Free Will: The Rumour That the Brain Decides First and Tells Consciousness Later

A person sits before a screen with a dot turning like a clock hand. They are told to choose any moment to flick a wrist. No one forces the timing. After each movement, they report the moment when they felt they wanted to act. Meanwhile, electrodes on the scalp record brain activity. In 1983, Benjamin Libet and colleagues published a result that made an old question frightening: a preparatory brain signal appeared before participants reported the intention to flick their wrist.