In the early 1970s, Craig Haney, Curt Banks, Carlo Prescott, and Philip Zimbardo conducted a landmark situational study at Stanford University. The experiment tested the fundamental attribution error: our tendency to attribute causes of behavior to personal factors, underestimating the influence of situational conditions.
For this study, a small group of college students volunteered to be subjects and were carefully tested for sound psychological and physical health. Half of the students were randomly selected to act as prisoners, the other half to act as guards. The study took place in a simulated jail facility in the Stanford University Psychology Department.
Once the study subjects entered the simulated jail, uniforms, rules, and other details distinguished the two groups from each other, and blurred the line between the reality of the study and life in prison. The students spent much of the day cramped in tiny cells, undergoing physical trials, and enduring the overall claustrophobic atmosphere of a small jail 24 hours a day. The guards, however, were allowed to return to their homes and normal surroundings after their shifts.
What happened during the study, originally planned to last two weeks, was more dramatic than anyone had anticipated, even the researchers themselves.
As the days passed, the boundary between roles and real life disappeared. Civilized students became aggressive guards, while formerly active students became listless, disengaged prisoners who passively underwent their trials and became depressed or disoriented. Some of the prisoners were so overpowered by the situation that they developed extreme stress reactions and had to be released from the study.
Eventually, after only six days, the study was forced to end. The behavior induced by the situation and physical environment shocked everyone, both students and researchers. But through this extreme example of situational manipulation, new understandings of social psychology, as well as the dynamics of life in a prison environment, were gained. When the study was over, the students returned to their normal lives, and extensive follow-ups have shown no negative long-term effects on the students.
An extensive Web site for the Stanford Prison Experiment, including day-by-day summaries, as well as images and video clips, is available.