. A. (2004). Visual sensing without seeing. Psychological Science, 15, 27–32.

Stevens, S. S. (1957). On the psychophysical law. Psychological Review 64(3):153—181. PMID 13441853

Introduction to Sensation and Perception Copyright © 2022 by Students of PSY 3031 and Edited by Dr. Cheryl Olman is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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22 Sensation versus Perception

Learning Objectives

By the end of this section, you will be able to:

• Distinguish between sensation and perception
• Describe the concepts of absolute threshold and difference threshold
• Discuss the roles attention, motivation, and sensory adaptation play in perception

What does it mean to sense something? Sensory receptors are specialized neurons that respond to specific types of stimuli . When sensory information is detected by a sensory receptor, sensation occurs. For example, light that enters the eye causes chemical changes in cells that line the back of the eye. These cells relay messages, in the form of action potentials (as you learned when studying biopsychology), to the central nervous system. The conversion from sensory stimulus energy to action potential is known as transduction .

You have probably known since elementary school that we have five senses: vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). It turns out that this notion of five senses is oversimplified. We also have sensory systems that provide information about balance (the vestibular sense), body position and movement (proprioception and kinesthesia), pain (nociception), and temperature (thermoception).

The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold. Absolute threshold refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time. The sensitivity of our sensory receptors can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away (Okawa & Sampath, 2007). Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962).

It is also possible for us to get messages that are presented below the threshold for conscious awareness—these are called subliminal messages . A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain; this is an absolute threshold. A message below that threshold is said to be subliminal; we receive it, but we are not consciously aware of it. Over the years there has been a great deal of speculation about the use of subliminal messages in advertising, rock music, and self-help audio programs. Research evidence shows that in laboratory settings, people can process and respond to information outside of awareness. But this does not mean that we obey these messages like zombies; in fact, hidden messages have little effect on behavior outside the laboratory (Kunst-Wilson & Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel, Sarrazin, Legrain, & Gobancé, 2009; Loersch, Durso, & Petty, 2013).

Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them. This is known as the just noticeable difference (jnd) or difference threshold . Unlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. As an example, imagine yourself in a very dark movie theater. If an audience member were to receive a text message on her cell phone which caused her screen to light up, chances are that many people would notice the change in illumination in the theater. However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice. The cell phone brightness does not change, but its ability to be detected as a change in illumination varies dramatically between the two contexts. Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has become known as Weber’s law: the difference threshold is a constant fraction of the original stimulus, as the example illustrates.

Try out the Just Noticeable Difference

The exercise below is to help demonstrate the concept of the just noticeable difference. On the left is a yellow circle on a black background. Below this image is a slider with two dots on either end. Notice how the yellow circle in the center becomes brighter when you click on the far right dot.

Now, consider the right-hand image where the yellow circle is against a white background. If you click between the two dots on either side of that slider, do you notice the yellow circle becoming brighter?

In both cases, the yellow dot increases in brightness with the same intensity. It is, however, much easier to notice when it is against a black background compared to when it is against a white background. This demonstrates how detecting small changes in a stimulus depends on the context around it.

Test Your Understanding

While our sensory receptors are constantly collecting information from the environment, it is ultimately how we interpret that information that affects how we interact with the world. Perception refers to the way sensory information is organized, interpreted, and consciously experienced. Perception involves both bottom-up and top-down processing. Bottom-up processing refers to the fact that perceptions are built from sensory input. On the other hand, how we interpret those sensations is influenced by our available knowledge, our experiences, and our thoughts. This is called top-down processing .

One way to think of this concept is that sensation is a physical process, whereas perception is psychological. For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the sensation is the scent receptors detecting the odor of cinnamon, but the perception may be “Mmm, this smells like the bread Grandma used to bake when the family gathered for holidays.”

Although our perceptions are built from sensations, not all sensations result in perception. In fact, we often don’t perceive stimuli that remain relatively constant over prolonged periods of time. This is known as sensory adaptation. Imagine entering a classroom with an old analog clock. Upon first entering the room, you can hear the ticking of the clock; as you begin to engage in conversation with classmates or listen to your professor greet the class, you are no longer aware of the ticking. The clock is still ticking, and that information is still affecting sensory receptors of the auditory system. The fact that you no longer perceive the sound demonstrates sensory adaptation and shows that while closely associated, sensation and perception are different.

There is another factor that affects sensation and perception: attention. Attention plays a significant role in determining what is sensed versus what is perceived. Imagine you are at a party full of music, chatter, and laughter. You get involved in an interesting conversation with a friend, and you tune out all the background noise. If someone interrupted you to ask what song had just finished playing, you would probably be unable to answer that question.

See for yourself how inattentional blindness works by checking out this selective attention test from Simons and Chabris (1999): selective attention test .

One of the most interesting demonstrations of how important attention is in determining our perception of the environment occurred in a famous study conducted by Daniel Simons and Christopher Chabris (1999). In this study, participants watched a video of people dressed in black and white passing basketballs. Participants were asked to count the number of times the team in white passed the ball. During the video, a person dressed in a black gorilla costume walks among the two teams. You would think that someone would notice the gorilla, right? Nearly half of the people who watched the video didn’t notice the gorilla at all, despite the fact that he was clearly visible for nine seconds. Because participants were so focused on the number of times the white team was passing the ball, they completely tuned out other visual information. Failure to notice something that is completely visible because of a lack of attention is called inattentional blindness .

In a similar experiment, researchers tested inattentional blindness by asking participants to observe images moving across a computer screen. They were instructed to focus on either white or black objects, disregarding the other color. When a red cross passed across the screen, about one-third of subjects did not notice it (Most, Simons, Scholl, & Chabris, 2000).

Motivation can also affect perception. Have you ever been expecting a really important phone call and, while taking a shower, you think you hear the phone ringing, only to discover that it is not? If so, then you have experienced how motivation to detect a meaningful stimulus can shift our ability to discriminate between a true sensory stimulus and background noise. The ability to identify a stimulus when it is embedded in a distracting background is called signal detection theory . This might also explain why a mother is awakened by a quiet murmur from her baby but not by other sounds that occur while she is asleep. Signal detection theory has practical applications, such as increasing air traffic controller accuracy. Controllers need to be able to detect planes among many signals (blips) that appear on the radar screen and follow those planes as they move through the sky. In fact, the original work of the researcher who developed signal detection theory was focused on improving the sensitivity of air traffic controllers to plane blips (Swets, 1964).

Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life experiences. As you will see later in this chapter, individuals who are deprived of the experience of binocular vision during critical periods of development have trouble perceiving depth (Fawcett, Wang, & Birch, 2005). The shared experiences of people within a given cultural context can have pronounced effects on perception. For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963) published the results of a multinational study in which they demonstrated that individuals from Western cultures were more prone to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa. One such illusion that Westerners were more likely to experience was the Müller-Lyer illusion: the lines appear to be different lengths, but they are actually the same length.

These perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context. People in Western cultures, for example, have a perceptual context of buildings with straight lines, what Segall’s study called a carpentered world (Segall et al., 1966). In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion (Segall et al., 1999). It is not just vision that is affected by cultural factors. Indeed, research has demonstrated that the ability to identify an odor, and rate its pleasantness and its intensity, varies cross-culturally (Ayabe-Kanamura, Saito, Distel, Martínez-Gómez, & Hudson, 1998).

Children described as thrill seekers are more likely to show taste preferences for intense sour flavors (Liem, Westerbeek, Wolterink, Kok, & de Graaf, 2004), which suggests that basic aspects of personality might affect perception. Furthermore, individuals who hold positive attitudes toward reduced-fat foods are more likely to rate foods labeled as reduced fat as tasting better than people who have less positive attitudes about these products (Aaron, Mela, & Evans, 1994).

Sensation occurs when sensory receptors detect sensory stimuli. Perception involves the organization, interpretation, and conscious experience of those sensations. All sensory systems have both absolute and difference thresholds, which refer to the minimum amount of stimulus energy or the minimum amount of difference in stimulus energy required to be detected about 50% of the time, respectively. Sensory adaptation, selective attention, and signal detection theory can help explain what is perceived and what is not. In addition, our perceptions are affected by a number of factors, including beliefs, values, prejudices, culture, and life experiences.

Review Questions

Critical thinking question.

This would be a good time for students to think about claims of extrasensory perception. Another interesting topic would be the phantom limb phenomenon experienced by amputees.

There are many potential examples. One example involves the detection of weight differences. If two people are holding standard envelopes and one contains a quarter while the other is empty, the difference in weight between the two is easy to detect. However, if those envelopes are placed inside two textbooks of equal weight, the ability to discriminate which is heavier is much more difficult.

Personal Application Question

Think about a time when you failed to notice something around you because your attention was focused elsewhere. If someone pointed it out, were you surprised that you hadn’t noticed it right away?

specialized neurons that respond to specific types of stimuli

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5 Sensation and Perception

Imagine standing on a city street corner. You might be struck by movement everywhere as cars and people go about their business, by the sound of a street musician’s melody or a horn honking in the distance, by the smell of exhaust fumes or of food being sold by a nearby vendor, and by the sensation of hard pavement under your feet.

We rely on our sensory systems to provide important information about our surroundings. We use this information to successfully navigate and interact with our environment so that we can find nourishment, seek shelter, maintain social relationships, and avoid potentially dangerous situations.

This chapter will provide an overview of how sensory information is received and processed by the nervous system and how that affects our conscious experience of the world. We begin by learning the distinction between sensation and perception. Then we consider the physical properties of light and sound stimuli, along with an overview of the basic structure and function of the major sensory systems. The chapter will close with a discussion of a historically important theory of perception called Gestalt.

Table of Contents

Sensation vs. perception.

Learning Objectives

By the end of this section, you will be able to:

• Distinguish between sensation and perception
• Describe the concepts of absolute threshold and difference threshold
• Discuss the roles attention, motivation, and sensory adaptation play in perception

What does it mean to sense something? Sensory receptors are specialized neurons that respond to specific types of stimuli. When sensory information is detected by a sensory receptor,  sensation  has occurred. For example, light that enters the eye causes chemical changes in cells that line the back of the eye. These cells relay messages, in the form of action potentials (as you learned when studying biopsychology), to the central nervous system. The conversion from sensory stimulus energy to action potential is known as transduction .

You have probably known since elementary school that we have five senses: vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). It turns out that this notion of five senses is oversimplified. We also have sensory systems that provide information about balance (the vestibular sense), body position and movement (proprioception and kinesthesia), pain (nociception), and temperature (thermoception).

The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold.  Absolute threshold  refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time. The sensitivity of our sensory receptors can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away (Okawa & Sampath, 2007). Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962).

Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them. This is known as the  just noticeable difference (jnd)  or   difference threshold . Unlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. As an example, imagine yourself in a very dark movie theater. If an audience member were to receive a text message that caused the cell phone screen to light up, chances are that many people would notice the change in illumination in the theater. However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice. The cell phone brightness does not change, but its ability to be detected as a change in illumination varies dramatically between the two contexts. Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has become known as Weber’s Law : The difference threshold is a constant fraction of the original stimulus, as the example illustrates.

While our sensory receptors are constantly collecting information from the environment, it is ultimately how we interpret that information that affects how we interact with the world.  Perception  refers to the way sensory information is organized, interpreted, and consciously experienced. Perception involves both bottom-up and top-down processing.  Bottom-up processing  refers to sensory information from a stimulus in the environment driving a process, and  top-down processing  refers to knowledge and expectancy driving a process, as shown in  Figure 5.2  (Egeth & Yantis, 1997; Fine & Minnery, 2009; Yantis & Egeth, 1999).

Imagine that you and some friends are sitting in a crowded restaurant eating lunch and talking. It is very noisy, and you are concentrating on your friend’s face to hear what she is saying. Suddenly, the sound of breaking glass and clang of metal pans hitting the floor rings out. The server dropped a large tray of food. Although you were attending to your meal and conversation, that crashing sound would likely get through your attentional filters and capture your attention. You would have no choice but to notice it. That attentional capture would be caused by the sound from the environment: it would be bottom-up.

Alternatively, top-down processes are generally goal directed, slow, deliberate, effortful, and under your control (Fine & Minnery, 2009; Miller & Cohen, 2001; Miller & D’Esposito, 2005). For instance, if you misplaced your keys, how would you look for them? If you had a yellow key fob, you would probably look for yellowness of a certain size in specific locations, such as on the counter, coffee table, and other similar places. You would not look for yellowness on your ceiling fan, because you know keys are not normally lying on top of a ceiling fan. That act of searching for a certain size of yellowness in some locations and not others would be top-down—under your control and based on your experience.

One way to think of this concept is that sensation is a physical process, whereas perception is psychological. For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the  sensation  is the scent receptors detecting the odor of cinnamon, but the  perception  may be “Mmm, this smells like the bread Grandma used to bake for holidays.”

There is another factor that affects sensation and perception: attention . Attention plays a significant role in determining what is sensed versus what is perceived. Imagine you are at a party full of music, chatter, and laughter. You get involved in an interesting conversation with a friend, and you tune out all the background noise. If someone interrupted you to ask what song had just finished playing, you would probably be unable to answer that question. Your attention prevented you from fully processing the information from the song to allow you to process your conversation with your friend.

One of the most interesting demonstrations of how important attention is in determining our perception of the environment occurred in a famous study conducted by Daniel Simons and Christopher Chabris (1999). In this study, participants watched a video of people dressed in black and white passing basketballs. Participants were asked to count the number of times the team dressed in white passed the ball. During the video, a person dressed in a black gorilla costume walks among the two teams. You would think that someone would notice the gorilla, right? Nearly half of the people who watched the video didn’t notice the gorilla at all, despite the fact that he was clearly visible for nine seconds. Because participants were so focused on the number of times the team dressed in white was passing the ball, they completely tuned out other visual information.  Inattentional blindness  is the failure to notice something that is completely visible because the person was actively attending to something else and did not pay attention to other things (Mack & Rock, 1998; Simons & Chabris, 1999).

In a similar experiment, researchers tested inattentional blindness by asking participants to observe images moving across a computer screen. They were instructed to focus on either white or black objects, disregarding the other color. When a red cross passed across the screen, about one third of subjects did not notice it ( Figure 5.3 ) (Most, Simons, Scholl, & Chabris, 2000).

Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life experiences. As you will see later in this chapter, individuals who are deprived of the experience of binocular vision during critical periods of development have trouble perceiving depth (Fawcett, Wang, & Birch, 2005). The shared experiences of people within a given cultural context can have pronounced effects on perception. For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963) published the results of a multinational study in which they demonstrated that individuals from Western  cultures  were more prone to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa. One such illusion that Westerners were more likely to experience was the  Müller-Lyer  illusion ( Figure 5.4 ): The lines appear to be different lengths, but they are actually the same length.

These perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context. People in Western cultures, for example, have a perceptual context of buildings with straight lines, what Segall’s study called a carpentered world (Segall et al., 1966). In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion (Segall et al., 1999). It is not just vision that is affected by cultural factors. Indeed, research has demonstrated that the ability to identify an odor, and rate its pleasantness and its intensity, varies cross-culturally (Ayabe-Kanamura, Saito, Distel, Martínez-Gómez, & Hudson, 1998).

Children described as thrill seekers are more likely to show taste preferences for intense sour flavors (Liem, Westerbeek, Wolterink, Kok, & de Graaf, 2004), which suggests that basic aspects of personality might affect perception. Furthermore, individuals who hold positive attitudes toward reduced-fat foods are more likely to rate foods labeled as reduced fat as tasting better than people who have less positive attitudes about these products (Aaron, Mela, & Evans, 1994).

Waves and Wavelengths

• Describe important physical features of wave forms
• Show how physical properties of light waves are associated with perceptual experience
• Show how physical properties of sound waves are associated with perceptual experience

Amplitude and Wavelength

Two physical characteristics of a wave are amplitude and wavelength ( Figure 5.5 ). The  amplitude  of a wave is the distance from the center line to the top point of the crest or the bottom point of the trough.  Wavelength  refers to the length of a wave from one peak to the next.

Wavelength is directly related to the frequency of a given wave form.  Frequency  refers to the number of waves that pass a given point in a given time period and is often expressed in terms of  hertz (Hz) , or cycles per second. Longer wavelengths will have lower frequencies, and shorter wavelengths will have higher frequencies ( Figure 5.6 ).

Light Waves

The  visible spectrum  is the portion of the larger  electromagnetic spectrum  that we can see. As  Figure 5.7  shows, the electromagnetic spectrum encompasses all of the electromagnetic radiation that occurs in our environment and includes gamma rays, x-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves. The visible spectrum in humans is associated with wavelengths that range from 380 to 740 nm—a very small distance, since a nanometer (nm) is one billionth of a meter. Other species can detect other portions of the electromagnetic spectrum. For instance, honeybees can see light in the ultraviolet range (Wakakuwa, Stavenga, & Arikawa, 2007), and some snakes can detect infrared radiation in addition to more traditional visual light cues (Chen, Deng, Brauth, Ding, & Tang, 2012; Hartline, Kass, & Loop, 1978).

Sound Waves

Like light waves, the physical properties of sound waves are associated with various aspects of our perception of sound. The frequency of a sound wave is associated with our perception of that sound’s  pitch . High-frequency sound waves are perceived as high-pitched sounds, while low-frequency sound waves are perceived as low-pitched sounds. The audible range of sound frequencies is between 20 and 20000 Hz, with greatest sensitivity to those frequencies that fall in the middle of this range.

As was the case with the visible spectrum, other species show differences in their audible ranges. For instance, chickens have a very limited audible range, from 125 to 2000 Hz. Mice have an audible range from 1000 to 91000 Hz, and the beluga whale’s audible range is from 1000 to 123000 Hz. Our pet dogs and cats have audible ranges of about 70–45000 Hz and 45–64000 Hz, respectively (Strain, 2003).

The loudness of a given sound is closely associated with the amplitude of the sound wave. Higher amplitudes are associated with louder sounds. Loudness is measured in terms of  decibels (dB) , a logarithmic unit of sound intensity. A typical conversation would correlate with 60 dB; a rock concert might check in at 120 dB ( Figure 5.9 ). A whisper 5 feet away or rustling leaves are at the low end of our hearing range; sounds like a window air conditioner, a normal conversation, and even heavy traffic or a vacuum cleaner are within a tolerable range.

Very loud sounds, those in the 80 dB to 130 dB range can cause hearing damage: These are sounds of a food processor, power lawnmower, heavy truck (25 feet away), subway train (20 feet away), live rock music, and a jackhammer. The threshold for pain is about 130 dB, a jet plane taking off or a revolver firing at close range (Dunkle, 1982).

About one-third of all hearing loss is due to noise exposure, and the louder the sound, the shorter the exposure needed to cause hearing damage (Le, Straatman, Lea, & Westerberg, 2017). For example, listening to music through earbuds at maximum volume (around 100–105 decibels) can cause noise-induced hearing loss after 15 minutes of exposure. Over time, listening to loud music increases the risk of age-related hearing loss (Kujawa & Liberman, 2006).

Of course, different musical instruments can play the same musical note at the same level of loudness, yet they still sound quite different. This is known as the timbre of a sound.  Timbre  refers to a sound’s purity, and it is affected by the complex interplay of frequency, amplitude, and timing of sound waves.

The Visual System

• Describe the basic anatomy of the visual system
• Discuss how rods and cones contribute to different aspects of vision
• Describe how monocular and binocular cues are used in the perception of depth

The visual system constructs a mental representation of the world around us ( Figure 5.10 ). This contributes to our ability to successfully navigate through physical space and interact with important individuals and objects in our environments. This section will provide an overview of the basic anatomy and function of the visual system. In addition, we will explore our ability to perceive color and depth.

Anatomy of the Visual System

The eye is the major sensory organ involved in  vision  ( Figure 5.11 ). Light waves are transmitted across the cornea and enter the eye through the pupil . The  cornea  is the transparent covering over the eye. It serves as a barrier between the inner eye and the outside world, and it is involved in focusing light waves that enter the eye through the pupil. The  pupil  is the small opening in the eye through which light passes, and the size of the pupil can change as a function of light levels as well as emotional arousal. The pupil’s size is controlled by muscles that are connected to the  iris , which is the colored portion of the eye. When light levels are low, the iris shrinks and the pupil becomes dilated, or expanded, to allow more light to enter the eye. When light levels are high, the iris grows larger and the pupil will constrict, or become smaller, to reduce the amount of light that enters the eye.

After passing through the pupil, light crosses the  lens , a curved, transparent structure that serves to provide additional focus. The lens is attached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects. In a normal-sighted individual, the lens will focus images perfectly on a small indentation in the back of the eye known as the  fovea , which is part of the  retina , the light-sensitive lining of the eye. The fovea contains densely packed specialized photoreceptor cells ( Figure 5.12 ). These  photoreceptor  cells, known as cones , are light-detecting cells. The  cones  are specialized types of photoreceptors that work best in bright light conditions. Cones are very sensitive to acute detail and provide tremendous spatial resolution. They also are directly involved in our ability to perceive color.

While cones are concentrated in the fovea, where images tend to be focused, rods , another type of photoreceptor, are located throughout the remainder of the retina.  Rods  are specialized photoreceptors that work well in low light conditions, and while they lack the spatial resolution and color function of the cones, they are involved in our vision in dimly lit environments as well as in our perception of movement on the periphery of our visual field.

We have all experienced the different sensitivities of rods and cones when making the transition from a brightly lit environment to a dimly lit environment. Imagine going to see a blockbuster movie on a clear summer day. As you walk from the brightly lit lobby into the dark theater, you notice that you immediately have difficulty seeing much of anything. After a few minutes, you begin to adjust to the darkness and can see the interior of the theater. In the bright environment, your vision was dominated primarily by cone activity. As you move to the dark environment, rod activity dominates, but there is a delay in transitioning between the phases. If your rods do not transform light into nerve impulses as easily and efficiently as they should, you will have difficulty seeing in dim light, a condition known as night blindness.

Rods and cones are connected (via several interneurons) to retinal ganglion cells . Axons from the retinal ganglion cells converge and exit through the back of the eye to form the  optic nerve . The optic nerve carries visual information from the retina to the brain. There is a point in the visual field called the  blind spot : Even when light from a small object is focused on the blind spot, we do not see it. We are not consciously aware of our blind spots for two reasons: First, each eye gets a slightly different view of the visual field; therefore, the blind spots do not overlap. Second, our visual system fills in the blind spot so that although we cannot respond to visual information that occurs in that portion of the visual field, we are also not aware that information is missing.

Try these labeling exercises (and don’t cheat!)

The optic nerve from each eye merges just below the brain at a point called the  optic chiasm . As  Figure 5.13  shows, the optic chiasm is an X-shaped structure that sits just below the cerebral cortex at the front of the brain. At the point of the optic chiasm, information from the right visual field (which comes from both eyes) is sent to the left side of the brain, and information from the left visual field is sent to the right side of the brain.

Once inside the brain, visual information is sent via a number of structures to primary visual cortex in the occipital lobe. Visual information is processed in parallel pathways which can generally be described as the “ what pathway ” and the “where/how” pathway. The “what pathway” is involved in object recognition and identification and primarily relies on regions in the temporal lobe.  The “ where/how pathway ” is involved with objects’ location in space and how one might interact with a particular visual stimulus (Milner & Goodale, 2008; Ungerleider & Haxby, 1994). The where/how pathway relies on regions of the parietal lobe. When you see a ball rolling down the street, the “what pathway” identifies what the object is, and the “where/how pathway” identifies its location and movement in space.

WHAT DO YOU THINK? The Ethics of Research Using Animals

David Hubel and Torsten Wiesel were awarded the Nobel Prize in Medicine in 1981 for their research on the visual system. They collaborated for more than twenty years and made significant discoveries about the neurology of visual perception (Hubel & Wiesel, 1959, 1962, 1963, 1970; Wiesel & Hubel, 1963). They studied animals, mostly cats and monkeys. Although they used several techniques, they did considerable single unit recordings, during which tiny electrodes were inserted in the animal’s brain to determine when a single cell was activated. Among their many discoveries, they found that specific brain cells respond to lines with specific orientations (called ocular dominance), and they mapped the way those cells are arranged in areas of the visual cortex known as columns and hypercolumns.

In some of their research, they sutured one eye of newborn kittens closed and followed the development of the kittens’ vision. They discovered there was a critical period of development for vision. If kittens were deprived of input from one eye, other areas of their visual cortex filled in the area that was normally used by the eye that was sewn closed. In other words, neural connections that exist at birth can be lost if they are deprived of sensory input.

What do you think about sewing a kitten’s eye closed for research? To many animal advocates, this would seem brutal, abusive, and unethical. What if you could do research that would help ensure babies and children born with certain conditions could develop normal vision instead of becoming blind? Would you want that research done? Would you conduct that research, even if it meant causing some harm to cats? Would you think the same way if you were the parent of such a child? What if you worked at the animal shelter?

Like virtually every other industrialized nation, the United States permits medical experimentation on animals, with few limitations (assuming sufficient scientific justification). The goal of any laws that exist is not to ban such tests but rather to limit unnecessary animal suffering by establishing standards for the humane treatment and housing of animals in laboratories.

As explained by Stephen Latham, the director of the Interdisciplinary Center for Bioethics at Yale (2012), possible legal and regulatory approaches to animal testing vary on a continuum from strong government regulation and monitoring of all experimentation at one end, to a self-regulated approach that depends on the ethics of the researchers at the other end. The United Kingdom has the most significant regulatory scheme, whereas Japan uses the self-regulation approach. The U.S. approach is somewhere in the middle, the result of a gradual blending of the two approaches.

There is no question that medical research is a valuable and important practice. The question is whether the use of animals is a necessary or even best practice for producing the most reliable results. Alternatives include the use of patient-drug databases, virtual drug trials, computer models and simulations, and noninvasive imaging techniques such as magnetic resonance imaging and computed tomography scans (“Animals in Science/Alternatives,” n.d.). Other techniques, such as microdosing, use humans not as test animals but as a means to improve the accuracy and reliability of test results. In vitro methods based on human cell and tissue cultures, stem cells, and genetic testing methods are also increasingly available.

Today, at the local level, any facility that uses animals and receives federal funding must have an Institutional Animal Care and Use Committee (IACUC) that ensures that the NIH guidelines are being followed. The IACUC must include researchers, administrators, a veterinarian, and at least one person with no ties to the institution: that is, a concerned citizen. This committee also performs inspections of laboratories and protocols.

Color and Depth Perception

We do not see the world in black and white; neither do we see it as two-dimensional (2-D) or flat (just height and width, no depth). Let’s look at how color vision works and how we perceive three dimensions (height, width, and depth).

Color Vision

Normal-sighted individuals have three different types of cones that mediate  color vision . Each of these cone types is maximally sensitive to a slightly different wavelength of light. According to the  trichromatic theory of color vision , shown in  Figure 5.14 , all colors in the spectrum can be produced by combining red, green, and blue. The three types of cones are each receptive to one of the colors.

CONNECT THE CONCEPTS

Colorblindness: a personal story.

Several years ago, I dressed to go to a public function and walked into the kitchen where my 7-year-old daughter sat. She looked up at me, and in her most stern voice, said, “You can’t wear that.” I asked, “Why not?” and she informed me the colors of my clothes did not match. She had complained frequently that I was bad at matching my shirts, pants, and ties, but this time, she sounded especially alarmed. As a single father with no one else to ask at home, I drove us to the nearest convenience store and asked the store clerk if my clothes matched. She said my pants were a bright green color, my shirt was a reddish-orange, and my tie was brown. She looked at my quizzically and said, “No way do your clothes match.” Over the next few days, I started asking my coworkers and friends if my clothes matched. After several days of being told that my coworkers just thought I had “a really unique style,” I made an appointment with an eye doctor and was tested ( Figure 5.15 ). It was then that I found out that I was colorblind. I cannot differentiate between most greens, browns, and reds. Fortunately, other than unknowingly being badly dressed, my colorblindness rarely harms my day-to-day life.

Some forms of color deficiency are rare. Seeing in grayscale (only shades of black and white) is extremely rare, and some people who do so only have rods, which means they also have very low visual acuity. The most common X-linked inherited abnormality is red-green color blindness (Birch, 2012). Individuals with red-green colorblindness struggle to differentiate between reds and greens. Approximately 8% of males with European Caucasian descent, 5% of Asian males, 4% of African males, and less than 2% of indigenous American males, Australian males, and Polynesian males have red-green color deficiency (Birch, 2012). Comparatively, only about 0.4% of females from European Caucasian descent have red-green color deficiency (Birch, 2012).

Another major theory of color vision is known as the  opponent-process theory . According to this theory, color is coded in opponent pairs: black-white, yellow-blue, and green-red. The basic idea is that some cells of the visual system are excited by one of the opponent colors and inhibited by the other. So, a cell that was excited by wavelengths associated with green would be inhibited by wavelengths associated with red, and vice versa. One of the implications of opponent processing is that we do not experience greenish-reds or yellowish-blues as colors. Another implication is that this leads to the experience of negative afterimages. An  afterimage  describes the continuation of a visual sensation after removal of the stimulus.

For example, when you stare briefly at a bright light and then look away from it, you may perceive a spot of darkness where the light was in your visual field. When color is involved in the stimulus, the color pairings identified in the opponent-process theory lead to a negative afterimage. You can test this concept using the flag in  Figure 5.16 .

The trichromatic theory of color vision and the opponent-process theory are not mutually exclusive. Research has shown that the two theories apply to different levels of the nervous system. Trichromatic theory describes the cone cells in our retina: we have three cone types that are responsive to three different wavelengths that represent red, blue, and green. Once the signal moves past the cones on its way to the brain, other neurons respond in a way consistent with opponent-process theory (Land, 1959; Kaiser, 1997).

Depth Perception

Our ability to perceive spatial relationships in three-dimensional (3-D) space is known as  depth perception . With depth perception, we can describe things as being in front, behind, above, below, or to the side of other things.

We use a variety of cues in a visual scene to establish our sense of depth. Some of these are  binocular   cues , which means that they rely on the use of both eyes. The basis of binocular depth cues is b inocular disparity , the slightly different view of the world that each of our eyes receives. To experience this slightly different view, do this simple exercise: extend your arm fully and extend one of your fingers and focus on that finger. Now, close your left eye without moving your head, then open your left eye and close your right eye without moving your head. You will notice that your finger seems to shift as you alternate between the two eyes because of the slightly different view each eye has of your finger.

A 3-D movie works on the same principle: the special glasses you wear allow the two slightly different images projected onto the screen to be seen separately by your left and your right eye. As your brain processes these images, you have the illusion that the leaping animal or running person is coming right toward you.

Although we rely on binocular cues to experience depth in our 3-D world, we can also perceive depth in 2-D arrays. Think about all the paintings and photographs you have seen. Generally, you pick up on depth in these images even though the visual stimulus is 2-D. When we do this, we are relying on a number of  monocular cues , or cues that require only one eye. If you think you can’t see depth with one eye, note that you don’t bump into things when using only one eye while walking—and, in fact, we have more monocular cues than binocular cues.

Monocular depth cues include occlusion (a nearer object blocks our view of a farther object), relative size (objects appear larger when they are nearby and smaller when they are further away), and linear perspective.  Linear perspective  refers to the fact that  parallel lines seem to converge in depth ( Figure 5.17 ). You might recognize the idea of linear perspective from art class where it is called a vanishing point. Many artists use linear perspective/vanishing points to establish depth in their works.

DIG DEEPER: Stereoblindness

Bruce Bridgeman was born with an extreme case of lazy eye that resulted in him being stereoblind, or unable to respond to binocular cues of depth. He relied heavily on monocular depth cues, but he never had a true appreciation of the 3-D nature of the world around him. This all changed one night in 2012 while Bruce was seeing a movie with his wife.

The movie the couple was going to see was shot in 3-D, and even though he thought it was a waste of money, Bruce paid for the 3-D glasses when he purchased his ticket. As soon as the film began, Bruce put on the glasses and experienced something completely new. For the first time in his life he appreciated the true depth of the world around him. Remarkably, his ability to perceive depth persisted outside of the movie theater.

There are cells in the nervous system that respond to binocular depth cues. Normally, these cells require activation during early development in order to persist, so experts familiar with Bruce’s case (and others like his) assume that at some point in his development, Bruce must have experienced at least a fleeting moment of binocular vision. It was enough to ensure the survival of the cells in the visual system tuned to binocular cues. The mystery now is why it took Bruce nearly 70 years to have these cells activated (Peck, 2012).

The Auditory System

• Describe the basic anatomy and function of the auditory system
• Explain how we encode and perceive pitch
• Discuss how we localize sound

Our auditory system converts pressure waves into meaningful sounds. This translates into our ability to hear the sounds of nature, to appreciate the beauty of music, and to communicate with one another through spoken language. This section will provide an overview of the basic anatomy and function of the auditory system. It will include a discussion of how the sensory stimulus is translated into neural impulses, where in the brain that information is processed, how we perceive pitch, and how we know where sound is coming from.

Anatomy of the Auditory System

The ear can be separated into three sections: the outer, middle, and inner ear. The outer ear includes the  pinna , which is the visible part of the ear that protrudes from our heads, the auditory canal, and the  tympanic membrane , or eardrum. The middle ear contains three tiny bones known as the  ossicles , which are named the  malleus  (or hammer),  incus  (or anvil), and the  stapes  (or stirrup). The inner ear contains the semi-circular canals, which are involved in balance and movement (the vestibular sense), and the cochlea. The  cochlea  is a fluid-filled, snail-shaped structure that contains the sensory receptor cells (hair cells) of the auditory system ( Figure 5.18 ).

Sound waves travel along the auditory canal and strike the tympanic membrane, causing it to vibrate. This vibration results in movement of the three ossicles. As the ossicles move, the stapes presses into a thin membrane of the cochlea known as the oval window. As the stapes presses into the oval window, the fluid inside the cochlea begins to move, eventually stimulating auditory receptor cells called hair cells. Hair cells do not grow hairs. Instead, they are called hair cells because they have thin projections of their cell membranes, called stereocilia, that look like hair ( Figure 5.19 ).

The activation of hair cells is a mechanical process. When the stereocilia of a hair cell bend from sound waves traveling through the cochlea, the hair cell becomes activated and stimulates the auditory nerve. Action potentials in the auditory nerve travel to the brain. Auditory information is shuttled to the inferior colliculus, the medial geniculate nucleus of the thalamus, and finally to the auditory cortex in the temporal lobe of the brain for processing. Like the visual system, there is also evidence suggesting that information about auditory recognition and localization is processed in parallel streams (Rauschecker & Tian, 2000; Renier et al., 2009).

Pitch Perception

Different frequencies of sound waves are associated with differences in our perception of the pitch of those sounds. Low-frequency sounds are lower pitched, and high-frequency sounds are higher pitched. How does the auditory system differentiate among various pitches?

The  place theory  of pitch perception suggests that different portions of the cochlea are sensitive to sounds of different frequencies. More specifically, hair cells in the base of the cochlea (nearest the stapes and oval window) respond best to high frequencies and hair cells near the tip of the cochlea respond best to low frequencies (Shamma, 2001).

Hearing Loss

Deafness  is the partial or complete inability to hear. Some people are born without hearing, which is known as  congenital deafness . Other people suffer from  conductive hearing loss , which is due to a problem delivering sound energy to the cochlea. Causes for conductive hearing loss include blockage of the ear canal, a hole in the tympanic membrane, problems with the ossicles, or fluid in the space between the eardrum and cochlea. Another group of people suffer from sensorineural hearing loss, which is the most common form of hearing loss. Sensorineural hearing loss can be caused by many factors, such as aging, head or acoustic trauma, infections and diseases (such as measles or mumps), medications, environmental effects such as noise exposure (noise-induced hearing loss, as shown in  Figure 5.20 ), tumors, and toxins (such as those found in certain solvents and metals).

Given the mechanical nature by which the sound wave stimulus is transmitted from the eardrum through the ossicles to the oval window of the cochlea, some degree of hearing loss is inevitable. With conductive hearing loss, hearing problems are associated with a failure in the vibration of the eardrum and/or movement of the ossicles. These problems are often dealt with through devices like hearing aids that amplify incoming sound waves to make vibration of the eardrum and movement of the ossicles more likely to occur.

When the hearing problem is associated with a failure to transmit neural signals from the cochlea to the brain, it is called  sensorineural hearing loss . One disease that results in sensorineural hearing loss is  Ménière’s disease . Although not well understood, Ménière’s disease results in a degeneration of inner ear structures that can lead to hearing loss, tinnitus (constant ringing or buzzing),  vertigo  (a sense of spinning), and an increase in pressure within the inner ear (Semaan & Megerian, 2011). This kind of loss cannot be treated with hearing aids, but some individuals might be candidates for a cochlear implant as a treatment option.  Cochlear implants  are electronic devices that consist of a microphone, a speech processor, and an electrode array. The device receives incoming sound information and directly stimulates the auditory nerve to transmit information to the brain.

WHAT DO YOU THINK? Deaf Culture

In the United States and other places around the world, deaf people have their own language, schools, and customs. This is called  deaf culture . In the United States, deaf individuals often communicate using American Sign Language (ASL); ASL has no verbal component and is based entirely on visual signs and gestures. The primary mode of communication is signing. One of the values of deaf culture is to continue traditions like using sign language rather than teaching deaf children to try to speak, read lips, or have cochlear implant surgery.

When a child is diagnosed as deaf, parents have difficult decisions to make. Should the child be enrolled in mainstream schools and taught to verbalize and read lips? Or should the child be sent to a school for deaf children to learn ASL and have significant exposure to deaf culture? Do you think there might be differences in the way that parents approach these decisions depending on whether or not they are also deaf?

The Other Senses

• Describe the basic functions of the chemical senses
• Explain the basic functions of the somatosensory, nociceptive, and thermoceptive sensory systems
• Describe the basic functions of the vestibular, proprioceptive, and kinesthetic sensory systems

Vision and hearing have received an incredible amount of attention from researchers over the years. While there is still much to be learned about how these sensory systems work, we have a much better understanding of them than of our other sensory modalities. In this section, we will explore our chemical senses (taste and smell) and our body senses (touch, temperature, pain, balance, and body position).

The Chemical Senses

Taste (gustation) and  smell  (olfaction) are called chemical senses because both have sensory receptors that respond to molecules in the food we eat or in the air we breathe. There is a pronounced interaction between our chemical senses. For example, when we describe the flavor of a given food, we are really referring to both gustatory and olfactory properties of the food working in combination.

Taste (Gustation)

You have learned since elementary school that there are four basic groupings of taste: sweet, salty, sour, and bitter. Research demonstrates, however, that we have at least six  taste  groupings. Umami is our fifth taste.  Umami  is actually a Japanese word that roughly translates to yummy, and it is associated with a taste for monosodium glutamate (Kinnamon & Vandenbeuch, 2009). There is also a growing body of experimental evidence suggesting that we possess a taste for the fatty content of a given food (Mizushige, Inoue, & Fushiki, 2007).

Molecules from the food and beverages we consume dissolve in our saliva and interact with taste receptors on our tongue and in our mouth and throat.  Taste buds  are formed by groupings of taste receptor cells with hair-like extensions that protrude into the central pore of the taste bud ( Figure 5.21 ). Taste buds have a life cycle of ten days to two weeks, so even destroying some by burning your tongue won’t have any long-term effect; they just grow right back. Taste molecules bind to receptors on this extension and cause chemical changes within the sensory cell that result in neural impulses being transmitted to the brain via different nerves, depending on where the receptor is located. Taste information is transmitted to the medulla, thalamus, and limbic system, and to the gustatory cortex, which is tucked underneath the overlap between the frontal and temporal lobes (Maffei, Haley, & Fontanini, 2012; Roper, 2013).

Smell (Olfaction)

Olfactory receptor  cells are located in a mucous membrane at the top of the nose. Small hair-like extensions from these receptors serve as the sites for odor molecules dissolved in the mucus to interact with chemical receptors located on these extensions ( Figure 5.22 ). Once an odor molecule has bound a given receptor, chemical changes within the cell result in signals being sent to the  olfactory bulb : a bulb-like structure at the tip of the frontal lobe where the olfactory nerves begin. From the olfactory bulb, information is sent to regions of the limbic system and to the primary olfactory cortex, which is located very near the gustatory cortex (Lodovichi & Belluscio, 2012; Spors et al., 2013).

There is tremendous variation in the sensitivity of the olfactory systems of different species. We often think of dogs as having far superior olfactory systems than our own, and indeed, dogs can do some remarkable things with their noses. There is some evidence to suggest that dogs can “smell” dangerous drops in blood glucose levels as well as cancerous tumors (Wells, 2010). Dogs’ extraordinary olfactory abilities may be due to the increased number of functional genes for olfactory receptors (between 800 and 1200), compared to the fewer than 400 observed in humans and other primates (Niimura & Nei, 2007).

Many species respond to chemical messages, known as  pheromones , sent by another individual (Wysocki & Preti, 2004). Pheromonal communication often involves providing information about the reproductive status of a potential mate. So, for example, when a female rat is ready to mate, she secretes pheromonal signals that draw attention from nearby male rats. Pheromonal activation is actually an important component in eliciting sexual behavior in the male rat (Furlow, 1996, 2012; Purvis & Haynes, 1972; Sachs, 1997). There has also been a good deal of research (and controversy) about pheromones in humans (Comfort, 1971; Russell, 1976; Wolfgang-Kimball, 1992; Weller, 1998). Thus far, there is little evidence that humans respond to pheromone signals.

Touch, Thermoception, and Nociception

A number of receptors are distributed throughout the skin to respond to various touch-related stimuli ( Figure 5.23 ). The receptors responsible for fine touch perception in your hands include Meissner’s corpuscles, Pacinian corpuscles, Merkel’s disks, and Ruffini corpuscles.  Meissner’s corpuscles  respond to pressure and lower frequency vibrations, and  Pacinian corpuscles  detect transient pressure and higher frequency vibrations.  Merkel’s disks  respond to light pressure, while  Ruffini corpuscles  detect stretch (Abraira & Ginty, 2013). These receptors work together to help you identify information like the texture of an object you are touching and whether something you are holding is falling from your grasp.

In addition to the receptors located in the skin, there are also a number of free nerve endings that serve sensory functions. These nerve endings respond to a variety of different types of touch-related stimuli and serve as sensory receptors for both  thermoception  (temperature perception) and  nociception  (a signal indicating potential harm and maybe pain) (Garland, 2012; Petho & Reeh, 2012; Spray, 1986). Sensory information collected from the receptors and free nerve endings travels up the spinal cord and is transmitted to regions of the medulla, thalamus, and ultimately to somatosensory cortex, which is located in the postcentral gyrus of the parietal lobe.

Pain Perception

Pain is an unpleasant experience that involves both physical and psychological components. Feeling pain is quite adaptive because it makes us aware of an injury, and it motivates us to remove ourselves from the cause of that injury. In addition, pain also makes us less likely to suffer additional injury because we will be gentler with our injured body parts.

Generally speaking, pain can be considered to be neuropathic or inflammatory in nature. Pain that signals some type of tissue damage is known as  inflammatory pain . In some situations, pain results from damage to neurons of either the peripheral or central nervous system. As a result, pain signals that are sent to the brain get exaggerated. This type of pain is known as  neuropathic pain . Multiple treatment options for pain relief range from relaxation therapy to the use of analgesic medications to deep brain stimulation. The most effective treatment option for a given individual will depend on a number of considerations, including the severity and persistence of the pain and any medical/psychological conditions.

Some individuals are born without the ability to feel pain. This very rare genetic disorder is known as  congenital insensitivity to pain  (or  congenital analgesia ). While those with congenital analgesia can detect differences in temperature and pressure, they cannot experience pain. As a result, they often suffer significant injuries. Young children have serious mouth and tongue injuries because they have bitten themselves repeatedly. Not surprisingly, individuals suffering from this disorder have much shorter life expectancies due to their injuries and secondary infections of injured sites (U.S. National Library of Medicine, 2013).

The Vestibular Sense, Proprioception, and Kinesthesia

The  vestibular sense  contributes to our ability to maintain balance and body posture. As  Figure 5.24  shows, the major sensory organs (utricle, saccule, and the three semicircular canals) of this system are located next to the cochlea in the inner ear. The vestibular organs are fluid-filled and have hair cells, similar to the ones found in the auditory system, which respond to movement of the head and gravitational forces. When these hair cells are stimulated, they send signals to the brain via the vestibular nerve. Although we may not be consciously aware of our vestibular system’s sensory information under normal circumstances, its importance is apparent when we experience motion sickness and/or dizziness related to infections of the inner ear (Khan & Chang, 2013).

In addition to maintaining balance, the vestibular system collects information critical for controlling movement and the reflexes that move various parts of our bodies to compensate for changes in body position. Therefore, both  proprioception  (perception of body position) and  kinesthesia  (perception of the body’s movement through space) interact with information provided by the vestibular system.

These sensory systems also gather information from receptors that respond to stretch and tension in muscles, joints, skin, and tendons (Lackner & DiZio, 2005; Proske, 2006; Proske & Gandevia, 2012). Proprioceptive and kinesthetic information travels to the brain via the spinal column. Several cortical regions in addition to the cerebellum receive information from and send information to the sensory organs of the proprioceptive and kinesthetic systems.

DIG DEEPER: The Depths of Perception: Bias, Prejudice, and Cultural Factors

In this chapter, you have learned that perception is a complex process. Built from sensations, but influenced by our own experiences, biases, prejudices, and  cultures , perceptions can be very different from person to person. Research suggests that implicit racial  prejudice  and  stereotypes  affect perception. For instance, several studies have demonstrated that non-Black participants identify weapons faster and are more likely to identify non-weapons as weapons when the image of the weapon is paired with the image of a Black person (Payne, 2001; Payne, Shimizu, & Jacoby, 2005). Furthermore, White individuals’ decisions to shoot an armed target in a video game is made more quickly when the target is Black (Correll, Park, Judd, & Wittenbrink, 2002; Correll, Urland, & Ito, 2006). This research is important, considering the number of very high-profile cases in the last few decades in which young Blacks were killed by people who claimed to believe that the unarmed individuals were armed and/or represented some threat to their personal safety.

Chapter Summary

5.1   sensation vs. perception.

Sensation occurs when sensory receptors detect sensory stimuli. Perception involves the organization, interpretation, and conscious experience of those sensations. All sensory systems have both absolute and difference thresholds, which refer to the minimum amount of stimulus energy or the minimum amount of difference in stimulus energy required to be detected about 50% of the time, respectively. Sensory adaptation, selective attention, and signal detection theory can help explain what is perceived and what is not. In addition, our perceptions are affected by a number of factors, including beliefs, values, prejudices, culture, and life experiences.

5.2 Waves and Wavelengths

Both light and sound can be described in terms of wave forms with physical characteristics like amplitude, wavelength, and timbre. Wavelength and frequency are inversely related so that longer waves have lower frequencies, and shorter waves have higher frequencies. In the visual system, a light wave’s wavelength is generally associated with color, and its amplitude is associated with brightness. In the auditory system, a sound’s frequency is associated with pitch, and its amplitude is associated with loudness.

Light waves cross the cornea and enter the eye at the pupil. The eye’s lens focuses this light so that the image is focused on a region of the retina known as the fovea. The fovea contains cones that possess high levels of visual acuity and operate best in bright light conditions. Rods are located throughout the retina and operate best under dim light conditions. Visual information leaves the eye via the optic nerve. Information from each visual field is sent to the opposite side of the brain at the optic chiasm. Visual information then moves through a number of brain sites before reaching the occipital lobe, where it is processed.

Two theories explain color perception. The trichromatic theory asserts that three distinct cone groups are tuned to slightly different wavelengths of light, and it is the combination of activity across these cone types that results in our perception of all the colors we see. The opponent-process theory of color vision asserts that color is processed in opponent pairs and accounts for the interesting phenomenon of a negative afterimage. We perceive depth through a combination of monocular and binocular depth cues.

5.4 Hearing

Sound waves are funneled into the auditory canal and cause vibrations of the eardrum; these vibrations move the ossicles. As the ossicles move, the stapes presses against the oval window of the cochlea, which causes fluid inside the cochlea to move. As a result, hair cells embedded in the basilar membrane become enlarged, which sends neural impulses to the brain via the auditory nerve.

Pitch perception and sound localization are important aspects of hearing. Our ability to perceive pitch relies on both the firing rate of the hair cells in the basilar membrane as well as their location within the membrane. In terms of sound localization, both monaural and binaural cues are used to locate where sounds originate in our environment.

Individuals can be born deaf, or they can develop deafness as a result of age, genetic predisposition, and/or environmental causes. Hearing loss that results from a failure of the vibration of the eardrum or the resultant movement of the ossicles is called conductive hearing loss. Hearing loss that involves a failure of the transmission of auditory nerve impulses to the brain is called sensorineural hearing loss.

5.5 The Other Senses

Taste (gustation) and smell (olfaction) are chemical senses that employ receptors on the tongue and in the nose that bind directly with taste and odor molecules in order to transmit information to the brain for processing. Our ability to perceive touch, temperature, and pain is mediated by a number of receptors and free nerve endings that are distributed throughout the skin and various tissues of the body. The vestibular sense helps us maintain a sense of balance through the response of hair cells in the utricle, saccule, and semi-circular canals that respond to changes in head position and gravity. Our proprioceptive and kinesthetic systems provide information about body position and body movement through receptors that detect stretch and tension in the muscles, joints, tendons, and skin of the body.

5.6 Gestalt Principles of Perception

Gestalt theorists have been incredibly influential in the areas of sensation and perception. Gestalt principles such as figure-ground relationship, grouping by proximity or similarity, the law of good continuation, and closure are all used to help explain how we organize sensory information. Our perceptions are not infallible, and they can be influenced by bias, prejudice, and other factors.

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specialized neurons that respond to specific types of stimuli

the detection of information by a sensory receptor

the conversion from sensory stimulus to action potentials

the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time.

the minimum difference in intensity between two stimuli to detect the difference

Ernst Weber's proposal that the difference threshold is a constant fraction of the original stimulus.

sensory information from a stimulus in the environment driving a process

knowledge and expectancy driving a process

the focusing of mental processing on a particular stimulus

the failure to notice something that is completely visible due to attention being focused elsewhere

the height of a wave form

length of a wave from one peak to the next

the number of waves that pass a given point in a period of time

cycles per second; a measure of the frequency of a waveform

psychological experience of the frequency of a sound wave

psychological experience of the amplitude of a sound wave

the psychological experience of a sound wave's complexity. The reason a saxophone and trombone playing the same note sound different.

the major sensory organ involved in vision

the transparent layer covering the outside front of the eye, protecting the iris and pupil

a small opening in the eye through which light passes

the colored portion of the eye, controls the size of the pupil

a curved, transparent structure behind the pupil that focuses light on the back of the eye

the central portion of the retina, responsible for high acuity, color vision due to high density of cone photoreceptors

the light-sensitive membrane at the back of the eye where phototransduction occurs

light-detecting cells that work best in bright light conditions; provide high acuity and color information

a light sensitive cell primarily found in the retinal periphery, responsible for vision in low-light and motion

neurons in the retina whose axons carry information from the eyes to the brain via the optic nerve

a bundle of neuron axons that carries information from the back of each eye to the thalamus in the brain

the region of the retina without photoreceptors due to the optic nerve leaving the eye

an X-shaped structure below the cerebral cortex where left visual field information crosses over to the right side of the brain, and right visual field information crosses over to the left side of the brain

the first area of the cerebral cortex to receive visual information

visual processing pathway that is responsible for object identification

objects' location in space and how one might interact with a particular visual stimulus; primarily relies on parietal regions

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Psychology Discussion

Experiments on perception | experimental psychology.

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List of psychological experiments on perception!

Experiment # 1. Selection and Grouping in Perception:

Our perception of stimuli depends on a series of organisational processes. This aspect has been studied extensively by the gestalt psychologists. The process of organisation depends on a number of factors, due to which our perception of the same stimulus elements differs on different occasions.

The individual experiences reversible figure – ground effects, though the objective stimulus itself remains the same. Such changes in perceptual organisation take place because of changes in the selection and grouping of different parts of the stimulus and therefore the perceptual images are not stable.

To demonstrate the changes in perceptual organisation accompanying changes in selection and grouping of stimuli.

Materials Required :

Figure ‘A’ containing 13 small X marks arranged in a square pattern on a white background (black X marks). The X marks are arranged in five parallel rows having three, two, three, two and three X marks respectively. Figure ‘B’ has 28 X marks (black X marks on a white background) arranged in a pyramid pattern with the base line having seven X marks, the next on 6 and the top there being only one X mark.

Procedure :

I. Figure ‘A’ is hung on the wall at a convenient height. The subject is seated at a distance of 8 to 10 feet and instructed to focus his vision on this figure.

Then as he is looking at it, the following descriptions of his experience are obtained:

1. What does the figure represent?

2. Does he experience any change in the pattern in which the dots are grouped? If so, he has to describe whether these changes in pattern appear gradually or suddenly.

3. Whether at any moment he sees two or three patterns, i.e., whether the different parts of the figure appear to be differently organised.

II. Take Figure ‘A’ away and after a few minutes of rest, place figure ‘B’ before the subject and repeat the experiment.

1. Analyse the responses of the subject and note the different factors which come into play in the grouping and organisation of the stimuli.

2. Find out whether shifts in perceptual organisation are sudden or gradual.

1. Repeat the experiment with figures in which we have dissimilar elements, e.g., marks and squares mixed.

2. Repeat the experiment with figures in which the distances among the dots in the same line are unequal.

3. Use figures in which the dots or X marks are not arranged in a regular shape or pattern.

Experiment # 2. Mental Set and Perception :

Our perception of a stimulus is influenced not only by its properties but also by certain other factors. Some of these are our needs, our past experiences and our present mental conditions or sets.

For example, if we are expecting a visitor, even the noise of rain drops falling on the wooden door is mistaken for footsteps. Again, if we are travelling in a train passing through a series of mountain ranges visible at a distance through the window, then even a cloud is mistaken for a hill. This illustrates influence of mental set on perception.

To demonstrate the effect of mental set on perception.

A large number of cartoon drawings falling into two categories- Category ‘A’ consisting of a number of animal figures, Category ‘B’ consisting of a large number of human figures and an ambiguous drawing.

For the purpose of this experiment, the subjects are categorised into two groups ‘A’ and ‘B’.

They are given the following instructions:

“You will be shown a series of pictures, each one for a short duration; you must judge what these pictures represent”. The pictures may be exposed through an exposure apparatus.

Procedure for Group ‘A’:

Present each of the animal pictures and note down the response for each. Then present the ambiguous picture. Note down the response, and ask the subject whether he sees anything else in this picture.

Procedure for Group ‘B’:

The procedure is similar to the above except that for this group the human pictures are shown first, followed by the ambiguous picture.

1. Count the frequency of ‘animal’ and ‘human’ responses for the ambiguous picture in group ‘A’ and group ‘B’. See whether the groups differ, significantly, in their responses to the ambiguous picture.

2. Tabulate as follows:

3. Test the significance of difference between the two groups, with reference to ‘animal’ and ‘human’ responses computing X 2 (Chi- square) with the above 2X2 contingency table or by computing CR for percentages.

Experiment # 3. Apparent Movement or Phi-Phenomenon:

When we go to see a movie, we see the objects and persons on the film moving continuously. However, in the actual film there in no such continuity. What appears as a continuous movement is actually a series of separate films. However, we do not see them separately and the motion has an apparent continuity.

This phenomenon was studied in the laboratory with the help of simple light stimuli by the German psychologist Max Wertheimer. From the results of this experiment, he developed an elaborate theory of perception   called the Gestalt theory of perception. This theory was later extended to learning, memory and other phenomena and the supporters of this theory came to be known as Gestalt Psychologists.

To determine the optimal distance and time- interval for the occurrence of phi-phenomenon or illusion of motion.

The Phi-phenomenon apparatus, a metronome and a stopwatch.

Description of the Phi-Phenomenon Apparatus:

The Phi-phenomenon apparatus consists of a board on which there are two lights, kept in line with each other. The two lights are movable, so that the distance between them can be adjusted. There is an adjustment by which the intensities of the lights can also be varied. By connecting a metronome (double-contact) in the circuit it is possible to regulate the time interval between the appearances of two lights.

The subject is seated at a distance of 3 feet from the apparatus and the following instructions are given to the subject:

“Focus your attention on the lights. When I switch on the light you will find one of these lights illuminated first, and then the other. When I say ‘ready’ keep on looking at it. At one point you will cease to see two separate lights. Instead, you will see one wave of light following along this glass screen placed in front of the two lights. Indicate to me when this happens by raising your hand”.

Now the experimenter sets the metronome at a speed of 60 beats per minute and conducts the experiment after giving the subject a ‘ready’ signal. As soon as the subject indicates that s/he has perceived a continuous moving light instead of two separate lights one after the other the experimenter notes the time. Five such trials are given. Then, the metronome is set at a speed of 90,120 etc., and the experiment is repeated. The experiment is also repeated with the subject seated at 6 feet and 9 feet distance.

On each occasion, give maximum time of three to four minutes for the subject to respond. If there is no response within this period, then the response is considered negative.

Tabulate the results as follows:

1. Find what speed in general the Phi-phenomenon occurs most frequently, irrespective of the distance.

2. Find out the speed at which the least time is taken.

3. Similarly, compare the responses when the distances change.

4. Is there any particular optimal combination of speed and distance?

5. Collect the group data and study individual variations.

Experiment # 4. Optical Illusion:

In the experiment on ‘perception and mental set’, our perceptions are influenced not only by the properties of the stimuli but also by several other factors, like the surroundings or past experience, mental set, etc. To quote a classical example, a rope lying on the floor at night is often mistaken for a snake.

This phenomenon of illusion or wrong perception can be demonstrated in the laboratory by a number of experiments. Several types of illusions have been designed for experimentation in the laboratory. Out of these, the simple and the most common ones are the ‘geometrical illusions’.

To demonstrate the occurrence of error or illusion effect in perceiving lines.

Apparatus Required :

A Muller-Lyer illusion board and a horizontal-vertical illusion board.

Description of the Apparatus:

1. Muller-Lyer Illusion Board:

The Muller-Lyer illusion board consists of two horizontal lines, side by side. One of the lines ‘A’ has its extremities flanked by two open arrowheads; the other one ‘B’ has at its extremities two closed arrowheads.

2. Horizontal-Vertical Illusion Board:

Here again there are two lines, one horizontal and the other vertical. The length of the vertical line can be increased or decreased by means of a mechanical arrangement.

This experiment is done using two conditions in two series:

(1) With ‘A’ as standard and

(2) With ‘B’ as standard; in-

(a) Descending series and

(b) Ascending series.

(1) ‘A’ as Standard:

Give the following instructions to the subject:

“Look at this board, there are two lines. These two lines as you can see are unequal in size. I will keep the length of this line ‘A’ constant and go on varying the length of ‘B’ in small units, either increasing or decreasing. At every step you should tell me whether ‘B’ is equal to ‘A’ or not. When you say, they are equal, I will stop”.

Under this condition as we have already mentioned, there are two series:

(a) Descending Series:

Here the experimenter after fixing the length of ‘A’ starts with ‘B’ perceptibly longer than ‘A’ and gradually shortens it step by step until the subject says both are of equal length. Then the actual lengths of ‘A’ and ‘B’ are measured and the difference is noted down. [Note how much shorter or longer ‘B’ is, put an appropriate minus (-) or plus (+) sign before the error value.]

(b) Ascending Series:

Here the experimenter starts with line ‘b’ perceptibly shorter than ‘A’ and goes on increasing its length until the subject says ‘A’ and ‘B’ are equal. The errors are noted down as above.

(2) ‘B’ as Standard:

The procedure here is exactly the same except that the length of line ‘B’ is kept constant while that of ‘A’ is varied. The subject is instructed to compare A’ and ‘B’ and indicate when they appear equal.

As before, the experiment is done in both the ascending and descending series. Under each of the two conditions, there will be ten trials in ascending series and ten in descending series alternately. There will then be a total of 40 trials.

1. Calculate the average errors in estimation of lines for each the subjects as below:

(a) Average error in all the 40 trials (P)

(b) Average error in condition one (Q)

(c) Average error in condition two (R)

(d) Average error for all ascending series put together (S)

(e) Average error for all descending series put together (T)

2. Tabulate the results for the group as follows:

1. Discuss the individual variations in all the columns.

2. Do individuals have positive or negative values in all the columns?

3. Discuss the variation among the column averages.

Horizontal-Vertical Illusion Procedure :

Here also there are two lines. One horizontal and the other vertical. The horizontal line is fixed and the vertical line is variable.

Hence, the subjects are given the following instructions:

‘Look at these two lines. They are unequal in size. I will go on changing the vertical line, increasing or decreasing its length. Tell me when you find the lines equal.’

As in the case of Muller-Lyer illusion, ascending and descending trials are taken. In the ascending series the experimenter starts keeping the vertical line perceptibly shorter and increases the length gradually while, in the descending series, the experiment/starts with the vertical line perceptibly longer and goes on gradually decreasing.

The errors are measured and noted with their appropriate algebraic signs.

i. Calculate the average errors for the descending and ascending series.

ii. In which series is the occurrence of error greater? Is there any difference in the positive or negative direction of the errors?

iii. Tabulate the group results and discuss the individual differences.

Experiment # 5. Binocular Fusion:

The human eye is innately equipped to perceive visual objects only in two dimensions, i.e., in length and width or in height and width. However, in daily life we respond to a third dimension also namely depth, distance, etc. We perceive objects as 3-dimensional objects. The 3-dimensional film is a classical example of this.

One of the factors which helps us in perceiving the third dimension is called retinal overlap. This overlap takes place because of an overlapping of two slightly disparate images produced on the two retina. This overlap takes place in a region called ‘horopter’.

This phenomenon can be illustrated by the following experiment:

To demonstrate the phenomenon of binocular fusion.

Materials Required:

A stereoscope, a set of stereoscopic pictures, a meter rod.

Slide the stereoscope on the meter rod through the groove in the stereoscope and clamp the meter rod at its two ends on two stands so that it is kept parallel to the surface of the table. Adjust the height of the two stands so that the meter rod is at level with the eyes of the subject who is comfortably seated on a chair.

“Look through this stereoscope (fix one of the stereograms in the holder of the stereoscope). Each eye will see a different picture. I will keep moving this along the scale. Tell me when you see a single picture instead of two pictures. For example on one side of this picture now you see a parrot, and on the other side you see a cage. At one point you will find that the parrot has gone into the cage. Tell me when that happens. After some time this oneness will change and again, as before, two pictures will appear. Tell me when you experience this change also.”

The experimenter makes note of the two transition points. A total of ten trials is given. For five of the trials the experimenter starts from a point close to the eye and keeps on moving the stereoscope away from the subject (outwards). For the other five trials the stereoscope is originally fixed at a point far away and gradually moved nearer to the subject (inwards). The inward and outward trials are alternated.

i. Find out the range of fusion for each trial.

ii. Is there any difference between the inward and outward trials?

Experiment # 6. Depth Perception:

One of the important problems of the psychology of vision has been the problem of perceiving depth of distance. The earliest scientists to attempt an explanation of this were made by Galen and Leonardo da Vinci. Leonardo emphasised the importance of shadow in the depth perception.

According to him, perception of distance is mainly a mediated process, i.e., it is not an immediate perceptual fact, but depends on factors like clarity, loss of details, etc. Helmholtz attributed perception of distance to unconscious inferences.

One of the important facts established with regard to perception of distance is the role played by binocular vision. The presence of two eyes makes perception of distance more efficient than vision with one eye.

To verify whether binocular vision enables more accurate perception of depth compared to monocular vision.

The depth perception box is an elongated box which is illuminated inside and contains three concealed vertical rods or pins. These pins can be seen by a subject through a small window. Two of these rods are fixed and the one in the middle is movable, resting on a pulley bottom, wheeled on a rod running completely across the length of the box. The top of the box has a long groove-like opening throughout the length of the box.

The movable rod projects above the box through the groove-like opening and ends in a handle. By moving the handle the movable vertical rod can be shifted to any position along the length of the box. A meter-scale is fixed to the groove-like opening on the top so that the exact position of the movable rod can be read.

The experiment is done in two parts-monocular and binocular.

Monocular Vision :

Instructions:

Seat the subject in a convenient position by using a chin rest before the slit window so that he has a good view of the three vertical rods. The slit window must be adjusted so that it is only wide enough to give view of the three rods and not the rest of the box.

Blindfold the right eye of the subject. Instruct the subject as follows:

“Through the opening you will see three vertical rods. Two of them are fixed and the third one is movable. (Demonstrate) Now, I will keep on moving this rod keeping it at different points. You should ask me to stop moving the rod whenever you see the movable rod exactly in line with the other two fixed rods.”

Descending Series:

Start from a position where the movable rod is very much behind or away from the two fixed rods. Move it until the subject says that the three are in a line. Repeat the experiment about ten times, starting from different points behind the fixed pulleys.

Ascending Series:

The procedure here is essentially the same, excepting that here the movable rod starts from a position closer to the subject and in front of the fixed rods and is moved to a position away from the subject. The experiment is repeated ten times.

The ascending and descending series must be alternately carried out. Repeat the experiment by blindfolding the left eye.

Binocular Vision:

Remove the blindfold and repeat the entire experiment with both eyes open.

1. Calculate the error, positive or negative, for each series for the right and the left eye and for binocular vision. The error is recorded in units of deviation in millimeters between the fixed and movable rods. If the movable rod is behind the fixed rods, that is, if the movable rod is farther than the fixed rods from the subject, the error is counted as positive, and if the movable rod is nearer than the fixed rods to the subject, the error is counted as negative.

2. Calculate the average algebraic error for each condition-the right eye, the left eye and binocular vision.

3. Tabulate the results as follows:

4. Calculate the Mean and SD for the group for all the conditions.

5. Compare the results of monocular with those of binocular vision.

The ascending and descending series are employed to overcome certain biases which may result if only one direction of movement is employed, called movement error.

Experiment # 7. Perceptual Constancies :

Perceptual Constancy is the tendency for a perceived object to resist change in spite of wide variations in the conditions of observation. In other words, we can say that the perceptual constancies influence the subject to perceive the shape, size and colour of the objects as they are, in spite of the variations in the viewing conditions or the background of the stimuli.

Psychologists have widely studied these three phenomena viz. – Shape Constancy, Size Constancy and the Colour Constancy. The former two of these constancies are grouped under object constancy.

The following two experiments are used to demonstrate the phenomena of:

A. Shape Constancy, and

B. Size Constancy.

A. Shape Constancy :

Introduction :

Shape Constancy is defined as the tendency on the part of the individual to perceive the shape of an object as having the same shape in spite of the wide variations in the conditions of viewing. For example, we consider the shape of a circular plate as circular whether we look at it, sitting or standing before the table or even from a corner of a room. Inspite of the image that is cast on the retina being elliptical, we still observe it as circular and not as elliptical. This is because of the operation of the phenomenon of Shape Constancy.

To demonstrate the phenomenon of Shape Constancy.

Shape Constancy Apparatus:

A circle is mounted on an upright rod so that the disc is in the vertical plane. In addition, several ellipses differing in width, but of the same height as the circle are also mounted on vertical rods. These ellipses are mounted in such a way that the long (major) axis is vertical. Provision is made to determine the extent to which the rod and circle have been rotated by means of a pointer and protector.

The projection of the diameter of the circle is calculated by means of the following formula:

p = d Cos θ

Where p = projection; d = diameter of the circle and θ = the angle of rotation.

The circle and an ellipse are placed parallel to the line of the subject’s sight at a distance of two meters and the subject is given the following instructions:

“There are two objects mounted on the vertical rods. One of them is a circle and the other an ellipse. I will rotate the circle till you perceive it as an ellipse. The moment the circle matches the ellipse, ask me to stop rotating the circular disc.” After the experimenter assures herself/himself that the instructions are clear to the subjects, he/she repeats the experiment about twenty times.

For one half of the trials the experimenter begins with the circle parallel to the line of sight and for the other half of the trials the circle is initially perpendicular to the line of sight. The starting positions should be alternated in random order. A new ellipse may then be substituted and the entire experiment repeated. The results are tabulated.

The projections of the diameter of the circle (p) on each trial with different ellipses are tabulated as shown below:

The larger the angle of rotation, the smaller the projection of the diameter of the circle needed to match the ellipse and hence the greater the constancy. The amount of constancy may be conveniently quantified by comparing the projection with the width of the ellipse. For this purpose, the average of the measurements of projection are computed.

The ratio width of ellipse/Mean Projection provides us with the index of constancy. If there were no constancy effect, the width of the ellipse and the mean projection would be equal and the ratio would be 1. The greater the constancy, the smaller the projection and hence the greater the ratio.

B. Size Constancy:

One of the optical properties of the eye is that the retinal image of the size of an object decreases as the distance of the object from the eye increases in accordance with the ‘Law of Visual Angle’. This law states that the linear size of the optical images is inversely proportional to the distance of the object. It is true that distant objects look smaller than the objects of similar size.

It is equally true that perceived size does not confirm the law of visual angle, according to which a man 10 meters away should appear half as tall as he should 5 meters away. Over a considerable range of distances, perceived size decreases much less than what would be predicted by the law of visual angle. The failure of perceived size to decrease in proportion to the distance is known as Size Constancy.

To demonstrate the phenomenon of ‘Size Constancy’.

Material Required:

A square (Standard stimulus) whose sides are 10 cms each is mounted on a vertical rod. Another square (Variable stimulus) is mounted on another vertical rod and its sides can be varied in length with the help of a pulley attached to this square.

A meter scale to measure the distance between the subjects and the standard square.

The experiment should be conducted in long corridors which are relatively free of furniture and other objects. The subject is comfortably seated and the standard stimulus (a fixed square which is also known as a test square) is first kept at a distance of one metre directly in front of the subject. The variable stimulus(the adjustable square which is also known as the Reference square) is kept at a distance of one metre, towards the side of the subjects so that he has to turn his head about 45 degrees in order to see it.

The experimenter then repeats the experiment in both ascending and descending orders. In the ascending series, the initial size of the reference square should be perceptibly smaller than the test square and in that of the descending series, the initial size of the reference square should be perceptibly larger than that of the test square.

The subjects are given the following instructions:

“(Showing the test square), this is a square and its size is fixed, (showing the reference square) and the size of this square is not fixed. That is, its size can be changed. In some trials I will keep the initial size of the reference square very small compared to that of the fixed square. I will keep increasing the size of the squares. In some trials I will adjust the initial size of this square such that it appears larger than the fixed square, then I keep decreasing the size of the square. You must ask me to stop when you perceive the sizes of the two squares as equal. I will repeat this experiment by placing this square (showing the reference square) towards your right and left always at a distance of one metre and I keep changing the distance of this fixed square (pointing towards the test square) from your seat. Whatever may be the alterations I make, your job is simply to ask me to stop whenever you perceive the sizes of the two squares as equal.”

The test square is thus successively moved to a distance of 2, 4 & 8 meters. At each of these distances, the sizes to the reference which are perceived as equal to test square are obtained as before. Besides, increasing the distance of the test square from the subject, it is desirable to decrease it successively from a distance of 8 meters to 1 metre. Thus, there is a receding and approaching series.

The lengths of the sides of the Reference Square matched to those of the Test Square are tabulated as shown below:

Overall averages are taken by rows to give a representative value for each of the distances. These averages obtained for each of the distances should be plotted on the same graph paper on which the theoretical functions defined by the law of the visual angle are plotted. Then the empirical function obtained from the experimental data may be discussed in comparison with the theoretical function.

It is possible to isolate the effects of receding, approaching ascending and descending series of presentation by plotting separate functions for each of these conditions.

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Experiments , Experimental Psychology , Perception , Experiments on Perception

Please check out my new Here is a small collection of tutorials and demonstrations related to our senses. Choose a topic and have fun. A brief review of some of the ways artists can create particular experiences.   . by John H. Krantz and Bennett L. Schwartz. A set of interactive illustrations designed to accompany by Bennett L. Schwartz & John H. Krantz Or why do we see things the size we do? This turoial illustrates a mathematical procedure, using only pictures, to illustrate how many complex images can be converted into a set of simple images. This applet lacks the explanatory material of above, but will let you play with the concepts some. This tutorial is a demonstration where you can see colors with a black and white stimulus. This tutorial covers some basic issues about how the brain processes visual, and other sensory, information. Too Follow up try these: Signal Detection Theory: Java Versions Related Sites: Neuroscience Animations . An open-source tool for the development of web-based surveys. If you have any comments or find the concept interesting please email me at [email protected] .  John H. Krantz, Ph.D . John H. Krantz, Ph.D. Version 1: 12 May, 1995 Current: 05.1 June, 2012 Sensation and Perception Living reference work entry Later version available View entry history First Online: 31 December 2020 Cite this living reference work entry Robert Gaschler 5 , Mariam Katsarava 5 & Veit Kubik 6   Part of the book series: Springer International Handbooks of Education ((SIHE)) 354 Accesses Often being covered in introductory psychology, the topic of sensation and perception offers ample opportunity to strengthen identification of students with psychology. On the one hand, this is due to the many recipes for classroom demonstrations of specific effects which should help to create durable memories of what it is to be in a psychology course. Reviewing these recipes, we draw attention to the challenges of linking classroom events to core content. On the other hand, the topic can be presented such that its central role for future work as a psychologist (e.g., in organizational or industrial psychology) becomes clear. It offers many opportunities for future psychologists to apply their methodological and content knowledge to tackle societal, economic, and ecological challenges. On the other hand, the topic can be used as a starting point to discuss core theoretical questions of psychology. Work in science studies suggests that sensation and perception are the domains where other science disciplines often need input from psychology. This is a preview of subscription content, log in via an institution to check access. Access this chapter Institutional subscriptions Similar content being viewed by others The Role of Experience in Perception Mutual Tuning-In Relationships and Phenomenological Psychology Ali, N., & Peebles, D. (2013). The effect of gestalt laws of perceptual organization on the comprehension of three-variable bar and line graphs. Human Factors: The Journal of the Human Factors and Ergonomics Society, 55 (1), 183–203. https://doi.org/10.1177/0018720812452592 . Article   Google Scholar   American Psychological Association. (2013). APA guidelines for the undergraduate psychology major : Version 2.0. Retrieved from http://www.apa.org/ed/precollege/undergrad/index.aspx American Psychological Association, Task Force on Guidelines for Master’s Programs in Psychology. (2018). APA guidelines on core learning goals for master’s degree graduates in psychology . Retrieved from https://www.apa.org/ed/precollege/about/psymajor-guidelines.pdf Barsz, K. (1990). Auditory sensory processes: The travelling wave on the basilar membrane. In V. Parker Makosky, C. C. Sileo, & L. G. Whittemore (Eds.), Activities handbook for the teaching of psychology (Vol. 3, pp. 70–71). Washington, DC: American Psychological Association. Google Scholar   Beins, B. C. (1983). The light box: A simple way of generating complex color demonstrations. Teaching of Psychology, 10 , 113–114. Biederman, I. (1972). Perceiving real-world scenes. Science, 177 , 77–80. https://doi.org/10.1126/science.177.4043.77 . Bilalić, M., Grottenthaler, T., Nägele, T., & Lindig, T. (2016). The faces in radiological images: Fusiform face area supports radiological expertise. Cerebral Cortex, 26 (3), 1004–1014. https://doi.org/10.1093/cercor/bhu272 . Brady, T. F., Shafer-Skelton, A., & Alvarez, G. A. (2017). Global ensemble texture representations are critical to rapid scene perception. Journal of Experimental Psychology: Human Perception and Performance, 43 , 1160–1176. https://doi.org/10.1037/xhp0000399 . Braitenberg, V. (1984). Vehicles: Experiments in synthetic psychology . Cambridge, MA: MIT Press. Brewer, F. W. (2012). The theory ladenness of the mental processes used in the scientific enterprise. In R. W. Proctor & J. E. Capaldi (Eds.), Psychology of science: Implicit and explicit processes (pp. 290–233). New York, NY: Oxford University Press. Bruner, J. S. & Goodman, C. C. (1947). Value and need as organizing factors in perception. Journal of Abnormal and Social Psychology, 42, 33–44. https://doi.org/10.1037/h0058484 . Online: https://psychclassics.yorku.ca/Bruner/Value/ Bruner, J. S. & Postman, L. (1949). On the perception of incongruity: A paradigm. Journal of Personality, 18, 206–223. https://doi.org/10.1111/j.1467-6494.1949.tb01241.x . Online: https://psychclassics.yorku.ca/Bruner/Cards/ Bubic, A., von Cramon, D. Y. & Schubotz, R. I. (2010) Prediction, cognition and the brain. Frontiers in Human Neuroscience, 4: e25. https://doi.org/10.3389/fnhum.2010.00025 . Butler, D. L. (1993). Graphics in psychology: Pictures, data, and especially concepts. Behavior Research Methods, Instruments, & Computers, 25 , 81–92. https://doi.org/10.3758/BF03204481 . Chéron, E. (2015). Effect of graphic images in cigarette health warning: A call for stricter packaging regulation in Japan. Journal of International Consumer Marketing, 27 (2), 137–151. https://doi.org/10.1080/08961530.2014.979306 . Clark, A. (2013). Whatever next? Predictive brains, situated agents, and the future of cognitive science. Behavioral and Brain Sciences, 36 , 181–204. https://doi.org/10.1017/S0140525X12000477 . Corey, J. R., & Tatz, S. J. (1990). Classroom measurement of visual illusions. In V. Parker Makosky, C. C. Sileo, & L. G. Whittemore (Eds.), Activities handbook for the teaching of psychology (Vol. 3, pp. 63–65). Washington, DC: American Psychological Association. Crichton, F., Dodd, G., Schmid, G., Gamble, G., & Petrie, K. J. (2014). Can expectations produce symptoms from infrasound associated with wind turbines? Health Psychology, 33 (4), 360–364. https://doi.org/10.1037/a0031760 . Cushman, W. B. (1981). Blue-blindness in the central fovea. In L. T. Benjamin Jr. & K. D. Lowman (Eds.), Activities handbook for the teaching of psychology, Volume 1 (pp. 36–37). Washington, DC: American Psychological Association. Dekker, S. (2002). The field guide to human error investigations . Hampshire, UK: Ashgate. Duda, J. J. (1981). Blind spot in vision. In L. T. Benjamin Jr. & K. D. Lowman (Eds.), Activities handbook for the teaching of psychology, Volume 1 (pp. 43–44). Washington, DC: American Psychological Association. Edkins, G. D., & Pollock, C. M. (1997). The influence of sustained attention on railway accidents. Accident Analysis & Prevention, 29 , 533–539. https://doi.org/10.1016/s0001-4575(97)00033-x . Evans, J. E., & Maunder, E. W. (1903). Experiments as to the actuality of the ‘Canals’ observed on Mars. Monthly Notices of the Royal Astronomical Society, 63 , 488–499. Fantino, B. (1981). Taste preferences: Influence of smell and sight. In L. T. Benjamin Jr. & K. D. Lowman (Eds.), Activities handbook for the teaching of psychology, Volume 1 (pp. 29–30). Washington, DC: American Psychological Association. Feng, X., Jiang, X., Yang, X., Duc, M., & Li, X. (2019). Computer vision algorithms and hardware implementations: A survey. Integration, 69 , 309–320. https://doi.org/10.1016/j.vlsi.2019.07.005 . Fernandez-Duque, D., & Johnson, M. L. (1999). Attention metaphors: How metaphors guide the cognitive psychology of attention. Cognitive Science, 23 (1), 83–116. https://doi.org/10.1016/S0364-0213(99)80053-6 . Fernandez-Duque, D., & Johnson, M. L. (2002). Cause and effect theories of attention: The role of conceptual metaphors. Review of General Psychology, 6 (2), 153–165. https://doi.org/10.1037/1089-2680.6.2.153 . Firestone, C., & Scholl, B. J. (2016). Cognition does not affect perception: Evaluating the evidence for “top-down” effects. Behavioral and Brain Sciences, 39 , 1–72. https://doi.org/10.1017/S0140525X15000965 . Galison, P. (1997). Image and logic: A material culture of microphysics . Chicago, IL: University of Chicago Press. Gaschler, R., & Frensch, P. A. (2009). When vaccinating against information reduction works and when it does not work. Psychological Studies, 54 , 43–53. https://doi.org/10.1007/s12646-009-0006-5 . Gaschler, R., Marewski, J. N., & Frensch, P. A. (2015). Once and for all – How people change strategy to ignore irrelevant information in visual tasks. Quarterly Journal of Experimental Psychology, 68 , 543–567. https://doi.org/10.1080/17470218.2014.961933 . Gaschler, R., Mata, J., Störmer, V., Kühnel, A., & Bilalic, M. (2010). Change detection for new food labels. Food Quality and Preference, 21 , 140–147. https://doi.org/10.1016/j.foodqual.2009.08.013 . Gaschler, R., Schwager, S., Umbach, V. J., Frensch, P. A., & Schubert, T. (2014). Expectation mismatch: Differences between self-generated and cue-induced expectations. Neuroscience and Biobehavioral Reviews, 46 , 139–157. https://doi.org/10.1016/j.neubiorev.2014.06.009 . Glashouwer, K. A., van der Veer, R. M. L., Adipatria, F., & de Jong, P. J., & Vocks, S. (2019). The role of body image disturbance in the onset, maintenance, and relapse of anorexia nervosa: A systematic review. Clinical Psychology Review https://doi.org/10.1016/j.cpr.2019.101771 . Godau, C., Vogelgesang, T., & Gaschler, R. (2016). Perception of bar graphs – a biased impression? Computers in Human Behavior, 59 , 67–73. https://doi.org/10.1016/j.chb.2016.01.036 . Goldstein, E. B. (2013). Sensation and perception . Wadsworth, OH, Cengage Learning. Griggs, R. A. (2014). Topical coverage in introductory textbooks from the 1980s through the 2000s. Teaching of Psychology, 41 (1), 5–10. https://doi.org/10.1177/0098628313514171 . Griggs, R. A., Jackson, S. L., Christopher, A. N., & Marek, P. (1999). Introductory psychology textbooks: An objective analysis and update. Teaching of Psychology, 26 (3), 182–189. https://doi.org/10.1207/S15328023TOP260304 . Grosofsky, A. (1996). Audition laboratory activities for teaching sensation and perception. Teaching of Psychology, 23 (1), 49–51. https://doi.org/10.1207/s15328023top2301_13 . Halvor Teigen, K. (2002). One hundred years of laws in psychology. The American Journal of Psychology, 115 (1), 103–118. https://doi.org/10.2307/1423676 . Hollingworth, A., Schrock, G., & Henderson, J. M. (2001). Change detection in the flicker paradigm: The role of fixation position within the scene. Memory & Cognition, 29 (2), 296–304. https://doi.org/10.3758/BF03194923 . Horner, D. T., & Robinson, K. D. (1997). Demonstrations of the size–weight illusion. Teaching of Psychology, 24 (3), 195–197. https://doi.org/10.1207/s15328023top2403_12 . Huestegge, L., & Philipp, A. M. (2011). Effects of spatial compatibility on integration processes in graph comprehension. Attention, Perception, & Psychophysics, 73 (6), 1903–1915. https://doi.org/10.3758/s13414-011-0155-1 . IPCC. (2014). Climate change 2014: Synthesis report. In Core Writing Team, R. K. Pachauri, & L. A. Meyer (Eds.), Contribution of working groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change . Geneva, Switzerland: IPCC. 151 pp. Kitayama, K., Duffy, S., Tadashi, K., & Larsen, J. (2003). Perceiving an object and its context in different cultures: A cultural look at new look. Psychological Science, 14 (3), 201–206. https://doi.org/10.1111/1467-9280.02432 . Koffka, K. (1922). Perception: An introduction to the Gestalt-theorie. Psychological Bulletin , 19 , 531–585. https://doi.org/10.1037/h0072422 . Online: https://psychclassics.yorku.ca/Koffka/Perception/perception.htm Koustanaï, A., Boloix, E., Van Elslande, P., & Bastien, C. (2008). Statistical analysis of “looked-but-failed-to-see” accidents: Highlighting the involvement of two distinct mechanisms. Accident Analysis and Prevention, 40 (2), 461–469. https://doi.org/10.1016/j.aap.2007.08.001 . Krüger, J. K., & Suchan, B. (2016). You should be the specialist! Weak mental rotation performance in aviation security screeners – Reduced performance level in aviation security with no gender effect. Frontiers in Psychology, 7 , e333. https://doi.org/10.3389/fpsyg.2016.00333 . Kubovy, M., & van den Berg, M. (2006). Grouping in random-dot patterns. Journal of Vision, 6 (6), 758–758. https://doi.org/10.1167/6.6.758 . Kubovy, M., & van den Berg, M. (2008). The whole is equal to the sum of its parts: A probabilistic model of grouping by proximity and similarity in regular patterns. Psychological Review, 115 (1), 131–154. https://doi.org/10.1037/0033-295X.115.1.131 . Kunkel, M. A. (1993). A teaching demonstration involving perceived lunar size. Teaching of Psychology, 20 (3), 178–180. https://doi.org/10.1207/s15328023top2003_14 . Larsen, J. D., & Fritsch, K. (1998). A valid demonstration of the missing fundamental illusion. Teaching of Psychology, 25 (1), 29–31. https://doi.org/10.1207/s15328023top2501_8 . Lautenbacher, S., Peters, J. H., Heesen, M., Scheel, J., & Kunz, M. (2017). Age changes in pain perception: A systematic-review and meta-analysis of age effects on pain and tolerance thresholds. Neuroscience and Biobehavioral Reviews, 75 , 104–113. https://doi.org/10.1016/j.neubiorev.2017.01.039 . LaVoie, A. L. (1987). Emmert’s law. In V. Parker Makosky, L. G. Whittemore, & A. M. Rogers (Eds.), Activities handbook for the teaching of psychology (Vol. 2, pp. 46–48). Washington, DC: American Psychological Association. Lawson, T. J., & Crane, L. L. (2014). Dowsing rods designed to sharpen critical thinking and understanding of ideomotor action. Teaching of Psychology, 41 (1), 52–56. https://doi.org/10.1177/0098628313514178 . Lawton, R., & Ward, N. J. (2005). A systems analysis of the Ladbroke grove rail crash. Accident Analysis & Prevention, 37 , 235–244. https://doi.org/10.1016/j.aap.2004.08.001 . Lewandowsky, S., Ballard, T., Oberauer, K., & Benestad, R. (2016). A blind expert test of contrarian claims about climate data. Global Environmental Change, 39 , 91–97. https://doi.org/10.1016/j.gloenvcha.2016.04.013 . Lunt, I., Job, R., Lecuyer, R., Peiro, J. M., & Gorbena, S. (2014). Tuning-EuroPsy: Reference points for the design and delivery of degree programmes in psychology . Retrieved from http://www.efpa.eu/professional-development/tuning-europsy-_-tuning-educational-structures-in-europe Luo, M., Cao, B., Ji, W., Ouyang, Q., Lin, B., & Zhu, Y. (2016). The underlying linkage between personal control and thermal comfort: Psychological or physical effects? Energy and Buildings, 111 , 56–63. https://doi.org/10.1016/j.enbuild.2015.11.004 . Luo, Y., & Zhao, J. (2019). Motivated attention in climate change perception and action. Frontiers in Psychology, 10 , e1541. https://doi.org/10.3389/fpsyg.2019.01541 . Luria, A. R. (1976). The cognitive development: Its cultural and social foundations . Harvard University Press. Marr, D. (1982). Vision: A computational investigation into the human representation and processing of visual information . San Francisco, CA: Freeman. Mason, J. R. (1981). A novel experiment for introductory psychology courses: Psychophysical assessment of olfactory adaptation. Teaching of Psychology, 8 (2), 117–119. https://doi.org/10.1207/s15328023top0802_21 . Mayer, R. E. (2014). The Cambridge handbook of multimedia learning . Cambridge, UK: Cambridge University Press. Book   Google Scholar   Menninghaus, W., Wagner, V., Wassiliwizky, E., Schindler, I., Hanich, J., Jacobsen, T., & Koelsch, S. (2019). What are aesthetic emotions? Psychological Review, 126 (2), 171–195. https://doi.org/10.1037/rev0000135 . Mitroff, S. R., & Biggs, A. T. (2014). The ultra-rare-item effect: Visual search for exceedingly rare items is highly susceptible to error. Psychological Science, 25 (1), 284–289. https://doi.org/10.1177/0956797613504221 . Nazzaro, J. R. (1981). Cutaneous two-point thresholds. In L. T. Benjamin Jr. & K. D. Lowman (Eds.), Activities handbook for the teaching of psychology, volume 1 (pp. 31–32). Washington, DC: American Psychological Association. Neuhoff, J. (2000). Classroom demonstrations in perception and cognition using presentation software. Teaching of Psychology, 27 (2), 142–144. https://doi.org/10.1207/S15328023TOP2702_11 . O’Dell, C. D., & Hoyert, M. S. (2002). Active and passive touch: A research methodology project. Teaching of Psychology, 29 (4), 292–294. https://doi.org/10.1207/S15328023TOP2904_07 . O’Regan, J. K. (2011). Why red doesn’t sound like a bell: Understanding the feel of consciousness. Oxford University Press. Draft version as PDF: http://nivea.psycho.univ-paris5.fr/ Palmer, S. E. (1975). The effects of contextual scenes on the identification of objects. Memory & Cognition, 3 , 519–526. https://doi.org/10.3758/BF03197524 . Peden, B. F., & Hausmann, S. E. (2000). Data graphs in introductory and upper level psychology textbooks: A content analysis. Teaching of Psychology, 27 (2), 93–97. https://doi.org/10.1207/S15328023TOP2702_03 . Pittenger, D. J. (1995). Teaching students about graphs. Teaching of Psychology, 22 (2), 125–128. https://doi.org/10.1207/s15328023top2202_9 . Proffitt, D. R. (2006). Embodied perception and the economy of action. Perspectives on Psychological Science, 1 , 110–122. https://doi.org/10.1111/j.1745-6916.2006.00008.x . Proffitt, D. R., Bhalla, M., Gossweiler, R., & Midgett, J. (1995). Perceiving geographical slant. Psychonomic Bulletin & Review, 2 , 409–428. https://doi.org/10.3758/BF03210980 . Prull, M. W., & Banks, W. P. (2005). Seeing the light: A classroom-sized pinhole camera demonstration for teaching vision. Teaching of Psychology, 32 (2), 103–106. https://doi.org/10.1207/s15328023top3202_5 . Riener, C. (2019). New approaches and debates on top-down perceptual processing. Teaching of Psychology, 46 (3), 267–272. https://doi.org/10.1177/0098628319853943 . Schnotz, W., & Bannert, M. (2003). Construction and interference in learning from multiple representation. Learning and Instruction, 13 (2), 141–156. https://doi.org/10.1016/S0959-4752(02)00017-8 . Schweiker, M., Fuchs, X., Becker, S., Shukuya, M., Dovjak, M., Hawighorst, M., & Kolarik, J. (2017). Challenging the assumptions for thermal sensation scales. Building Research and Information, 45 (5), 572–589. https://doi.org/10.1080/09613218.2016.1183185 . Schweiker, M., Huebner, G. M., Kingma, B. R. M., Kramer, R., & Pallubinsky, H. (2018). Drivers of diversity in human thermal perception – A review for holistic comfort models. Temperature, 5 (4), 308–342. https://doi.org/10.1080/23328940.2018.1534490 . Solomon, P. R. (1980). Perception, illusion, and magic. Teaching of Psychology, 7 (1), 3–8. https://doi.org/10.1207/s15328023top0701_1 . Steg, L., & de Groot, J. I. M. (2019). Environmental psychology: An introduction . Wiley-Blackwell. Thompson, T., Correll, C. U., Gallop, K., Vancampfort, D., & Stubbs, B. (2016). Is pain perception altered in people with depression? A systematic review and meta-analysis of experimental pain research. The Journal of Pain, 17 (12), 1257–1272. https://doi.org/10.1016/j.jpain.2016.08.007 . Thornton, T. L., & Gilden, D. L. (2007). Parallel and serial processes in visual search. Psychological Review, 114 (1), 71–103. https://doi.org/10.1037/0033-295X.114.1.71 . VanderStoep, S. W., Fagerlin, A., & Feenstra, J. S. (2000). What do students remember from introductory psychology? Teaching of Psychology, 27 (2), 89–92. https://doi.org/10.1207/S15328023TOP2702_02 . Wertheimer, M. (1912). Experimentelle Studien über das Sehen von Bewegung. Zeitschrift für Psychologie, 61 , 161–265. Wertheimer, M. (1938). Laws of organization in perceptual forms. In W. Ellis, W (Ed. & Trans.), A source book of gestalt psychology (pp. 71–88). London, England: Routledge & Kegan Paul. Online: https://psychclassics.yorku.ca/Wertheimer/Forms/forms.htm Westwood, D. A., & Goodale, M. A. (2011). Converging evidence for diverging pathways: Neuropsychology and psychophysics tell the same story. Vision Research, 51 (8), 804–811. https://doi.org/10.1016/j.visres.2010.10.014 . Witt, J. K., Proffitt, D. R., & Epstein, W. (2005). Tool use affects perceived distance, but only when you intend to use it. Journal of Experimental Psychology: Human Perception and Performance, 31 , 880–888. https://doi.org/10.1037/0096-1523.31.5.880 . Wittkopf, P. G., Lloyd, D. M., & Johnson, M. I. (2018). The effect of visual feedback of body parts on pain perception: A systematic review of clinical and experimental studies. European Journal of Pain, 22 (4), 647–662. https://doi.org/10.1002/ejp.1162 . Download references Author information Authors and affiliations. Department of Psychology, FernUniversität in Hagen, Hagen, Germany Robert Gaschler & Mariam Katsarava Department of Psychology, Universität Bielefeld, Bielefeld, Germany You can also search for this author in PubMed   Google Scholar Corresponding author Correspondence to Robert Gaschler . Editor information Editors and affiliations. School of Education, Univ of Salzburg, Salzburg, Austria Joerg Zumbach Department of Psychology, University of South Florida, Bonita Springs, FL, USA Douglas Bernstein Psychology Learning & Instruction, Technische Universität Dresden, Dresden, Sachsen, Germany Susanne Narciss DISUFF, University of Salerno, Salerno, Salerno, Italy Giuseppina Marsico Section Editor information University of Salzburg, Salzburg, Austria Department of Psychology, University of South Florida, Tampa, FL, USA Douglas A. Bernstein Psychologie des Lehrens und Lernens, Technische Universität Dresden, Dresden, Deutschland Department of Human, Philosophic, and Education Sciences, University of Salerno, Salerno, Italy Rights and permissions Reprints and permissions Copyright information © 2021 Springer Nature Switzerland AG About this entry Cite this entry. Gaschler, R., Katsarava, M., Kubik, V. (2021). Sensation and Perception. In: Zumbach, J., Bernstein, D., Narciss, S., Marsico, G. (eds) International Handbook of Psychology Learning and Teaching. Springer International Handbooks of Education. Springer, Cham. https://doi.org/10.1007/978-3-030-26248-8_6-1 Download citation DOI : https://doi.org/10.1007/978-3-030-26248-8_6-1 Received : 30 December 2019 Accepted : 24 February 2020 Published : 31 December 2020 Publisher Name : Springer, Cham Print ISBN : 978-3-030-26248-8 Online ISBN : 978-3-030-26248-8 eBook Packages : Springer Reference Education Reference Module Humanities and Social Sciences Reference Module Education Publish with us Policies and ethics Chapter history DOI: https://doi.org/10.1007/978-3-030-26248-8_6-2 DOI: https://doi.org/10.1007/978-3-030-26248-8_6-1 Find a journal Track your research Window views psychological effects on indoor thermal perception: A comparison experiment based on virtual reality environments Song, Dexuan Previous studies have indicated that window views significantly impact residents' indoor thermal perception, but the exact pathways and extent of this cross-modal influence are not fully understood. This research explores how outdoor visual attributes affect indoor thermal comfort through visual-thermal interaction, potentially aiding energy reduction in built environments. Utilizing the Landscape Visual Quality Assessment (LVQA) method, the study quantified window views with five green visibility indicators in 16 virtual environments. The experiment involved 24 participants in two temperature settings, revealing that specific window view attributes notably affect thermal perception and emotional responses. Elevated Biophilic Design Attributes and a heightened Visible Green Index correlate with increased thermal comfort. An augmented Sky View Factor and Color Richness may be associated with an elevated thermal sensation. However, Observer Landscape Distance appears to have no significant correlation with thermal perception. The findings highlight that positive emotional dimensions correlate with improved thermal comfort and acceptance, whereas negative emotions are associated with discomfort. This study elucidates the interactive effects of window view attributes on thermal perception, providing valuable insights for energy-efficient outdoor environment design. 370 IMAGES 45 Science Activities for Kids to Learn the 5 Senses Psychology Experiment About Sensation and Perception MzKaylaPinz: Sensory Perception Experiments Ciênsação hands-on experiment "Temperature perception": biology, senses One Closed Eye Experiment Psychology Experiment VIDEO Deception of the brain vs sensory perception experiment! Sensation and Perception-(Memory) Unit 3: Introduction to Sensation & Perception Notes #1 psychology part 2 sensation , perception,illusion, hallucination emotions, memory,thinking Sensation and Perception Part 3 Theories of Colour vision Sensation and Perception Chapter 6 (Part 2) COMMENTS Top 9 Experiments on Sensation Proceed in this manner until the subject reports the coloured sensation. (Gray colour) 5. When he reports sighting a gray colour stop the experiment and measure the proportions of green and red necessary to produce a gray colour. 6. Repeat the experiment with the blue and the yellow discs. Sensation and Perception 4. Sensation and Perception. Figure 5.1 If you were standing in the midst of this street scene, you would be absorbing and processing numerous pieces of sensory input. (credit: modification of work by Cory Zanker) Imagine standing on a city street corner. You might be struck by movement everywhere as cars and people go about their business, by ... Senses Experiments cookie sheet or metal baking pan. Stretch the plastic wrap over the bowl tightly. This is your eardrum. Place 20 or so rice grains on the tightened plastic wrap. Hold the pan or cookie sheet close to the blow, but not touching. Bang on the pan with your hand or large spoon making a loud noise. Watch the rice. Interactive Sensation Laboratory Exercises (ISLE) Interactive Sensory Laboratory Exercises (ISLE) is a complementary set of activities, experiments, and illustrations that allow students to engage the concepts of Sensation & Perception by interacting with the phenomena discussed in the book, including anatomical diagrams, visual illusions, auditory illusions, and musical selections. In working ... PDF SENSATION AND PERCEPTION a unit lesson plan for high school psychology e explanation is accurate.LESSON 1 is an overview of sensation and perception. The main purpose of the less. n is to give students the vocabulary for the study of sensation and perception. Lesson 1. onnects these concepts to real-life situations such. as hearing or vision tests.LESSON 2 describes the visual and a. Exploring Sensory Neuroscience Through Experience and Experiment In effect, students can experiment with illusions using themselves as subjects. Keywords: illusion, adaptation, aftereffect, receptive field, motion, color, pitch, size, orientation. In addition to their immediate aesthetic appeal, illusions have historically been used to investigate mechanisms of perception. Sensation and Perception Sensation and perception are two separate processes that are very closely related. Sensation is input about the physical world obtained by our sensory receptors, and perception is the process by which the brain selects, organizes, and interprets these sensations. ... Intriguingly, in such subliminal mere-exposure experiments, participants ... 5.1 Sensation versus Perception One way to think of this concept is that sensation is a physical process, whereas perception is psychological. For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the sensation is the scent receptors detecting the odor of cinnamon, but the perception may be "Mmm, this smells like the bread Grandma used to ... Journal of Experimental Psychology: Human Perception and Performance The Journal of Experimental Psychology: Human Perception and Performance ® publishes studies on perception, control of action, perceptual aspects of language processing, and related cognitive processes. All sensory modalities and motor systems are within its purview. The journal also encourages studies with a neuroscientific perspective that contribute to the functional understanding of ... Perception: The Sensory Experience of the World Perception refers to our sensory experience of the world. It is the process of using our senses to become aware of objects, relationships, and events. It is through this experience that we gain information about the environment around us. Perception relies on the cognitive functions we use to process information, such as utilizing memory to ... PDF Chapter 1 What is Sensation and Perception? Sensation is often considered to involve all those processes that are necessary for the basic detection that something exists in the world. For example, a sensory process might be detecting the loudness of a sound or the type of taste in a food. Perception identifies and interprets this sensory information. Sensation and Perception ISLE Activities. Interactive Sensory Laboratory Exercises (ISLE) is a set of activities, experiments, and illustrations that allow students to engage the concepts of Sensation & Perception by interacting with the phenomena discussed in the book, including anatomical diagrams, visual illusions, auditory illusions, and musical selections. Access sample chapter-specific activities under each ... 5.1 Sensation versus Perception just noticeable difference: difference in stimuli required to detect a difference between the stimuli. perception: way that sensory information is interpreted and consciously experienced. sensation: what happens when sensory information is detected by a sensory receptor. sensory adaptation: not perceiving stimuli that remain relatively constant ... Visual Perception Psychology A few experiments that will help you find out if people have a dominant hand, foot, eye and ear. [ E] The effect of color on the perception of its taste [ E] [ P] [ P] Compare reaction time of peripheral and straight vision. [ E] Explore the relationship between hand dominance and eye dominance [ E] Which is the most effective learning stimuli ... Introduction to Sensation and Perception Sensation is input about the physical world obtained by our sensory receptors, and perception is the process by which the brain selects, organizes, and interprets these sensations. In other words, senses are the physiological basis of perception. Perception of the same senses may vary from one person to another because each person's brain ... Psychophysical Methods 15. Psychophysical Methods. The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold. Absolute threshold refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or ... Sensation versus Perception This is called top-down processing. One way to think of this concept is that sensation is a physical process, whereas perception is psychological. For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the sensation is the scent receptors detecting the odor of cinnamon, but the perception may be "Mmm, this ... PDF Chapter 2 Psychophysics accomplish sensation and perception. These methods will be used throughout the book, as you will use them in many of the demonstrations and experiments that are contained in the media portion of this book. It is important to note that these are not the only methods used in sensation and perception. Sensation and Perception Sensation and Perception. Figure 5.1 If you were standing in the midst of this street scene, you would be absorbing and processing numerous pieces of sensory input. (credit: modification of work by Cory Zanker) Imagine standing on a city street corner. You might be struck by movement everywhere as cars and people go about their business, by the ... Experiments on Perception Experiment # 1. Selection and Grouping in Perception: Our perception of stimuli depends on a series of organisational processes. This aspect has been studied extensively by the gestalt psychologists. The process of organisation depends on a number of factors, due to which our perception of the same stimulus elements differs on different occasions. Tutorials in Sensation and Perception Sensation and Perception Tutorials. Please check out my new Cognition Laboratory Experiments. Here is a small collection of tutorials and demonstrations related to our senses. Choose a topic and have fun. Use of Visual Information in Art A brief review of some of the ways PDF Classic experiments in sensation and perception Summary. We will use the course to develop and design a number of classic experiments into online labs that can enrich a hypothetical 2nd year course on Sensation and Perception. At the end we will produce a detailed user manual for each lab. Teams composed of one graduate student and two undergraduate student will take on the individual lab ... Sensation and Perception The Touch Metaphor for Vision. Material on vision dominates teaching of sensation and perception (cf. Prull & Banks, 2005).Yet, separating teaching on vision from the teaching concerning other senses might, as a side effect, help to sustain wrong lay-theories about visual perception (cf. O'Regan, 2011).O'Regan in turn suggested to use a touch metaphor to correct misbeliefs about vision: w ... Window views psychological effects on indoor thermal perception: A The experiment involved 24 participants in two temperature settings, revealing that specific window view attributes notably affect thermal perception and emotional responses. ... An augmented Sky View Factor and Color Richness may be associated with an elevated thermal sensation. However, Observer Landscape Distance appears to have no ... essay homework paper phd project resume review speech study thesis