New Findings on Free Will

Libet's experiment was thought-provoking, but imprecise. The followup study, by Itzhak Fried, Roy Mukamel, and Gabriel Kreiman, leverages new technologies that allow neuroscientists to monitor individual neurons, rather than huge brain regions. It also takes advantage of new clinical situations. Nowadays, super-small electrodes are sometimes inserted deep into the brains of epilepsy patients during pre-surgery diagnostic tests. Fried, Mukamel, and Kreiman asked these patients to perform a version of the Libet experiment.

What did they find? First, they discovered that W, the sensation of 'making a decision,' is correllated with activity in the motor areas of the brain -- not in some specific decision-making area. Second, they found that the W moment involves decreases in brain activity, as well as increases. Writing in Neuron, Patrick Haggard, a neuroscientist, argues that it's now "wrong to think of W as a prior intention, located at the very earliest moment of decision in an extended action chain. Rather, W seems to mark an intention-in-action, quite closely linked to action execution.... [occurring when] the brain transforms a prior plan into a motor act." The decreases in neural activity before W, meanwhile, suggest that the brain is set up to "tonically inhibit unwanted actions": the sensation of making a decision might not be about hatching a new plan, but about green-lighting one of many competing impulses.