What if a machine could know when you are going to make a decision before you yourself know you are going to make a decision? Eerily, researchers have demonstrated just this phenomenon: fMRI machines are capable of predicting a person's decision up to seven seconds before the person is even aware of making a decision. Does this mean that our decisions are predetermined by our brain, beyond our conscious control?
The age-old question of whether we have free will has crept out of the realm of speculative philosophy and has laid itself bare to the empirical investigations of the neuroscientist and the physicist. For a discussion of the physics perspective, see Why Quantum Physics Ends the Free Will Debate and Nature is Fundamentally Random, Not Deterministic (Says Quantum Mechanics). Here, we will explore the results of a famous experiment conducted in 1983 by Benjamin Libet that seemed to cast serious doubt on the prospect that we have free will, which four years ago was reproduced with even more startling results.
Considering the immense gravitas of the findings, the setup of Libet's study was surprisingly simple. Participants were fastened with electrodes to their scalp that recorded electrical activity in their brain, and were asked to carry out a simple motor task like flexing a finger or pressing a button. They were also instructed to make note of the time at which they had developed the conscious urge to make the decision to initiate a particular motor action. It was found that there was a 200 ms differential between the time that participants made their decisions and carried out the motion. But the shocking finding was that electrical activity in parts of the brain relevant to planning and carrying out the decision could be detected up to 300 ms before participants noted that they were conscious of having made a decision!
Four years ago, Libet's results were confirmed and magnified in dramatic fashion by a team at the Max Planck Institute. In this study, participants had to choose between pressing a button with either their left or right hand. Equipped with more advanced imaging technology than Libet, the team used an fMRI machine to map neuronal activity shifts in frontopolar cortex, a region involved in high-level action planning, and in parietal cortex, a region involved in integrating sensory information, up to seven seconds before participants became aware of making a conscious decision. The data was able to consistently predict which hand participants pressed the button with.
Before leaping to interpretations of these results, let's clarify exactly what has been observed. A significant period of unconscious brain activity that begins the process of executing one's decision has been found to precede the conscious awareness of having made a decision. At first glance this appears to be a pretty fatal blow to free will. How can we be said to freely make decisions if our brain is actually going off on its own, initiating decisions, and then kindly alerting us of its actions several seconds later? Libet himself actually offers a solution that keeps free will alive. Though consciousness may not play a role in instigating volitional acts, he says, we may still ultimately have the final say in deciding whether we carry out or withhold from the process that our subconscious is trying to generate. This is something that Rene Descartes actually commented on centuries ago in his Meditations. Descartes separated the understanding from the will, and maintained that we could always use our will to either act or not act on our understanding. When something is outside the scope of our understanding, such as, say, the existence of God, we can simply use our will to withhold judgment on the issue. Likewise, we can also abstain from judging or acting on something even if it is within our understanding, because what we do ultimately depends on our will which we consciously control. Other theories more in support of determinism state that consciousness is simply an after-effect, a device to make us aware of actions that our brain carries out that are out of our control. You might think of it as like a "Facebook Notification", whose only function is to draw our attention to something that has already happened.
To date, there is no consensus from the scientific community about the nature of free will.
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