In 1971, Philip Zimbardo created an experiment to understand abusive behavior within the prison system and to learn how situations can impact human behavior. He posed the question: what would happen if dignity and individuality were stripped away from individuals? The result was the infamous Stanford Prison Experiment: one of the most telling experiments produced in the field of psychology.

Zimbardo and his team transformed the basement of the Stanford University psychology department into a mock prison. He advertised in the local papers for participants, offering $15 a day for a two-week study. Of the respondents, twenty-four male subjects were chosen that were deemed to be emotionally and mentally sound, and were mostly middle class and white. The twenty-four men were then randomly divided into two groups: twelve prison guards and twelve prisoners. Zimbardo was to act as warden of the prison.

Dressed for the Occasion

The prison guards were dressed in military-style uniforms and sunglasses (to prevent eye contact), and were each given wooden batons to establish their status. The prisoners were to wear stocking caps, uncomfortable smocks, no underwear, and were only allowed to go by identification numbers, not names. They also wore a small chain on one leg as a reminder that they were inmates. Inside of their prison cells, they were only given a mattress and plain food.

Before the experiment began, the prisoners were told to go back to their homes and await further instruction. When home, without any warning, their homes were raided by actual local police (who had agreed to help in the experiment), and they were each charged with armed robbery. They were then read their rights, had fingerprints and mug shots taken, and were stripped, searched, deloused, and brought into their prison cells, where they would spend the next two weeks. There were three prisoners to each cell, and prisoners were required to stay in the cell day and night. The prison guards, however, did not have to stay once their shift ended, and they were given free reign to run the prison however they wanted, with the only exception being no physical punishment.

The Results

The Stanford Prison Experiment was forced to stop just six days into the two-week study. By the second day, prisoners in Cell 1 used their mattresses to blockade the door. Guards from different shifts volunteered to work to suppress the riot and used fire extinguishers on the prisoners.

The guards then decided to create a “privilege cell,” where prisoners not involved in the riot would be given a special reward, such as a meal that was of better quality. The prisoners in the “privilege cell,” however, refused to eat the food and stayed in solidarity with their fellow inmates.

A mere thirty-six hours into the study, one prisoner, #8612, began screaming wildly, cursing, and got so out of control that Zimbardo saw no other choice but to release him.

The prison guards began punishing the prisoners by making them repeat their assigned numbers, forcing them to exercise, and confiscating their mattresses so they had no choice but to sleep on the hard, cold concrete. The prison guards turned the use of the toilet into a privilege and frequently denied bathroom access to the prisoners, instead giving them a bucket in their cells. They also made the prisoners clean the toilet with their bare hands. In an effort to humiliate the prisoners, some were forced to strip completely naked.

One-third of the prison guards showed sadistic tendencies, and even Zimbardo himself became immersed in his role as prison ward. On day four, there were rumors that the prisoner who had been released was going to come back to free the remaining prisoners. Zimbardo and the guards moved the prison to another floor, and Zimbardo waited in the basement in case the prisoner returned, where he would tell him that the experiment ended early. The prisoner never showed, however, and the prison was once again rebuilt in the basement.

When a new prisoner was introduced, he was given the instructions to go on a hunger strike in response to the treatment of his fellow prisoners. Instead of viewing him as a fellow victim, the other prisoners saw this new prisoner as a troublemaker. The prison guards put the new prisoner in solitary confinement and gave the rest of the prisoners an option: they could give up their blankets to let the man out of solitary confinement. Everyone except for one prisoner decided to keep their blankets.

Surprisingly, none of the inmates wanted to quit early, even when they were told they would not get the money for participating. Zimbardo concluded that the prisoners had internalized and adopted their roles, becoming institutionalized.

After six days of the experiment, a graduate student was brought in to interview the prisoners and guards, and was absolutely shocked by what she saw. As a result of this outside perspective, Zimbardo ended the experiment. He noted that of the fifty visitors, she was the only person to have questioned the morality of the experiment.

The Stanford Prison Experiment is one of the most important and controversial psychological experiments to ever have been conducted. Under the current Ethics Code of the American Psychological Association, the experiment could not be replicated because it does not meet many of today’s ethical standards. However, Zimbardo successfully showed how behavior could be influenced by the situation a person is in, and there are numerous real-world examples that prove Zimbardo’s work, including the abuse of prisoners at Abu Ghraib in Iraq.