Philip Zimbardo was curious about why prisons are such violent places. Is it because of the character of their inhabitants, or is it due to the corrosive effect of the power structure of the prisons themselves?
To find out, Zimbardo created a mock prison in the basement of the Stanford psychology department. He recruited clean-cut young men as volunteers — none had criminal records and all rated “normal” on psychological tests — and he randomly assigned half of them to play the role of prisoners and the other half to play guards. His plan was that he would step back for two weeks and observe how these model citizens interacted with each other in their new roles.
What happened next has become the stuff of legend.
Social conditions in the mock prison deteriorated with stunning rapidity. On the first night the prisoners staged a revolt, and the guards, feeling threatened by the insubordination of the prisoners, cracked down hard. They began devising creative ways to discipline the prisoners, using methods such as random strip-searches, curtailed bathroom privileges, verbal abuse, sleep deprivation, and the withholding of food.
Under this pressure, prisoners began to crack. The first one left after only thirty-six hours, screaming that he felt like he was “burning up inside.” Within six days, four more prisoners had followed his lead, one of whom had broken out in a full-body stress-related rash. It was clear that for everyone involved the new roles had quickly become more than just a game.
Even Zimbardo himself felt seduced by the corrosive psychology of the situation. He began entertaining paranoid fears that his prisoners were planning a break-out, and he tried to contact the real police for help. Luckily, at this point Zimbardo realized things had gone too far. Only six days had passed, but already the happy college kids who had begun the experiment had transformed into sullen prisoners and sadistic guards.
Zimbardo called a meeting the next morning and told everyone they could go home. The remaining prisoners were relieved, but tellingly, the guards were upset. They had been quite enjoying their new-found power and had no desire to give it up.
The appeal of the experiment has a lot to do with its apparently simple setup: prisoners, guards, a fake jail, and some ground rules. But, in reality, the Stanford County Prison was a heavily manipulated environment, and the guards and prisoners acted in ways that were largely predetermined by how their roles were presented. To understand the meaning of the experiment, you have to understand that it wasn’t a blank slate; from the start, its goal was to evoke the experience of working and living in a brutal jail.