Stanford Prison Experiment: Summary & Ethics

Instructor: Natalie Boyd

Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.

In 1971, Philip Zimbardo conducted a notorious study on human behavior by setting up a fake prison. Learn more about the Stanford Prison Experiment and the ethical questions it raised, and test your knowledge with a quiz.

The Prison Experience

When news articles began to surface in 2004 that U.S. soldiers had tortured prisoners in Iraq's Abu Ghraib prison, people were shocked. How could people tasked with overseeing prisoners commit such horrible crimes? To many, it seemed unthinkable.

Not to Philip Zimbardo. More than 30 years earlier, Zimbardo had learned how vicious normally good people could be when tasked with keeping control of a group of prisoners. He ran a study in 1971 that simulated the prison experience with volunteers. The results catapulted Zimbardo and his study into the news, and the Stanford Prison Experiment (as it is known) became notorious.

The Study

Zimbardo and his colleagues in the Stanford University psychology department were interested in studying social roles and the way they influence people's behaviors. They advertised for volunteers who wanted to earn $15 dollars a day for two weeks. The 24 men who were chosen for the experiment - mostly middle-class college students - were randomly divided into two groups: prisoners and guards. They were placed in the basement of a building at Stanford.

Jordan Hall, Site of the Experiment
Jordan Hall at Stanford University

The guards were told that they had to keep control of the prisoners, but were not allowed to use physical force. The prisoners were given a list of seventeen rules that the guards wrote up. They included the requirement that prisoners address each other by their prisoner number, not name, and they were not allowed to refer to their situation as an experiment. The researchers monitored the situation via video cameras.

On the second day, the prisoners staged a revolt. After getting the prisoners under control, the guards realized that they needed to assert their authority. Because they were not allowed to use violence, the guards got creative about how to control the prisoners. They woke the prisoners up several times during the night, causing sleep deprivation. They forced some of them to clean toilets with their bare hands. One of the guards said that he asked himself, 'How can we top what we did yesterday? How do we do something even more outrageous?' As a result, the degradation of the prisoners continued to grow more and more out of hand.

The Intervention

Early on, the prisoners began to display anxiety and depression as a result of the humiliation from the guards. The experimenters released several prisoners early due to severe psychological reactions. But none of the researchers questioned whether the study should end early, despite the escalating actions of the guards.

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