The Stanford Prison Experiment

Description, Results and Conclusions

In 1971 psychologist Philip Zimbardo, professor at Stanford University, carried out the Stanford prison experiment. The experiment was funded by the US Office of Naval Research which wanted to know what causes the conflict between the guards and prisoners in military gaols. 24 students, who were judged to be psychologically normal, were chosen from 75 and paid $15 for each day they took part in the experiment. By random selection 12 of the chosen group were assigned to be guards during the experiment, while 12 were given the role of prisoner (3 of the 'prisoners' were kept on standby at home, so there were only 9 locked in the gaol). The conditions of the simulated prison experience were kept as realistic as possible. 

The guards were given uniforms, whistles, handcuffs and dark glasses. This made eye contact with the prisoners impossible. They were given wooden batons as weapons but were warned that no physical violence was allowed during the course of the experiment. Zimbardo told the guards that they could instill a sense of fear in the prisoners, however, and that they could make them feel like their existence was arbitrary and controlled by the 'system.' He explained that they would take away the individuality of the prisoners and that they would be left feeling powerless. Three groups of 3 guards were to each work 8 hour shifts on rotation, while the remaining 3 stayed on standby at their homes.

The prisoners were arrested without notice and escorted to the police station. They were treated exactly as they would be if they were real criminals. Their fingerprints were taken. They were photographed and 'booked.' Then they were taken, blindfolded, to Stanford University where the basement had been converted into the temporary gaol. The doors and windows were barred and the walls were bare. Three groups of 3 each had to share a small cell between them. They were stripped, deloused and assigned a number. Their personal possessions were taken away and they were given a uniform to wear. They had no underwear and each had to wear a chain around his ankle. These humiliating processes were the beginning of the dehumanization process.

Zimbardo in his role as Prison Superintendent, studied the behavior of the other participants over six days. He had expected that the prisoners and guards would conform to their new roles and display the usual behavior found in real-life prison situations. However, even he was surprised at the extent to which the participants readily adapted to their designated roles. The experiment was initially intended to run for a fortnight but, because of the extent to which it quickly became unpleasantly realistic, it was curtailed after just six days.

Within just hours, a few of the guards started to harass some prisoners. They were brutal and sadistic, enjoying their power. Before long more guards joined in and began to pick on other prisoners. The prisoners were dehumanized. They were ordered to do petty, boring tasks and taunted. Not long afterward, the prisoners began to display the similarly expected behavioral patterns. They started to take the prison rules enormously seriously and some 'told tales' on others. Some of them even sided with the guards against other prisoners if they were found to be breaking the rules. They talked almost constantly about prison issues.

The abuse of the prisoners escalated. The prisoners started a riot on the second day but, over the six days the prisoners became increasingly submissive and beaten down. Accordingly the guards became more sadistic in their treatment of them. Some prisoners weren't even allowed to defecate or urinate. Harsh physical exercise was meted out as punishments. After three days one prisoner had to be released because he had become so distressed and angry that he cried and screamed uncontrollably.

Zimbardo would have allowed the experiment to continue but his then partner, Christine Maslach, came into the mock prison to conduct interviews. She expressed such concern about the situation that it brought him to the realization that he must conclude the experiment early. Nearly 50 other outsiders had witnessed the conditions and abuse, however, and had not urged him to end the experiment. Zimbardo had expected the depersonalization, deindividualization and disorientation of the prisoners. However, even he was shocked at the extent to which it took place and how quickly it had happened. He was also disturbed at his own participation afterward, as he himself had effectively condoned the abuse in his role as Prison Superintendent.

The Stanford prison experiment has been argued to show that people are impressionable and obedient when given a legitimizing ideology backed with institutional and social support. It seems to very well illustrate the power of authority. The results have also been used to support the situational attribution, rather than the dispositional attribution, of behavior, i.e. that people will behave a certain way in a given situation and their behavior is not dependent on their individual characteristics, or disposition. Certainly some of the guards were upset at their abuse of the prisoners when looking back at the Stanford prison experiment, indicating that they acted in ways that they normally wouldn't have done. Also, many of the prisoners thought themselves assertive before the experiment and were surprised to have become so submissive in that particular circumstance.

Phillip G. Zimbardo, Professor of Psychology at Stanford University, Ran the Prison Experiment in 1971