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Iconic Memory and Visual Stimuli

• Visual Persistence

Frequently Asked Questions

There are many different types of memories . One type is known as iconic memory, which involves the memory of visual stimuli. Iconic memory is how the brain remembers an image we've seen in the world around us.

Here we dive a bit deeper into iconic memory, including talking more about what it is, how it works, and how it was first discovered. We also explore important phenomena that influence the persistence of visual stimuli when creating this memory type.

What Is Iconic Memory?

The word 'iconic' refers to an icon, and an icon is a pictorial representation or image. So, iconic memory is the storage for visual memory that allows us to visualize an image after the physical stimulus is no longer present.

For example, look at an object in the room you are in now, and then close your eyes and visualize that object. The image you "see" in your mind is your iconic memory of that visual stimulus.

Iconic memory is part of the visual memory system, which includes long-term memory and visual short-term memory . It is a type of sensory memory that lasts just milliseconds before fading.

One study found considerable variability in the duration of iconic memory. For some participants, it lasted up to 240ms while for others, it lasted no more than 120ms. The researchers suggested that this may indicate that iconic memory has different layers linked to specific levels of visual hierarchy.

History of Iconic Memory

In 1960, George Sperling performed experiments designed to demonstrate the existence of visual sensory memory. He was also interested in exploring the capacity and duration of this memory type.

In Sperling's experiments, he showed participants a series of letters on a mirror tachistoscope. These letters were only visible for a fraction of a second. While the subjects were able to recognize at least some letters in that short time frame, few were able to identify more than four or five.

The results of these experiments suggested that the human visual system is capable of retaining information even if the exposure is very brief. The reason so few letters could be recalled, Sperling suggested, was because this type of memory is so fleeting.

In additional experiments, Sperling provided clues to help prompt memories of the letters. Letters were presented in rows and the participants were asked to recall only the top, middle, or bottom row.

The participants were able to remember the prompted letters relatively easily, suggesting it is the limitations of this type of visual memory that prevent us from recalling all of the letters. We see and register them, Sperling believed, but the memories simply fade too quickly to be recalled.

In 1967, psychologist Ulric Neisser labeled this form of quickly fading visual memory as iconic memory. Interestingly, Neisser is also known as the father of cognitive psychology .

Examples of Iconic Memory

It can be helpful to consider a few examples of iconic memory and how it exists in daily life. Consider some of these scenarios:

• You glance over at a friend's phone as she is scrolling through her Facebook newsfeed. You spot something as she quickly thumbs past it, but you can close your eyes and visualize an image of the item very briefly.
• You wake up at night to get a drink of water and turn the kitchen light on. Almost instantly, the bulb burns out and leaves you in darkness, but you can briefly envision what the room looked like from the glimpse you were able to get.
• You are driving home one night when a deer bounds across the road in front of you. You can immediately visualize an image of the deer bolting across the road illuminated by your headlights.

Iconic Memory and Visual Persistence

Iconic memory involves the persistence of visual information. There are three different types of visual persistence when it comes to iconic memory:

• Neural persistence : This type of persistence involves the continuation of neural activity even after the visual stimulus is no longer present. 
• Visible persistence : This form of persistence involves continuing to see an image after it is no longer present. An example would be briefly continuing to see the brightness of a flashlight after it has been turned off.
• Informational persistence : This relates to the information that is still available once a stimulus is no longer visible. For example, after an object is no longer visible, you may still be able to see the space around its previous location.

Research has found three important effects that influence iconic memory for visual stimuli:  

• Inverse duration effect : The longer a stimulus lasts, the shorter its persistence after it is absent.
• Inverse intensity effect : The more intense a visual stimulus is, the briefer its persistence once it disappears.
• Inverse proximity effect : The greater the proximity between dots in a matrix, the shorter its persistence.

It is important to note that these phenomena do not apply to afterimages. Afterimages are produced when a stimulus is so intense that the retinal impression causes the continued activation of the visual system.

Impact of Iconic Memory

Iconic memory is believed to play a role in  change blindness . This refers to the failure to detect changes in a visual scene.

In experiments, researchers have shown that people struggle to detect differences in two visual scenes when they are interrupted by a brief interval. Introducing a brief interruption erases iconic memory, making it much more difficult to make comparisons.

One study added that individual differences in change blindness were related to both the strength and stability of the visual image as well as visual ability, including the strength of iconic memory.

Iconic memory is primarily stored and processed in the occipital lobe, which also contains the visual cortex. Visual information is transmitted from the eyes to the occipital lobe. It can then be briefly stored, as it is for iconic memory. Paying attention to visual information may result in it being transmitted to other regions of the brain where it can then enter short-term memory or, potentially, long-term memory.

Both iconic and photographic memory involve the memory of images. However, photographic memory is different from iconic in that it involves the ability to remember the image in great detail, which isn't necessarily the case with iconic memory.

Iconic memory is very brief, lasting just milliseconds. However, research suggests that there are individual differences in this ability. While iconic memory lasts less than 120 milliseconds for some individuals, it can last up to 240 milliseconds for others.

Rensink RA. Limits to the usability of iconic memory .  Front Psychol . 2014;5:971. doi:10.3389/fpsyg.2014.00971

Sperling G. The information available in brief visual presentations . Psycholog Monographs Gen App . 1960;74(11):1-29. doi:10.1037/h0093759

Sperling G. A brief overview of computational models of spatial, temporal, and feature visual attention . In: Invariances in Human Information Processing .

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Spalek TM, Di Lollo V. Metacontrast masking reduces the estimated duration of visible persistence . Atten Percep Psychophys . 2022;84:341-346. doi:10.3758/s13414-021-02431-w

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Cleveland Clinic. Occipital lobe .

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

Partial report is an experimental methodology developed by George Sperling (1960) in the late 1950's. At that time there was a cognitive concept called the span of apprahension, bet you did not read about it in your textbook, that said human's are able to recall between 4-6 items in a single glance, if you will. This limit represented the limit of information we can take in instantly. This conclusion was drawn using a methodlogy Sperling termed whole report. In whole report you present a string of letters or numbers and ask the participant to recall all of them that they can.

Partial report takes a different attack. Instead of a string, an array of letters (3 x 3 or 4 x 4 are common) and after the letters are presented, a signal is given to indicate which row the person is to recall. So the participant is asked to recall only some of the items but they cannot know which items before hand. Thus, Sperling called this partial report. By multiplyig the percent correct by the total number of items, he determined the total items the person had when the arrow was shown (this is why the person cannot know which row will be indicated until after the letters are removed). He found rates from 8 (for 3 x 3 arrays) to 10 (for 4 x 4) letters available (Sperling, 1960) when the arrow immediately followed the array. These numbers are much greater than the span of apprahension concept allowed, and, thus, your not reading about it in class. As the delay was increased, the number of letters available declined to the range of the span of apprahension by about 500 ms.

These findings led to an important changes in how we understand how we take in information. One of the changes was the proposal that in addition to short-term and long-term memory, we have short-term sensory stores that last for very brief periods of time. Neisser (1967) termed the one for the visual system, that Sperling studied, iconic memory.

In this experment you can try out the partial report method. There are several parameters below you can alter to make your own unique

References: Neisser, U. (1967). Cognitive psychology . New York: Appleton-Century-Crofts. Sperling, G. (1960). The information available in brief visual presentations. Psychological Monographs: General and Applied, 74(11, Whole No. 498) . 1-29.

Setup Instructions

You can adjust several parameters to design your own version of the experments. The settings are discussed below.

Settings for the Stimuli

You can adjust several parameters to design your own version of the experments. The settings are discuss below.

Number of Rows : Number of rows in the letter array to present. Number of Columns : The number of items in each row of the letter array. Report What? : you can ask the participant to report either rows or coumns of the letter array. Duration of Stimulus (ms) : how long the stimulus is presented. Sperling (1960) used 50 ms but that his hard for most monitors to reproduce well. He used a tachistoscope. Font Size : choose the font size of the letters. The bigger the letters the farther the outside letters will be from the fovea. Background Gray Level : the brightness of the background, in basic display units. This variable alters the contrast between the letters and the background. Duration of Fixation (ms) : how long the fixation mark is on (ms). Stimulus Delay (ms from end of fixation) : how long after the fixation mark is removed till the beginning of the stimulus. This number needs to be big enough for any arrows that occur before the stimulus (the negative numbrer includes the duration of the stimulus). Reset Stimulus At the top of the settings is a Reset Stimulus button. Pressing this button restores the method settings to their default values.

Experimental Method Settings

Select the delays between the end of the letters and the presentation of the arrow you w ish to use. (0 is presented just as the array is removed and - values are presented before the array is removed) : this is the principle independent variable during the experiment. This is the different levels of delay from the end of the stimlus to the beginning of the arrow. As stated above, negative numbers will occur before the stimluls is removed. Number of Trials/Delay : how many trials at each level of delay. Reset Method At the top of the settings page is a Reset Method button. Pressing this button restores the stimulus settings to their default values.

Change the settings below to alter the stimulus parameters in this experiment.

Change the settings below to alter the parameters of the experimental method.

Instructions for Experiment

Below, press the spacebar or the Open Experiment Window button on the screen to open the window where the experiment will run. When this screen opens, press the spacebar or click the "Start" button to begin the experiment. There are instructions above the "Start" button. Read them to know how to perform the experiment. Keep your eyes fixated on the red plus sign in the middle of the screen. Press the space bar to go to the next trial.

Results Tab

Your data will be presented on the results tab. The x-axis will have the delays. The y-axis will show the percent correct for each delay. To download your trial-by-trial, press the Show Data link. To download the summary data press the Show Summary link. This data will be stored in a csv format readable by most spreadsheet and statistical programs.

Your Results

Iconic Memory

Introduction.

How much can you see in 1/10 of a second? Test yourself with . Even though you could probably report only 3 or 4 letters, you may have felt that you saw all of them but could only remember a few long enough to say them. It is as if you had a rapidly fading visual image of the display, a brief visual memory store or sensory register.

As a graduate student in the late 1950s, George Sperling set out to test this idea. First, he gave people a series of tests like the one you just tried, confirming that most people can report only 3 to 4 of 12 letters. He reasoned that if the entire display is initially available, then one should be able to report any arbitrary 3 to 4 letters from it. Try to see how this works. Again, you could probably report 3 or 4 letters. Because you did not know in advance which of the three rows to report, three times as many letters (9 to 12) were available.

Experiments

You are now ready to investigate the sensory register (also known as iconic memory) by replicating several of Sperling’s (1960) experiments. Each experiment starts with whole report trials followed by trials in which report of a single row is cued. These experiments may work best if the experiment window is maximized. You may also want to use headphones for the tone cue in the second half of each experiment.

Existence and Capacity

(24 trials, 6 min.) uses a 12-letter array like the one you saw in the first examples. This will allow you to measure the effect that you saw in the above demonstrations. Next, try (51 trials, 10 min.). This experiment varies the number of letters in the array. Is there a fixed limit to the number of letters that can be reported, regardless of the number presented? (If you only have time for one of these experiments, do .)

If the sensory register lasts only briefly, what do you expect to happen if the partial-report cue is delayed after the letter array is presented? Test your prediction with (48 trials, 10 min). This gives an estimate of how quickly the visual sensory register decays.

Interference

In the experiments you have done so far, the display was blank after the letter array was presented. What do you expect if a pattern is shown before the partial-report cue is given? Try (36 trials, 10 min.). This shows that the sensory register not only decays with time but can be disrupted by interference.

Your results should look something like those in . Collectively, they show that: (A) More is seen than can be reported, as revealed by partial report. This suggests the existence of a very short-term memory, the sensory register (the visual icon). (B) Regardless of the number of letters presented, we can only report about 4 of them. (C) The visual icon decays rapidly and is essentially gone after one second. (D) The visual icon can be disrupted by subsequent visual patterns.

Further Exploration

• There are several other ways to investigate iconic memory. For example, watch a repeating sample of random dots ( ). With a long cycle time, you may not be aware that the pattern repeats. At a shorter cycle time, you can see that it repeats, because your iconic memory still holds an image of the display.
• An auditory analog of Sperling’s experiment demonstrated a sensory register for hearing, also known as echoic memory (Darwin et al. 1972). An estimate of echoic memory comes from cycling different durations of noise; the longest duration at which repetition is perceived is duration of echoic memory ( ).
• Why does delaying the partial report cue in give an estimate of the duration of the sensory register?
• How do you know that the sensory register is not just an afterimage on the retina or elsewhere in early visual processing?
• Sperling G (1960). The information available in brief visual presentations. Psych. Monographs 74 (Whole No. 498). [ ]
• Darwin CJ, Turvey MT, Crowder RG (1972). An auditory analogue of the Sperling partial report procedure: Evidence for brief auditory storage. Cognitive Psychology 3:255-267. [ ]

Sensory Memory

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Sensory registers

Stimulation of human sense organs is initially represented in sensory memory for a brief period by a literal, labile, and modality-specific neural copy. The term iconic memory stands for the initial representation of visual stimuli, and echoic memory is its counterpart for auditory stimulation (Neisser 1967 ). Sensory memory is often contrasted with short-term memory and working memory which are assumed to be less modality specific, and all of these are distinct from long-term memory. In functional terms, sensory memory is comparable to a register in a computer. In a human, if you want to know what the last sensory input was, you examine the sensory register. The prevailing view of human memory systems is that there are one or more modality-specific sensory registers in each sensory modality, plus a register or registers for short-term and/or working memory, plus functionally distinct long-term memory systems for episodic, semantic, procedural, and...

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Lu, ZL. (2012). Sensory Memory. In: Seel, N.M. (eds) Encyclopedia of the Sciences of Learning. Springer, Boston, MA. https://doi.org/10.1007/978-1-4419-1428-6_257

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Iconic memory requires attention

Marjan persuh.

1 Program in Cognitive Neuroscience, City College, City University of New York, NY, USA

2 Department of Psychology, City College, City University of New York, NY, USA

Boris Genzer

Robert d. melara.

Two experiments investigated whether attention plays a role in iconic memory, employing either a change detection paradigm (Experiment 1) or a partial-report paradigm (Experiment 2). In each experiment, attention was taxed during initial display presentation, focusing the manipulation on consolidation of information into iconic memory, prior to transfer into working memory. Observers were able to maintain high levels of performance (accuracy of change detection or categorization) even when concurrently performing an easy visual search task (low load). However, when the concurrent search was made difficult (high load), observers' performance dropped to almost chance levels, while search accuracy held at single-task levels. The effects of attentional load remained the same across paradigms. The results suggest that, without attention, participants consolidate in iconic memory only gross representations of the visual scene, information too impoverished for successful detection of perceptual change or categorization of features.

Introduction

The standard model of iconic memory considers it a pre-attentive store of visual information (Sperling, 1960 ). Here, we evaluated this model using two distinct paradigms. In the traditional paradigm, iconic memory of letters or digits is measured using partial-report (Sperling, 1960 ; Averbach and Coriell, 1961 ); more recent tests have expanded the stimulus set to include colors (Houtkamp and Braun, 2010 ), orientations (Houtkamp and Braun, 2010 ; Sergent et al., 2011 ) and shapes (Ruff et al., 2007 ). A new paradigm, the cued change detection task (Becker et al., 2000 ; Landman et al., 2003 ; Sligte et al., 2008 , 2010 ), has proven especially effective in capturing the initial coding of information in iconic memory. The goal of the current study was to use both partial-report and cued change detection to address the question of whether attention mediates the formation of early iconic representations.

People frequently fail to notice change between two visual images, even when the change is relatively large. One explanation for such instances of “change blindness” (Rensink, 2002 ; Simons and Rensink, 2005 ) links the phenomenon to capacity limitations in visual scene perception (Rensink et al., 1997 ; O'Regan and Noë, 2001 ). On this account, limited attentional resources are available to encode the initial display in its entirety, leaving insufficient information to detect the image change. Consistent with this idea, the number of items people are able to monitor for change (i.e., approximately four; Luck and Vogel, 1997 ; Pashler, 1988 ; Rensink, 2000 ) closely matches estimates of capacity, in either attention (Pylyshyn and Storm, 1988 ; Rensink, 2000 ; Scholl, 2000 ) or working memory (Cowan, 2001 ). Further support is found in multi-unit recordings of monkey area V1 during change detection, which reveal a close correspondence between the neural activity elicited by the initial display and successful task performance (Landman et al., 2004 ). Likewise, in humans, the magnitude of event related potentials (ERPs) elicited by the initial display under different attentional manipulations predicts accuracy of change detection (Koivisto and Revonsuo, 2005 ).

A competing explanation is rooted in interpretations of the now classic experiments of George Sperling (Sperling, 1960 ) using a partial-report procedure, which revealed that, when post-cued, observers could accurately report any item from a brief multi-item visual display. Sperling concluded that the brief display was stored in an iconic memory, a pre-attentive, large capacity repository of detailed visual information, which required attention (post-cue) to transfer a subset of the information into a more durable form for inspection in working memory. Change blindness can thus be understood as the disruption of iconic memory (Becker et al., 2000 ; Landman et al., 2003 ). On this view, the intervening interval between images masks or overwrites the iconic memory of the initial image, leaving too sparse a representation to detect the image change.

Participants performing partial-report tasks often comment spontaneously that they seem to see all of the items in the display, but are unable to report them all due to forgetting. Such reflections imply that we experience more than we can report, and we report only what is attended. Several popular theories of consciousness have emerged from this view (Block, 1990 ; Lamme, 2003 ) 1 . For example, Lamme (Lamme, 2003 ) proposed that attention operates at a stage conceptually and operationally distinct from that required for conscious perception: we are conscious of many different visual inputs, however, attention allows only behavioral reporting, playing no role in whether visual information reaches a conscious state. Indeed, recent investigations using ERPs and magnetoenchephalography (MEGs) suggest that the earliest neural correlates of visual awareness, including the visual awareness negativity component (VAN; Koivisto and Revonsuo, 2003 ), function independently of spatial attention (Koivisto and Revonsuo, 2007 ; Wyart et al., 2011 ). In one study of change blindness that provided evidence consistent with this proposal, Landman et al. (Landman et al., 2003 ) cued participants during the intervening interval on the item changed between images. They found that the cue dramatically improved change detection for as long as 1.5 s after the initial display disappeared (see also Becker et al., 2000 ; Hollingworth, 2003 ). Reminiscent of Sperling's (Sperling, 1960 ) seminal results (see also Coltheart et al., 1974 ; Coltheart, 1980 ), the authors concluded that participants had awareness of roughly the entire visual scene, with attention acting to select from this rich, fleeting representation items to be stored in working memory.

Block (Block, 1990 , 2005 ) advanced a similar proposal, drawing a distinction between “phenomenal” consciousness—detailed and possibly unlimited in capacity—and “access” consciousness—limited to the “consumer” information residing in the brain's systems of memory, reasoning, planning, and rational control of action. Possible neural correlates link phenomenal consciousness to posterior brain regions (e.g., visual cortex) and access consciousness to anterior regions (e.g., prefrontal cortex, see Lamme, 2006 ; Goodale, 2007 ). From this perspective, phenomenal consciousness simply “overflows” access consciousness. Although several extant experiments are consistent with Block's idea (Becker et al., 2000 ; Landman et al., 2003 ), in none was attention manipulated during presentation of the initial image. And although strong evidence exists for the role of attention in transferring information to working memory, it is unclear whether attention is required to create the initial iconic representation.

The purpose of the current study was to carry out this crucial manipulation in two separate experiments. In the first experiment we followed recent examples (e.g., Landman et al., 2003 ) in using a cued change detection task to measure participants' baseline ability to form an iconic memory of an initial visual display. This is an attractive paradigm because the comparison task enhances sensitivity to information encoded in the first display. In a second experiment we employed the traditional partial-report procedure (Sperling, 1960 ). In each case, we asked whether taxing attentional resources during the display affects iconic memory formation, thus representing an advance over previous studies using these paradigms. To manipulate attention we introduced a concurrent visual search task, which required participants to divide attention with the iconic memory task. Visual search was either easy, drawing relatively little on attentional resources, or hard, drawing heavily on resources. If the availability of attention is irrelevant in the formation of iconic memory representations, then visual search should leave change blindness or partial-report unaffected. However, if attention and consciousness are interrelated and perhaps even synonymous, as several authors have claimed (Posner, 1994 ; Prinz, 2000 ; O'Regan and Noë, 2001 ), then the formation of iconic memories (and, by implication, phenomenal consciousness) requires attention, which in the current study would cause instances of change blindness or report failure to multiply as the demands of the visual search task increase. Such results would demonstrate that, in the absence of attention, participants had impoverished iconic memory representations, which were insufficient for the successful transfer of target items to working memory.

Materials and methods

Experiment 1, participants.

Twenty-four undergraduate students (12 female, ages 18–32, M = 19.3) from the City College of the City University of New York participated in the experiment for course credit. All students reported normal or corrected-to-normal vision. None reported a history of neurologic illness, head trauma, or psychiatric illness. All participants were given written informed consent according to institutional guidelines prior to testing. The City College Human Research Review Committee approved the consent form, which contained detailed information regarding the purpose, risks, and benefits of participating.

Apparatus and stimuli

The stimuli appeared on a 16″ CRT monitor (Sony Model G220) with refresh rate of 100 Hz.

Visual search task. Stimuli for the visual search were a set of eight small white circles, each subtending 0.65°, presented within a gray disk, subtending 3.4°, superimposed on textured background (Figure ​ (Figure1). 1 ). The positions of the circles were selected randomly on each trial from a set of 10 predetermined positions. In easy visual search, participants were asked to find a pegged circle (i.e., circle with attached white bar subtending 0.16° × 0.33°) among smooth distractor circles (i.e., no white bar), (Figure ​ (Figure1). 1 ). Conversely, in hard visual search, participants were asked to find a smooth target circle among pegged distractor circles (attached white bar subtending 0.16° × 0.16°). In each condition, targets appeared with probability 0.5.

An example of a trial sequence in Experiment 1. Here, visual search is easy and the change detection task includes a change. Rectangles in vertical or horizontal orientation were composed of texture identical to background (inset).

Change detection task. Participants were asked to detect a change between two displays in the orientation (vertical to horizontal or vice versa) of one of eight rectangles. The rectangles, each measuring 2.3° × 1.3° and offset from the background in textural orientation (Figure ​ (Figure1, 1 , inset), appeared in an imaginary circle (diameter = 5.1°) at equally spaced positions. To prevent grouping, the positions were randomly jittered ±0.8° in radial direction.

Participants sat in a dimly lit, sound attenuated testing chamber at a viewing distance of 57 cm. Participants performed five different tasks over the course of the experimental session, three single-tasks (200 trials each) and two dual tasks (400 trials each). The single-tasks were: (1) change detection alone, (2) easy visual search alone and (3) hard visual search alone. The dual tasks were (4) change detection with easy visual search and, (5) change detection with hard visual search. Each of the five different tasks included the display of circles (used in visual search) and the display of rectangles (used in change detection). This tack enabled us to equate the amount and type of visual stimulation across task conditions. Tasks were completed separately and presented in blocks of 50 trials separated by short breaks. All participants first completed a set of the three single-tasks, followed by the two dual tasks. Order of tasks within each set and response assignments were counterbalanced.

At trial onset a fixation cross subtending 0.2° appeared for 1000 ms, followed immediately by a display of eight white circles, which remained displayed for 250 ms. 50 ms after circle onset, eight randomly oriented rectangles appeared for 200 ms (see Figure ​ Figure1). 1 ). In visual search alone, a blank screen was then shown with the question “Did you see the target?” until participants made non-speeded “yes” or “no” responses to the target circles, ignoring the rectangles.

In change detection alone, a cue—a yellow line subtending 1.9° × 0.13° at an eccentricity of 0.9°—appeared for 100 ms at one of the eight positions previously occupied by a rectangle. Cue location was determined randomly on each trial. The screen was then made blank for 900 ms, followed by a second display of eight rectangles, which appeared for 250 ms, with the orientation of the rectangle at the cued location changing orientation on half of the trials. All other rectangles were identical across the two displays. A subsequent response prompt “Change?” signaled participants to decide whether the rectangle in the cued location had changed orientation. Trials were response terminated.

In the dual tasks, participants were required to attend to both circles and rectangles, with the relevant task (search or change detection) indicated on each trial only after the onset of the first display (see Figure ​ Figure1). 1 ). Participants were instructed to maintain high performance on visual search, while simultaneously attending to orientation change. The search prompt appeared with probability 0.6 to ensure that performance on the search task was maintained.

Experiment 2

The results of Experiment 1 were extremely robust: each of the participants showed better performance in change detection during low load. Consequently, we elected to test relatively fewer participants in Experiment 2. Six undergraduate students (3 female, ages 20–33, M = 24.7) from the City College of the City University of New York participated in the experiment. All students were neurologically normal individuals reporting normal or corrected-to-normal vision. Participants read and signed a consent form approved by the City College IRB. None participated in Experiment 1.

Apparatus, stimuli, and procedure

The apparatus matched Experiment 1. In both single and dual tasks, a checkerboard pattern mask presented centrally and exactly overlapping the search array, appeared for 50 ms immediately after the display of circles and rectangles. In visual search alone, the response prompt appeared immediately after the pattern mask. The change detection task from Experiment 1 was replaced with a partial-report task. In partial-report alone, the pattern mask was followed by a yellow cue that appeared for 200 ms at one of the eight positions previously occupied by a rectangle. A subsequent response cue “V or H?” prompted participants to decide whether the rectangle was oriented vertically or horizontally. In the dual tasks, participants were again required to attend to both circles and rectangles, with the relevant task (search or partial-report) indicated on each trial immediately after the offset of the pattern mask. All other aspects mimicked Experiment 1.

To examine whether attention is required for iconic memory, in our first experiment we paired a change detection task with a visual search task. Participants were asked to detect change in the orientation (vertical or horizontal) of a visual object (rectangle). Attentional demands from the dual task were either made easy—simultaneously searching for a readily seen target—or made hard—searching for a less visible target. We were careful to assess each participant's baseline ability to detect change or search targets by measuring performance in each task alone before asking participants to perform dual tasks. In this way, we could gauge any decrements in change detection performance from adding an easy dual task (easy search), and then any further decrements that accompany a difficult dual task (hard search). Change detection should be unaffected by the attentional load manipulation if attention is uninvolved in the formation of iconic memories.

We first performed a series of manipulation checks. A comparison of the visual search tasks performed alone indicated that we were successful in manipulating attentional load: accuracy during easy visual search ( M = 98.88%, SD = 2.59%) was significantly higher than during hard visual search ( M = 69.40%, SD = 5.54%), t (23) = 21.42, p < 0.001. We also found that participants were able to maintain high accuracy when performing change detection alone ( M = 87.85%, SD = 5.90%), a result consistent with previous studies indicating improved performance when the change location is cued (Becker et al., 2000 ; Landman et al., 2003 ). Finally, we found that participants were able to maintain search accuracy under dual task conditions: as shown in Figure ​ Figure2A, 2A , there was no difference in visual search performance between single and dual conditions in either easy, t (23) = 0.19, p = 0.851, or hard, t (23) = 1.35, p = 0.190, search tasks.

(A) Accuracy for visual search for single and dual tasks as a function of search type in Experiment 1. (B) Change detection accuracy in dual tasks as a function of attentional load in Experiment 1.

The primary analyses involved evaluating the effects of attentional load on change detection under dual task conditions. Figure ​ Figure2B 2B depicts performance in change detection as a function of load. We found that the accuracy of detecting change fell from single-task performance ( M = 87.85%, SD = 5.90%) when paired with easy visual search ( M = 76.35%, SD = 7.16%), t (23) = 8.83, p < 0.001. Yet the more appropriate comparison is between the two dual task conditions (low vs. high load), as any dual task condition is more demanding than a single-task condition (e.g., in requiring that two sets of instructions be held in memory). Here, change detection dropped to near-chance levels when paired with hard visual search ( M = 59.83%, SD = 5.43%). The difference in change detection when paired with easy or hard search was highly significant, t (23) = 12.81, p < 0.001. Importantly, each of the individual participants revealed an identical pattern of performance. These results are in line with the view that the formation of an iconic memory of object orientation is impaired when attentional resources are reduced.

Although the cued change detection task (Experiment 1) is now a common technique to probe iconic memory formation (Becker et al., 2000 ; Landman et al., 2003 ; Sligte et al., 2008 , 2010 ) it is unlike the partial-report task Sperling ( 1960 ) used in his seminal studies of iconic memory because the former requires a comparison between two images presented sequentially. This key procedural difference invites another interpretation of our results: perhaps attentional load undermined the process of comparing the first and second displays, leaving untouched the iconic image of the first display (see Simons et al., 2002 ; Mitroff et al., 2004 ). To be sure, a previous study (Landman et al., 2003 ), which used our identical paradigm, has already ruled this explanation out; it also is highly unlikely that attentional resources could interfere with comparison processes 1.5 s later. Nevertheless, we felt compelled in Experiment 2 to confront this alternative directly. We also considered here the possibility that the cue used to query change was relatively ineffective under high load, even though the cue's very appearance, which masked the search array, made continued search irrelevant. Either of these alternatives is consistent with the findings of the Experiment 1.

The purpose of Experiment 2 was to address these alternative explanations using a reporting procedure closer in spirit to that employed by Sperling ( 1960 ). Here, we eliminated the second display entirely, instead asking participants merely to report the orientation of the cued rectangle in the first (now, the only) display. To ensure that participants were able to use the cue effectively we doubled its duration from 100 ms to 200 ms. Finally, to ensure that the iconic image formed to the rectangles for partial-report did not also include the search items, a pattern mask spatially overlapping only the search items appeared immediately after the display. Thus, participants could not continue searching the array once the reporting cue appeared. If attentional load disrupts partial-report in this modified Sperling paradigm, it will have provided especially strong and convergent evidence that iconic memory formation requires attention.

Presentation of the pattern mask had no discernible effect on visual search performance. As in the previous experiment, participants were significantly more accurate when search was easy ( M = 99.42%, SD = 0.49%) than when it was hard ( M = 68.33%, SD = 5.95%), t (5) = 13.17, p < 0.001. Once again we found that, search performance was virtually identical between single and dual tasks (Figure ​ (Figure3A) 3A ) whether search was easy, t (5) = 0.94, p = 0.393, or hard, t (5) = −0.51, p = 0.635. We also again found that the accuracy of performance (here, categorization using partial-report) fell from single-task levels ( M = 81.92%, SD = 6.78%) when coupled with easy visual search ( M = 70.08%, SD = 10.88%), t (5) = 2.77, p = 0.039, but was indistinguishable from chance responding when coupled with hard visual search ( M = 52.70%, SD = 4.41%), a difference that was highly significant t (5) = 5.26, p = 0.003 (Figure ​ (Figure3B). 3B ). Moreover, as in Experiment 1, each of the individual participants evinced the same pattern of performance. In replicating the results of our previous experiment within a traditional partial-report paradigm, Experiment 2 effectively rules out the two chief alternative explanations of attentional load on change detection: disruption to comparison processes and ineffectiveness of reporting cue. The current results instead support the view that attention is required in the formation of iconic memories, an explanation that captures parsimoniously the principal findings of both experiments.

(A) Accuracy for visual search for single and dual tasks as a function of search type in Experiment 2. (B) Partial-report accuracy in dual tasks as a function of attentional load in Experiment 2.

Two experiments investigated the role of attention in forming iconic representations. In each, attention was taxed during initial display presentation, focusing the manipulation on the consolidation of information into iconic memory, prior to transfer into working memory. Observers were able to maintain high levels of accuracy even when concurrently performing an easy visual search task (low attentional load). However, when the concurrent search was made difficult (high attentional load), observers' performance dropped to almost chance levels, whereas search accuracy nevertheless remained at single-task levels. Moreover, the effects of attentional load were essentially the same whether observers were asked to detect change (Experiment 1) or to categorize features using traditional partial-report (Experiment 2). These results suggest that, without attention, participants consolidate in iconic memory only gross representations of the visual scene.

Theoretical implications

Several recent theories of consciousness embrace a conceptual division between access consciousness and phenomenal consciousness (Block, 1990 , 2005 ; Lamme, 2003 ). Access consciousness involves reportable experience, which is directly accessible, requires attention, and is severely limited in capacity. By contrast, phenomenal consciousness is thought to be pre-attentive, not directly accessible, and large, possibly unlimited, in capacity. Lamme (Lamme, 2003 ), for example, claims that attention is necessary only for experiential reporting (i.e., access consciousness), and so is dispensable for phenomenal consciousness. The classic experiments investigating iconic memory (Sperling, 1960 ), as well as more recent behavioral (Coltheart et al., 1974 ; Coltheart, 1980 ; Becker et al., 2000 ; Landman et al., 2003 ) and electrophysiological (Koivisto and Revonsuo, 2007 ; Wyart et al., 2011 ) demonstrations, undergird this theoretical perspective in suggesting a separation between what humans experience and what they are able to report. Yet the results of the present study are consistent with the opposing view that phenomenal consciousness, like access consciousness, depends heavily on attention.

Recent evidence from neuroimaging bears on these views. Houtkamp and Brown (Houtkamp and Braun, 2010 ) measured the magnitude of the BOLD response in primary visual cortex (V1) and extrastriate cortex (V2) to a peripheral task (color or orientation discrimination) under dual task conditions. They concluded that attention acts to amplify already-formed iconic traces. However, the investigators did not manipulate attention to the central task, leaving unanswered the question of whether attention modulates iconic trace formation. Sergent and colleagues (Sergent et al., 2011 ) found that the magnitude of neural activation in visual areas V1 and V2 to the initial stimulus display predicted the accuracy of partial-report. These results are consistent with a possible role for attention in forming the display's iconic trace, as are the recent results of Koivisto and colleagues showing modulation by attention of early ERP correlates of consciousness in the occipital region (Koivisto et al., 2009 ). As in our study, both of these studies employed strong attentional manipulations. We believe that the inconsistency in demonstrating the role of attention on neural correlates of consciousness is due in part to the varying effectiveness of the attentional manipulations used across studies.

We recognize that our conclusions concerning the role of attention in phenomenal consciousness rests on the assumption that iconic memory is a form of phenomenal consciousness. Still, to the best of our knowledge, ours is the first study to evaluate rigorously the role of attention in phenomenal consciousness by manipulating attentional load during the time of the iconic image formation (cf. Braun and Julesz, 1998 ; Li et al., 2002 ). We found in both experiments that iconic image formation was severely disrupted by an increase in attentional load, indexed by a significant drop in change detection or categorization. In fitting the view that phenomenal consciousness relies heavily upon attention, our results suggest an intimate relationship between consciousness and attention (see also Posner, 1994 ; Merikle and Joordens, 1997 ; Prinz, 2000 ; O'Regan and Noë, 2001 ). Indeed, our results essentially undo the conceptual distinction between phenomenal and access consciousness (cf. Kouider et al., 2010 ). As an alternative, we propose that consciousness is best conceived as a binary phenomenon, with the contents of consciousness varying along a continuous scale. Here, consciousness always requires attention, though we leave open the possibility that attention and consciousness are fully distinct phenomena (Koch and Tsuchiya, 2007 ).

Alternative explanations

One might advance other interpretations of our findings. Perhaps attention is unnecessary to actually form iconic memories, but the diversion of attention accelerates subsequent memory decay or forgetting. In this case, hard visual search might be said to have a more pronounced effect than easy visual search on the rate of decay, leading to relatively poorer change detection under high attentional load. Of course, our post-cue was immediate, leaving little room for iconic decay. Moreover, investigators who have tackled the question of iconic decay directly (e.g., Landman et al., 2003 ) have shown that the rate of decay in iconic memory is unaffected by attentional focus, enabling us to rule this explanation out.

In the current study, we varied across experiments the delay after the initial display in prompting a response, from 900 ms in Experiment 1 to 200 ms in Experiment 2. This manipulation offers an additional means to test the hypothesis of decay in iconic memory, which implies that the information available from the iconic store falls off with delay. We found, however, that the pattern of performance was the same whether the response prompt followed the display by 200 ms or 900 ms, demonstrating that attentional load influenced the intercept (i.e., memory formation) rather than the slope (i.e., memory decay).

Another possibility is that attentional load differentially interfered with the process of transfer after the formation of the iconic image. Yet previous studies (Landman et al., 2003 ), as well as our own pilot experiments, have demonstrated that iconic memory representations in this paradigm persist for at least 500–1000 ms after the disappearance of display. We, therefore, think it highly unlikely that the attentional load manipulation affected the transfer of information.

Perhaps low attentional load afforded participants an opportunity to foveate peripheral stimuli sequentially, yielding relatively good task performance (change detection or partial-report) in this condition. However, two points argue against differential eye movements as an explanation of good performance during easy search. First, our design employed presentation times too brief to permit the sequential foveation of stimuli. Second, even if possible, sequential foveation here would actually have produced worse performance than constant fixation. The reason is that in both experiments the target rectangle was not known in advance, but instead required participants to wait until the cue appeared after the rectangle display terminated (and, in Experiment 1, for a second display to appear). Here, the optimal strategy is to fixate at the center of the display, equidistant from all rectangles, to form an iconic image of the set of rectangles. By contrast, looking directly at any single rectangle would, on average, result in relatively poor performance. Indeed, a recent ERP study found that during successful change detection attention is spread across the display, whereas during change blindness attention tends to be focused on specific locations (Koivisto and Revonsuo, 2005 ). Thus, our finding of good performance during easy visual search rules out differential eye movements as a potential confound in this study.

The current study considered only the effects of spatial attention on performance in iconic memory tasks. Yet experiments investigating the effects of masking (Koivisto et al., 2005 ) have demonstrated dissociation between consciousness and attention for objects occupying a central spatial position. Thus, it is possible that the effects of object attention on the formation of iconic memories are distinct from those of spatial attention. Future experiments could investigate this possibility by examining the effects of attentional load when the objects of search and change or partial-report are spatially superimposed.

We have demonstrated in two experiments that the formation of iconic memory, which traditionally is considered pre-attentive, is disrupted when attention is diverted. We showed this in experiments that required either detection of perceptual change or categorization of features. Our data thus provide evidence that phenomenal consciousness, although conceptually and theoretically distinct from attention, still requires attention. The role of attention, therefore, goes beyond the transfer from iconic to working memory stores, suggesting that phenomenal consciousness is indistinct from access consciousness.

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

1 For the purposes of the present study, we define attention as spatial and top-down selection, and consciousness as the subjective experience or visibility of stimuli.

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Sensory Memory (Definition + Examples)

Think about the memory of your first prom. Or a day at the park with your dog. Or a joke that your friend made the other day.

The memories that stay in our long-term memory storage stuck out to us for a reason. The things that we saw, felt, or heard were significant and worthy of being remembered. They made the cut.

We see, feel, and hear a lot of things throughout the day. We take in many, many pieces of information every millisecond.

As you begin to learn more about how memory works, you know that not all of these pieces of information make it very far into our memories. They go through different levels of memory storage to make it to the long-term memory.

What is Sensory Memory?

Also known as the sensory register, sensory memory is the storage of information that we receive from our senses. Examples of Sensory memory include seeing a dog, feeling gum under a chair, or smelling chicken noodle soup. Our eyes, nose, and nerves send that information to the brain.

Before memories go into short-term memory storage or long-term memory storage, they sit in sensory memory storage. Sensory memory may be accurate, but it is very briefly in our minds before it is stored. There are many different types of sensory memory. While some types of sensory memories stick in our minds for up to four seconds, other disappear within milliseconds. It’s up to the brain to decide which of these memories moves onto working memory and later, long-term memory.

Where Does Sensory Memory Come From?

From our senses! Think of sensory memory as pieces of data that explain the world around us.

How does data travel from our eyes or ears to our sensory memory? The process is slightly different depending on which sense is collecting information. Fortunately, if you've got questions, I've got answers.

Vision : Sensory information is picked up first through multiple layers of the retina. By the time it reaches the optic nerve, that sensory information has transformed from light to electrical signals. The optic signal is the connecting piece between the eye and the brain. Electrical signals are finally processed in many areas of the brain like the thalamus and visual cortex.

Hearing :  This process mirrors the path that visual information takes from the eyes to the visual cortex. Of course, the eyes are not involved in hearing. The ears pick up vibrations and convert that information into electrical signals in the Organ of Corti. Then, the signals travel through the cochlear nerve and to the auditory canal and cortex.

Touch and Balance:  (Yes, balance is a sense!) The ear needs mechanoreceptors to pick up on sensory information. This type of receptor cell is also important in collecting information about touch and balance. Touch receptors are found all over the body!

Taste and Smell :  Did you know we process taste and smell at the same time? Taste begins at the taste buds, which contain receptor cells much like a layer of the retina or layer of the inner ear that picks up sensory information. As we chew, our food breaks down and gaseous particles enter our olfactory receptors. This information is converted again and travels through the facial nerve, vagus nerve, and glossopharyngeal nerve.

Sensory Information and COVID

One of the most bizarre symptoms of the Coronavirus is the temporary loss of taste and smell. Researchers are still trying to understand this, but they believe that cells that support olfactory neurons are damaged when COVID enters the body. Olfactory neurons are not directly affected, as they are when attacked by other viruses. If you lose your sense of smell while experiencing COVID symptoms, you're likely to get it back.

Is Sensory Memory Unlimited?

In terms of capacity; seemingly, yes. In terms of duration; no. Sensory memory only lasts for about a second. Unless the brain decides to move that information along to short-term memory storage, however, the information is lost forever. (Or until you feel that gum under your chair again.)

How is Sensory Memory Encoded?

Sensory memories become memories in our brain through a process called encoding. There are three types of this encoding: visual encoding, acoustic encoding, and semantic encoding. Seeing an image in your mind, like the Adidas logo or the image of your favorite album cover, is the result of visual encoding. Having a tune stuck in your head is the result of acoustic encoding. And any impact, feelings, or context that connect these visual and acoustic memories is the result of semantic encoding.

Experiments with Sensory Memory

How do we know the length of sensory memory? A cognitive psychologist named George Sperling helped us find the answer.

In the 1960s, Sperling produced an experiment to test sensory storage and memory. He each participant a viewfinder. In the viewfinder, participants would see three rows of letters for just 1/20th of a second. In the blink of an eye, the letters were gone.

Then, Sperling ran a bell that indicated to participants that they needed to recite the top, middle, or bottom row of letters. Sometimes, this bell went off within 1/4th of a second after the letters disappeared. Other times, the bell went off a second or two after the letters disappeared.

Sperling found that the letters stuck in the participants’ memories long enough if the bell rang within 1/4th of a second. Once a second or more had passed by, the participants lost the memory of the letters. Sensory memory moves fast.

Why? One theory is that sensory storage is limited. We know that working memory, or short-term memory, is quite limited. Unless things are committed to long-term memory fast, they will go away. This rings true for sensory memory as well. Our eyes, ears, etc. are constantly taking in new sensory information. When new information comes in, something has got to go.

There Are More Than Five Senses

Before you started watching this video, you could probably guess that sensory memory had to do with the senses: sight, sound, smell, taste, and touch. In reality, there are many more senses than just the five we are taught in grade school. Proprioception, for example, is the awareness of our bodies in space. Our sense of balance is also another sense that is often forgotten in textbooks and classroom discussions.

All of these different senses contribute to our overall sensory memory. But I’m not going to dive into all of the types of sensory memory that have to do with proprioception, nociception, etc. I’m just going to talk about three main types of sensory memory: iconic memory, echoic memory, and haptic memory.

We say that sensory memory lasts for one second, but that’s not the whole story. Each different type of sensory memory may stick around for a longer or shorter period of time.

Iconic Memory

George Sperling’s early experiments tested participants on what they saw. Seven years after his experiment, a psychologist named Ulric Neisser said that this quickly-fading memory storage was iconic memory . Ionic memory is the memory of the things we take in with our eyes.

Iconic memory doesn’t stick around for very long - most iconic memories disappear within ½ second. It can last just milliseconds and then what we have seen is “gone forever,” or at least until we see it again. Our eyes typically have the ability to scan the same item over and over again, so this quick rate of disappearance is not usually dramatic or significant.

This quick rate of disappearance could contribute to the ideas of inattentional blindness and our ability to “not see” things that are right in front of us.

Echoic Memory

Iconic memory moves fast compared to echoic memory. Echoic memory is the storage of auditory information. The sounds we hear go into our echoic memory.

Echoic memory lasts a bit longer than iconic memory - some sounds will stay in echoic memory storage for as long as four seconds. Why? Evolution may be the answer.

Echoic memory is also unique in that the brain can store more than one piece of auditory information at a time. If you are having a conversation with a friend and suddenly hear a lion in the distance, your brain will be able to hold both pieces of information until they disappear or move into short-term memory.

Haptic Memory

The last type of sensory memory I’m going to mention in this video is haptic memory. Haptic memory is the storage of information about the things that we touch and feel. These memories will only stay in sensory memory storage for two seconds - so they last longer than iconic memory, but not as long as echoic memory.

Sensory Memory Can Mess With You!

As you've read this article, you've probably recalled sensory memories that have stuck with you - for better or for worse. This Reddit post discusses some of the most vivid, frustrating, and impactful sensory memories that users have:

Memories of Food

"I have plenty of food issues, and most of them are there because I can't handle certain textures at all, but certain odors tastes can be as difficult. There are stuff that I only experienced once, as a child or as a teenager, and to this day the memory of the sensation is clear and makes me uneasy. On the other hand, maybe because my SPD also presents itself in the form of craving stimuli, I also have fond and very detailed memories of certain touches, down to how deep was the pressure, how long it lasted, etc, even woth some of those memories being 20+ years old."

"I also experience very vivid sensory memories! Like if I have a bad texture experience with a food I’ll often years later remember exactly how it felt whenever I look at that food. It very nearly ruined avocados for me! I can also still remember the precise sounds, feelings, and smells I used to struggle with at the orthodontist as a kid. 😂" 

New Environments

"I actually just moved into a new house and different things about it, the feel of the carpet, the way the AC makes the air taste/feel, the color scheme of the rooms. It’s like mini flashbacks all over the place. It’s been interesting, if a little disconcerting, trying to nail down all the various input/nostalgia going on around me as I adjust to the house."

Nails on a Chalkboard (Or Living Room Wall)

"When I was a kid I once scraped my nails along the living room wall, and I never did it again after that. The texture of the wall scraping along my nails was awful, and I can still imagine exactly how it felt. Just thinking about it makes me want to rip my nails off and yeet them into the sun."

Of course, there are things that we feel, hear, and see that we will remember forever. These pieces of information have made it past sensory memory into short-term and long-term memory storage. But before we make memories that last for life, we have to store and process information in the sensory memory storage.

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GEORGE SPERLING’S EXPERIMENT ON SENSORY MEMORY

Related Papers

Consciousness and Cognition

Miguel Sebastian

"Cognitive theories claim whereas Non-cognitive theories deny that the cognitive access underlying reportability, which seems to depend on the working memory, is constitutive of consciousness. Arguments in favor of non-cognitive theories are based on the high capacity of participants in partial report experiments compared to the capacity of this memory. In reply, defenders of cognitive theories have search for alternative interpretations of these experiments that make it compatible visual awareness with the capacity of the working memory. Instead of entering the debate among alternative interpretations of partial reports experiments, this paper aims at offering an alternative methodology to contribute to settle the discussion between Cognitive and Non-Cognitive theories of consciousness. This methodology combines research in the neural mechanisms underlying cognitive access and the neurophysiological research in the study of sleep."

The essay is a study of phenomenal specificity. By ‘phenomenal’ here we mean conscious awareness, which needs to be cashed out in detail throughout the study. Intuitively, one dimension of phenomenology is along with specificity. For example it seems appropriate to say that one’s conscious awareness in the middle of the visual field is in some sense more specific than the awareness in the periphery under normal circumstances. However, it is difficult to characterise the nature of phenomenal specificity in an accurate way. This essay seeks to do just that. In the introduction, I set up the discussion by invoking a threefold Campbellian framework. Chapter 1 introduces a key notion of the analogue, its roots in sciences, and its applications in philosophy. Chapter 2 focuses on the major case study – the Sperling iconic memory paradigm – and explains how the relevant notion of the analogue can be used to explain phenomenal specificity involved in the Sperling case. Chapter 3 discusses functions of attention, as it is a crucial element in the Sperling case. Chapter 4 extends the project by explaining how visual demonstratives fit into the present picture. Finally chapter 5 discusses several directions for future researches. This essay is not an attempt to discuss all the issues concerning the Sperling case, but to provide a new angle in seeing the issue: most people agree that visual phenomenology is in some sense specific, but there are not enough attempts to model phenomenal specificity explicitly. On this occasion we use a notion of the analogue and related ideas to understand phenomenal specificity and how it applies to certain empirical cases.

Child Development

J Scott Saults

Adrian Ionita

Attention, Perception, & Psychophysics

Muge Erol , Jason Clarke

Whether or not awareness entails attention is a much debated question. Since iconic memory has been generally assumed to be attention-free, it has been considered an important piece of evidence that it does not (Koch & Tsuchiya, 2007). Therefore the question of the role of attention in iconic memory matters. Recent evidence (Persuh, Genzer, & Melara, 2012), suggests that iconic memory does depend on attention. Because of the centrality of iconic memory to this debate, we looked again at the role of attention in iconic memory using a standard whole versus partial report task of letters in a 3  2 matrix. We manipulated attention to the array by coupling it with a second task that was either easy or hard and by manipulating the probability of which task was to be performed on any given trial. When attention was maximally diverted from the matrix, participants were able to report less than a single item, confirming the prior results and supporting the conclusion that iconic memory entails attention. It is not an instance of attention-free awareness.

Guille Castellano

Báá Pinheiro

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Echoic Memory: Definition & Examples

Ayesh Perera

B.A, MTS, Harvard University

Ayesh Perera, a Harvard graduate, has worked as a researcher in psychology and neuroscience under Dr. Kevin Majeres at Harvard Medical School.

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On This Page:

Take-home Messages

• Ulric Neisser introduced the term ‘echoic memory’ to signify a type of sensory memory that registers and temporarily holds auditory information (sounds) until it is processed and comprehended.
• The initial search for echoic memory emulated Sperling’s experiments on iconic memory , but subsequent research has utilized more advanced neuropsychological techniques.
• The brain regions involved in echoic memory include Broca’s area , the dorsal premotor cortex, the posterior parietal cortex, the superior temporal gyrus , and the inferior temporal gyrus.
• Research suggests that echoic memory grows with age until adulthood, and then declines with old age.

Echoic memory is a type of sensory memory that registers and temporarily holds auditory information (sounds) until it is processed and comprehended (Carlson, 2010). This sensory store can retain a great amount of auditory information for a brief period of 3 to 4 seconds (Clark, 1987).

Following the initial registration, the sounds resonate and are replayed in the mind (Radvansky, 2005). Echoic memory encodes only a stimulus’ moderately primitive features (Strous, Cowan, Ritter, Javitt, 1995).

The German-American psychologist Ulric Neisser introduced the term ‘echoic memory’ in 1967 to denote the abovementioned short representation of auditory stimuli (Darwin, Turvey & Crowder, 1972).

The initial search for a possible sensory memory store in the auditory domain resembled the paradigm of partial report studies George Sperling employed in his iconic memory research.

Subsequently, more advanced neuropsychological techniques were utilized to estimate the duration, location, and capacity associated with the echoic memory store.

Listening to a song: When we listen to music, our brains briefly recall each note and connect it to the ensuing note. Consequently, the brain recognizes the sequences of notes as a song.

Conversing with another person : When we hear spoken language, our echoic memories retain every individual syllable. Our brains comprehend words by associating each syllable with the preceding one.

Repeated speech : When what someone says to us is not clear, we may request the repetition of what was mentioned. If the repetition resembles the original statement, our echoic memories will identify the repeated statement as familiar.

Employing the model used by George Sperling and utilizing partial report and whole report experiments, researchers have discovered that the auditory sensory store can retain memories for a maximum of 4 seconds (Darwin, Turvey & Crowder, 1972).

However, the duration of the echo that exists following the presentation of the hearing signal seems to be a point of debate. While Julesz and Guttman have implied that it may be a second or even less, Johnson and Eriksen have indicated that it can take up to 10 seconds (Eriksen & Johnson, 1964).

In 1974, Graham Hitch and Alan Baddeley proposed a human memory model with a phonological loop that attends in two ways to auditory stimuli (Baddeley & Hitch, 1974; Baddeley, Eysenck & Anderson, 2009). One section of the phonological storage contains the words we hear.

The other section comprises a sub-vocal process of rehearsal that refreshes the original memory trace by utilizing the individual’s inner voice. This model, nonetheless, could not adequately describe the relationship between the initial auditory input and the subsequent memory process.

Nelson Cowan, a psychologist at the University of Missouri, attempted to address this issue by introducing a short-term memory model that implies the existence of a pre-attentive sensory system that can retain a huge amount of accurate information for a brief period (Glass, Sachse & Suchodoletz, 2008).

This system supposedly comprises an initial 200 to 400-ms input phase followed by an information transferring phase. During the second phase, the information enters a more long-term memory store in order to be incorporated into working memory.

Methods for Testing

Whole reporting and partial reporting.

George Sperling’s research on iconic memory in the 1960s subsequently inspired other researchers to test the same phenomenon utilizing similar means in the auditory domain (Darwin, Turvey & Crowder, 1972). For instance, the participants in Sperling’s experiments had to repeat the letters that they saw.

Likewise, the subjects in the echoic memory experiments had to repeat sequences of syllables, words, or tones that they heard. Just as with iconic memory experiments, performance on partial reporting seemed superior to that on whole reporting.

Furthermore, the length of the interstimulus interval seemed to be inversely related to the ability to recall.

ABRM (Auditory Backward Recognition Masking)

ABRM involves presenting a brief target stimulus to the subjects and then, following a brief interval, presenting the mask [a second stimulus] (Bjork & Bjork, 1996). The interstimulus interval’s length manipulates the length of the duration wherein the auditory information is available.

Performance seems to improve as the interstimulus interval is raised to 250ms. While the mask does not seem to inhibit the procuring of information from the stimulus, it does seem to interfere with further processing.

Mismatch Negativity

The more objective and independent mismatch negativity tasks utilize electroencephalography to record alterations in activation in the brain (Näätänen & Escera, 2000).

Although these do not demand focused attention, they can measure auditory sensory memory.

Furthermore, mismatch negativity tasks can register the elements of the event-related potentials of brain activity evoked 150-200ms following an auditory stimulus.

This infrequent and deviant stimulus is presented among the standard stimuli, thereby enabling the comparison of the deviant stimulus with a memory trace (Sabri, Kareken, Dzemidzic, Lowe & Melara, 2004).

Neurology Related to Iconic Memory

Echoic memory involves several distinct brain regions on account of its various processes. Most of the related brain areas are in the prefrontal cortex, which contains the executive control and deals with the direction of attention (Bjork & Bjork, 1996).

The rehearsal system and the phonological store seem to be left-hemisphere systems with increased brain activity (Kwon, Reiss & Menon, 2002). Moreover, Broca’s area in the ventrolateral prefrontal cortex is responsible for the articulatory process and verbal rehearsal.

While the dorsal premotor cortex is associated with rhythmic organization, the localization of spatial objects is associated with the posterior parietal cortex.

Finally, the superior temporal gyrus and the inferior temporal gyrus too, seem to play a vital role in echoic memory (Schonwiesner, Novitski, Pakarinen, Carlson, Tervaniemi & Naatanen, 2007).

Echoic Memory and Age

Increased activation inside the neural structures over time implies that age may be positively correlated with the ability to process auditory sensory information (Kwon, Reiss & Menon, 2002).

As mismatch negativity research suggests, such cognitive and developmental growth is likely to occur until adulthood before experiencing a decline in old age (Glass, Sachse & Suchodoletz, 2008). One study suggests that the duration of auditory memory rises significantly, from 500 to 5000ms, between 2 and 6 years of age.

Frequently Asked Questions

What is echoic memory.

Echoic memory is a type of sensory memory that temporarily stores auditory information or sounds for a brief period, typically for up to 3-4 seconds. It allows the brain to process and comprehend sounds even after the original sound ceases.

What does echoic memory store?

Echoic memory stores auditory information or sounds. It’s a part of sensory memory and holds these sounds for a brief period, typically around 3 to 4 seconds, even after the original sound has ceased. This allows time for the brain to process the auditory information.

Alain, C., Woods, D. L., & Knight, R. T. (1998). A distributed cortical network for auditory sensory memory in humans. Brain research, 812 (1-2), 23-37.

Baddeley, A. D. (1986). Working memory . Oxford: Oxford University Press.

Baddeley, A. D. (2000). The episodic buffer: A new component of working memory? Trends in Cognitive Sciences , 4, (11): 417-423.

Baddeley, A. D., & Hitch, G. (1974). Working memory. In G.H. Bower (Ed.), The psychology of learning and motivation: Advances in research and theory (Vol. 8, pp. 47–89). New York: Academic Press.

Bjork, E, & Bjork, R. (1996). Memory . New York: Academic Press.

Carlson, N. R., Buskist, W., & Martin, G. N. (1997). Psychology: The science of behavior . Needham Heights, MA: Allyn and Bacon.

Clark, T. (1987). Echoic memory explored and applied . Journal of services marketing.

Darwin, C. J., Turvey, M. T., & Crowder, R. G. (1972). An auditory analogue of the Sperling partial report procedure: Evidence for brief auditory storage . Cognitive Psychology, 3 (2), 255-267.

Eriksen, C. W., & Johnson, H. J. (1964). Storage and decay characteristics of nonattended auditory stimuli. Journal of Experimental Psychology, 68 (1), 28.

Glass, E., Sachse, S., & von Suchodoletz, W. (2008). Development of auditory sensory memory from 2 to 6 years: an MMN study. Journal of Neural Transmission, 115 (8), 1221-1229.

Kwon, H., Reiss, A. L., & Menon, V. (2002). Neural basis of protracted developmental changes in visuo-spatial working memory. Proceedings of the National Academy of Sciences, 99 (20), 13336-13341.

Kwon, H., Reiss, A. L., & Menon, V. (2002). Neural basis of protracted developmental changes in visuo-spatial working memory. Proceedings of the National Academy of Sciences, 99(20), 13336-13341.

Näätänen R, Escera C (2000). “Mismatch negativity: clinical and other applications”. Audiol. Neurootol, 5 (3–4), 105–10.

Nunez, Kirsten. (1 Nov. 2019). Echoic Memory vs. Iconic Memory: How We Perceive the Past. Healthline, Healthline Media, www.healthline.com/health/echoic-memory.

Radvansky, G. (2005). Human Memory . Boston: Allyn and Bacon.

Sabri, M., Kareken, D. A., Dzemidzic, M., Lowe, M. J., & Melara, R. D. (2004). Neural correlates of auditory sensory memory and automatic change detection. Neuroimage, 21 (1), 69-74.

Schonwiesner, M., Novitski, N., Pakarinen, S., Carlson, S., Tervaniemi, M., & Naatanen, R. (2007). Heschl’s gyrus, posterior superior temporal gyrus, and mid-ventrolateral prefrontal cortex have different roles in the detection of acoustic changes. Journal of neurophysiology, 97 (3), 2075-2082.

Strous, R. D., Cowan, N., Ritter, W., & Javitt, D. C. (1995). Auditory sensory (” echoic”) memory dysfunction in schizophrenia. The American journal of psychiatry .

Further Information

• Echoic Memory Explored and Applied
• Öğmen, H., & Herzog, M. H. (2016). A new conceptualization of human visual sensory-memory. Frontiers in psychology, 7, 830.
• Sligte, I. G., Vandenbroucke, A. R., Scholte, H. S., & Lamme, V. (2010). Detailed sensory memory, sloppy working memory. Frontiers in Psychology, 1, 175.

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Sensory Memory

When information is brought in and retained by the senses, this is what is known as sensory memory. The effects are extremely short term with this information forgotten within a few seconds. It is also known as the first level of memory.

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Browse Full Outline

• 1 Memory Storage
• 2.1 Sensory Memory
• 2.2 Short-Term Memory
• 2.3 Long-Term Memory
• 2.4.1 Forgetting
• 3 Levels of Processing
• 4 Working Memory Model
• 5 Classification of Memories
• 6.1 Explicit Memory
• 6.2 Semantic Memory
• 6.3.1 Retrospective Memory
• 6.3.2 Prospective Memory
• 6.3.3 Autobiographical Memory
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• 7.2 Procedural Memory
• 8.1 Habituation
• 8.2 Sensitization
• 8.3 Classical Conditioning
• 8.4 Operant Conditioning
• 8.5 Cognitive Learning
• 8.6 Social Learning
• 8.7 Social Development
• 8.8 Socialization
• 8.9 Neuroplasticity

An example of this form of memory is when a person sees an object briefly before it disappears. Once the object is gone, it is still retained in the memory for a very short period of time. The two most studied types of sensory memory are iconic memory (visual) and echoic memory (sound).

Iconic Memory

Sensory memory actually refers to memories of all senses while iconic memory relates to the memory of sight only. Various experiments have shown that once an image is viewed, the brain scarcely has time to process it and the visual memory is stored for less than half a second.

George Sperling

The idea of iconic memory came about because of George Sperling's experiments in the 1960s. He used a tachistoscope to show letters to his test subjects. There were 12 letters in all, arranged in a box shape of three rows of four. The tachistoscope was created in 1859 and was designed to improve people's reading speed or enhance memory.

It displays images on a screen for less than a second. Sperling used this device to see how many letters his subjects could read during the brief flash of the projector. He found that on average, the test subjects could read three to four letters during his experiment.

Following on from this, Sperling conducted the same experiment but with one significant change. He added sound to the images one quarter of a second after the appearance of the letters. He used high, medium and low tones and asked his subjects to read letters from the top, middle and bottom rows according to the tone they heard.

The common response was for the subjects to read three or four letters from a row after they heard the tone. Sperling concluded that his subjects saw a memory of the letters for a quarter of a second and were able to read from this image once they heard the various sounds. Ulric Neisser came up with the phrase 'iconic memory' in 1967.

Echoic Memory

With echoic memory, it is possible to remember sounds for up to four seconds after last hearing them. As this only lasts a short period of time, it is known as a type of sensory memory.

An example of echoic memory is asking a test subject to remember a series of numbers someone was reciting immediately after the sequence was stopped. If the subject responds immediately, the possibility of remembering all the numbers is high. However, should the subject wait a few seconds, the memory of the numbers will fade because echoic memory only lasts a few seconds.

Sensory memory is often confused with short term memory but there is a significant difference. Sensory memory cannot be controlled and lasts only a few seconds at most whereas short term memories can last for approximately 20-30 seconds.

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Iconic Memory: Psychology Definition, History & Examples

Iconic memory represents a fundamental concept within the field of cognitive psychology, pertaining to the visual sensory memory register. This form of memory allows for the retention of a high-fidelity, brief copy of visual stimuli, lasting mere milliseconds.

Historically, the exploration of iconic memory can be traced back to the seminal work of George Sperling in the 1960s, whose experiments underscored the transient nature of visual information storage . Examples of iconic memory include the persistence of a trail of light following a moving sparkler or the retention of an image on the retina after a camera flash.

Understanding iconic memory is crucial for comprehending the complex processes involved in perception , information encoding , and the initial stages of memory storage.

This introduction sets the stage for a deeper dive into the nuances of iconic memory, its historical development, and practical illustrations.

Table of Contents

Iconic memory is a visual memory system that holds onto visual information for a very short time, allowing us to perceive a continuous stream of visual information.

It has a high level of detail but fades quickly unless we pay attention to it.

Understanding iconic memory helps us understand how we perceive and remember visual information.

In the realm of cognitive psychology, the concept of iconic memory originated in the early 1960s through the groundbreaking research of psychologist George Sperling. Sperling’s experiments, conducted at the University of California, Berkeley, shed light on the transient nature of visual sensory storage. His findings challenged prior assumptions about the limitations of sensory memory and opened up new avenues for understanding human information processing.

George Sperling’s key study involved presenting participants with a brief display of letters arranged in a grid pattern. After the display disappeared, participants were asked to recall as many letters as possible. Sperling found that participants were able to recall only a fraction of the letters, suggesting that the visual sensory store had a limited capacity.

Building on these findings, Sperling introduced the concept of iconic memory as a high-capacity storage system that holds visual information for a brief moment. He proposed that this temporary storage, which lasts for only a fraction of a second, allows for subsequent cognitive processing.

Sperling’s rigorous methodology and robust evidence for iconic memory challenged existing theories and sparked further research in the field. His work paved the way for subsequent studies that explored the intricacies of human information processing and the role of iconic memory in perception and cognition .

Although iconic memory may seem like a complex concept, it is actually something that we experience in our everyday lives. Here are some practical examples that can help you better understand how iconic memory works:

• Imagine you are watching a magic show, and the magician quickly pulls a rabbit out of a hat. Even though the rabbit is only visible for a split second, you can still ‘see’ the image of the rabbit in your mind for a short period of time after it disappears. This is an example of iconic memory at work, as it allows you to retain a visual image even after the stimulus is gone.
• Have you ever been driving on a busy highway and caught a glimpse of a billboard with a catchy slogan or image? Even if you only saw it for a moment, you may find yourself able to recall and remember the details of that advertisement later on. This is because iconic memory helps us retain visual information for a short time, allowing us to process and remember important details.
• Let’s say you are at a party and you briefly make eye contact with someone across the room. Even if you don’t have a chance to speak with them, you may still have a mental image of their face in your mind. This is another example of iconic memory, as it allows us to retain visual information and recognize familiar faces even after a brief encounter.

These examples demonstrate how iconic memory plays a role in our everyday lives, helping us retain and process visual information even after the stimuli have disappeared. By understanding how iconic memory works, we can better appreciate its impact on our perception and memory in various real-life situations.

Related Terms

Iconic memory, as a fundamental component of the visual memory system, is closely related to other cognitive processes such as short-term memory, visual perception, and echoic memory.

Short-term memory, also known as working memory, involves the active manipulation and temporary storage of information. It works in conjunction with iconic memory by engaging in the processing and retention of visual information that is initially captured by iconic memory. While iconic memory holds visual information for a brief period, short-term memory allows for the active rehearsal and manipulation of this information.

Visual perception, on the other hand, refers to the interpretation and understanding of visual stimuli. Iconic memory plays a crucial role in visual perception as it provides a transient record of these stimuli before they are either dismissed or encoded into short-term memory. In this way, iconic memory helps bridge the gap between the initial perception of visual information and its further processing and interpretation.

Additionally, echoic memory, the auditory counterpart to iconic memory, also plays a significant role in sensory memory. Echoic memory preserves auditory information for a brief period, similar to how iconic memory preserves visual information. Both types of sensory memory work together to capture and retain sensory stimuli, providing a foundation for further cognitive processing.

Building upon the concepts of iconic memory and its related cognitive processes, the following reputable sources, studies, and publications have contributed knowledge about this psychology term. These academically credible references provide a comprehensive overview of the academic research and literature that has shaped our understanding of iconic memory.

• Sperling, G. (1960). The information available in brief visual presentations. Psychological monographs: General and applied, 74(11), 1-29. doi:10.1037/h0093759
• Coltheart, M. (1980). Iconic memory and visible persistence. Perception & Psychophysics , 27(3), 183-228. doi:10.3758/bf03204258
• Averbach, E., & Coriell, A. S. (1961). Short-term memory in vision. Bell System Technical Journal, 40(4), 309-328. doi:10.1002/j.1538-7305.1961.tb03968.x
• Irwin, D. E., & Andrews, R. V. (1996). Integration and accumulation of information across saccadic eye movements. In Attention and Performance XVI: Information Integration in Perception and Communication (pp. 125-155). MIT Press.

These sources delve into the empirical studies, theoretical frameworks, and historical developments that have contributed to our current conceptualizations of iconic memory. They offer insights into the nuanced interplay between perception, attention, and memory encoding.

Each citation within this compendium is selected for its rigor, relevance, and contribution to the field, ensuring that the synthesis of iconic memory presented is grounded in authoritative scholarly discourse. Further reading of these academically credible references will provide a solid foundation for understanding iconic memory in psychology.

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