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Quando Libet

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.

Posted in Conscious Entities.