I have been primarily interested in how and why ordinary people do unusual things, things that seem alien to their natures. Why do good people sometimes act evil? Why do smart people sometimes do dumb or irrational things?

The prisoners who had been thought to have organized the escape were disciplined and harassed with more pushups and toilet cleaning. Zimbardo is the co-author of an introductory Psychology textbook entitled Psychology and Life which is used in many American undergraduate psychology courses. The Stanford Prison Experiment participants were actually arrested for crimes which they did not commit while those in the BBC study were just brought to the location by a blacked out car.

He is president of the Heroic Imagination Project. Philip George Zimbardo (born March 23 1933) is a psychologist and a professor emeritus at Stanford University.