In The Lucifer Effect: Understanding How Good People Turn Evil, Philip Zimbardo theorizes that people discount situational influences when judging the actions of others. In particular, he recounts in detail the events of the 1971 Stanford Prison Experiment (SPE), which he designed and directed: He replicated a prison block in a Stanford building and assigned male undergraduate volunteers to act the part of guards and prisoners.

The experiment, which was originally planned for two weeks, grew so dangerously out of control that Zimbardo was forced to shut it down after less than a week.

Drawing on his experience as an expert witness for the court-martial hearings on Abu Ghraib, Zimbardo presents a body of research evidence to suggest that the military as well as the Bush administration fostered a situation that turned ordinary soldiers into torturers and abusers. Zimbardo also suggests, however, that the power of situations can be used to promote good behavior and turn ordinary people into heroes. The Lucifer Effect is at times unbalanced and disjointed but well worth reading to remind us that where we are may affect us as much as who we are.