‘In the 1970s, Benjamin Libet, a physiologist at the University of California, San Francisco, wired up the brains of volunteers to an electroencephalogram and told the volunteers to make random motions, like pressing a button or flicking a finger, while he noted the time on a clock. Dr. Libet found that brain signals associated with these actions occurred half a second before the subject was conscious of deciding to make them. The order of brain activities seemed to be perception of motion, and then decision, rather than the other way around. In short, the conscious brain was only playing catch-up to what the unconscious brain was already doing. The decision to act was an illusion, the monkey making up a story about what the tiger had already done.’