Watch CBS News

Stanford psychologist behind the controversial "Stanford Prison Experiment" dies at 91

Philip G. Zimbardo, the psychologist behind the controversial "Stanford Prison Experiment" that was intended to examine the psychological experiences of imprisonment, has died. He was 91.

Stanford University announced Friday that Zimbardo died Oct. 14 at his home in San Francisco. A cause of death was not provided.

In the 1971 prison study, Zimbardo and a team of graduate students recruited college-aged males to spend two weeks in a mock prison in the basement of a building on the Stanford campus.

Slide-12.jpg
It's considered one of the most notorious psychology experiments ever conducted - and for good reason. The "Stanford prison experiment" - conducted in Palo Alto, Calif. 40 years ago - was conceived by Dr. Philip G. Zimbardo as a way to use ordinary college students to explore the often volatile dynamic that exists between prisoners and prison guards - and as a means of encouraging reforms in the way real-life prison guards are trained. But what started out as make-believe quickly devolved into an all-too-real prison situation. Some student "guards" became sadistic overlords who eagerly abused the "prisoners," many of whom began to see themselves as real prisoners.Just what happened in the basement of the Stanford psychology department all those years ago? Keep clicking for a glimpse back in time... Philip G. Zimbardo, Inc.

The study was ended after six days as the students playing guards became psychologically abusive and those playing prisoners became anxious, emotionally depressed and enraged, according to the Stanford statement.

Zimbardo was criticized for taking the role of superintendent – becoming an active participant in the study and no longer a neutral observer.

Slide-30.jpg
Parents eventually called Zimbardo, asking if they could contact a lawyer to get their kids out of "prison." The calls, combined with the increasingly abusive treatment of the "prisoners," convinced Zimbardo that the experiment had gone too far. But Zimbardo ended the experiment only after being admonished by a newly minted PhD who had returned to Stanford and was shocked by what she saw. Philip G. Zimbardo, Inc.

"The outcome of our study was shocking and unexpected," Zimbardo would later co-write with one of the graduate students who was part of the project.

The experiment is now used in psychology classes to study the psychology of evil and the ethics of psychological research with human subjects, Stanford said.

Zimbardo's research also included persuasion, hypnosis, cults, shyness, time perspective, altruism, and compassion, Stanford said.

Zimbardo is survived by his wife, Christina Maslach Zimbardo, three children and four grandchildren.

View CBS News In
CBS News App Open
Chrome Safari Continue
Be the first to know
Get browser notifications for breaking news, live events, and exclusive reporting.