Random Brain Waves Save Free Will?

By Neuroskeptic | November 15, 2013 8:45 am

A new paper adds to the perennial free will debate, by casting doubt on the famous Libet experiment.

Back in 1983, neuroscientists led by Benjamin Libet found that, about two seconds before someone presses a button ‘of their own free will’, a negative electrical potential – dubbed the Readiness Potential (RP) – began to build up in the cortex. Their EEG study showed that the brain seemed to have ‘decided’ before the conscious mind did – bad news for free will.

Since then, the meaning of the RP has been extensively debated. But the new study by Han-Gue Jo and colleagues of Freiburg makes a strong case that the “RP” is not really a ‘thing’ at all.

They say that, in the two seconds before a button press, you see both negative and positive changes, in roughly equal numbers. There are slightly more negative ones, so on average, there is a small negative “RP”, but only on average.


Almost half the button presses were not preceded by a negative potential, yet the button still got pressed – which means that the negative “RP” can’t directly reflect the decision to press.

Jo et al also ran a comparison condition, where participants had to listen to a beep, instead of pressing a button. So there was no ‘free choice’ to make, yet there were potential shifts in the two seconds before the beeps, just as there were before button presses. The difference was that in the beep task, there were equal numbers of positive and negative potentials, and they cancelled out to zero on average.

Jo et al say that these shifts are more or less random, spontaneous background changes in the brain – nothing to do with ‘readiness’ or decisions.

But why then are negative potentials more common just before movements? They suggest that

the negative deflections facilitate a movement in the near future, but they are not a neural sign of decision processes to move.

In other words, they don’t reflect a choice being made, rather they contribute to making a choice. Random brain changes influencing our choices… is that good news for free will?

Anyway, Jo et al did find a more substantial negative RP preceding button presses – albeit only about half a second beforehand. This occurred whether or not the ongoing slow wave was positive or negative:

late_rpCould this -0.5 second ‘late RP’ be the real marker of the decision to move? If so, it would still precede the moment of the conscious decision, which on average occurred at -0.25 seconds before the button got pushed.

ResearchBlogging.orgHan‑Gue Jo, Thilo Hinterberger, Marc Wittmann, Tilmann Lhündrup Borghardt, & Stefan Schmidt (2013). Spontaneous EEG fluctuations determine the readiness potential: is preconscious brain activation a preparation process to move? Exp Brain Res DOI: 10.1007/s00221-013-3713-z

  • reasonsformoving

    Here’s a question I’ve always had about the famous Libet experiment: How do they account for the time between when a person decides to push the button, his or her motor neurons activating, and the actual pushing of the button? Couldn’t this be 2 seconds?

  • tom_campbel_ricketts

    Nobody will ever provide empirical evidence for or against libertarian free will, because it is neither true nor false, but rather incoherent nonsense. You might as well plan an experiment to test Chomsky’s sentence.

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  • http://www.whatismind.com/ Parag Jasani

    Thousands of years old mysteries like free will, consciousness, etc. solved – made possible via discoveries of simple mechanisms that enable them – explained using common sense logic on http://www.whatismind.com

    • Mo Jo

      Hey everybody, look! It’s Dan Dennett…again! Good luck defining “mechanism.”

  • http://brightumbra.wordpress.com/ BrightUmbra

    “Random” anything and “Free Will” seem to be mutually exclusive… Ultimately there is a physical cause for this “random” behavior, which means it isn’t random at all. Even if it were, and even if this ‘random’ behavior somehow did influence decision making, this would still not be *free* will.

    • jagiela

      The point is that this random movement is what was detected not some “readiness” impulse. Its disproving the notion that this brain movement is a precursor to the motion.

      It doesn’t prove free will. It just proves that this is not evidence of a lack of free will

    • svman

      To an outsider, free will and random appear to be the same.

      • http://blogs.discovermagazine.com Cohoe Tom

        I agree. If a behavior can be predicted it can’t be free.

    • citicrab

      Exactly. Unpredictability and/or randomness do not equate free will. It just can not exist, other than supernaturally.

      • http://blogs.discovermagazine.com Cohoe Tom

        Supernatural and unpredictable are the same thing, essentially.

        • citicrab

          Are they? Isn’t unpredictability fundamental in nature?

          • http://blogs.discovermagazine.com Cohoe Tom

            I’m leaving out a lot here.

            Most of what we call unpredictable is predictable in principal. We just don’t have enough information or can’t calculate fast enough. The toss of a die, for example. But there is true unpredictability associated with natural phenomena – at least there is according to quantum mechanics.

            Nature is what scientists study and write rules about. Scientists can write a rule about coherent quantum phenomena, a statistical rule. That, after 87 years, they cannot write a rule that removes the probability from individual events – where a particle will land in a double slit experiment, for example – has lead many or most scientists to conclude that that randomness _is_ fundamental – that there is no rule.

          • Archie Meijer

            87 years is a short short amount of time in science.

            It could very well be that the processed materials (measuring devices) to measure these things more definitively just haven’t been invented yet.

          • Archie Meijer

            But then we run into what ever effects those measuring devices have.
            It could be that everything we look at and say is fundamentally unpredictable today will one day be predictable but that in the process we will discover yet new things which can’t be predicted.

          • http://blogs.discovermagazine.com Cohoe Tom

            To put this another way, if we – scientists – can write a rule about it, even if only in principle, we call it “natural”. We say it is part of nature. That leaves for “supernatural” whatever is left. Thus, the “supernatural” can only be whatever there is for which there is no rule, even in principle. That’s whatever there is that is fundamentally random.

    • http://blogs.discovermagazine.com Cohoe Tom

      No, “deterministic” and “free will” are mutually exclusive. If we have free will, then any time we make a decision in which free will plays an important role the decision could not be predicted by, or is not determined by, a rule – even if the state of every particle in the universe were allowed as input.

      Unpredictability is a form of freedom or power. It means not being bound by a rule. A hunter can bag a deer because the deer is not smart enough to predict the hunter’s action.

      I believe that most of our decisions are controlled by habit or by subconscious but deterministic mechanisms. Feeling and obeying an impulse to have a smoke after eating is a habit. Putting one foot in front of the other while walking is a subconscious mechanism. The mechanism studied in the experiment discussed above falls under subconscious and does not impact the question of whether free will exists.

      Now breaking a habit, like smoking, is something more likely to be a true exercise of free will.

      Science allows for free will via quantum mechanics. Random thermal noise causes neurons to fire at a low rate with unpredictable spontaneity. Thus the brain can exist in superposed decoherent states. An exercise of free will would be the determination of which of the states the universe turns on. The lower the probability, the harder the decision (and sticking to it).

      The truth of the question of free will is important. Justice and reward assume free will. We have always functioned as though free will exists. To assume it does not would be revolutionary, but whatever the communists say, it would not be just because under the assumption justice does not exist.

      My mechanism may be wrong. It is beyond science. The important thing to understand is that science does not rule it out. Other “interpretations” of quantum mechanics do rule it out, but they too are beyond science. It is, really, a matter of faith (either way). But then, so is your understanding of the meaning of the word “Mom”, and so is your knowledge that your mother really is your mother (some people find out late in life that their “mother” was not their mother, others in mistaken belief never find out).

      • http://neuroautomaton.com/ Zachary Stansfield

        Your colloquial explanation of “unpredictability”, or the inability of one ignorant being to predict how another will act, is not the same as randomness. Ignorance of a mechanism does not equate to a lack thereof.

        I also disagree with you on two points:

        a) “Randomness” does not suggest that “free will” exists. If our world is not perfectly deterministic, the individual is caught between deterministic processes and random events or variability that produce a sort of “causal jitter”, ensuring that most events are partly unpredictable. There is no room for free will here.

        b) Determinism is not mutually exclusive with free will. In fact, free will lacks coherence unless we assume determinism plus some loophole. That is, the world operates under rules of complete, atomic causality, and humans have some external source of “will”, such as a soul, which allows us to inject a “free actions” into the mix.

        • http://blogs.discovermagazine.com Cohoe Tom

          If you read the first paragraph of my “colloquial” post, you will see that I explained clearly what I meant by “unpredictability” (I wrote “could not be predicted”), and my explanation had nothing to do with “ignorant beings”.

          Do you like mathematics?

          • http://neuroautomaton.com/ Zachary Stansfield

            Tom, you wrote that unpredictability means “not bound by a rule” and then clarified this with an analogy to the situation in which the deer lacks knowledge of the hunter’s mind. The former definition is muddier by the latter explanation, which contradicts it. You were not nearly as clear as you seem to believe.

          • http://blogs.discovermagazine.com Cohoe Tom

            I am sorry that you can’t understand me.

            I’m done with this.

        • http://blogs.discovermagazine.com Cohoe Tom

          The rest of your post doesn’t really seem to address anything I wrote. I don’t think you understood me at all. I make no claim as to whose fault that is. I wrote below that I was leaving a lot out, so the fault could easily be mine.

          • http://neuroautomaton.com/ Zachary Stansfield

            You state that determinism is mutually exclusive with free will, which I refute. You also claim that there are alternate deterministic and potentially “free will” driven decisions, but this presumes that “randomness” equates to free will, a second point that I refute.

            I don’t address the rest of your post about quantum mechanics, because the scientific cover this argument offers is predicated upon randomness and unpredictability being equivalent to free will, a point I already refuted!

          • http://blogs.discovermagazine.com Cohoe Tom

            Neither disagreement nor contradiction constitute refutation. I guess we don’t talk the same language.

          • http://neuroautomaton.com/ Zachary Stansfield

            Tom, “refute” is synonymous with “contradiction”. Feel free to check an English dictionary. Is there some other language that you are referring to?

            You repeatedly imply that there is some sort of communication barrier between us, and yet you fail to recognize that this is because you won’t give any effort to addressing the comments I have made. If you aren’t willing to provide a good-faith effort to participate in this conversation, then why are you bothering to reply?

      • http://blogs.discovermagazine.com Albert Fonda

        Accepting Cohoe Tom’s predicate that “most of our decisions are controlled by habit or by subconscious but deterministic mechanisms,” what follows (IMO) is NOT that (as he says) “deterministic” and “free will” are mutually exclusive. Just the opposite; and they are consistent because most of our decisions (if not all) lead to plastic modification of the brain on a survival-of-the-fittest basis. We literally “change our minds” by using them — entirely deterministically, with “de facto” free will as the result. There are no two mutually exclusive or somehow compatible things; there is one thing only, namely deterministic free will. Consistent, BTW, with Libet’s reports — the “feeling” is an effect which succeeds the deterministic but teachable cause.

    • disqus_Y9qxQ3cLQI

      Determinism does not mean that randomness cannot exist. See complexity theory in mathematics.

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  • Barak Nitzan


    The number I’ve always heard talked about was 0.5 a second (500 ms):
    ” In series with type II RPs, onset of the main negative shift in each RP preceded the corresponding mean W value by an average of about 350 ms, and by a minimum of about 150 ms. In series with type I RPs, in which an experience of preplanning occurred in some of the 40 self-initiated acts, onset of RP preceded W by an average of about 800 ms (or by 500 ms, taking onset of RP at 90 per cent of its area).”

    “. It was noted that brain activity involved in the initiation of the action, primarily centered in the secondary motor cortex, occurred, on average, approximately five hundred milliseconds before the trial ended with the pushing of the button. That is to say, researchers recorded mounting brain activity related to the resultant action as many as three hundred milliseconds before subjects reported the first awareness of conscious will to act.”

    Where does the two seconds figure come from?

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      If you Google “Libet 2 seconds” there are several references to the idea of a RP appearing “up to” 2 seconds prior, but you’re quite right that the most commonly quoted time is -500 ms. Thanks for the comment.

      -500 ms is the onset of the “late” RP that this study showed exists regardless of whether you believe in the earlier potentials.

  • T Clark

    Will the results of experiments like those described here change anyone’s mind about whether or not people should be held responsible for their actions? If not, then what does “free will” mean?

    • disqus_Y9qxQ3cLQI

      Well we can reframe the question of “free will” into the question of “free won’t”. Perhaps, people can’t control the decisions that “pop up in their heads” but they can consciously choose to selectively suppress some of these decision making processes.

      • figrin1

        People can’t control their decisions but they can decide not to engage in certain decision-making processes? That sounds a little contradictory to me.

    • Archie Meijer

      If free will isn’t real then we have no free will in whether or not to hold people responsible for the debate over whether to hold people responsible for their actions degenerates into meaninglessness.

  • poppp

    What’s incredible is the way experiments like this and their interpretations can affect people’s outlook on life, especially laypeople who are less likely to be critical of the results. It wouldn’t be hard to imagine a reader who didn’t believe in free will because of Libet’s experiment, now defected after reading about Jo et al. Free will: gone one day and back again the next.

  • http://neuroautomaton.com/ Zachary Stansfield

    The readiness potential or “Bereitschaftspotential” has always provided a rather weak argument against the idea of free will. It is actually better understood in relation to the concept of consciousness, which is clearly distinct from free will.

    If a decision is made, and an electrical potential predicts that decision, then it suggests something about the underlying physiological processes that mediate the decision, not whether these processes are uncoupled from conscious control. Nonetheless, the idea that consciousness represents an “epiphenomenon”, only occurring “after the fact” and acting as a simple observer is implausible. Rather it is much more likely that the conscious experience itself is a read-out of necessary processes that are directly coupled to the events that allow decisions to occur in the first place–eliminate consciousness and these necessary processes disappear as well.

    Regardless, none of this talk of consciousness supports concepts like “free will”, which lack any instantiation in reality. Free will is supposed to provide an explanation for how decisions come about, and yet this term provides absolutely no explanatory value. We would be better suited by looking at situational and personality factors or genetic predispositions (none of which are perfect, but all of which provide at least some predictive value) than we would by simply stating that a person made a “free” decision.

    Put it this way: if I took away your “free will” would you somehow be less immune to the influences of internal biological processes, societal pressures, appetitive drives or negative emotional states? Doubtful.

    I am all for believing in a personal sense of volition (which is probably quite useful), but it’s important to not pretend that this is anything like the mind-bending nonsense that is free will.

    • Humfree1859@yahoo.com

      You have done well in attempting to describe the deterministic neurological machine that comprises the “mind”. I use the word “mind” instead of “brain” because there are a large number of other centers of cognition in the body, all of which may contribute to thought processes leading to an interface with the external world. (BTW, if there is no external world, but only an over laying “matrix” type program, our responses could be no different, could they?) In any event, free will turns out to be a fiction, an illusion that we use to disguise the maelstrom of neural activity, and mask the confusions of contrasting and merging information. Nice job.

  • jhertzli

    To make matter worse, these experiments tend to have minute samples. If every decision were marked by the same potentials and delay, we might not need large samples but in the real world we do.

  • http://petrossa.me/ petrossa

    I’s like a cult. The cult of Free Will. Else we are faced with the annoying reality that we’re just another primate. Better delude then face reality. It is what made religion great.

    • disqus_Y9qxQ3cLQI

      Illusion might be a better word than cult.

      • http://petrossa.me/ petrossa

        It has all the aspects of a cult. People worship it, vehemently deny any questioning of it, have no proof it exists, write big books about full of abstract concepts, etc. It might be an illusion, but it is a cult.But then again, which religion isn’t illusion?

  • Jeffrey Guterman PhD

    What is the debate? If there were any question about free will, then it would be unlikely that there would any civil societies. For example, the only reason I drive my car is because I am confident that other drivers have the free will to stop at red lights and thereby not hit me when I pass through green lights. So what’s all the fuss about free will?

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      Or is it the other way around? You are confident to pass a green light because you trust that the red light (and all the conditioning, incentives etc. that lie behind it) will determine the behavior of other drivers, and stop them?

      If the other drivers were truly free, might they not just as well cross a red light as stop at one? Or get out of their car and dance a jig in the middle of the road?

      • Jeffrey Guterman PhD

        Thanks for your reply. Of course. You punctuate events from a behavioral, deterministic perspective, and I don’t wish to refute your point as doing so would require collapsing the behavioral paradigm. I really think the free will and determinism debate is, like many issues, a both/and thing. May I suggest, though, that the driver stops at the red light (free willingly) because they don’t want to get hit by me as I pass through the green light.

        • http://neuroautomaton.com/ Zachary Stansfield

          On the other hand, you punctuate events from a “free will” perspective, premising our entire society upon its existence.

          The simple distinction between these perspectives is that the behavioral arguments provide explanatory value, whereas the free will argument offers nothing.

          Perhaps there are no other driver’s at the light, why does he stop? At some point we will see that most driver’s do so to follow societal obligations, which powerfully influence a person’s actions. In contrast, the person who decides to flaunt those societal obligations may run the light because of impatience or frustration, either of which may be situational characteristics or enduring features of the individual. But if these determinants are guided by brain processes and the attendant factors that have set such processes in place, then it is unnecessary and uninformative to claim that this person has “free will”.

          How would a person who lacks free will behave in this situation?

      • Nick Stuart

        Is it possible that my unconscious mind has free will? I may not be conscious of the choice I (my self) make but my unconscious mind decides which is a better action to take given the circumstances? For example.. I meet a tiger – my unconscious mind decides whether to stay still or to run. My conscious mind has not evolved to make these decisions fast enough. Is it possible that evolution has forced good decision making into an automatic response? When I played soccer for example.. it was best to let my unconscious mind make decisions.. if I was thinking too hard about what I should do.. I was too slow. I ponder too much?

    • fungus_Amongus

      I think you are totally missing the point.

      first of all, people run red lights all the time and cause serious and deadly accidents, so i’m not even sure what your trying to prove.

      the same “unconscious” mechanisms that these fMRI experiments keep telling us exist are are measurable can just as easily tell us to stop at the light as to run it, for whatever reasons (neuroscience may never be able to tell us that but it sure would be great if they could someday)

      the point of this debate isn’t so much why people do what they do, but how the brain processes that make them decide what they do work…i like the term “meta-cognition”

  • http://blogs.discovermagazine.com John Schenkel

    Free will makes evolutionary sense. The alternative to free will is an inborn algorithm that can account for the substantial range of novel circumstances inherent in the world. Not possible! Algorithm or not, we will be held responsible, if not by the courts then by Mother Nature. If there is no free will then what is the purpose of our imagination which allows us to explore possibilities prior to making a decision?

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  • Eugen Roth DC

    Does this work the same for women and for men or is there a difference between the sexes?

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  • http://blogs.discovermagazine.com John Ahlstrom

    First we need a dfn or definitions of Free Will.
    I suggest that Free Will means
    there is nothing outside of the mind of a person
    that can force a decision or action by that person;
    not a divinity or a devil,
    not fate
    not chance
    not the norns
    not anything outside the mind of the person.

    Your definition may vary. Please share it with us.

    If that is the definition of Free Will, all manner of things that were or are outside a person can influence a choice by being incorporated in the mind of the person. Someone holding a knife at my daughter’s throat and threatening to kill her will change my perception of what is going on and may change my decision of what to do. But a person holding a knife to my daughter cannot exert some force on my brain or mind that will initiate an action. And so forth.

    • fungus_Amongus

      the definition of free will is that we actually consciously decide things.

      what fMRI studies like these and many other are showing over and over is that there are detectable brain activities that occur *before your conscious mind even is engaged* (major emphasis) that for-lack-of-a-better-metaphor TRICK your “conscious” mind (the thing that we all believe is us “up-there”) into thinking IT made the decision, even though in reality it didn’t

      before just glazing over what I just said, please….stop for a few seconds and ponder what this SCIENCE is actually telling us!

  • fungus_Amongus

    no i disagree totally T Clark…no matter what the truth may be, we can never, as a functioning society, allow people to NOT be held responsible for their actions.

    Perhaps, though, if we accept the truth of the real *reproducible* science of this fascinating research, we can use this knowledge to really help people and to perhaps stop looking at people who make bad decisions as such bad people and instead people in need of radical new therapies that can be designed using applied Neuroscience.

    Remember, Einstein’s theory’s were pretty much laughed at by the general public “hahah he thinks time and space are the same thing when we all KNOW but common sense that that just isn’t possible!”

    It took over 20 years for science to prove he was right, and we are still to this day using this knowledge for the benefit of mankind.

    What I am convinced of is that we will eventually be able to use research like this to help us come up with therapies that WE CAN ACTUALLY SEE WORK changing “behind the scene” brain function instead of just “hoping” it will or being fooled by the subject who has just been conditioned to “say the right things” or whatever.

    What could be more important to work on?

  • http://blogs.discovermagazine.com Michael Boessen

    Possibly I don’t understand this topic. Let’s use the example of my video game playing kid when he is deep into the advanced levels of a game. To watch him is amazing. He is making complex decisions, making projections, computing probabilities and performing relevant, appropriate actions at a rate that appears to me on the order of 3 or 4 per second. There is no way there is a “2 second RP” before each button press or instantantaneous joystick deflection.

    • fungus_Amongus

      What your seeing almost surely is the minds ability to chain together actions made by one underlying decision thru experience and practice.

      It’s been know for a very long time that the typical reaction time to even life-threatening events is 0.6-0.8 seconds (600-800ms), so by definition it is not possible to react faster then this.

      This is why the 500ms “meta-cognition” period is so interesting to study.

  • LBRB

    There seems to be a lot of confusion about what free will and determinism even means. Here’s the best way I know how to explain it. Pick some time in the deep past, let’s say one minute after the big bang. At that moment in time, the stage was set, all the matter and all the energy were already in place. From that moment, there was no doubt, it was already determined, that the Earth would revolve around the Sun and the Rocky Mountains would poke up from it’s surface. That seems like common sense. I mean, how could they not, for they did. And they did so because the preconditions of the matter and energy that came before. From that moment, 15 billion years ago or so, the Rockies were inevitable.

    Now, some say that, likewise, there also was no doubt that I would be writing this right now, and that it is already determined who my granddaughter will someday marry. Everything is inevitable, for whatever happens is the only thing that could happen given the exact status of matter and energy that came before.

    Others say “Free Will” can trump that. That the human mind is so ethereal and mysterious, like a beautiful vapor, that mere matter and energy are not enough to contain it’s decisions.

    What do you say?

  • LBRB

    There seems to be a lot of confusion about what free will and
    determinism even means. Here’s the best way I know how to explain it. Pick some time in the deep past, let’s say one minute after the big bang. At that moment in time, the stage was set, all the matter and all the energy were already in place. From that moment, there was no doubt, it was already determined, that the Earth would revolve around the Sun and the Rocky Mountains would poke up from it’s surface. That seems like common sense. I mean, how could they not, for they did. And they did so because the preconditions of the matter and energy that came before. From that moment, 15 billion years ago or so, the Rockies were inevitable.

    Now, some say that, likewise, there also was no doubt that I would be writing this right now, and that it is already determined who my granddaughter will someday marry. Everything is inevitable, for whatever happens is the only thing that could happen given the exact status of matter and energy that came before.

    Others say “Free Will” can trump that. That the human mind is so ethereal and mysterious, like a beautiful vapor, that mere matter and energy are not enough to contain it’s decisions.

    What do you say?

    • rsanchez1

      I say that if physics could solve the human mind it would have done so already.


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About Neuroskeptic

Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.


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