The Stanford Prison Experiment: 40 years on

Philip Zimbardo’s Stanford Prison Experiment, which was conducted 40 years ago this week, is one of the most influential studies in the history of psychology. It has been used to explain everything from 9/11 to the Abu Graib abuses to the recent London riots.

But two British psychologists argue that Zimbardo’s findings have been increasingly questioned over the years and that more subtle explanations of human cruelty are now available to us.

In the Stanford Experiment a mock prison was set up in the basement of the university’s psychology building and students were randomly chosen to play the role of prisoners or officers. The participants took to their roles with great enthusiasm, leading the officers to display extreme authoritarian behaviour and ultimately even to subject some prisoners to torture.

Philip Zimbardo used this experience to argue that people are unable to resist the situational influences that are placed upon them. Put them in the uniform of an oppressor and they will behave like oppressors.

However, Professor Alex Haslam from the University of Exeter argues that our understanding has moved on since 1971: “The Stanford study is a landmark in the history of psychology, but Zimbardo’s explanation of his findings and the way to use explain social events are not accepted by most psychologists today.”

In particular, Professor Haslam points to the BBC Prison Study, which he conducted with Professor Stephen Reicher in 2002.

The findings of this experiment, which has replaced the Stanford study on the school psychology syllabus in Britain, suggest that people go along with roles only when they actively identify with them and believe in what they are doing. If people act abusively it is not because they don’t realise or care what they are doing, it because they believe that what they are doing is right.

Professor Reicher, now at the University of St Andrews, says: “Zimbardo’s conclusion – that people get swept away by the situation and do things they really don’t believe in – is highly misleading. Whether as guards in a prison or as rioters in a crowd, people in groups behave in terms of shared beliefs. So what they do tells you about their view of the world and their sense of right and wrong.”

You can read more from Alex Haslmar and Stephen Reicher in the archives of our monthly magazine The Psychologist. They have written on their BBC Prison Study and on our understanding of evil.

Philip Zimbardo's book The Lucifer Effect was reviewed for The Psychologist by Phil Banyard.