The researchers wanted to study the mechanisms behind evil actions and recruited 24 young male students who, for a few weeks, would act as "prison guards" and "prisoners" in the university's basement.
But already on the second day, the study began to go awry, and the experiment had to be interrupted after six days. By then, the "prisoners" had been humiliated by the increasingly sadistic "prison guards". Zimbardo has later, in his book "The Lucifer effect", drawn parallels to the abuses that American and British soldiers and prison guards subjected prisoners to at the Iraqi Abu Ghraib prison in 2003-2004.
Zimbardo's role in the experiment was questioned, and so were the methods used. The experiment is one of the most studied in the field of psychology.
Philip Zimbardo was born in 1933 in New York as the son of Italian immigrants, and his experiences of growing up poor in the Bronx shaped his interest in human behavior. He died surrounded by his wife and children, 91 years old.
Corrected: In an earlier version of the text, Zimbardo's age was incorrect.
