Experiment: Stanford Prison

A sign that reads "Stanford County Prison" and a guard

A Mighty Guard

The Purpose:

To investigate the environmental influence on behavior. Phillip Zimbardo wanted to see how readily individuals would conform to their roles.

The Participants: 

24 undergraduate males were selected out of a group of 70 volunteers to take part in the study. They volunteered to be part of a two week study, for $15 a day. They understood that they would be randomly selected to role-play as either a prisoner or a guard. To make the experiment more realistic, those who were randomly selected to be prisoners were arrested at their homes without warning- in front of their family and neighbors. They were taken to a police station where they were treated like any other

Prisoners behind bars

A clear barrier between guard and prisoners

criminal (fingerprinted, photographed etc). They were eventually escorted to a basement in Stanford University that was set up as a prison.

The Study:

There were three 6ft X 9ft cells held 3 prisoners each where each would sleep on a cot. There was a sm

all closet/room for solitary confinement and small space for they called ‘the yard’. The guards rotated in 8-hour shifts while the prisoners stayed confined for the duration of the study. At first, the prisoners did not take the guards seriously. They were mocking them until they realized the guards were serious about their authority. To gain control, the guards would have the prisoners do physical exercises, such as push ups. On the second day, the prisoners vented their frustration by throwing a riot. They rebelled by taking off their prison uniforms and pushing their cots up against the cell doors. The guards were furious and called for backup.

Once the guards were able to get into the cells, they stripped the inmates naked, tore apart the beds and the cell, and put the prisoners who had started the rebellion in solitary confinement. As all nine guards could not be on duty at once, they began rewarding the prisoners for good behavior. The prisoners who had not been involved in starting the riot were allowed to lie in their beds, wash themselves and brush their teeth and eat while those who had started the riot were not allowed to. The guards continued to use tormenting tactics to break up the prisoners relations with each other to avoid further organized resistance. In the case with one prisoner, who was a smoker, the guards were able to control his behavior because they decided when and if he was allowed to smoke.Less than two full days into the experiment, one inmate began suffering from depression, uncontrolled rage, crying and other mental dysfunctions. The prisoner was eventually released after screaming and acting unstable in front of the other inmates. This prisoner was replaced with one of the alternates (Wikipedia).

Even going to the bathroom was considered a privilege, for if you acted out you had to defecate and urinate in a bucket. One of the key factors that lead to the dehumanization and breakdown of the prisoners was that the guards did not refer to them by name, but by their designated prison number. Being stripped of your name within an environment like that had damaging affects. On the third day of the experiment, they even allowed the prisoners parents to come in for a visitation. However, the visitation was heavily monitored by the guards and Zimbardo himself even told their families everything was splendid.

Zimbardo, deeming himself the “prison ward”, let the study go on even though he was witnessing this abuse. From the urge of graduate student Christina Mas, Zimbardo eventually ended the study prematurely– after 6 days. He was noted saying: “Only a few people were able to resist the situational temptations to yield to power and dominance while maintaining some semblance of morality and decency; obviously I was not among that noble class” (About Psychology).


From their uniforms to the environment, everything played a role in changing the participants behavior. Remember: all participants were mentally and physically stable and were randomly selected for each part. This goes to show you how powerful the situation can be. Think of how relevant this is today. Notice how confident cops are when their in uniform? It gives you sense of entitlement, superiority – even if you’re not. Just the clothing alone has a psychological affect on you. I highly recommend watching the YouTube clip of the experiment. It’s captivating and disturbing at the same time.


Posted on October 23, 2013, in Experiments. Bookmark the permalink. Leave a comment.

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