The term ‘brainwashing’ was first recorded in 1950, but it is an expression of a much older concept: the forcible and full-scale alteration of a person’s beliefs. Over the past 50 years the term has crept into popular culture, served as a topic for jokes, frightened the public in media headlines, and slandered innumerable people and institutions. It has also been the subject of learned discussion from many angles: history, sociology, psychology, psychotherapy, and marketing. Despite this variety, to date there has been one angle missing: any serious reference to real brains. Descriptions of how opinions can be changed, whether by persuasion, deceit, or force, have been almost entirely psychological.