How Monsters are Made

What makes ordinary people do evil things? It was a question that long fascinated the psychologist Philip Zimbardo, who died in October. Zimbardo was best known for the controversial Stanford prison experiment, in which he created a simulated prison in the basement of a university building and recruited volunteers to act as prisoners and guards. This week, we explore how Zimbardo came to create one of psychology's most notorious experiments – and inadvertently became the poster child for the human weaknesses he was trying to study.