Friday, 27 May 2011

Debunking people's belief in free will takes the intention out of their movements

Undermining a person's belief in free will alters the way their brain prepares for a voluntary movement. Davide Rigoni and his colleagues, who made the finding, aren't sure what the precise mechanism for this effect is, but they speculated that bursting the free will bubble somehow causes people to put less intentional effort into their movements.

Rigoni's team tested thirty participants on a version of Benjamin Libet's classic task from the 1980s. This requires that participants watch a dot proceed round a clock face, that they make a voluntary finger movement at a time of their choosing (the current study had participants press a button), and then make a mental note of the position of the clock at the time they made their decision to move. Libet's controversial discovery, replicated here, was that the brain begins preparing for the finger movement several hundred milliseconds prior to the conscious decision to move, as revealed by electrical activity recorded via electrodes on the scalp. The finding implies that free will is illusory.

For Rigoni's task, an additional detail was that half the participants read a passage debunking our sense of free will (see comments for the text) before they completed the Libet task. The other half acted as controls and read a passage about consciousness that didn't mention free will.

The new finding was that the earliest phase of preparatory brain activity known as "the readiness potential" differed between the two groups. This early component (around 1300 to 400 ms prior to the voluntary movement) was weaker in the brains of the participants who'd had their belief in free will diminished. Moreover, a questionnaire administered afterwards showed that this effect on brain activity was greater among the participants who reported having less belief in free will. In contrast, later phases of the brain's preparatory brain activity were not correlated with belief in free will.

What do we know about the early phase of preparatory brain activity that was affected? Quoting Lang (2003), Rigoni and his colleagues said that this early phase is associated specifically with movements that are executed with the "introspective feelings of the willful realisation of the intention to move at a particular time." In English, this means the early phase of preparatory brain activity is associated with just the kind of movement under study - a deliberate movement initiated at a consciously chosen time. The implication is that undermining someone's sense of free will leads them to invest less intention into an intentional movement. Exactly how one does that, and what it means, remains unclear. Rigoni's team conceded in their conclusion: "How disbelief in free will affects intentional effort is an open question."

They added: "In sum, our results indicate that beliefs about free will can change brain processes related to a very basic motor level, and this suggests that abstract belief systems might have a much more fundamental effect than most people would expect."

The study builds on past research showing how undermining people's belief in free will affects their social behaviour, for example encouraging them to cheat.

ResearchBlogging.orgRigoni, D., Kuhn, S., Sartori, G., and Brass, M. (2011). Inducing Disbelief in Free Will Alters Brain Correlates of Preconscious Motor Preparation: The Brain Minds Whether We Believe in Free Will or Not. Psychological Science, 22 (5), 613-618 DOI: 10.1177/0956797611405680

Previous Digest reports featuring Libet's classic task: Libet Redux: Free will takes another hammering and Exposing some holes in Libet's classic free will study.

This post was written by Christian Jarrett for the BPS Research Digest.


Christian Jarrett said...

Below I've pasted the debunking free will passage that half the participants read. It's taken from Dr Francis Crick's The Astonishing Hypothesis and participants were also given a short bio about Crick (co-discoverer of molecular structure of DNA). Control participants read another passage from the same book, but their passage didn't mention free will.

“You,” your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules. Who you are is nothing but a pack of neurons. Most religions hold that some kind of spirit exists that persists after one’s bodily death and, to some degree, embodies the essence of that human being. Religions may not have all the same beliefs, but they do have a broad agreement that people have souls.
Yet the common belief of today has a totally different view. It is inclined to believe that the idea of a soul, distinct from the body and not subject to our known scientific laws, is a myth. It is quite understandable how this myth arose without today’s scientific knowledge of nature of matter and radiation, and of biological evolution. Such myths, of having a soul, seem only too plausible. For example, four thousand years ago almost everyone believed the earth was flat. Only with modern science has it occurred to us that in fact the earth is round.
From modern science we now know that all living things, from bacteria to ourselves, are closely related at the biochemical level. We now know that many species of plants and animals have evolved over time. We can watch the basic processes of evolution happening today, both in the field and in our test tubes and therefore, there is no need for the religious concept of a soul to explain the behavior of humans and other animals. In addition to scientists, many educated people also share the belief that the soul is a metaphor and that there is no personal life either before conception or after death.
Most people take free will for granted, since they feel that usually they are free to act as they please. Three assumptions can be made about free will. The first assumption is that part of one’s brain is concerned with making plans for future actions, without necessarily carrying them out. The second assumption is that one is not conscious of the “computations” done by this part of the brain but only of the “decisions” it makes – that is, its plans, depending of course on its current inputs from other parts of the brain. The third assumption is that the decision to act on one’s plan or another is also subject to the same limitations in that one has immediate recall of what is decided, but not of the computations that went into the decision. So, although we appear to have free will, in fact, our choices have already been predetermined for us and we cannot change that. The actual cause of the decision may be clear cut or it may be determined by chaos, that is, a very small perturbation may make a big difference to the
end result. This would give the appearance of the Will being “free” since it would make the outcome essentially unpredictable. Of course, conscious activities may also influence the decision mechanism. One’s self can attempt to explain why it made a certain choice. Sometimes we may reach the correct conclusion. At other times, we will either not know or, more likely, will confabulate, because there is no conscious knowledge of the ‘reason’ for the choice. This implies that there must be a mechanism for confabulation, meaning that given a certain amount of evidence, which may or may not be misleading, part of the brain will jump to the simplest conclusion.

Nora Miller said...

I'm curious about the conclusion that "The finding implies that free will is illusory" and about Francis Crick's statement that "our choices have already been predetermined for us." By whom? These comments seems almost ludicrously dualistic to me. It almost sounds as if someone else occupies my brain, making decisions and merely informing me, the bus driver, of where we are now headed.

But isn't the whole brain "me"? Just because it takes a while for my decisions to percolate up to the verbalizing, conscious part, does not imply that "I" didn't make the decision! When I ride a bike, is the feat of balance "already pre-performed" for me? No, I accomplish balance by developing brain connections that take care of that work while I daydream about other stuff. In the same way, I freely make my decisions by passing information to those non-verbalizing parts, where it is mulled and massaged until "I" make a decision, at which point the news is passed on to the part of me that says things, like "I want chocolate ice cream, thanks."

If we look at the study without the preconception that "free will" implies "conscious decision", we might instead draw the conclusion that "we use a lot more of our brains when we make decisions than traditional notions of free will used to assume"!

Rich said...

I don’t think that Dr. Crick intended that predetermination was established by an entity, or even a dualist mentality. Instead, I think he meant that our life experiences predetermine the choices made by our brains; and while the choices themselves are often derived from many unconscious sources, they consciously appear to be a matter of our own free will. For comparison, consider that computers can’t generate random numbers. They can be programmed (the subconscious) to generate number using an algorithm that is so complex that we can’t possibly predict the next number. So when a computer generates a random number, it appears to us (the conscious) to be random, when in fact, it is part of a predetermined series.

I wonder that Dr. Crick would have equated the concepts of instinct and free will. If we actually do make some choices that can be said to be instinctual or preprogrammed, and not a matter of our life experience, then what happens in the brain when the instinctual information is contrary to the life experience information? Is this conflict resolved by free will?

Stephan Schleim said...

The study is based on a nice idea, but what does it show about the will and freedom? Interestingly, if people's belief about their mental capacities is causally effective (i.e. by influencing the amount of intention before a movement), then this study even confirms one of our central intuitions about the functioning of our mind, namely that our beliefs cause (or at least causally influence) our behavior.

Before people make these far-reaching claims about complex notions ("The finding implies that free will is illusory" is a non sequitur), they should at least read a bit about the wider discussion of a complicated topic.

Why Libet's experiments do not tell us much about free will has been discussed quite extensively already (and has already been stated quite clearly by Libet himself in the 1980s). Who still thinks that they refute free will, should at least take into consideration that the readiness potential can be measured regardless of whether people make the movement or not (for a recent replication, see Trevena & Miller [2010], Brain preparation before a voluntary action: Evidence against unconscious movement initiation. Conscious & Cognition 19: 447-456). It is thus not the cause of the behavior. Dozens of further counter arguments can be provided upon request.

Christian Jarrett said...

Stephan and others. The Libet finding is generally taken by many as implying that our sense of free will is illusory. If all our movements are initiated by non-conscious, involuntary brain activity that precedes the willful decision to move, then the will appears to be an epiphenomenon. That's not to say there aren't all sorts of potential problems with the Libet study and many ways to interpret it. Such a discussion was beyond the scope of this blog post. However, I did provide a link at the bottom of this post to an earlier Digest entry that took a critical look at the Libet methodology. For the space available I really wanted to focus on the new finding about belief in free will affecting preparatory brain activity, rather than digressing into a debate about whether there is such a thing as free will.

Stephan Schleim said...

Thanks, Christian, for the link to the previous discussion. I regret that it focuses on the methodology merely and not on the concept of free decisions. E.g. if you look at the instructions (also of the Soon et al. fMRI replication, Supp. Mat.), then you see pretty obviously that the subjects where not asked to make a decision, but to become aware of an urge to press a button, quite spontaneously and mimicking the behavior of a random number generator. Indeed, the conductors made sure that their behavior resembled that of a random number generator (Supp. Mat.).

"The Libet finding is generally taken by many as implying that our sense of free will is illusory."

According to my experience, they are not that many; and those few who remain usually have to admit pretty soon that Libet et al. does not tell much about free decisions.

"If all our movements are initiated by non-conscious, involuntary brain activity that precedes the willful decision to move…"

But that is not what the Libet experiment has shown.

Besides, what do you think what the contrary result, i.e. conscious and voluntary brain activity would have looked like?

But regarding the previous study: Reading the passage from Crick's book (which is, for the most part, about whether there is a soul) made subjects, on average, feel 11% less free as assessed with the "FreeWill and Determinism" scale, but only on the personal subscale. But why should they only consider themselves to be less free, but not other people, after reading the excerpt (p. 615)? Crick's statement is quite general and about all human beings.

We could go on with questions like these for hours; my point is just that this research is based on a far-fetched misunderstanding about freedom.

LuchinG said...

So that´s why I suck at soccer...

Anonymous said...

"Will" is a mental process directed by your brain. Hence, "Free Will" can only exist if you had freely created your own brain. Absurd. The more interesting and practical question (hinted at by this article) is how the Conscious influences the Unconscious, i.e. how conscious thought can change the direction of our lives.

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