The photographs of prisoner abuse from Abu Ghraib shocked most Americans. But social psychologist Philip Zimbardo had seen it all 30 years before in the basement of the psychology building at Stanford University, where he randomly assigned college students to be “guards” or “prisoners” in a mock prison environment. The experiment was to last two weeks but was terminated after just six days, when these intelligent and moral young men were transformed into cruel and sadistic guards or emotionally shattered prisoners.