New light on Libet’s challenge to free will; this interesting BQO piece by Ari N Schulman focuses on a talk by Patrick Haggard.

Libet’s research has been much discussed, here as well as elsewhere. He asked subjects to move their hand at a time of their choosing, while measuring neural activity in their brain. He found that the occurrence of a ‘Readiness Potential’ or RP (something identified by earlier researchers) always preceded the hand movement. But it also preceded the time of the decision, as reported by subjects. So it seemed the decision was made and clearly registered in brain activity as an RP before the subjects’ conscious thought processes had anything to do with it. The research, often reproduced and confirmed, seemed to provide a solid scientific demonstration that our feeling of having free conscious control over our own behaviour is a delusion.

However, recent research by Aaron Schurger shows that we need to re-evaluate the RP. In the past it has been seen as the particular precursor of intentional action; in fact it seems to be simply a peak in the continuing ebb and flow of neural activity. Peaks like this occur all the time, and may well be the precursors of various neural events, not just deliberate action. It’s true that action requires a peak of activity like this, but it’s far from true that all such peaks lead to action, or that the decision to act occurred when the peak emerged. If we begin with an action and look back, we’ll always find an RP, but not all RPs are connected with actions. It seems to me a bit like a surfer, who has to wait for a wave before leaping on the board; but let’s suppose there are plenty of good waves and the surfer is certainly not deprived of his ability to decide when to go.

This account dispels the impression that there is a fatal difficulty here for free will (of course there are plenty of other arguments on that topic); I think it also sits rather nicely with Libet’s own finding that we have ‘free won’t’ – ie that even after an RP has been detected, subjects can still veto the action.

Haggard, who has done extensive work in this area, accepts that RPs need another look; but he contends that we can find more reliable precursors of action. His own research analysed neural activity and found significantly lowered variability before actions, rather as though the disorganised neural activity of the brain pulled together just before an action was initiated.

Haggard’s experiments were designed to address another common criticism of Libet’s experiments, namely the artificiality of the decision involved. Being told to make your hand for no reason at a moment of your choosing is very unlike most of the decisions we make. In particular, it seems random, whereas it is argued that proper free will takes account of the pros and cons. Haggard asked subjects to perform a series of simple button-pushing tasks; the next task might follow quickly, or after a delay which could be several minutes long. Subjects could skip to the next task if they found the wait tedious, but that would reduce the cash rewards they got for performing the tasks. This weighing of boredom against profit is much more like a real decision.

Haggard persuasively claims that the essence of Libet’s results is upheld and refreshed by his results, so in principle we are back where we started. Does this mean there’s no free will? Schulman thinks not, because on certain reasonable and well-established conceptions of free will it can ‘work in concert with decisional impulses’, and need not be threatened by Haggard’s success in measuring those impulses.

For myself, I stick with a point mentioned by Schurger; making a decision and becoming aware of the decision are two distinct events, and it is not really surprising or threatening that the awareness comes a short time after the actual decision. It’s safe to predict that we haven’t heard the last of the topic, however.


  1. 1. Paul Torek says:

    Your(/Schurger’s) point is right, but unnecessary in this context. Haggard doesn’t claim that the reduced-brain-noise phenomenon during decision times is an unconscious process. In fact he suggests the opposite, that this is a measure of conscious activity. Haggard is not making the same claims as Libet.

    Haggard trips himself up verbally, because he’s an incompatibilist (and, I suspect, not even aware that there’s an issue there). Thus he puts quote marks around “voluntary” even though it’s crystal clear he’s finding distinctive neural features of voluntary action. Sigh. What can you do? The intuitive understanding of causality is vastly different from the modern scientific understanding, but most scientists aren’t aware of these developments, so incompatibilism seems intuitive (is that a single, or double entendre?) to them.

  2. 2. Peter Martin says:

    Taking an engineer’s approach to implementation of a decision to act, of course there is ordered neural activity in the run up to the point of the decision, that’s how the selection between alternatives is done. I have free will, but in the sense that it is my neural wetware that determines the outcome, in a way that reflects my experience that has been embodied in how my neurons are connected up. Anyone that thinks this undermines free will is forcing themselves to underpin free will with magic fairy dust or something else outside the physical realm….good luck with that!

  3. 3. John Davey says:

    Big problem with libet will always be it’s tendency to assume the brain is simply audited by watching electrons in motion. That seems to me most likely to be hugely simplistic. More importantly the evidence in favour of the ‘blip is something’ model can be taken with a pinch of salt, so vast is the ignorance.

    Still, experiments like these are a start. But having the temerity to say such speculative science can ‘sweep away’ free will- or confirm it – is the impatience of an era’s hubris in action.
    It’s ridiculous.

    It’s natural that your science is limited to the state of art technology that you can use. But you still have the discretion – in fact, the obligation – to assume that this is a limitation. This basic fact doesn’t seem to bother some people- after all , what about brains can’t be analyzed by our current tools, lies the unjustified addumption ? The answer is we don’t know, but the very fact there is such a struggle to come to even basic conclusions might suggest there is a need for a lot more scientific and technological breakthroughs before we can even start to make progress.

    In the meantime a bit more patience is in order.


  4. 4. Lloyd says:

    I’m with Peter Martin. Do some people think that “free will” would be distinct from neural activity? Something that occurs first, and then the neurons get the message and jump into action??? It’s all mechanistic and determined by history. Call that “free” if you like.

  5. 5. Tom Clark says:

    Peter says:

    “Does this mean there’s no free will? Schulman thinks not, because on certain reasonable and well-established conceptions of free will it can ‘work in concert with decisional impulses’, and need not be threatened by Haggard’s success in measuring those impulses.”

    Note how the free will issue has this semantic, definitional component. Compatibilists say free will simply involves acting voluntarily on our own recognizance, while incompatibilists say free will requires not only voluntary action, but that we somehow initiate behavior de novo, such that what we do isn’t completely traceable to the past.

    Who’s right here? Well, both conceptions of free will exist out there in the culture, and it’s pretty clear we often act voluntarily but aren’t de novo generators of behavior. So we do have (compatibilist) free will and don’t have (incompatibilist) free will. Disputes about definitions aside, what’s important is getting clear about the behavior control capacities of human agents, and whether or not we can reasonably suppose we could have done otherwise in actual situations, as libertarians about free will are wont to claim.

  6. 6. What If Consciousness Is Not What Drives The Human Mind? – The Conversation | We Seek the Truth! says:

    […] mind through readiness potential and it’s a bone of contention for Peter Hankins in Quando Libet. Injecting a little Conscious Humour into the matter, Peter Rogerson’s thoroughly enjoyed […]

  7. 7. John Davey says:


    Compatibilists say free will simply involves acting voluntarily on our own recognizance

    I actually think the matter of the ‘free will’ debate isn’t that complicated. ‘Free will’ is poorly defined, probably stemming naturally from it’s old roots, before the acceptance of the existence of the unconscious. The Libet experiment leads to lot of triumphalism from the AI crowd because it seems to contradict a certain conscious-led conception of free will (that’s if you can believe it, which has now been thrown into doubt). However, if you believe (as I do) that most human actions arise from unconscious activity – we just ‘do it’ – the Libet experiment (even if true) hasn’t any bearing.

    I think the only real contemporary debate can be this : is the development of the universe predetermined or isn’t it ? Or rather – even if it isn’t predetermined exactly (as quantum mechanics would suggest) does the physical state of the universe at time T, S(T), determine it’s subsequent state at a later time S(T+?) ? And is the universe state at the time S(T+?) solely linked to the state S(T) through the application of forces and natural phenomena represented by mathematical laws ? If so of course, the consequences are dramatic.

    I’ve always thought compatibilism a lot of junk dreamt up by liberals who don’t like the amoral consequences of their beliefs, and their employment of the woolly term ‘free will’ as a way of sidestepping that angst. But they can’t.

    If the universe is predetermined then mental activity becomes just nonsense. Advocacy is pointless, arguing for a more liberal legal system (as the alleged determinist Sam Harris does) utterly nonsensical – Fred was always going to murder Jim – Steve was always going to sexually abuse his children, and Sam Harris’ favourite torture techniques for islamists would have no effect. In fact, determinists, Islamists (as well as most calvinist protestants) have a lot in common – a total belief in the impossibility of humans to change events.

    I actually don’t believe a lot of liberals really believe that, they just want a conception of morality that doesn’t involve religion. But switching to a god of physics does lead, I’m afraid to a world in which children have to die, murderers had no alternative and the victims of the Las Vegas shooting simply had been waiting to die like that since birth. End of story. It really is as simple as that.

    And it may well be true. But the unfortunate fact is that we’ll never know. We can’t eradicate the idea of the the capacity of conscious agents to initiate actions. It’s a cognitive limitation. We can’t alter physical models to do anything other than follow mathematical rules ( i hate the term laws, it’s nonsense). Two solid and very useful cognitive precepts and not an ounce of capacity to allow us to conclude that one is true and the other isn’t. Belief in predeterminism doesn’t stop being a belief by marshalling mathematical evidence : in the end all scientific knowledge is belief, albeit guided by evidence. But nothing is ever conclusive.

    So the free will debate is no such thing- it’s a consequence of being biological agents with cognitive scope and limits, and as such constrained by our biological inheritance.


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