Warning: this post may change your brain.
Well, all of my posts change your brain, because everything changes your brain. But this one might make a rather bigger impact than usual.
According to a new paper in Psychological Science, reading a short article which argues that free will is an illusion causes measurable changes in brain function: Inducing Disbelief in Free Will Alters Brain Correlates of Preconscious Motor Preparation.
The authors took 30 people and randomly assigned them to read one of two passages from this book. One of the quotes was a fairly forceful attack on the concept of free will, saying that all of our actions are determined by our genes and environment. The other, placebo extract, was the same length and talked about conciousness but made no reference to free will.
After that, all the volunteers were given EEG while performing the Libet Task. This was invented by the neuroscientist Benjamin Libet, and it's famous as evidence against free will. Basically, the task just involves pushing a button, and you can make an entirely free choice as to when to push it. You then report, with the help of a clock, the moment at which you decided to push it.
What Libet found, using EEG recording, was that there's an electrical change in the brain, a negative voltage called the readiness potential, which starts about 2 seconds before you move. However, most people report "deciding" to move just 200 milliseconds before the actual button click - long after "their brain decided to move", in terms of the readiness potential. Maybe.
Anyway, in the current study they found that reading about determinism reduced the size of the readiness potential, although it still happened:
So ironically, reading an argument against free will reduces the size of a phenomenon which is itself used as an argument against free will... it's enough to make your head spin. The authors say that this fits with earlier work showing that "The early RP...is restricted to movements that are executed with the 'introspective feelings of the willful realization of the intention to move at a particular time'."
This is interesting, but there's a few caveats. The result was nicely significant with a p value of 0.011, but we're not shown the data from individual participants, only the group averages so the effect might be driven by one or two outliers with huge or absent readiness potentials.
Also, it's possible that the effect wasn't about belief in free will as such, but just some kind of distraction. Maybe being confronted with the idea that free will is an illusion just shook the participants up and got them thinking hard, distracting them from the task. To their credit the authors did try to control for this by also measuring EEG responses to simple visual stimuli, finding no effect, but ideally I'd want to see a control consisting of a very controversial, non-free-will article.
In case you were wondering, here's the start of the readiness-potential-reducing passage:
“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...It goes on, but I'll stop there... for the sake of your brain.
Rigoni D, Kühn S, Sartori G, & 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 : a journal of the American Psychological Society / APS, 22 (5), 613-8 PMID: 21515737