Stanford Prison Experiment

Stanford prison experiment was a study conducted by a team of researchers led by professor Philip Zimbardo that took place in August of 1971. Funded by the US office of Naval Research, the experiment was supposed to show the causes of conflict between guards and prisoners in military prisons as well as civilian ones.


Located in the basement at Stanford University, professor Zimbardo and his team made a mock up prison they would use in the experiment over the following six days. They chose 24 volunteers out of a group of 75 and then randomly assigned them with guard or prisoner roles. The participants were dominantly white middle-class males without any criminal record who were deemed most psychologically fit and generally healthy. As the goal of the experiment was to determine what is the reason for conflicts between guards and prisoners, guards were equipped with wooden batons, mirror sunglasses to prevent eye contact, and clothing that was very close in comparison to that of real prison guards. Prisoners on the other hand, were ill fitted with inadequate clothing while wearing ankle chains. It is important to mention that professor Zimbardo took a role of superintendent while one of his under graduate students assumed the role of prison warden.


The experiment began with a series of arrests where the prisoner participants were arrested in their homes and went trough the full procedure in the local police station, courtesy of Palo Alto Police Dept. They were then transported to mock prison after they were properly booked and fingerprinted. The first day of imprisonment went rather uneventful. However, on the second day prisoners of Cell 1 barricaded their doors with their beds while refusing to follow guard’s instruction. It is worth mentioning that guards were instructed not to use physical force on prisoners during the experiment. Guard’s conduct in subduing the revolt in Cell 1 already proved that personal restrain might be a problem since they used fire extinguishers to bring Cell 1 under control without any supervision from the research team. Although there were no more physical confrontations during the experiments, guards turned to use of psychological methods to instill order and punish prisoners. Few of these methods were consisted of making prisoners repeat their designated prisoner numbers out loud in an effort to depersonalize them, denying the prisoners clothes or making prisoners urinate and defecate in a bucket placed in the middle of a cell and then refusing to empty the content of the bucket. Naturally, sanitary conditions deteriorated along with mental health of prisoners. Experiment was terminated after six days, eight days short of planned schedule. This was due to an argument made by Zimbardo’s girlfriend that the experiment is too cruel.


After the experiment was terminated most of the guards were genuinely angry that the experiment was abruptly ended so soon while roughly one third of them demonstrated true sadistic tendencies. The results of the experiment showed that the situation, rather than their individual personalities, caused the participants’ behavior, thus being in alignment with the results of Milgram’s experiment.

Naturally, there was a lot controversy about the experiment as some argued that it was too cruel and dangerous since the guards overstepped their boundaries, thus exposing participants to potential psychological damage. Others noted that it wasn’t very objective since Zimbardo and his team were involved as participants of one side. Controversial or not, Stanford prison experiment is one of the most famous experiments in the field of psychology to this date.

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