This is part two of a four-part blog series on the science of free will.
In the previous entry in this series, I described a classic free will experiment performed by Benjamin Libet in the 1980s. Brain scanning technology has come a long way since then. Can modern scanning shed more light on free will?
In 2007, the neuroscientist John Dylan Haynes of the Bernstein Center for Computational Neuroscience in Berlin, Germany, ran a new experiment. In each trial a subject was given a window of time to make a decision and act on it. The decision was to either press a button in the left hand or a button in the right hand. At the same time, the subject was watching a screen which flashed a series of letters in rapid succession. Subjects were asked to note which letter was being displayed on the screen at the moment that they made the decision to press one button or another.
While Libet used EEG technology, Haynes used more advanced fMRI. Both technologies record brain function in action, but an fMRI reading provides more spatial resolution--it more precisely identifies the specific parts of the brain as they activate. Haynes claimed that, by analyzing the the fMRI data from one specific part of the brain, frontopolar cortex, he could predict which button the subject would choose--left or right--with 60% accuracy seven whole seconds before the participant was consciously aware of his or her decision.
Few scientists are convinced that this is the death knell for free will, though. Marcel Brass, of the University of Ghent, Belgium, points out that the 60% figure is not that much better than chance, but adds, "It shows our decisions are influenced by stuff that happens in our brain before we decide. But it is not showing our decisions are completely pre-determined." Jeff Miller, of the University of Otago in New Zealand, agrees: "Finding that brain activity predicts a decision does not undermine free will." He explained the brain activity used to make the prediction could just be a leaning towards one choice or another, and that the final decision could still have been made consciously.
Haynes himself accepts this possibility. "Maybe this early signal isn't a full decision, it's just like a nudge that you get, it's just biasing you one way, but its not really finally making up your mind." So what is "making up your mind?"
Not free will, says Haynes. "Decisions are caused by unconscious brain processes, then consciousness kicks in later." In Haynes' view, our conscious decisions are predetermined by brain activity even if we cannot yet completely decode that activity. "It is subjective experience that you think that you have free will. It's something that is implausible, its incompatible with the scientific deterministic universe anyway."
So why weren't Haynes' predictions perfect? Haynes lays the blame on technology. FMRI probes regions of the brain but cannot access the activity of single neurons. The next step, Haynes anticipates, may be the experiments currently going on that do monitor single neurons.
At this point, you might wonder whether John Dylan Haynes went into this research with an anti-free will agenda in mind. He would tell you that the answer is no: "People talk to me about determinism and free will a lot, but I actually thought the experiment was about conscious and unconscious processing." And why does he focus on this area? Simply, "I am interested in interesting questions."
To Mark Hallett, chief neurologist at the Human Motor Control Section of the National Institute of Neurological Disorders and Stroke at the National Institutes for Health, the question is of more than philosophical interest. He believes that it could help patients who suffer from a relatively common condition called a psychogenic movement disorder. "The movements look like they are voluntary, but the patients say they are involuntary. It's hard to understand that unless we can understand where the notion of the voluntariness comes from," says Hallett. From studying these patients and performing his own experiments, which explore the human perception of volition, he has concluded, "Free will is not a driving force for movement."
Today we are learning more about how the brain prepares our body to perform actions. At the very least we know as Marcel Brass said, some "stuff" happens in our heads before we are aware of it happening. Some take this as evidence against free will as the cause of our actions, and some do not feel O.K to go that far yet. As technology improves we can predict with more accuracy what that "stuff" might be telling us, but as Haynes noted there is a difference between finding brain patterns that are predictive of our actions and ones that determine our actions. It will be a long time before we have a definite answer as to how exactly real-life decisions, which have greater importance than deciding to press a button, work.