So it turns out that there are neurons in your brain that know you are about to make a movement the better part of a second before you know it yourself. What does that mean?
Scientists from UCLA and Harvard — Itzhak Fried, Roy Mukamel and Gabriel Kreiman — have taken an audacious step in the search for free will, reported in a new article in the journal Neuron. They used a powerful tool – intracranial recording – to find neurons in the human brain whose activity predicts decisions to make a movement, challenging conventional notions of free will.
Such neurons, they found, abound in a region of the frontal lobe called the supplementary motor area, which is involved in the planning of movements. But here is the interesting thing:
- About a quarter of these neurons began to change their activity before the time patients declared as the moment they felt the urge to press the button
- The change began as long as a second and a half before the decision
- and as early as seven tenths of a second before it, this activity was robust enough that the researchers could predict with over 80 percent accuracy not only whether a movement had occurred, but when the decision to make it happened.
It might be tempting to conclude that free will is an illusion. Some have believed this since the days of Libet, who recorded EEG and found it contained a specific pattern that predicted his subjects movements before they felt the conscious will to act. EEG measures electrical activity on the surface of the head, combining information from billions of neurons; Fried and his colleagues have gone further, by finding individual neurons that do this.
But before reaching any sweeping conclusions, it is important to remember that this study looked at a very rudimentary kind of action. The decision to move a finger hardly ranks as the same kind of free will we exercise when we make moral choices or major life decisions. To conclude that we aren’t fully responsible for our actions, for example, would be extremely far-fetched.
…some activity in our brains may significantly precede our awareness of wanting to move. Libet suggested that free will works by vetoing: volition (the will to act) arises in neurons before conscious experience does, but conscious will can override it and prevent unwanted movements.
…Deciding what to do and when to do it may be the result of a process in which all the currently-available options are assessed and weighted. Rather than free will being the ability to do anything at all, it might be an act of selection from the present range of options. And the decision might be made before you are even aware of it. Think about that next time you reach for the remote
By Daniela Schiller and David Carmel | Tuesday, March 22, 2011