Stanford Prison Experiment

The Stanford Prison Experiment (SPE) has become a classic in the social sciences for its dramatic demonstration of the power of situational processes over individual dispositions of its participants. It pitted a powerful set of situational variables, which together comprised what is worse in the psychological experience of imprisonment, against the will to resist by a group of normal, healthy young men playing roles of prisoners or guards.

The SPE was conducted in 1971 by a group of Stanford research psychologists, led by Professor Phillip Zimbardo, and two of Zimbardo's graduate students, Curtis Banks and Craig Haney. The experiment was designed to control for the individual personality variables that were often used at that time to explain behavior in prison and other institutional settings. That is, the researchers in the SPE neutralized the explanatory argument that pathological traits alone could account for extreme and abusive behavior by (a) selecting a group of participants who were psychologically healthy and who had scored in the normal range of the numerous personality variables that they measured and selected for, and (b) assigning participants to either the role of prisoner or guard on a completely random basis. The behavior that resulted when these otherwise healthy, normal participants were placed in the extreme environment of a simulated prison would have to be explained largely if not entirely on the basis of the characteristics of the social setting or situation in which they had been placed.

The setting itself was designed to be as similar to an actual prison as possible. Constructed in the basement of the Psychology Department at Stanford University, the “Stanford County Prison” had barred doors on the small rooms that served as cells, cots on which the prisoners slept, a hallway area that was converted to a prison “yard” where group activities were conducted, and a small closet that served as a short-term “solitary confinement” cell that could be used for disciplining unruly prisoners. The prisoners wore uniforms that were designed to de-emphasize their individuality and underscore their powerlessness. Guards, on the other hand, donned military-like garb, complete with reflecting sunglasses and nightsticks. These guards generated a set of rules and regulations that in many ways resembled those in operation in actual prisons, and prisoners were expected to comply with their orders. However, guards were instructed not to resort to physical force to gain prisoner compliance.

Despite the lack of any legal mandate for the “incarceration” of the prisoners and despite the fact that both groups were told that they had been randomly assigned to their roles (so that, e.g., guards knew that prisoners had done nothing to “deserve” their degraded prisoner status), the behavior that ensued was remarkably similar to behavior that takes place inside actual prisons and surprisingly extreme in intensity and effect. Thus, initial prisoner resistance and rebellion was met forcibly by guards, who quickly struggled to regain their power and then proceeded to escalate their mistreatment of prisoners throughout the study at the slightest sign of affront or disobedience. In some instances, the guards conspired to physically mistreat prisoners outside the presence of the experimenters and to leave prisoners in the solitary confinement cell beyond the 1-hour limit that the researchers had set.

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