Professionalism/Stanford Prison Experiment


In 1971, Professor Zimbardo started the Stanford Prison Experiment to study the psychological effects of imprisonment. This experiment was funded by the U.S. Office of Naval Research and was of interest to both the U.S. Navy and Marine Corps as an investigation into the causes of conflict between military guards and prisoners.[1]

Experiment SummaryEdit

Preparation for the ExperimentEdit

Professor Zimbardo and his students posted an advertisement in the newspaper asking for volunteers for a study on prison life. They received over 70 volunteers and screened each one individually. His graduate student staff did psychological interviews of each one. They selected two dozen of the most mature, emotionally stable, normal, intelligent young men. Volunteers were arbitrarily divided into prisoners and guards by a flip of a coin. All volunteers were paid at $15 per day for their work.

A prison with bars on cells was recreated at Stanford University using empty offices. The guards were given guidelines but were allowed to improvise any new rules to maintain law order and respect in the prison. All guards were dressed in identical uniforms of khaki, and they carried a whistle around their neck and a billy club borrowed from the police. Guards also wore special sun-glasses.

The prisoners were unexpectedly picked up by the police on a charge of armed robbery, and escorted to the prison. Each prisoner was systematically searched and stripped naked. Prisoners were given a number as their identification in the prison.

When the experiment started, professor Zimbardo and his graduate student staff observed and recorded all the significant daily events. Prisoners and guards were interviewed and tested at various points throughout the study.

Conflict between prisoners and guardsEdit

A rebellion broke out on the morning of the second day. The prisoners removed their stocking caps, ripped off their numbers, and barricaded themselves inside the cells by putting their beds against the door.

The guards were angered and frustrated because the prisoners also began to taunt and curse them. The three guards who were waiting on stand-by call at home came in, and the night shift of guards voluntarily remained on duty to bolster the morning shift. The guards met and decided to treat force with force. They broke into each cell, stripped the prisoners naked, took the beds out, forced the ringleaders of the prisoner rebellion into solitary confinement, and generally began to harass and intimidate the prisoners.

One of the measures the guards used to prevent future rebellion was to set up one cell as a privilege cell. They told those in the other two cells they could not eat in attempt to divide the prisons. The three prisoners least involved in the rebellion were given special privileges.

Termination of the ExperimentEdit

Three prisoners were released in the first 4 days because they had such acute traumatic reactions. The study was terminated on August 20, 1971, the sixth day of the experiment. At that point most of the subjects had indeed become prisoners or guards, no longer able to clearly differentiate between role-playing and self. There were dramatic changes in virtually every aspect of their behavior.

Some implications of this study include that individual behavior is largely under control of social forces and environmental contingencies. It is obvious that the power of the forces in the social environment is underestimated. Prisons of concrete and steel are the metaphors for the social prisons. [2][3]

Research EthicsEdit

Research ApprovalEdit

Most research studies must be approved by a review board to ensure participant safety. Biomedical and psychological research require more extensive review because of potential long term effects. In 1971, Zimbardo attained approval from the Stanford Human Subjects Review Committee, the Stanford Psychology Department, and the Group Effectiveness Branch of the Office of Naval Research.[4] To ensure participant medical safety, the Stanford Student Health Department was notified of the experiment in case any medical attention was needed. After the study, Zimbardo also requested that the American Psychological Association evaluate the ethics of the study; the conclusion stated all ethical guidelines were followed.

Prior to the study, Zimbardo completed approval steps expected of him. However, the results of the experiment suggest otherwise. The review committees that approved the Stanford Prison Experiment were criticized for being too lenient and not predicting dangers. In response to controversial studies such as this, and many other notorious research abuses, the Institutional Review Board was formed in 1974 to protect subjects from physical and psychological harm.[5]

Research StandardsEdit

The American Psychological Association sets guidelines for research methods and conditions. In 2010, they combined previously published ethical guidelines into the Ethical Principles of Psychologists and Code of Conduct.[6] Under Standard 8: Research and Publication, the American Psychological Association prohibits deception of participants unless it would interfere with the results of the experiment. In psychology, deception is used to eliminate demand characteristics, an artifact that refers to participants interpreting the purpose of the experiment and changing their behavior to fit that purpose. Ideally, Zimbardo would have liked to eliminate demand characteristics to study unbiased behavior between prisoners and guards. However, the infamous guard John Wayne, clearly points out that his actions were dictated by demand characteristics.

“I arrived independently at the conclusion that this experiment must have been put together to prove a point, about prisons being a cruel and inhumane place. And I would do my part to help those results come about…Somebody ought to stir things up a bit.”[7]

The presence of demand characteristics has created controversy about the validity of the studies’ findings. Peter Gray, a psychology professor at Boston College, chooses to not include the Stanford Prison Experiment in his widely used introductory Psychology textbook because it did not follow ethical research practices.[8]


Research code of conduct demands that researchers take responsibility in safeguarding participants’ rights and safety. During the experiment, Zimbardo held this responsibility by being able to limit dangerous action or stop the experiment altogether. The prisoners of the experiment were subject to mental torture and isolation under Zimbardo’s watch. Prisoner #8612 requested to leave early because of harsh treatment. Rather than prioritizing his safety, Zimbardo replied by promising better treatment for the prisoner if he became a snitch. This led to prisoner #8612 believing he was trapped and feigning insanity to be released. Zimbardo lost his identity as a research supervisor and became too invested in the experiment’s results. His actions demonstrated his Machiavellian mindset that the ends of his experiment justified the means to attain them. Only Zimbardo and his staff supervised the experiment; thus the assessment of safety remained subjective. Because all parties involved had a stake in the results, participant safety was jeopardized. In this experiment, there was nobody to watch the watchmen. The severity of the experiments conditions were only realized by Zimbardo and his staff when Christina Maslach, an invited psychology graduate student, questioned the morality of the experiment and objected to its continuation.

Lesson to Professional EthicsEdit


Being held accountable for one's actions is the driving force for most ethics. In the Stanford prison experiment, Zimbardo gave the guards of the experiment a role in which they should be held accountable for their actions and decisions, but some guards soon realized that this was not the case. Zimbardo never stepped in to tell the guards to tone down the humiliation or degrading actions. The guards knew that they were following the lead of a legitimate authority figure and that Zimbardo was accepting responsibility for the results of the experiment. This is a common mindset of people when they are asked to do an action that contradicts their morals or ethical codes. This mindset can be seen in the Nazi Regime as they followed the lead of Hitler and was also seen in the Milgram Experiment in one of the compliant participants of the experiment. The participant in this experiment was seemingly asked to give a deadly electric shock to a man in another room. The participant was clearly distraught by the idea of hurting the man in the other room. Though distraught the participant complies in the end and does push the button that he thinks will shock the man in the other room. But before he does so he asks, “Who’s gonna take the responsibility if anything happens to that gentleman? You accept all responsibility?” By asking this question this man is able to convince himself that he is relieved of all accountability and can no longer be held responsible for the action that he is about to make.

Another way that the guards in the prison experiment were made to feel as they were not accountable for their actions, was through the wearing of their highly reflective sunglasses. These sunglasses hid their eyes, the most telling part of a person's feelings and intentions, and also hid most of their faces. These glasses acted as a Ring of Gyges that hid their true identities from the world and allowed them to better embrace the role of a prison guard. By feeling that they were no longer themselves, the guards' personal ethical codes no longer had any dictation over their actions and made them feel unaccountable.

Infrastructure and InstitutionsEdit

In order to keep people accountable for their actions, infrastructures and institutions must be put in place. This was seen shortly after the Stanford prison experiment, as the Institutional Review Board was formed in 1974 in order to protect subjects of psychological studies and keep the psychologists accountable for the results of their experiments. A connected infrastructure and institution that was put in place keep people accountable is the law and the police department. The law tells people what they can and can't do and the police enforce it by arresting and punishing those who break the laws. Each criminal is held accountable for their actions and must pay the price. A professional code of ethics in the workplace has similar powers of accountability. A professional code of ethics provides employees with a benchmark to internally evaluate their actions and provides employers with a benchmark to externally evaluate their employees. Without a professional code of ethics, employees may feel that they have an excuse to act unethically, but with the code of ethics, they have no reason to not be held accountable.


  1. Zimbardo, P. G. (1971). The power and pathology of imprisonment. Congressional Record. (Serial No. 15, October 25, 1971). Hearings before Subcommittee No. 3, of the Committee on the Judiciary, House of Representatives, 92nd Congress, First Session on Corrections, Part II, Prisons, Prison Reform and Prisoners' Rights: California.Washington, DC: U.S. Government Printing Office.
  2. Haney, C., Banks, W. C., & Zimbardo, P. G. (1973). Interpersonal dynamics in a simulated prison. International Journal of Criminology and Penology, 1, 69-97.
  4. "Stanford Prison Experiment FAQs". 2015. 
  5. "Historical Cases of Unethical Research". University of North Dakota. 2001. 
  6. "Ethical Principles of Psychologists and Code of Conduct". American Psychology Association. 2010. 
  7. "Feature Film – The Stanford Prison Experiment". BBC. 2013. 
  8. "Why Zimbardo’s Prison Experiment Isn’t in My Textbook". 2013.