Stanford Prison Experiment

The Stanford Prison Experiment is a famous psychological experiment conducted in 1971 by American psychologist Philip Zimbardo. The experiment is a psychological study of a person’s response to the restriction of freedom, to the conditions of prison life, and to the influence of an imposed social role on behavior.

If you give a person power over someone defenseless, someone humiliated, that’s when absolute power corrupts absolutely.

Professor David Wilson, criminologist

Volunteers played the roles of guards and prisoners and lived in a conditional prison arranged in the building of the Department of Psychology. Prisoners and guards quickly adapted to their roles, and, contrary to expectations, truly dangerous situations began to arise. Sadistic inclinations were found in every third guard, and the prisoners were severely morally traumatized, and two were excluded from the experiment ahead of time. Despite the apparent loss of control over the experiment, only one of the 50 observers, Christina Maslach, opposed its continuation. Zimbardo finished the experiment ahead of time.

Ethically, the experiment is often compared to the Milgram experiment conducted in 1963 at Yale by Stanley Milgram, a former classmate of Zimbardo’s.

Goals and means

The study was paid for by the US Navy in order to explain the conflicts in its correctional facilities and in the Marine Corps.

Participants were recruited through a newspaper ad and were offered $15 a day (adjusted for [inflation equivalent to $76 in 2006) for two weeks of participation in a «simulated prison.» Of the 70 people who responded to the ad, Zimbardo and his team chose 24 who they considered the most healthy and psychologically stable. These participants were predominantly middle-class white males. They were all college students.

A group of twenty-four young men were randomly divided into «prisoners» and «guards.» Interestingly, it then seemed to the prisoners that they were taken to the guards for being tall, but in fact they were honestly chosen by lot by tossing a coin, and there was no objective difference in physical data between the two groups.

Actually, the conditional prison was set up on the basis of the Stanford Department of Psychology. The undergrad lab assistant was appointed «supervisor» and Zimbardo himself was appointed manager.

Zimbardo created a series of specific conditions for the participants, which were supposed to contribute to disorientation, loss of a sense of reality and their self-identification.

The guards were given wooden truncheons and military-style khaki uniforms that they chose from the store. They were also given mirrored sunglasses to hide their eyes. Unlike prisoners, they were required to work shifts and return home on weekends, although many subsequently participated in unpaid overtime.

Prisoners had to dress only in deliberately ill-fitting muslin robes without underwear and rubber slippers. Zimbardo claimed that such clothing would cause them to assume «unaccustomed body posture» and they would experience discomfort, which would contribute to their disorientation. They were only called by numbers instead of names. These numbers were sewn onto their uniforms and prisoners were required to wear tight-fitting pantyhose over their heads to mimic the shaved heads of recruits undergoing basic military training. In addition, they wore a small chain around their ankles as a constant reminder of their imprisonment and oppression.

The day before the experiment, the guards attended a short orientation session, but were given no instructions other than that no physical abuse was to be tolerated. They were told that it was their duty to make rounds of the prison, which they could do as they pleased.

Zimbardo made the following statement to the guards at the meeting:

Create in the prisoners a sense of longing, a sense of fear, a sense of arbitrariness, that their life is completely controlled by us, the system, you, me, and they have no personal space … We will take away their individuality in different ways. All this together will create in them a sense of powerlessness. So in this situation, we will have all the power, and they will have none.

The participants, who were chosen to pose as prisoners, were told to wait at home until they were «summoned» for the experiment. Without any warning, they were «charged» with armed robbery and arrested by the Palo Alto Police Department, which was involved in this phase of the experiment.

The prisoners underwent a full police examination, including being fingerprinted, photographed and having their rights read out. They were brought to a conditional prison, where they were examined, ordered to strip naked, “cleaned of lice” and assigned numbers.

The results

The experiment quickly got out of hand. The prisoners experienced sadistic and abusive treatment from the guards, and by the end, many of them showed severe emotional distress.

After a relatively calm first day, a riot broke out on the second day. The guards volunteered to work overtime and, without guidance from the researchers, put down the riot, while attacking the prisoners with fire extinguishers. After this incident, the guards tried to separate the prisoners and pit them against each other by choosing «good» and «bad» corps, and made the prisoners think that there were «informants» in their ranks. These measures had a significant effect, and there were no further disturbances of a large scale. According to Zimbardo’s ex-convict consultants, this tactic was similar to that used in real American prisons.

Prisoner counts, which were originally conceived to help them get used to identification numbers, turned into hour-long trials during which guards harassed prisoners and subjected them to physical punishment, including forcing them to do long physical exercises.

The prison quickly became dirty and gloomy. The right to bathe became a privilege that could, and often was, denied. Some prisoners were forced to clean toilets with their bare hands. Mattresses were removed from the «bad» cell, and the prisoners had to sleep on an uncovered concrete floor. Food was often denied as punishment. Zimbardo himself speaks of his growing immersion in the experiment, which he led and actively participated in. On the fourth day, upon hearing of the escape plot, he and the guards attempted to relocate the entire experiment to a real, unused cell block at the local police station, as a more «safe» one. The police department turned him down, citing security concerns, and Zimbardo says he was angry and frustrated at the lack of cooperation between him and the police penitentiary system.

During the experiment, several guards turned more and more into sadists — especially at night, when it seemed to them that the cameras were turned off. The experimenters claimed that about one in three guards showed real sadistic tendencies. Many of the guards became upset when the experiment was aborted prematurely.

Subsequently, the prisoners were offered «on parole» to leave the prison if they refused to pay, the majority agreed to this. Zimbardo uses this fact to show how much the members have grown into the role. But the prisoners were later refused, and no one left the experiment.

One of the participants developed a psychosomatic rash all over his body when he learned that his parole request had been denied (Zimbardo turned him down because he thought he was trying to cheat and feign illness). Confused thinking and tears became common among the prisoners. Two of them experienced such a severe shock that they were taken out of the experiment and replaced.

One of the replacement prisoners, No. 416, was horrified by the guards’ treatment and went on a hunger strike. He was locked up in a closet for solitary confinement for three hours. During this time, the guards forced him to hold sausages, which he refused to eat. Other prisoners saw him as a bully. To play on these feelings, the guards offered the other prisoners a choice: either they would refuse blankets, or No. 416 would spend the whole night in solitary confinement. The prisoners preferred to sleep under blankets. Zimbardo later stepped in and released #416.

Zimbardo decided to end the experiment prematurely when Christina Maslach, a student not previously familiar with the experiment, protested the intimidating conditions of the prison after she went there to give talks. Zimbardo mentions that of all the fifty witnesses to the experiment, she was the only one who raised the question of its morality. Although the experiment was scheduled for two weeks, it was terminated after six days.

Conclusions

The results of the experiment were used to demonstrate the receptivity and submissiveness of people when there is a justifying ideology supported by society and the state. They were also used as an illustration of the theory of cognitive dissonance and the influence of the power of authorities.