Philip Zimbardo was the leader of the notorious 1971 Stanford Prison Experiment — and an expert witness at Abu Ghraib. His book The Lucifer Effect explores the nature of evil; now, in his new work, he studies the nature of heroism. Philip Zimbardo knows what evil looks like. After serving as an expert witness during the Abu Ghraib trials, he wrote The Lucifer Effect: Understanding How Good People Turn Evil . From Nazi comic books to the tactics of used-car salesmen, he explores a wealth of sources in trying to explain the psychology of evil. A past president of the American Psychological Association and a professor emeritus at Stanford, Zimbardo retired in 2008 from lecturing, after 50 years of teaching his legendary introductory course in psychology. In addition to his work on evil and heroism, Zimbardo wrote The Time Paradox , exploring different cultural and personal perspectives on time.