The Stanford Prison Experiment was a controlled experiment that included a prison setting with volunteer participants that took the roles of either prisoners or guards. "The goal was to investigate how readily people would conform to the roles of guard and prisoner in a role playing exercise that simulated prison life." (Saul). Zimbardo wanted to test the dispositional hypothesis that would help determine if prison atmospheres were controlled by the environment or the people in them. "The dispositional hypothesis has been embraced by the proponents of the prison status quo (blaming conditions on the evil in the prisoners), as well as by its critics (attributing the evil to guards and staff with their evil motives and deficient personality structures)." (Zimbardo, 71). This would mean that the reason there is a violent prison atmosphere is because of the people within the prison and not the environment of the prison itself. If the participants in the experiment were more peaceful and non-aggressive, then the dispositional hypothesis could be true. If the opposite happened, which means the volunteers acted aggressive like the real prisoners and guards, then it would support a situational explanation.

The twenty-two participants were selected from seventy-five volunteers to be subjects in the prison life experiment for fifteen dollars a day. "Those who responded to on ad in the newspaper completed an extensive questionnaire concerning their family background, physical and mental health history, prior experience and attitudinal propensities with respect to sources of psychopathology (including their involvements in crime)." (73) The participants who passed the initial questionnaire were then interviewed by an experimenter, and the most mentally and physically stable with the least amount of anti-social behaviors were eligible for the study. All of those selected for the study were strangers to one another, healthy, Caucasian, except for one that was from Oriental descent, and college male students in the Stanford University area for the summer. (Zimbardo says) "The final sample of subjects were administered a battery of psychological tests on the day prior to the start of the simulation, but to avoid any bias, the cores were calculated after the study was completed." (Zimbardo, 73). Before the experiment started, one subject dropped out, which left ten prisoners and eleven guards.

The initial procedure and set up of the experiment started with creating a "mock" prison that was similar to a real prison in certain aspects. The used a basement underneath the Psychology building at Stanford University. Those randomly assigned to the prisoner roles were arrested in their home without warning, taken to a local police station for fingerprinting and mugshots, then blind folded to be driven to the "mock" prison. Prisoners were stripped from their clothes and possessions deloused, given a prison uniform, shackles and an identification number. While they were in the prison, they were only allowed to use the ID numbers instead of their real names. Prisoners signed a contract stating: they would be given a sufficient amount of food to survive, little to no privacy, would be subject to the guards methods of control without physical abuse, and their rights would be suspended during the experiment to create the role they were given to be more authentic. Participants playing the role of the guard were given khaki uniform, a whistle, a police club, and sunglasses. They were given orders to do anything necessary to maintain law and order in the prison setting, and to command respect from prisoners without the use of physical violence. (Zimbardo says) "The prisoners remained in the "mock" prison twenty-four hours per day for the duration of the study... The guards worked on three-man, eight-hour shifts; remaining in prison environment only during their work shifts, going about usual lives at other times." Zimbardo acted as the prison warden and also observed the behavior of both the prisoners and guards.

During the study, data was collected through videotaping audio recording interactions of participants, and group rating scales for emotional changes in prisoner and guard participants, and personal observations. There was also an individual difference scale, which the participants took the day before the study and also after the study was completed. The individual scale included " F-scale of Authoritarian Personality [1], and the Machiavellianism Scale [2] - as well as areas of possible personality pathology through the newly developed Comrey Personality Scale [3]. The subscales of this latter test consist of: trustworthiness, orderliness, conformity, activity, stability, extroversion, masculinity, and empathy." (Zimbardo, 78).
References:
McLeod, Saul. "Stanford Prison Experiment." Simply Psychology. N.p., 24 Sept. 2016. Web. 27 Sept.
2016.
Banks, Curtis. Haney, Craig. Zimbardo, Philip. "International Journal of Criminology and Penology."
Intropersonal Dynamics in Simulated Prison. (1973) 69-97. Web. 27 Sept. 2016.
Breil, Jeff. Plous, Scott. Jensenius, David. "Prisonexp.org." Stanford Prison Experiment. Social
Psychology Network, 2015. Web. 27 Sept. 2016.