Since the early 20th century, the name of the Russian scientist Ivan Pavlov has been associated with the idea of brainwashing. Pavlov's experiments, in which he trained dogs to salivate in response to a signal such as a bell, showed that the mind could be conditioned to react automatically to stimuli. But he looked forward to a time when science could manipulate the brain directly. In a passage eerily accurate in describing today's neural imaging, he wrote: "If we could look through the skull into the brain of a consciously thinking person…then we should see playing over the cerebral surface a bright spot with fantastic, waving borders, constantly fluctuating in size and form, and surrounded by a darkness, more or less deep, covering the rest of the hemispheres."

We still don't have a precise topography of the brain in terms of specific thoughts or feelings. It's hard to imagine where one would begin if one wanted to surgically force someone to reveal a particular secret, or to persuade him or her to vote for a certain candidate. But since Pavlov's time, science has moved much closer to enabling direct physical control of the brain. In this century, neuroscientists' insights into memory, cognition, pleasure and pain may make coercive "mind control" a reality.