Libet Unreadied

Benjamin Libet’s famous experiments have been among the most-discussed topics of neuroscience for many years. Libet’s experiments asked a subject to move their hand at a random moment of their choosing; he showed that the decision to move could be predicted on the basis of a ‘readiness potential’ detectable half a second before the subject reported having made the decision. The result has been confirmed many times since, and even longer gaps between prediction and reported decision have been claimed. The results are controversial because they seem to be strong scientific evidence against free will. If the decision had been made before the decider knew it, how could their conscious thought have been effective? My original account (14 years ago, good grief) is here.

Libet’s findings and their significance have been much disputed philosophically, but a new study reported here credibly suggests that the readiness potential (RP) or Bereitschaftspotential has been misunderstood all along.

In essence the RP is a peak of neural activity, which seemed to the original researchers to represent a sort of gathering of neural resources as the precursor of an action. But the new study suggests that this appearance is largely an artefact of the methods used to analyse the data, and that the RP really represents nothing more than the kind of regular peak which occurs naturally in any system with a lot of background noise. Neural activity just does ebb and flow like that for no particular reason.

That is not to say that the RP was completely irrelevant to the behaviour of Libet’s subjects. In the rather peculiar circumstances of the original experiment, where subjects are asked to pick a time at random, it is likely that a chance peak of activity would tip the balance for the unmotivated decision. But that doesn’t make it either the decision itself or the required cause of a decision. Outside the rather strange conditions of the experiment, it has no particular role. Perhaps most tellingly, when the original experiments were repeated with a second group of subjects who were asked not to move at all, it was impossible to tell the difference between the patterns of neural activity recorded; a real difference appeared only at the time the subjects in the first group reported having made a decision.

This certainly seems to change things, though it should be noted that Libet himself was aware that the RP could be consciously ‘over-ruled’, a phenomenon he called ‘Free Won’t’. It can, indeed, be argued that the significance of the results was always slightly overstated. We always knew that there must be neural precursors of any given decision, if not so neatly identifiable as the RP. So long as we believe the world is governed by determined physical laws (something I think it’s metaphysically difficult to deny) the problem of Free Will still arises; indeed, essentially the same problem was kicked around for centuries in forms that relied on divine predestination or simple logical fatalism rather than science.

Nevertheless, it looks as though our minds work the way they seem to do rather more than we’ve recently believed. I’m not quite sure whether that’s disappointing or comforting.

21 thoughts on “Libet Unreadied

  1. Notwithstanding this latest news, the Libet results have little real significance in my opinion. Even if Libet’s signal detection was bogus, a detectable signal likely exists that indicates a decision and its direction. It also seems likely that this signal occurs before we register the decision in our consciousness. The mind consists of many processes and processes take time. To believe that the decision is made when we think it gets made is to believe either (a) everything happens at the same time or (b) consciousness has access to all decision-making activity during the entire process. I suppose some think that our consciousness initiates every decision of this kind but that seems unlikely as well. How could a decision to move a finger arise from nothing? Introspection tells us that a lot of influences get integrated before a decision is reached. Although the task of moving a finger at a random interval might have fewer such influences, I see no reason to think they don’t exist at all. If there are influences, they take time to process and aren’t all conscious.

  2. New site design. Nice!

    Personally, I’ve always thought the Libet results were much ado about nothing. It seemed like it required a particularly arbitrary interpretation of the data, making it vulnerable to simply being reinterpreted. The results only seemed surprising from a dualist standpoint.

    I say this as someone who doesn’t think we have contra-causal free will (although I do think social responsibility remains a coherent and useful concept).

  3. ‘New site design’

    Sort of involuntary. WordPress required me to update the version of php I was using, and my existing theme was not compatible – it was very old and had been hacked by me in various inexpert ways I no longer remember. So a new one was indicated!

    I may do some further customisation if I can summon the energy (I haven’t been in great health recently, hence the less frequent posts)

  4. I always thought the RP indicated motor planning activity – something like “this is what it would require to move this hand.” Is that interpretation shot down by the new results?

    Since Libet’s subjects were told to move on arbitrary impulse – they aren’t allowed to plan moves in advance – they first have to *feel* an impulse. It’s extremely plausible that motor planning regions would go through some preparations whenever you feel an impulse to move. In that case, Libet’s findings are an artifact of his experimental design.

  5. It’s okay to say fields, but lets say fields philosophically…
    …We have different kinds of fields to support our experience towards free will. These fields provide many different means to meanings for our minds.

    …fields of sensation, of emotion, of mentation and instinct are in play, as who we are, every second of our lives…These fields seem independent of each other.

    Apparently there is consciousness or awareness that sees this independence.
    …as oneself…The will to be free …thanks

  6. It’s been interesting watching some of the reactions to free will-related cognitive research during the past 5-6 years. This isn’t the first hit that Libet’s results have taken. And it’s not a happy time for some people. That’s because for decades, the Libet experiment served as the foundation upon which all free will denial was built. And what was really weird was this: you had this hard-core group of people—-philosophers, hard determinists, neuroscientists, and atheists—-who seemed genuinely gleeful and ecstatic of the prospect that neuroscientists had somehow found a way to deny free will, even their own. Ignored was the fact that LIbet experiment was always on relatively shaky ground to begin with. But that didn’t stop Willusionists and Neuromaniacs from being all too happy to support the Libet Paradigm and even over-extrapolate its results to all parts of mental life.

  7. Peter, did you see the new Free Will project that Uri Maoz is leading? It’s funded by quite a lot of grant money. It’s a sensible next step to the “Big Questions in Free Will Project” that Alfred Mele led. Take a look at this link. Quite a few leading thinkers in the field are being assembled for this project. .https://www.sciencemag.org/news/2019/03/philosophers-and-neuroscientists-join-forces-see-whether-science-can-solve-mystery-free

  8. Why does philosophy seem to favor existence over experience…

    Is it that existence some how defines experience…
    …what existence…

    I think it better defined as, existence is my experience…

    Where’s Peter

  9. ||”So long as we believe the world is governed by determined physical laws (something I think it’s metaphysically difficult to deny) the problem of Free Will still arises”||

    I have no idea why people always say this. If the world is governed by physical laws then objects fall down due to the law of gravitation rather than gravitation itself.

    Physical laws are surely best thought of as mere *descriptions* of what happens.

    OK, you can hold the position that the world is governed by the 4 forces in nature. Two problems.

    a) How do you know there are any forces. Perhaps objects fall because that’s just the way reality is. Or maybe we live in a simulation. Lots of explanations.

    b) How do we know that the 4 forces are responsible for all change in the world? Why can’t consciousness affect the world? We haven’t detected it? How hard has it been looked for?

    In short, I have no idea why it is maintained that it is difficult to deny that the world is governed by determined physical laws or governed by forces. I deny it. It is how I am able to type this message.

  10. ”So long as we believe the world is governed by determined physical laws (something I think it’s metaphysically difficult to deny) the problem of Free Will still arises”

    This would be a bit more convincing if those same physical laws predicted the existence of mental phenomena, which they don’t. They are ontologically exclusive. It’s a bit like expecting an apple to give rise to orange seeds. It’s no surprise whatsoever that physical and mental realities collide if you make the stock issue western assumption that the physical is “more real” than the mental.

    We seem to turn a blind eye to the main hypocritical feature of some aspects of pseudo-scientific mental-denying thinking – that is, that all theories of the physical are derived from mental experiences as well as cognition. No human mind, no physics.

  11. Why do physical laws have to predict anything? The discovery of the laws of physics didn’t predict many technological inventions – that doesn’t mean those technologies are somehow not of this world.

  12. I think John Davey’s argument is that the mental is of this world, just that this world is not just what can be described by physics alone.

    For example, he’s not proposing the kind of magical Platonism the Computationalist needs to get us to believe we can upload our minds onto a Turing Machine.

  13. Not of these physics/not of this world, they are the same thing.

    On the matter that physics should somehow predict mentality when it hasn’t predicted a bunch of technologies, that dismissal is either shot down or it’s a matter of sometimes people just wont acknowledge any point (just a one way street in terms of communication)

  14. I think you’re just begging the question, or at the least merely repeating yourself, unless you have an explanation for why you think physics determines what is “of this world” rather than being a particular description of it.

    This argument based on predicting technologies doesn’t seem very convincing – the technologies can be described by the so called “laws” and were built upon them. That they weren’t explicitly predicted doesn’t strike me as comparable to laws not having any reference to mentality – which would include the lived experiential time Smolin mentions as missing from physics in Time Reborn. (I suppose, however, one could note the Consciousness Causes Collapse folks as a case where one could say mentality and physics intersect.)

    That said “predict” may be the wrong word to describe the argued-for gap between “laws” of physics and mental phenomenon.

  15. Daily Nous reports: “The Journal of the History of Philosophy has announced the winner of it 2019 book prize, which is awarded for the best book written in history of philosophy in 2018.The winner is Richard Arthur (Professor Emeritus, McMaster University), for his book, Monads, Composition, and Force: Ariadnean Threads Through Leibniz’s Labyrinth.”…

    Democritean phenomena: as means for meaning’s…as life for living…time for timing…
    …Phenomenal complexity comes from including oneself as phenomenon for phenomena…

  16. Here’s a poem: “Sent as a present from Amman. A red cockatoo. Colored like the peach tree blossom, and speaking with the speech of men. And they did to it, what is always done, to the learned and eloquent. They took a cage with stout bars and shut it up inside.” Guess which famous philosopher, while in prison, received this translation of a Chinese poem.

  17. callan

    Now you’ve got me confused. What technologies specifically that you can think of aren’t compatible with physics and wasn’t enabled by it ?

    A quick list of physics based technology :-
    i) all mechanical, electrical and chemical engineering disciplines in the post-roman era
    ii) semiconductors
    iii) aerospace (incl GPS)
    iv) networking and telecoms
    v)automotive

    … etc (excluding biotech, as physics doesn’t understand life)


    “On the matter that physics should somehow predict mentality when it hasn’t predicted a bunch of technologies, that dismissal is either shot down or it’s a matter of sometimes people just wont acknowledge any point (just a one way street in terms of communication)”

    The only value – the ONLY value – that physics has is in terms of what it can predict. Can you please tell me what it’s other assets are ? It’s a mathematical discipline with an ontological mapping to certain highly limited, well-defined concepts : space, time, mass (and arguably I suppose the semantically distinct thermodynamic notions – temperature, energy, entropy, pressure etc) . The important thing is it makes no attempt to explain any of it, so explanation is certainly something that physics does not do nor ever attempts to do (as distinct from ‘physicists’, the professional practitioners, who may well do so but which in no way affects the viability of a physics theory) .

    And although physics could provide a mathematical reason for a prior set of know facts, it’s only worth comes (the ‘proof’) when it predicts unknown facts. Everybody ridiculed newton’s gravitation until it was applied with such frequency to such a wide range of situations with such accuracy that such ridicule itself is now the subject of ridicule. Einstein’s General Rel was only taken seriously once his prediction about the perihelion of mercury came true. Until then it was just scratches on bits of paper.

    In other words, the only value of physics (although not necessary other sciences) is in its predictive capabilities. It serves no other purpose. From the particular, set up the general mathematical framework and predict a wider framework of facts.

    In the case of mental phenomena though, the problem with physics is far deeper. It simply doesn’t possess the conceptual and semantic width to predict consciousness (any more than it can predict other biological notions such as sex, trait etc). It’s doomed to failure as a total framework for reality, but our enlightenment culture hasn’t grown out of it’s naivete in this regard – mainly because our culture is still determined by arts and philosophy graduates who never understood science (and particularly physics) in the first place.

    J

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