benjamin libet experiment free will

Benjamin Libet and the Denial of Free Will

How did a flawed experiment become so influential.

Posted September 5, 2017 | Reviewed by Abigail Fagan

You might feel that you have the ability to make choices, decisions and plans — and the freedom to change your mind at any point if you so desire — but many psychologists and scientists would tell you that this is an illusion.

The denial of free will is one of the major principles of the materialist worldview that dominates secular western culture. Materialism is the view that only the physical stuff of the world — atoms and molecules and the objects and beings that they constitute — are real. Consciousness and mental phenomena can be explained in terms of neurological processes.

Materialism developed as a philosophy in the second half of the nineteenth century, as the influence of religion waned. And right from the start, materialists realised the denial of free will was inherent in their philosophy. As one of the most fervent early materialists, T.H. Huxley, stated in 1874, “Volitions do not enter into the chain of causation…The feeling that we call volition is not the cause of a voluntary act, but the symbol of that state of the brain which is the immediate cause."

Huxley anticipated the ideas of some modern materialists, such as psychologist Daniel Wegner, who claim that free will is literally a “trick of the mind.” According to Wegner, “The experience of willing an act arises from interpreting one’s thought as the cause of the act.” In other words, our sense of making choices or decisions is just an awareness of what the brain has already decided for us. When we become aware of the brain’s actions, we think about them and falsely conclude that our intentions have caused them. You could compare it to an imbecilic king who believes he is making all his own decisions but is constantly being manipulated by his advisors and officials, who whisper in his ear and plant ideas in his head.

Many materialists believe that evidence for a lack of free will was found when, in the 1980s, the scientist Benjamin Libet conducted experiments that seemed to show that the brain “registers” the decision to make movements before a person consciously decides to move. In Libet’s experiments, a participant would be asked to perform a simple task such as pressing a button or flexing their wrist. Sitting in front of a timer, they were asked to note the moment at which they were consciously aware of the decision to move, while EEG electrodes attached to their head monitored their brain activity.

Libet showed consistently that there was unconscious brain activity associated with the action – a change in EEG signals that Libet called “readiness potential” — for an average of half a second before the participants were aware of the decision to move. This experiment appears to offer evidence of Daniel Wegner’s view that decisions are first made by the brain, and there is a delay before we become conscious of them — at which point we attribute our own conscious intention to the act.

However, if we look more closely, Libet’s experiment is full of problematic issues. For example, it relies on the participants’ own recording of when they feel the intention to move. One issue here is that there may be a delay between the impulse to act and their recording of it — after all, this means shifting their attention from their own intention to the clock. In addition, it is debatable whether people are able to accurately record the moment of their decision to move. Our subjective awareness of decisions is very unreliable. If you try the experiment yourself, you’ll become aware that it’s difficult to pinpoint the moment at which you make the decision. You can do it right now, by holding out your own arm and deciding at some point to flex your wrist.

A further, more subtle (and more arguable) issue is that Libet's experiment seems to assume that the act of willing consists of clearcut decisions, made by a conscious, rational mind. But decisions are often made in a more fuzzy, ambiguous way. They can be made on a partly intuitive, impulsive level, without clearcut conscious awareness. But this doesn't necessarily mean that you haven't made the decision.

As the psychiatrist and philosopher Iain McGilchrist, author of the Master and His Emissary, points out while making this argument that Libet's apparent findings are only problematic "if one imagines that, for me to decide something, I have to have willed it with the conscious part of my mind. Perhaps my unconscious is every bit as much 'me.'" Why shouldn't your will be associated with deeper, less conscious areas of your mind (which are still you)? You might sense this if, while trying Libet’s experiment, you find your wrist seeming to move of its own accord. You feel that you have somehow made the decision, even if not wholly consciously.

An even more serious issue with Libet’s experiment is that it is by no means clear that the electrical activity of the “readiness potential” is related to the decision to move, and the actual movement. Some researchers have suggested that the readiness potential could just relate to the act of paying attention to the wrist or a button, rather than the decision to move. Others have suggested that it only reflects the expectation of some kind of movement, rather than being related to a specific moment. In a modified version of Libet’s experiment (in which participants were asked to press one of two buttons in response to images on a computer screen), participants showed readiness potential even before the images came up on the screen, suggesting that it was not related to deciding which button to press.

Others have suggested that the area of the brain where the readiness potential occurs — the supplementary motor area — is usually associated with imagining movements rather than actually performing them. The experience of willing is usually associated with other areas of the brain (the parietal areas). And finally, in another modified version of Libet’s experiment, participants showed readiness potential even when they made a decision not to move, which again casts doubt on the assumption that the readiness potential is actually registering the brain’s “decision” to move.

Because of issues such as these — and others that I don’t have space to mention — it’s mystifying that such a flawed experiment has become so influential, and has been used frequently as evidence against the idea of free will. The reason why the experiment has been so enthusiastically embraced is surely because the apparent findings fit so well with the principles of materialism. It seems to prove what materialism implies: that human beings are automatons.

But how can a self choose, of its own free will, to argue that it has no free will? Do the theorists who argue against free will seriously believe that they have somehow been pre-ordained to formulate their arguments and write their articles by their own brain processes or genetic disposition? In developing their theories, they have constantly exercised their free will — for example in deciding which articles to read, which ideas to reject or accept, to the point of deciding that the theory is worth writing up and sitting down to begin writing it. They might argue that they accept that free will is an illusion, and are simply allowing the illusion to express itself through them — but if this was the case, why would they trust this illusory power, and follow its dictates so assiduously, allowing it to determine their lives? Would you allow a genie in a bottle to tell you what to do with your life?

It’s interesting to ponder why so many intellectuals are so intent (with their own free will) on proving that they have no free will. As the philosopher Alfred North Whitehead pointed out ironically, “scientists animated by the purpose of proving themselves purposeless constitute an interesting subject for study.”

In my view, this is connected to the general nihilism of our culture, the collapse of values that has followed from materialistic science. Such absurd views could only arise — and make any kind of sense — amidst the climate of meaninglessness and confusion that scientific materialism has given rise to.

Steve Taylor, Ph.D., is a senior lecturer in psychology at Leeds Beckett University. He is the author of Spiritual Science: Why Science needs spirituality to make sense of the world.

Steve Taylor, Ph.D., is senior lecturer in psychology at Leeds Beckett University. He is the author of several best-selling books, including The Leap and Spiritual Science.

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December 6, 2019

How a Flawed Experiment “Proved” That Free Will Doesn’t Exist

It did no such thing—but the result has become conventional wisdom nevertheless

By Steve Taylor

Getty Images

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American

In the second half of the 19th century, scientific discoveries—in particular, Darwin’s theory of evolution—meant that Christian beliefs were no longer feasible as a way of explaining the world. The authority of the Bible as an explanatory text was fatally damaged. The new findings of science could be utilized to provide an alternative conceptual system to make sense of the world—a system that insisted that nothing existed apart from basic particles of matter, and that all phenomena could be explained in terms of the organization and the interaction of these particles.

One of the most fervent of late 19th century materialists, T.H. Huxley, described human beings as “conscious automata” with no free will. As he explained in 1874, “Volitions do not enter into the chain of causation…. The feeling that we call volition is not the cause of a voluntary act, but the symbol of that state of the brain which is the immediate cause."

This was a very early formulation of an idea that has become commonplace amongst modern scientists and philosophers who hold similar materialist views: that free will is an illusion. According to Daniel Wegner, for instance, “The experience of willing an act arises from interpreting one’s thought as the cause of the act.” In other words, our sense of making choices or decisions is just an awareness of what the brain has already decided for us. When we become aware of the brain’s actions, we think about them and falsely conclude that our intentions have caused them. You could compare it to a king who believes he is making all his own decisions, but is constantly being manipulated by his advisors and officials, who whisper in his ear and plant ideas in his head.

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Many people believe that evidence for a lack of free will was found when, in the 1980s, scientist Benjamin Libet conducted experiments that seemed to show that the brain “registers” the decision to make movements before a person consciously decides to move. In Libet’s experiments, participants were asked to perform a simple task such as pressing a button or flexing their wrist. Sitting in front of a timer, they were asked to note the moment at which they were consciously aware of the decision to move, while EEG electrodes attached to their head monitored their brain activity.

Libet showed consistently that there was unconscious brain activity associated with the action—a change in EEG signals that Libet called “readiness potential”—for an average of half a second before the participants were aware of the decision to move. This experiment appears to offer evidence of Wegner’s view that decisions are first made by the brain, and there is a delay before we become conscious of them—at which point we attribute our own conscious intention to the act.

However, if we look more closely, Libet’s experiment is full of problematic issues. For example, it relies on the participants’ own recording of when they feel the intention to move. One issue here is that there may be a delay between the impulse to act and their recording of it—after all, this means shifting their attention from their own intention to the clock. In addition, it is debatable whether people are able to accurately record the moment of their decision to move. Our subjective awareness of decisions is very unreliable. If you try the experiment yourself—and you can do it right now, just by holding out your own arm, and deciding at some point to flex your wrist—you’ll become aware that it’s difficult to pinpoint the moment at which you make the decision.

An even more serious issue with the experiment is that it is by no means clear that the electrical activity of the “readiness potential” is related to the decision to move, and to the actual movement. Some researchers have suggested that the readiness potential could just relate to the act of paying attention to the wrist or a button, rather the decision to move. Others have suggested that it only reflects the expectation of some kind of movement, rather being related to a specific moment. In a modified version of Libet’s experiment (in which participants were asked to press one of two buttons in response to images on a computer screen), participants showed “readiness potential” even before the images came up on the screen, suggesting that it was not related to deciding which button to press.

Still others have suggested that the area of the brain where the "readiness potential" occurs—the supplementary motor area, or SMA—is usually associated with imagining movements rather than actually performing them. The experience of willing is usually associated with other areas of the brain (the parietal areas). And finally, in another modified version of Libet’s experiment, participants showed readiness potential even when they made a decision not to move, which again casts doubt on the assumption that the readiness potential is actually registering the brain’s “decision” to move.

A further, more subtle, issue has been suggested by psychiatrist and philosopher Iain McGilchrist. Libet's experiment seems to assume that the act of volition consists of clear-cut decisions, made by a conscious, rational mind. But McGilchrist points out that decisions are often made in a more fuzzy, ambiguous way. They can be made on a partly intuitive, impulsive level, without clear conscious awareness. But this doesn't necessarily mean that you haven't made the decision.

As McGilchrist puts it, Libet’s apparent findings are only problematic "if one imagines that, for me to decide something, I have to have willed it with the conscious part of my mind. Perhaps my unconscious is every bit as much 'me.'" Why shouldn't your will be associated with deeper, less conscious areas of your mind (which are still you)? You might sense this if, while trying Libet’s experiment, you find your wrist just seeming to move of its own accord. You feel that you have somehow made the decision, even if not wholly consciously.

Because of issues such as these—and others that I don’t have space to mention—it seems strange that such a flawed experiment has become so influential, and has been (mis)used so frequently as evidence against the idea of free will. You might ask: why are so many intellectuals so intent on proving that they have no free will? (As the philosopher Alfred North Whitehead pointed out ironically, “Scientists animated by the purpose of proving themselves purposeless constitute an interesting subject for study.”)

This is probably because the nonexistence of free will seems a logical extension of some of the primary assumptions of the materialist paradigm—such as the idea that our sense of self is an illusion, and that consciousness and mental activity are reducible to neurological activity. However, as I suggest in my book Spiritual Science, it is entirely possible that these assumptions are false. The mind may be more than just a shadow of the brain, and free will may not be an illusion but an invaluable human attribute, which can be cultivated and whose development makes our lives more meaningful and purposeful.

A Famous Argument Against Free Will Has Been Debunked

For decades, a landmark brain study fed speculation about whether we control our own actions. It seems to have made a classic mistake.

A group of skydivers pose as they fall through the air

The death of free will began with thousands of finger taps. In 1964, two German scientists monitored the electrical activity of a dozen people’s brains. Each day for several months, volunteers came into the scientists’ lab at the University of Freiburg to get wires fixed to their scalp from a showerhead-like contraption overhead. The participants sat in a chair, tucked neatly in a metal tollbooth, with only one task: to flex a finger on their right hand at whatever irregular intervals pleased them, over and over, up to 500 times a visit.

The purpose of this experiment was to search for signals in the participants’ brains that preceded each finger tap. At the time, researchers knew how to measure brain activity that occurred in response to events out in the world—when a person hears a song, for instance, or looks at a photograph—but no one had figured out how to isolate the signs of someone’s brain actually initiating an action.

The experiment’s results came in squiggly, dotted lines, a representation of changing brain waves. In the milliseconds leading up to the finger taps, the lines showed an almost undetectably faint uptick: a wave that rose for about a second, like a drumroll of firing neurons, then ended in an abrupt crash. This flurry of neuronal activity, which the scientists called the Bereitschaftspotential , or readiness potential, was like a gift of infinitesimal time travel. For the first time, they could see the brain readying itself to create a voluntary movement.

This momentous discovery was the beginning of a lot of trouble in neuroscience. Twenty years later, the American physiologist Benjamin Libet used the Bereitschaftspotential to make the case not only that the brain shows signs of a decision before a person acts, but that, incredibly, the brain’s wheels start turning before the person even consciously intends to do something. Suddenly, people’s choices—even a basic finger tap—appeared to be determined by something outside of their own perceived volition.

As a philosophical question, whether humans have control over their own actions had been fought over for centuries before Libet walked into a lab. But Libet introduced a genuine neurological argument against free will. His finding set off a new surge of debate in science and philosophy circles. And over time, the implications have been spun into cultural lore.

Today, the notion that our brains make choices before we are even aware of them will now pop up in cocktail-party conversation or in a review of Black Mirror . It’s covered by mainstream journalism outlets, including This American Life , Radiolab , and this magazine . Libet’s work is frequently brought up by popular intellectuals such as Sam Harris and Yuval Noah Harari to argue that science has proved humans are not the authors of their actions.

It would be quite an achievement for a brain signal 100 times smaller than major brain waves to solve the problem of free will. But the story of the Bereitschaftspotential has one more twist: It might be something else entirely.

The Bereitschaftspotential was never meant to get entangled in free-will debates. If anything, it was pursued to show that the brain has a will of sorts. The two German scientists who discovered it, a young neurologist named Hans Helmut Kornhuber and his doctoral student Lüder Deecke, had grown frustrated with their era’s scientific approach to the brain as a passive machine that merely produces thoughts and actions in response to the outside world. Over lunch in 1964, the pair decided that they would figure out how the brain works to spontaneously generate an action. “Kornhuber and I believed in free will,” says Deecke, who is now 81 and lives in Vienna.

To pull off their experiment, the duo had to come up with tricks to circumvent limited technology. They had a state-of-the-art computer to measure their participants’ brain waves, but it worked only after it detected a finger tap. So to collect data on what happened in the brain beforehand, the two researchers realized that they could record their participants’ brain activity separately on tape, then play the reels backwards into the computer. This inventive technique, dubbed “reverse-averaging,” revealed the Bereitschaftspotential .

The discovery garnered widespread attention. The Nobel laureate John Eccles and the prominent philosopher of science Karl Popper compared the study’s ingenuity to Galileo’s use of sliding balls for uncovering the laws of motion of the universe. With a handful of electrodes and a tape recorder, Kornhuber and Deecke had begun to do the same for the brain.

What the Bereitschaftspotential actually meant, however, was anyone’s guess. Its rising pattern appeared to reflect the dominoes of neural activity falling one by one on a track toward a person doing something. Scientists explained the Bereitschaftspotential as the electrophysiological sign of planning and initiating an action. Baked into that idea was the implicit assumption that the Bereitschaftspotential causes that action. The assumption was so natural, in fact, no one second-guessed it—or tested it.

Libet, a researcher at the University of California at San Francisco, questioned the Bereitschaftspotential in a different way. Why does it take half a second or so between deciding to tap a finger and actually doing it? He repeated Kornhuber and Deecke’s experiment, but asked his participants to watch a clocklike apparatus so that they could remember the moment they made a decision. The results showed that while the Bereitschaftspotential started to rise about 500 milliseconds before the participants performed an action, they reported their decision to take that action only about 150 milliseconds beforehand. “The brain evidently ‘decides’ to initiate the act” before a person is even aware that decision has taken place, Libet concluded.

To many scientists, it seemed implausible that our conscious awareness of a decision is only an illusory afterthought. Researchers questioned Libet’s experimental design, including the precision of the tools used to measure brain waves and the accuracy with which people could actually recall their decision time. But flaws were hard to pin down. And Libet, who died in 2007, had as many defenders as critics. In the decades since his experiment, study after study has replicated his finding using more modern technology such as fMRI.

But one aspect of Libet’s results sneaked by largely unchallenged: the possibility that what he was seeing was accurate, but that his conclusions were based on an unsound premise. What if the Bereitschaftspotential didn’t cause actions in the first place? A few notable studies did suggest this, but they failed to provide any clue to what the Bereitschaftspotential could be instead. To dismantle such a powerful idea, someone had to offer a real alternative.

In 2010, Aaron Schurger had an epiphany. As a researcher at the National Institute of Health and Medical Research in Paris, Schurger studied fluctuations in neuronal activity, the churning hum in the brain that emerges from the spontaneous flickering of hundreds of thousands of interconnected neurons. This ongoing electrophysiological noise rises and falls in slow tides, like the surface of the ocean—or, for that matter, like anything that results from many moving parts. “Just about every natural phenomenon that I can think of behaves this way. For example, the stock market’s financial time series or the weather,” Schurger says.

From a bird’s-eye view, all these cases of noisy data look like any other noise, devoid of pattern. But it occurred to Schurger that if someone lined them up by their peaks (thunderstorms, market records) and reverse-averaged them in the manner of Kornhuber and Deecke’s innovative approach, the results’ visual representations would look like climbing trends (intensifying weather, rising stocks). There would be no purpose behind these apparent trends—no prior plan to cause a storm or bolster the market. Really, the pattern would simply reflect how various factors had happened to coincide.

“I thought, Wait a minute ,” Schurger says. If he applied the same method to the spontaneous brain noise he studied, what shape would he get? “I looked at my screen, and I saw something that looked like the Bereitschaftspotential .” Perhaps, Schurger realized, the Bereitschaftspotential ’s rising pattern wasn’t a mark of a brain’s brewing intention at all, but something much more circumstantial.

Two years later, Schurger and his colleagues Jacobo Sitt and Stanislas Dehaene proposed an explanation. Neuroscientists know that for people to make any type of decision, our neurons need to gather evidence for each option. The decision is reached when one group of neurons accumulates evidence past a certain threshold. Sometimes, this evidence comes from sensory information from the outside world: If you’re watching snow fall, your brain will weigh the number of falling snowflakes against the few caught in the wind, and quickly settle on the fact that the snow is moving downward.

But Libet’s experiment, Schurger pointed out, provided its subjects with no such external cues. To decide when to tap their fingers, the participants simply acted whenever the moment struck them. Those spontaneous moments, Schurger reasoned, must have coincided with the haphazard ebb and flow of the participants’ brain activity. They would have been more likely to tap their fingers when their motor system happened to be closer to a threshold for movement initiation.

This would not imply, as Libet had thought, that people’s brains “decide” to move their fingers before they know it. Hardly. Rather, it would mean that the noisy activity in people’s brains sometimes happens to tip the scale if there’s nothing else to base a choice on, saving us from endless indecision when faced with an arbitrary task. The Bereitschaftspotential would be the rising part of the brain fluctuations that tend to coincide with the decisions. This is a highly specific situation, not a general case for all, or even many, choices.

Other recent studies support the idea of the Bereitschaftspotential as a symmetry-breaking signal. In a study of monkeys tasked with choosing between two equal options, a separate team of researchers saw that a monkey’s upcoming choice correlated with its intrinsic brain activity before the monkey was even presented with options.

In a new study under review for publication in the Proceedings of the National Academy of Sciences , Schurger and two Princeton researchers repeated a version of Libet’s experiment. To avoid unintentionally cherry-picking brain noise, they included a control condition in which people didn’t move at all. An artificial-intelligence classifier allowed them to find at what point brain activity in the two conditions diverged. If Libet was right, that should have happened at 500 milliseconds before the movement. But the algorithm couldn’t tell any difference until about only 150 milliseconds before the movement, the time people reported making decisions in Libet’s original experiment.

In other words, people’s subjective experience of a decision—what Libet’s study seemed to suggest was just an illusion—appeared to match the actual moment their brains showed them making a decision.

When Schurger first proposed the neural-noise explanation, in 2012 , the paper didn’t get much outside attention, but it did create a buzz in neuroscience. Schurger received awards for overturning a long-standing idea. “It showed the Bereitschaftspotential may not be what we thought it was. That maybe it’s in some sense artifactual, related to how we analyze our data,” says Uri Maoz, a computational neuroscientist at Chapman University.

For a paradigm shift, the work met minimal resistance. Schurger appeared to have unearthed a classic scientific mistake, so subtle that no one had noticed it and no amount of replication studies could have solved it, unless they started testing for causality. Now, researchers who questioned Libet and those who supported him are both shifting away from basing their experiments on the Bereitschaftspotential . (The few people I found still holding the traditional view confessed that they had not read Schurger’s 2012 paper.)

“It’s opened my mind,” says Patrick Haggard, a neuroscientist at University College London who collaborated with Libet and reproduced the original experiments.

It’s still possible that Schurger is wrong. Researchers broadly accept that he has deflated Libet’s model of Bereitschaftspotential , but the inferential nature of brain modeling leaves the door cracked for an entirely different explanation in the future. And unfortunately for popular-science conversation, Schurger’s groundbreaking work does not solve the pesky question of free will any more than Libet’s did. If anything, Schurger has only deepened the question.

Is everything we do determined by the cause-and-effect chain of genes, environment, and the cells that make up our brain, or can we freely form intentions that influence our actions in the world? The topic is immensely complicated, and Schurger’s valiant debunking underscores the need for more precise and better-informed questions.

“Philosophers have been debating free will for millennia, and they have been making progress. But neuroscientists barged in like an elephant into a china shop and claimed to have solved it in one fell swoop,” Maoz says. In an attempt to get everyone on the same page, he is heading the first intensive research collaboration between neuroscientists and philosophers, backed by $7 million from two private foundations, the John Templeton Foundation and the Fetzer Institute. At an inaugural conference in March, attendees discussed plans for designing philosophically informed experiments, and unanimously agreed on the need to pin down the various meanings of “free will.”

In that, they join Libet himself. While he remained firm on his interpretation of his study, he thought his experiment was not enough to prove total determinism—the idea that all events are set in place by previous ones, including our own mental functions. “Given the issue is so fundamentally important to our view of who we are, a claim that our free will is illusory should be based on fairly direct evidence,” he wrote in a 2004 book. “Such evidence is not available.”

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Does Free Will Exist? New Study Challenges Classic Libet Experiments

By National Research University Higher School of Economics October 27, 2023

Man Standing at the Edge of Cliff Free Will

Neuroscientists from HSE University have questioned the conclusions of famous studies, primarily those by Benjamin Libet, that challenge the existence of free will. Libet’s experiments in the 1970s and 1980s used EEG to show that brain activity indicating a decision occurred before individuals were consciously aware of their intention to act. The HSE team’s recent research suggests flaws in Libet’s measurement of intention awareness and asserts that the readiness potential doesn’t directly correlate with the decision itself. Their findings highlight the need for a fresh approach to the debate on free will.

You can’t blame your brain for your actions!

Neuroscientists at HSE University have challenged the famous studies that question the free will of our decisions. You can’t shift responsibility for your actions to the brain. The results of the new work were recently published in the journal Neuropsychologia .

Historical Context of the Free Will Debate

The dispute about how much free will people have in making their decisions has been going on for decades. Neuroscientists have joined this discussion thanks to the electroencephalographic (EEG) experiments of Benjamin Libet. In the 1970-1980s, he showed that 0.5–1.5 seconds before conscious awareness of the intention to perform a movement, subjects emit EEG activity that predicts this movement. It turns out that the brain makes a decision and sends readiness potential before a person realizes it, and our actions are nothing more than the result of an unconscious physiological process in the brain.

The results of Libet’s experiments have generated a lot of controversy about free will, and some neurophysiologists have even concluded that it does not exist. Moreover, Libet’s experiment has been repeated using functional magnetic resonance imaging, and it turns out that the decision of the subject can be predicted even 6-10 seconds before their conscious awareness of it.

HSE University’s Take on the Paradigm

The staff of the HSE Institute for Cognitive Neuroscience questioned this experimental paradigm and in their new study confirmed that the time of intention awareness in Libet’s experiments was determined incorrectly. In addition, EEG activity, or the brain signal indicating the readiness of a decision, which was recorded by Benjamin Libet before the decision was made, actually has no direct link to this decision.

In the Libet’s original experiment, the subjects were asked to occasionally bend their wrists and at the same time remember the moment when they felt ready to perform this action. The time of intention awareness was recorded from the words of the subjects themselves: they observed a point that moved along the screen dial, similar to a clock hand, and indicated the position of the point when they felt the desire to bend their hand. The moment of the final decision was determined by the exact reading of the sensor attached to the wrist of the subjects.

The HSE neuroscientists repeated the experiment with two groups of subjects, adding small changes to the task in one of the groups. Using behavioral reports and hypersensitive EEG techniques, the scientists investigated the correlation between the time of intention awareness and the time of final decision. It turned out that the time of awareness can be influenced by experimental procedures: for example, without certain training, the subjects are barely able to determine their intentions, and the traditional Libet paradigm pushes them to the feeling that they can determine the moment of decision-making and intention. Apparently, the instruction itself in the Libet task makes the participants feel that the intention should emerge long before the final decision is made.

In addition, the study confirmed that there is no direct link between the activity of the brain preceding the action and the intention to perform the action. The sense of intention emerged in the subjects at different points in time, whereas the readiness potential was always registered at about the same time. Thus, the readiness potential may reflect the general dynamics of the decision-making process about making a move, but it does not mean that the intention to act has already been generated.

Concluding Thoughts

“Our study highlights the ambiguity of Libet’s research and proves the absence of a direct correlation between the brain signal and decision-making. It appears that the classical Libet paradigm is not suitable for answering the question of whether we have free will while making decisions. We need to come up with a new approach to this extremely interesting scientific puzzle,” says Dmitry Bredikhin, author of the research and junior Research Fellow at the Centre for Cognition & Decision Making.

“Neuroscience tries to answer key questions in our life, including questions of free will and responsibility for our actions. We need to be especially precise in order to draw conclusions that affect our outlook and attitude toward life. Therefore, we tried to understand the predetermination of our decisions and confirmed a number of shortcomings in the famous experiments of Benjamin Libet. This does not mean that we have closed this issue of the illusory nature of our free will, but rather emphasizes that the discussion continues. This might be one of the most interesting questions in modern science, to which we have yet to give a definitive answer,” comments Vasily Klucharev, Project coordinator and leading Research Fellow of the Institute for Cognitive Neuroscience.

Reference: “(Non)-experiencing the intention to move: On the comparisons between the Readiness Potential onset and Libet’s W-time” by Dimitri Bredikhin, Ksenia Germanova, Vadim Nikulin and Vasily Klucharev, 29 April 2023, Neuropsychologia . DOI: 10.1016/j.neuropsychologia.2023.108570

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2 comments on "does free will exist new study challenges classic libet experiments".

Naïve to the predecessor research and the techniques involved, I’m deferring to my own explorations of brain/mind function beginning with at-home-alone self-hypnosis for self-improvement in late 1975. What I find from the article is multiple investigators attempting to discern free will by experimenting with reflexology. Certainly, to my experience, free will and responsibility are not integral to reflex reactions.

Does the brain physiology matter!? We are protein machines acting out according to physical laws, not magicians.

What the paper does say, on a statistically weak cohort of persons, is that the Lisbet W-time (introspective timing of the intention to move) “might actually reflect the intention to move, at least to some extent.” Additionally they observe that experimental conditions affect the timing, especially training (repeated experiments), which is biologically plausible.

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Why neuroscience does not disprove free will

Affiliations.

1 Department of Experimental Psychology, Ghent University, Henri Dunantlaan 2, Ghent, 9000, Belgium. Electronic address: [email protected].
2 Racah Institute of Physics, Edmond and Lily Safra Center for Brain Sciences, The Hebrew University Jerusalem, Edmond J. Safra Campus, Jerusalem, 9190401, Israel. Electronic address: [email protected].
3 Department of Philosophy, Florida State University, 151 Dodd Hall, Tallahassee, 32306-1500, USA. Electronic address: [email protected].
PMID: 31059730
DOI: 10.1016/j.neubiorev.2019.04.024

While the question whether free will exists or not has concerned philosophers for centuries, empirical research on this question is relatively young. About 35 years ago Benjamin Libet designed an experiment that challenged the common intuition of free will, namely that conscious intentions are causally efficacious. Libet demonstrated that conscious intentions are preceded by a specific pattern of brain activation, suggesting that unconscious processes determine our decisions and we are only retrospectively informed about these decisions. Libet-style experiments have ever since dominated the discourse about the existence of free will and have found their way into the public media. Here we review the most important challenges to the common interpretation of Libet-style tasks and argue that the common interpretation is questionable. Brain activity preceding conscious decisions reflects the decision process rather than its outcome. Furthermore, the decision process is configured by conditional intentions that participants form at the beginning of the experiment. We conclude that Libet-style tasks do not provide a serious challenge to our intuition of free will.

Keywords: Attention; Awareness; Bias-signal; COINTOB model; Choice; Conditional intention; Decision; Drift-diffusion model; Free will; Implementation intention; Integration-to-bound process; Intentional action; Libet; Picking; Psychopathology; Readiness potential; Stochastic noise; Vetoing; Volition; W time.

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Will I or won’t I? Scientists still haven’t figured out free will, but they’re having fun trying

Associate Professor and Head of Decision Neuroscience Laboratory, The University of Melbourne

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Stefan Bode receives funding from the Australian Research Council.

University of Melbourne provides funding as a founding partner of The Conversation AU.

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Social media algorithms, artificial intelligence, and our own genetics are among the factors influencing us beyond our awareness. This raises an ancient question: do we have control over our own lives? This article is part of The Conversation’s series on the science of free will .

In 1983, American physiologist Benjamin Libet conducted an experiment that became a landmark in the field of cognitive sciences. It got psychologists, neuroscientists, and philosophers either very excited or very concerned.

The study itself was simple. Participants were connected to an apparatus that measured their brain and muscle activity, and were asked to do two basic things. First, they had to flex their wrist whenever they felt like doing so.

Second, they had to note the time when they first became aware of their intention to flex their wrist. They did this by remembering the position of a revolving dot on a clock face. The brain activity Libet was interested in was the “readiness potential”, which is known to ramp up before movements are executed.

Libet then compared the three measures in time: the muscle movement, the brain activity, and the reported time of the conscious intention to move. He found both the reported intention to move and the brain activity came before the actual movement, so no surprises there. But crucially, he also found brain activity preceded the reported intention to move by around half a second.

This seemed to suggest participants’ brains had already “decided” to move, half a second before they felt consciously aware of it.

Had neuroscience just solved the free will problem?

Some researchers have since argued that the intuitive idea that we have a consciousness (or a “self”) that is distinct from our brains — and that can cause things in the real world — might be wrong. Really being the “author” of our actions seemed to suggest, at least for many people, that an “I” is making the decisions, not the brain. However, only brains (or neurons) can really cause us to do things, so should we be surprised to find that an intention is a consequence rather than the origin of brain activity?

Others were less convinced of Libet’s study and have attacked it from all possible angles. For example, it has been questioned whether flexing the wrist is really a decision, as there is no alternative action, and whether we can really judge the moment of our intention so precisely. Perhaps, sceptics suggested, the findings could be a lot of fuss about nothing.

But Libet’s findings have been successfully replicated. By using other neuroimaging methods such as functional magnetic resonance imaging (fMRI) in combination with clever new analysis techniques, it has been shown that the outcome of decisions between two alternatives can be predicted [ several seconds before the reported conscious intention].

Even Libet himself did not seem comfortable claiming our “will” does not matter at all. What if we could still say “no” to what the brain wants to do? This would at least give us a “ free won’t ”. To test this, one study asked participants to play a game against a computer that was trained to predict their intentions from their brain activity. The research found participants could cancel their actions if the computer found out quickly what they intended to do, at least up to around 200 milliseconds before the action, after which it was too late.

But is the decision not to do something really so different from a decision to do something?

It depends what you mean by free

Another way to look at Libet’s study is to recognise it might not be as closely related to the “free will” problem as initially thought. We might be mistaken in what we think a truly free decision is. We often think “free will” means: could I have chosen otherwise? In theory, the answer might be no — being transported back in time, and placed into exactly the same circumstances, the outcome of our decision might necessarily be exactly the same. But maybe that doesn’t matter, because what we really mean is: was there no external factor that forced my decision, and did I freely choose to do it? And the answer to that might still be yes.

If you are worried about “free will” just because sometimes there are external factors present that influence us, think about this: there are also always factors inside of us that influence us, from which we can never fully escape — our previous decisions, our memories, desires, wishes and goals, all of which are represented in the brain .

Some people might still maintain that only if nothing influences our decision at all can we be really free. But then there is really no good reason to choose either way, and the outcome might just be due to the random activity of neurons that happen to be active at the time of decision-making. And this means our decisions would also be random rather than “willed”, and that would seem even less free to us.

Most of our decisions require planning because they are more complex than the “spontaneous” decisions investigated in Libet-style studies , like whether to buy a car, or get married, which are what we really care about. And interestingly, we don’t tend to question whether we have free will when making such complex decisions, even though they require a lot more brain activity.

If the emerging brain activity reflects the decision process rather than the outcome , we might not even have a philosophical contradiction on our hands . It matters a lot what we call “the decision” — is it the moment we reach an outcome, or the entire process that leads to reaching it? Brain activity in Libet-style studies might simply reflect the latter, and that suddenly does not sound so mysterious anymore.

Where to from here?

While Libet’s classic study might not have solved the problem of free will, it made a lot of clever people think hard. Generations of students have argued long nights over beer and pizza whether they have free will or not, and researchers have conducted increasingly innovative studies to follow in Libet’s footsteps.

Exciting questions have arisen, such as which brain processes lead to the formation of a voluntary action, how we perceive agency , what freedom of will means for being responsible for our actions , and how we change our mind after making an initial decision .

Researchers had to acknowledge they might not be able to provide a definite answer to the big philosophical question. But the field of cognitive neuroscience and voluntary decisions is more alive, interesting and sophisticated than ever before, thanks to the bold attempts by Libet and his successors to tackle this philosophical problem using science.

Neuroscience
The science of free will

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Free: Why Science Hasn't Disproved Free Will

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2 Benjamin Libet: If Not Now, When?

Published: November 2014
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This chapter examines the experiments conducted by neurobiologist Benjamin Libet to show that free will does not exist, and instead we make all of our decisions unconsciously. It considers Libet's experimental design, in which he studied conscious experiences—urges, intentions, decisions—and their correlation with measurable brain events. The subjects were instructed to flex a wrist at least forty times during each session, and Libet made readings of electrical conductivity from the scalp using EEG (electroencephalogram) technology. The chapter summarizes Libet's argument and his findings, arguing that his conclusions are not supported by the evidence.

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December 6, 2019

How a Flawed Experiment “Proved” That Free Will Doesn’t Exist

It did no such thing—but the result has become conventional wisdom nevertheless

By Steve Taylor

Getty Images

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American

On supporting science journalism

However, if we look more closely, Libet’s experiment is full of problematic issues. For example, it relies on the participants’ own recording of when they feel the intention to move. One issue here is that there may be a delay between the impulse to act and their recording of it—after all, this means shifting their attention from their own intention to the clock. In addition, it is debatable whether people are able to accurately record the moment of their decision to move. Our subjective awareness of decisions is very unreliable. If you try the experiment yourself—and you can do it right now, just by holding out your own arm, and deciding at some point to flex your wrist—you’ll become aware that it’s difficult to pinpoint the moment at which you make the decision.

Brain might not stand in the way of free will

By Anil Ananthaswamy

6 August 2012

Our decision-making process remains hazy

(Image: Jannes Glas/Getty)

Editorial: “ Can we live without free will? “

Advocates of free will can rest easy, for now. A 30-year-old classic experiment that is often used to argue against free will might have been misinterpreted.

In the early 1980s, Benjamin Libet at the University of California in San Francisco, used electroencephalography (EEG) to record the brain activity of volunteers who had been told to make a spontaneous movement. With the help of a precise timer that the volunteers were asked to read at the moment they became aware of the urge to act, Libet found there was a 200 millisecond delay, on average, between this urge and the movement itself.

But the EEG recordings also revealed a signal that appeared in the brain even earlier – 550 milliseconds, on average – before the action. Called the readiness potential, this has been interpreted as a blow to free will, as it suggests that the brain prepares to act well before we are conscious of the urge to move.

This conclusion assumes that the readiness potential is the signature of the brain planning and preparing to move. “Even people who have been critical of Libet’s work, by and large, haven’t challenged that assumption,” says Aaron Schurger of the National Institute of Health and Medical Research in Saclay, France.

One attempt to do so came in 2009. Judy Trevena and Jeff Miller of the University of Otago in Dunedin, New Zealand, asked volunteers to decide, after hearing a tone, whether or not to tap on a keyboard. The readiness potential was present regardless of their decision , suggesting that it did not represent the brain preparing to move. Exactly what it did mean, though, still wasn’t clear.

Crossing a threshold

Now, Schurger and colleagues have an explanation. They began by posing a question: how does the brain decide to make a spontaneous movement? They looked to other decision-making scenarios for clues. Previous studies have shown that when we have to make a decision based on visual input, for example, assemblies of neurons start accumulating visual evidence in favour of the various possible outcomes. A decision is triggered when the evidence favouring one particular outcome becomes strong enough to tip its associated assembly of neurons across a threshold.

Schurger’s team hypothesised that something similar happens in the brain during the Libet experiment. Volunteers, however, are specifically asked to ignore any external information before they make a spontaneous movement, so the trigger to act must be internal.

The random fluctuations of neural activity in the brain. Schurger’s team reasoned that movement is triggered when this neural noise accumulates and crosses a threshold.

To probe the idea, the team first built a computer model of such a neural accumulator. In the model, each time the neural noise crossed a threshold it signified a decision to move. They found that when they ran the model numerous times and looked at the pattern of the neural noise that led up to the decision it looked like a readiness potential.

Next, the team repeated Libet’s experiment, but this time if, while waiting to act spontaneously, the volunteers heard a click they had to act immediately. The researchers predicted that the fastest response to the click would be seen in those in whom the accumulation of neural noise had neared the threshold – something that would show up in their EEG as a readiness potential.

This is exactly what the team found. In those with slower responses to the click, the readiness potential was absent in the EEG recordings.

Spontaneous brain activity

“Libet argued that our brain has already decided to move well before we have a conscious intention to move,” says Schurger. “We argue that what looks like a pre-conscious decision process may not in fact reflect a decision at all. It only looks that way because of the nature of spontaneous brain activity.”

So what does this say about free will? “If we are correct, then the Libet experiment does not count as evidence against the possibility of conscious will,” says Schurger.

Cognitive neuroscientist Anil Seth of the University of Sussex in Brighton, UK, is impressed by the work, but also circumspect about what it says about free will. “It’s a more satisfying mechanistic explanation of the readiness potential. But it doesn’t bounce conscious free will suddenly back into the picture,” he says. “Showing that one aspect of the Libet experiment can be open to interpretation does not mean that all arguments against conscious free will need to be ejected.”

According to Seth, when the volunteers in Libet’s experiment said they felt an urge to act, that urge is an experience, similar to an experience of smell or taste. The new model is “opening the door towards a richer understanding of the neural basis of the conscious experience of volition”, he says.

Journal reference: Proceedings of the National Academy of Sciences , DOI: 10.1073.pnas.1210467109

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The libet experiment and its implications for conscious will.

Dr Peter Clarke considers whether the experiments of Benjamin Libet call into question the reality of human will. Although quite a technical paper, Dr Clarke makes it clear that there is far more to the discussion, and far more uncertainty, than is allowed in the popular interpretations of these experiments. Whether or not you hold the same philosophical position on monism and dualism as Dr Clarke, this paper will help you challenge interpretations of Libet's experiments that deny the reality of human conscious will.

Summary: A famous experiment of Benjamin Libet and his colleagues has been interpreted as showing that our brains initiate voluntary movements before we are aware of having decided to move, and that this calls into question the efficacy of our wills. These claims have been contested by many neuroscientists and philosophers. This paper provides an introduction to the controversy.

The neurophysiological experiments of Benjamin Libet and his collaborators in the 1980s [1] have been interpreted by the authors and many others as showing that our brains initiate conscious voluntary movements as well as the will to move before we are consciously aware of the will to move. I shall refer to this claim as the Libet claim for brevity. It is controversial, but if valid would have important implications for our understanding of how the mind relates to the brain and for the role of conscious will in the performance of voluntary actions. Before going into details about the Libet experiment, I must first provide some information about the mind-brain relationship and the neurophysiology of voluntary movement.

The Mind-Brain Relationship and the Libet Claim

It is generally accepted that the electrical activity of our brains underlies our conscious thought, including our decision making. How a physical thing, the brain, can be the basis of consciousness is a subject of debate that has given rise to many different philosophical positions, but these can be grouped in two main categories: dualism and monism.

So great was the influence of Descartes on western philosophy that, from the late seventeenth century until around 1950 or so, most westerners accepted some form of interactive dualism, involving an immaterial soul acting on a material brain. Since then this view has lost favour, for a variety of reasons, including the arguments of philosophers such as Ryle, Place and Feigl. In addition, atheistic materialists rejected it because it invokes a nonmaterial entity, but so did most Christian academics, because advances in the analysis of biblical texts in the mid twentieth century and since tended to support a monistic conception of man, not a dualistic one. [2] This realisation was not entirely revolutionary, because there had always been a monistic strand in Christian thought due to the influence of Thomas Aquinas. Thus, during his Gifford Lectures in 1956-57, Anglican theologian Austin Farrer criticised the dualistic views of neurobiologist (and future Nobel prize-winner) John Eccles, writing:

We will have nothing to do with the fantastic suggestion, that what the supersensitive ‘reactors’ in the cortex react to, is the initiative of a virtually disembodied soul. To what, then, are we to say that they do react? What else, than to the motions of the embodied soul, that is to say, other motions in the same nervous system? [3]

For these reasons, with a few exceptions, [4] most modern philosophers and neuroscientists, whether theist or atheist, accept some form of monism, but this does not have to involve eliminative materialism that rejects mind as illusory. Many theists, agnostics and atheists adopt more moderate monist positions such as two aspect monism, according to which our subjective, first-personal, account of our inner life and neuroscience’s objective, third-personal account of our brain’s activity refer to complementary aspects of a single entity. [5] An alternative view is the mind-brain identity theory, according to which the mind and the brain’s activity are considered to be the same entity, not two aspects of the same entity. I prefer two-aspect monism because mind-brain identity seems to me linguistically problematic, but the two formulations make identical predictions at the level of brain function.

if brain events come first, this would support epiphenomenalism, the view that mind events are mere by-products of brain events, with no causal role.

A striking aspect of the Libet claim is that it goes against the main versions of both dualism and monism. Cartesian dualism predicts that mind events should precede brain events, since the nonphysical mind (or soul etc.) is considered to be the real source of our decisions. Two-aspect monism and mind-brain identity theory both predict that mind and brain events should be synchronous, since mind-level descriptions and brain-level descriptions are considered complementary (and equally valid) accounts of the same processes. But if brain events come first, this would support epiphenomenalism, the view that mind events are mere by-products of brain events, with no causal role. This would deny the causal efficacy of conscious will.

The Neurophysiology of Voluntary Movement

It is important to be clear about what is, and is not, being claimed when a movement is called voluntary. Even though these movements involve, by definition, an act of conscious will, that is not to say that every aspect of the movement is conscious or willed. For example, the movements of a tennis player as she serves are voluntary, but their control involves many automatic subroutines in the cerebellum and elsewhere. Furthermore, to claim that conscious acts of will initiate voluntary movements is not to deny that the acts of will arise out of brain processes that are largely unconscious. [6]

What is the nature of the ‘I’ (or self) that willed the movement and performed it? The use of such terms does not imply dualism. The ‘I’ (or self, or mind etc.) is generally conceived as being embodied in (or emerging from) the brain’s activity.

The neural circuits involved in voluntary motor control are exceedingly complicated, and I here give only some simplified information that is necessary for understanding the Libet experiment. Voluntary movements are controlled primarily by the motor cortex (in the back part of the frontal lobe – Fig. 1) but in cooperation with many other motor centres including the basal ganglia and the cerebellum. Motor commands are sent from the primary motor cortex (and to some extent from other areas) to motoneurons in the brainstem and spinal cord, which in turn control the muscles. The initiation and programming of movements depend on activity in many areas including the supplementary motor area (Fig. 1) and the preSMA, and several areas in the parietal cortex. These areas feed directly or indirectly into the premotor cortex and motor cortex. Electrical stimulation of the motor areas produces movements, but not the will to move. In contrast, electrical stimulation of areas BA-39 and BA-40 in the parietal lobe (Fig. 1) elicits the will to move, but does not cause a movement. [7]

The Libet Experiment, a Challenge to the Role of Conscious Will

An important background to the Libet experiment was the discovery in the 1960s that, before people make a voluntary movement, there is a slow build-up of electrical potential measured from the skull over the motor cortex, beginning as much as a second earlier for simple movements and even longer for complex series of movements. [8] This electrical change is called the readiness potential (RP).

Libet was interested in the relative timing of the RP compared with the movement and the conscious decision to move. He therefore asked his experimental subjects to perform simple movements, in most cases flexion of the fingers or wrist, and to estimate the time of conscious awareness of the urge (or will or decision) to move (W) by reporting the position of a spot moving in a circle on an oscilloscope screen. They were told to perform the movement whenever they felt like doing so, and to pay close attention to the time when they were first aware of the ‘urge to move’. He also recorded the RP by electroencephalography, and the time of the movement itself was estimated from the electromyogram [ measurement of the electrical impulses in muscles - ed] . Libet found that time W came only about 200 msec before the movement, whereas the RP began much earlier, usually about 550 msec before the movement (Fig. 2). The fact that the change in brain potential occurred before the conscious decision was interpreted by Libet and by many commentators to imply that our conscious decision to act is not the true cause of the movement. They deduced that conscious will is too slow to make things happen, and that volitional acts must result from unconscious processes in the brain, not from conscious willing. This seemed to imply that our intuitive notion of conscious will must be an illusion.

There appeared to be a small loophole in that Libet’s subjects still had the power to veto a movement in the 200 msec between time W and the movement. He therefore argued that even though the initiation of the movement was not the result of conscious will, its vetoing was. This argument has not attracted great interest, but was supported by eminent free-will philosopher Robert Kane. [9]

The Libet experiment provoked considerable interest and intense controversy, and stimulated further experimentation.

Single Neuron Recordings During the Libet Experiment

The overall conclusion on timing has to be that the problems have not so far been resolved.

It is rarely possible to record from single neurons in the brains of humans, but this can occasionally be done in epilepsy patients using electrodes that have been implanted to localise the zones that cause seizures. Thus, remarkably, Itzhak Fried and his collaborators managed to record from more than 1,000 neurons in the medial frontal cortex of epilepsy patients (and especially in the supplementary motor area, which generates most of the early part of the RP) as they performed the Libet experiment. It was found that a few neurons changed their firing rate (by an increase or a decrease) almost 1.5 sec before time W, and more and more neurons did so over the following 1.5 sec, with about 25% of the neurons firing several tenths of a second before W. The authors conclude that their findings support the view that the experience of will emerges as the culmination of premotor activity starting several hundreds of msec before awareness. [10]

Criticisms of the Libet Claim

Despite the fame of the Libet experiment and its frequent acceptance in popular and semi-popular writings, it has been the subject of intense controversy. Indeed, most specialists in the philosophy of free will who have addressed the Libet claim have rejected it. [11] Most of the criticisms focused on difficulties of judging the time of awareness, of interpreting the RP, or of philosophical interpretation, as is discussed below.

Problems of judging the time of awareness

It was central to Libet’s claim that the readiness potential began distinctly before time W. The published data of several groups do indeed support this claim, but critics have objected to the use of subjective recall after the event, because there is evidence that this can be very unreliable. Furthermore, those such as Alfred Mele [12] who have tried the experiment for themselves have found that W is difficult to define. I have done this too, and you may wish to try it using a ‘clock’ available on the web. [13] When I try this, I find it very hard to judge the precise time when I decided to move my finger / wrist. It would be useful to quantify the reliability of our judgements, but this is difficult for a purely subjective decision. For this reason, several research groups have instead measured the reliability of timing judgements for perceptual events, which is easier to do. Results have been variable, but several groups found serious biases, [14] raising doubts about the interpretation of the Libet experiment. A different critique of the timing was made by Dennett and Kinsbourne, [15] who point out that Libet’s experiment involves an attention shift from the participants’ subjective intention to the clock, which may have introduced temporal mismatches between the felt experience of will and the perceived position of the clock hand.

To try to solve these problems, Matsuhashi and Hallett devised an alternative methodology for estimating time W. They found that the RP (which they called BP1) occurred before W in only about two thirds of the subjects; worse, the lateralised RP (LRP) that we shall discuss below, always occurred after W. [16]

In view of the controversy about the measurement of subjective timing, considerable attention was devoted in the public media to a paper published in Nature Neuroscience that used brain scanning technology (functional magnetic resonance imaging – fMRI) in a Libet-like experimental paradigm, and included in the summary a claim that a "decision can be encoded in brain activity of prefrontal and parietal cortex almost 10 sec before it enters awareness" . [17] After all the subtle debate about a few hundreds of milliseconds, 10 sec was an enormous amount of time, and the wording of the abstract gave the impression that the temporal priority of the neural decision with respect to the subjective one was finally established. I assume that some journalists and bloggers only had access to the abstract (available free on the web) and not to the full paper, because the main text made only the much weaker claim that the activity of prefrontal and parietal cortex was correlated with the decision (to use the left or right hand) with 60% prediction accuracy, up to 10 sec before the conscious decision. That is very different! To reflect a neural decision, the correlation would need to be at 100%, not 60%. The paper provided valuable information about brain activity leading ultimately to a decision, but did nothing to rescue the Libet experiment from the criticisms about timing.

Doubts as to whether the readiness potential reflects a decision to move

The Libet claim assumes that the RP reflects a neural ‘decision’ to move, and that the neural activity underlying the RP causes both the will to move and the movement. Even if such causality could be demonstrated, this would not strictly be sufficient to validate the Libet claim, because the decision must presumably be caused by a chain of preceding neural events, and the RP might reflect some of these. But the Libet claim certainly assumes causality. This is part of the claim, and it has never been proved.

Libet et al. explicitly pointed out that their conclusions applied only to spontaneous, rapidly performed movements

To be precise, we are really talking about the earliest part of the RP, because the timing argument focuses on the RP’s onset. To attribute such a decisional and causal role to this earliest part of the RP seems surprising, because it originates mainly in the SMA (Fig. 1), which has been known for more than thirty years to be strongly activated when subjects ‘programme’ (imagine) a complex movement without actually performing it. [18] This is not to deny that activity in SMA can cause movements in some cases, such as when it is stimulated electrically, but it cannot be assumed that the earliest part of the RP necessarily reflects neural processes underlying a decision to move. And there are at least six specific reasons to doubt this.

First, even though electrical stimulation of the SMA can cause movements, it does not cause a will to move, which requires stimulation of parietal areas. [19] This suggests that the RP does not cause the will to move.

Second, if the RP truly caused the conscious will and the movement, one would expect trial-to-trial variations in the onset of the RP to correlate with trial-to-trial variations in time W; that is to say that trials with an early RP should also have an early W. Haggard and Eimer tested this, using a variant of the Libet experiment, and found there was little correlation, ruling out the RP as a cause of the will or decision to move. They did, however, find that the ‘lateralized readiness potential’ (LRP: i.e. the RP from the cortex on the opposite side relative to the movement minus the RP from the same side) gave a positive correlation, suggesting that the brain processes underlying the LRP might cause the will to move. [20] At the time, their paper did not seem to challenge the Libet claim, because the LRP seemed to fulfil the role formerly attributed to the RP. However, the LRP occurs later than the RP, and subsequent experiments have sometimes found that the LRP occurs even after time W as is discussed above, [21] so the LRP seems a fragile candidate to replace the RP.

Third, Alfred Mele has pointed out a flaw in Libet’s experimental paradigm that vitiates attempts to deduce a causal influence between the RP and the movement (and the will to move). [22] In all Libet’s experiments, the permanent storage of electroencephalographic data was triggered by the finger / wrist movements. This was necessary as part of the averaging procedure that is necessary to detect the RP, which would otherwise be masked by other concurrent activity in the EEG. If there was no movement, the data were not stored, so any RPs that occurred without being followed by movements would not have been detected. If such RPs without movement did occur, then RPs are not sufficient to cause movements, and more probably reflected brain activity occurring prior to the decision to move. This possibility is difficult to evaluate, because the averaging procedure has to be triggered at a moment defined by the movement.

Fourth, experiments by Hermann et al. cast further doubt on the interpretation of the RP as causally related to the decision and movement. [23] These researchers used a modified version of the Libet experimental paradigm, in which the participants were instructed to press one of two buttons, depending on a presented stimulus. An RP occurred well before the motor response, as in the Libet experiment. But, importantly, it occurred even before the stimulus presentation, so it clearly did not reflect a decision as to which button to press. The authors argue that the RP does not specifically determine the movement, but may reflect a general expectation (which is indeed what the RP was initially thought by Kornhuber and Deecke to reflect, not a decision but a state of readiness, hence its name).

Fifth, Trevena and Miller devised a modified version of the Libet experiment in which participants made spontaneous decisions to move, or not, and found that the RP was no stronger before a decision to move than before a decision not to move, which is not what one would expect if the RP reflected a neural decision to move. [24]

Sixth, computational analysis suggests that the neural decision to move occurs only very late during the time-course of the RP, not at its onset. [25]

Debate about the philosophical interpretation

Even if the Libet claim is accepted – which is very controversial, as we have seen – there is also debate about the philosophical interpretation.

Libet ... maintained that conscious will can still play a genuine role in the vetoing of initiated acts.

I have here used systematically the term ‘conscious will’ rather than ‘free will’ to avoid the broader philosophical associations of the latter term. Nevertheless, many supporters of the Libet claim, including Libet himself [26] , have used the term ‘free will’. This has aroused further controversy, because many critics have argued that Libet’s experimental paradigm was irrelevant to the question of free will. When we talk about free will, we are usually referring to choices among a variety of options, often with moral implications, and this may require careful deliberation over a period of minutes or hours or days. The Libet experiment is just the opposite. The subject was not making a moral decision, and was not even deciding whether to move, but only when. Moreover, the subjects were specifically instructed not to deliberate but to act spontaneously, and in their original 1983 paper Libet et al. explicitly pointed out that their conclusions applied only to spontaneous, rapidly performed movements. [27] Thus, even if we accept the debatable claim that the finger / wrist movements in the Libet experiment were not the result of conscious will, this conclusion cannot automatically be extended to situations for which the term free will would normally be applied.

Another problem is that those who support an anti-free-will interpretation appear to have in mind only rather marginal notions of free will. For example, in a review on the neuroscience of volition, neurobiologist Haggard, a former collaborator of Libet and leading protagonist of the anti-free-will interpretation, mentions the possibility that the brain’s circuits might be influenced by "an unspecified and uncaused cause (the 'will')" . Haggard rejects this view, and concludes the article by stating that "modern neuroscience is shifting towards a view of voluntary action being based on specific brain processes…" . [28] This gives the impression that ‘modern neuroscience’ is gradually triumphing against the illusion of free will, but this is confusing for at least two reasons. First, only a tiny minority of modern philosophers conceive of the will as an ‘uncaused cause’, so why use such a marginal definition? Second, the words about modern neuroscience’s "shifting towards a view of voluntary action being based on specific brain processes" are strange, because this has been the standard view in neuroscience for over half a century. In the same review, Haggard states that the Libet experiment "seems to disprove the everyday concept of 'free will'" ; his reference to ‘everyday concept’ suggests that he recognises that this challenge does not extend to more sophisticated concepts of free will.

Libet’s 1983 experiment reported that brain activity (the RP) reflecting a decision to flex a finger or wrist occurred several hundred milliseconds before the subject became aware of her decision (or urge or will) to move. This has been interpreted, controversially, to suggest that our subjective impression that our conscious wills initiate the movement is illusory. Libet accepted this interpretation, but maintained that conscious will can still play a genuine role in the vetoing of initiated acts.

Many neuroscientists and most philosophers contest the claims about the supposed inefficacy of conscious will, and this paper summarises their arguments. At the neurophysiological level, it has not been shown convincingly that a neural ‘decision’ sufficient to cause the movement occurs before the time of awareness of the decision to move. Even if this could be shown, it would not undermine the conceptions of free will that are defended by most philosophers.

Acknowledgments

The author is grateful to Martyn Frame and Stuart Judge for their helpful comments on an earlier draft of this paper.

[1] Libet, B., Gleason, C.A., Wright, E.W. & Pearl, D.K. ‘Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act’, Brain (1983) 106: 623- 642. [2] Green, J.B. Body, Soul and Human Life: The Nature of Humanity in the Bible , Carlisle: Paternoster (2008). [3] Farrer, A. The Freedom of the Will , London: A & C Black (1958), p.87. [4] Goetz, S. and Taliaferro, C. A Brief History of the Soul , Chichester, UK: Wiley-Blackwell (2011). [5] Nagel, T. The View From Nowhere , Oxford: Oxford University Press (1986), chap.3, p.28; Jeeves, M. & Brown, W.S. Neuroscience, Psychology and Religion , West Conshohocken, PA: Templeton Foundation Press (2009). [6] Gomes, G. ‘The timing of conscious experience: a critical review and reinterpretation of Libet's research’, Consciousness & Cognition (1998) 7: 559-595. [7] Desmurget, M., Reilly, K.T., et al. ‘Movement intention after parietal cortex stimulation in humans’, Science (2009) 324, 811-813. [8] Kornhuber, H.H. and Deecke, L. ‘Hirnpotentialänderungen bei Willkürbewegungen und passiven Bewegungen des Menschen: Bereitschaftspotential und reafferente Potentiale‘, Pflügers Archiv (1965) 284: 1-17. [9] Kane, R. The Significance of Free Will , New York / Oxford: Oxford University Press (1996), p.232. [10] Fried, I., Mukamel, R. & Kreiman, G. ‘Internally generated preactivation of single neurons in human medial frontal cortex predicts volition’, Neuron (2011) 69: 548-562. [11] Bayne, T. ‘Libet and the case for free will scepticism’, in Swinburne, R. (ed.) Free Will and Modern Science , Oxford: Oxford University Press (2011). [12] Mele, A. R. Effective Intentions: The Power of Conscious Will , New York / Oxford: Oxford University Press (2009). [13] There is a suitable clock at http://www.informationphilosopher.com/freedom/libet_experiments.html . [14] Danquah, A.N., Farrell, M.J. & O'Boyle, D.J. ‘Biases in the subjective timing of perceptual events: Libet et al. (1983) revisited’, Consciousness & Cognition (2008) 17: 616-627. [15] Dennett, D.C. & Kinsbourne, M. ‘Time and the observer’, Behavioral and Brain Sciences (1992) 15: 183–247. [16] Matsuhashi M. & Hallett, M. ‘The timing of the conscious intention to move’, European Journal of Neuroscience (2008) 28: 2344-2351. [17] Soon, C.S., Brass, M., Heinze, H.J. & Haynes, J.D. ‘Unconscious determinants of free decisions in the human brain’, Nature Neuroscience (2008) 11: 543-545. [18] Roland, P.E., Larsen, B., Lassen, N.A. & Skinhoj, E. ‘Supplementary motor area and other cortical areas in organization of voluntary movements in man’, Journal of Neurophysiology (1980) 43: 118-136. [19] Desmurget et al. op. cit. , (see [7]). [20] Haggard P. & Eimer M. ‘On the relation between brain potentials and the awareness of voluntary movements’, Experimental Brain Research (1999) 126: 128-133. [21] Matsuhashi & Hallett op. cit. , (see [16]). [22] Mele op. cit. , (see [12]). [23] Herrmann, C.S., Pauen, M., Min, B.K., Busch, N.A. & Rieger, J.W. ‘Analysis of a choice-reaction task yields a new interpretation of Libet's experiments’, International Journal of Psychophysiology (2008) 67, 151-157. [24] Trevena, J. & Miller, J. ‘Brain preparation before a voluntary action: evidence against unconscious movement initiation’, Consciousness & Cognition (2010) 19, 447-456. [25] Schurger, A., Sitt, J.D. & Dehaene, S. ‘An accumulator model for spontaneous neural activity prior to self-iniated movement’, Proceedings of the National Academy of Sciences . USA doi:10.1073/pnas.1210467109 (2012). [26] Libet, B. Mind Time , Cambridge Mass. / London, UK: Harvard University Press (2004). [27] Libet et al. op. cit. , (see [1]). [28] Haggard, P. ‘Human volition: towards a neuroscience of will’, Nature Reviews Neuroscience (2008) 9: 934-946.

The Libet experiment and its implications for conscious will FARADAY PAPER NO 17

Faraday Papers

The Faraday Papers are published by the Faraday Institute for Science and Religion , St Edmund’s College, Cambridge, CB3 0BN, UK, a charitable organisation for education and research ( www.faraday-institute.org ). The opinions expressed are those of authors and do not necessarily represent the views of the Institute. The Faraday Papers address a broad range of topics related to the interactions between science and religion. A full list of current Faraday Papers can be viewed at www.faraday-institute.org from where free copies can be down-loaded in pdf format. Print copies can also be obtained in bulk quantities of ten or more at £1.50 per 10 copies + postage (check current rates). Secure on-line ordering details are at www.faraday-institute.org .

Peter G.H. Clarke

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Benjamin Libet and the Denial of Free Will
Many materialists believe that evidence for a lack of free will was found when, in the 1980s, the scientist Benjamin Libet conducted experiments that seemed to show that the brain "registers ...
How a Flawed Experiment "Proved" That Free Will Doesn't Exist
Many people believe that evidence for a lack of free will was found when, in the 1980s, scientist Benjamin Libet conducted experiments that seemed to show that the brain "registers" the ...
A Famous Argument Against Free Will Has Been Debunked
Graiki / Getty. September 10, 2019. The death of free will began with thousands of finger taps. In 1964, two German scientists monitored the electrical activity of a dozen people's brains. Each ...
Neuroscience of free will
Benjamin Libet himself did not interpret his experiment as evidence of the inefficacy of conscious free will — he points out that although the tendency to press a button may be building up for 500 milliseconds, the conscious will retain a right to veto any action at the last moment.
Why Libet's Studies Don't Pose a Threat to Free Will
Libet argues that subjects refer their conscious experiences to a time that is prior to the actual time at which they become conscious of them (Libet et al., 1979). Libet's reasoning is based largely on C1, the claim that cortex must be active for approximately 500 ms before stimuli reach awareness.
Does Free Will Exist? New Study Challenges Classic Libet ...
New Study Challenges Classic Libet Experiments. Neuroscientists from HSE University have questioned the conclusions of famous studies, primarily those by Benjamin Libet, that challenge the existence of free will. Libet's experiments in the 1970s and 1980s used EEG to show that brain activity indicating a decision occurred before individuals ...
Does the brain "initiate" freely willed processes? A philosophy of
The pioneering experiment by Benjamin Libet and co-workers (see Libet, Gleason,Wright, & Pearl, 1983) is still being discussed, related experiments have been performed or are being proposed, and strong conclusions concerning the existence of a free will are drawn on the basis of these experiments.
The neuroscientific study of free will: A diagnosis of the ...
process in Libet's experiment (550 ms). Despite this, Haynes and colleagues were able to replicate the basic result of the Libet experiment. As in the experiment by Haggard and Eimer, participants were given a free choice between two actions (pressing one of two buttons with either their left or right index finger). Using statistical pattern
Why neuroscience does not disprove free will
Abstract. While the question whether free will exists or not has concerned philosophers for centuries, empirical research on this question is relatively young. About 35 years ago Benjamin Libet designed an experiment that challenged the common intuition of free will, namely that conscious intentions are causally efficacious.
PDF The Libet experiment and its implications for conscious will
A famous experiment of Benjamin Libet and his colleagues has been interpreted as showing that our brains The mind-brain relationship and the Libet claim underlies our conscious thought, including our decision making. categories: dualism and monism. dualism, involving an immaterial soul acting on a material brain. ic writing: ,
Will I or won't I? Scientists still haven't figured out free will, but
In 1983, American physiologist Benjamin Libet conducted an experiment that became a landmark in the field of cognitive sciences. It got psychologists, neuroscientists, and philosophers either very ...
Free Will Is Only an Illusion if You Are, Too
In his research, Dominik replicated neuroscientist Benjamin Libet's 1980s experiment on brain activity and people's reported intention, or urge, to move but also showed a problem with Libet ...
The Libet Experiment: Is Free Will Just an Illusion?
Are our 'conscious decisions' just reports on what is already happening? Narrated by Harry Shearer. Scripted by Nigel Warburton.From the BBC Radio 4 series ...
Libet on Free Will: Readiness Potentials, Decisions, and Awareness
Scientific work on free will has gained a lot of momentum in recent years. It features some striking claims. For example, Benjamin Libet contends both that "the brain 'decides' to initiate or, at least, prepare to initiate [certain actions] before there is any reportable subjective awareness that such a decision has taken place" (1985, p. 536) 1 and that "if the 'act now' process ...
Benjamin Libet: If Not Now, When?
Abstract. This chapter examines the experiments conducted by neurobiologist Benjamin Libet to show that free will does not exist, and instead we make all of our decisions unconsciously. It considers Libet's experimental design, in which he studied conscious experiences—urges, intentions, decisions—and their correlation with measurable brain ...
How a Flawed Experiment "Proved" That Free Will Doesn't Exist
Many people believe that evidence for a lack of free will was found when, in the 1980s, scientist Benjamin Libet conducted experiments that seemed to show that the brain "registers" the ...
Brain might not stand in the way of free will
A 30-year-old classic experiment that is often used to argue against free will might have been misinterpreted. In the early 1980s, Benjamin Libet at the University of California in San Francisco ...
PDF Journal of Consciousness Studies
48 B. LIBET Figure 1 Readiness potentials (RP) preceding self-initiated voluntary acts. Each horizontal row is the computer-averaged potential for 40 trials, recorded by a DC system with an active electrode on the
PDF Do We Have Free Will?
Benjamin Libet Do We Have Free Will? I have taken an experimental approach to this question. Freely voluntary acts are preceded by a specific electrical change in the brain (the 'readiness potential', RP) that begins 550 ms before the act. Human subjects became aware of intention to act 350-400 ms after RP starts, but 200 ms. before the motor act.
Benjamin Libet
Benjamin Libet (/ ˈ l ɪ b ə t /; April 12, 1916 - July 23, 2007) was an American neuroscientist who was a pioneer in the field of human consciousness.Libet was a researcher in the physiology department of the University of California, San Francisco.In 2003, he was the first recipient of the Virtual Nobel Prize in Psychology from the University of Klagenfurt, "for his pioneering ...
Neuroscience and Free Will
Watch how Libet's experiment challenges the notion of free will and learn from neuroscience experts and philosophers about its implications.
The Libet Experiment and its Implications for Conscious Will
The neurophysiological experiments of Benjamin Libet and his collaborators in the 1980s have been interpreted by the authors and many others as showing that our brains initiate conscious voluntary movements as well as the will to move before we are consciously aware of the will to move. I shall refer to this claim as the Libet claim for brevity.

Benjamin Libet and the Denial of Free Will

How a Flawed Experiment “Proved” That Free Will Doesn’t Exist

On supporting science journalism

A Famous Argument Against Free Will Has Been Debunked

Does Free Will Exist? New Study Challenges Classic Libet Experiments

You can’t blame your brain for your actions!

Historical Context of the Free Will Debate

HSE University’s Take on the Paradigm

Concluding Thoughts

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Will I or won’t I? Scientists still haven’t figured out free will, but they’re having fun trying

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How a Flawed Experiment “Proved” That Free Will Doesn’t Exist

On supporting science journalism

Brain might not stand in the way of free will

Crossing a threshold

Spontaneous brain activity

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The Mind-Brain Relationship and the Libet Claim

The Neurophysiology of Voluntary Movement

The Libet Experiment, a Challenge to the Role of Conscious Will

Single Neuron Recordings During the Libet Experiment

Criticisms of the Libet Claim

Problems of judging the time of awareness

Doubts as to whether the readiness potential reflects a decision to move

Debate about the philosophical interpretation

Acknowledgments

The Libet experiment and its implications for conscious will FARADAY PAPER NO 17

Faraday Papers

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