The Illusion of Choice

In the 1980s, neuroscientist Benjamin Libet found something disturbing. When subjects decided to flick their wrist, their brain showed a readiness potential - electrical activity related to preparation for movement - up to half a second before they consciously reported the urge or intention to move.

Your brain may begin preparing for action before you are aware of choosing. That makes conscious choice look less simple than it feels, but it does not prove that the brain has already made a completed decision and merely informs you after the fact. More recent studies have reported above-chance prediction of simple choices seconds before action, but how much that says about ordinary deliberation remains disputed.