Review: A Study of Prisoners and Guards in a Simulated Prison

Review: A Study of Prisoners and Guards in a Simulated Prison

Wednesday, January 06, 2021

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Journal Article Review

This is a basic journal article review and provides a template for reviewing articles using the Stanford Prison Experiment as an example.

Independent Variable- The independent variable in the Stanford Prison Experiment (SPE) was the random assignment of participants to the role of prison guards or prisoners. This was referred to in the experiment as the ‘single treatment variable’ which relates to the different roles as conditions of the experiment.

Dependent Variable- The dependent variable is the effect or measured outcome of the SPE experiment. This variable was both the measure of individual and group behavioral changes.

Control Group — No control group present.

Experimental Group — The experimental group consisted of 24 subjects who were chosen based on stable psychological and physical attributes. This group was chosen based on having the least number of anti-social behaviors such as drug use and physical ailments. A group of 22 was chosen with 2 alternatives and the chosen group was randomly assigned roles of guard or prisoner.

Research Method — The research method was a simulated prison environment utilizing a single treatment variable of participants being assigned the role of “guard” or “prisoner” condition. The concept was to create close proximity to real imprisonment and as such the conditions were provided different directives such as guards having to maintain order but without using physical violence or certain forms of psychological abuse such as racism. Prisoners were given directives that were intended to mimic the real prison environment such as asking to go to the bathroom or writing a letter. The behavior of both groups was observed, recorded, and analyzed.

Data Collection Technique — The data collection method was observational in nature using video and audio recordings of the simulated prison environment. At the end of the experiment, the groups were debriefed and their experiences were recorded. One interesting aspect of the data collection was the fact that the video and audio were recorded using both covert and overt methods.

Sample (size, breakdown, where were they found) — The sample size was 24 with 22 participating subjects. The sample was taken from mostly college students who were large of middle-class socioeconomic status and Caucasian. There was one Oriental subject. The 24 subjects were chosen from a pool of 75 individuals who were found through a “newspaper ad asking for male volunteers to participate in a psychological study of “prison life” in return for the payment of $15 per day” (Haney, Banks, & Zimbardo, 1973). Only 24 participants were chosen due to the extensive questionnaire concerning, “family background, physical and mental health history, prior experience and attitudinal propensities with respect to sources of psychopathology (including their involvements in crime)” (Haney, Banks, & Zimbardo, 1973). Twenty-four participants passed the examination phase and 22 were chosen to participate with two alternatives.

Population — are the findings generalizable to that population? — While clearly something is taking place at the psychological level of the individual participants it is unclear if these findings are generalizable to that population. There are other factors that would need to be considered such as the demographics of most real prisons.

Hypothesis — According to Zimbardo (1973), “No specific hypotheses were advanced other than the general one that assignment to the treatment of “guard” or “prisoner” would result in significantly different reactions on behavioral measures of interaction, emotional measures of mood state and pathology, attitudes toward self, as well as other indices of coping and adaptation to this novel situation” (Haney, Banks, & Zimbardo, 1973). The researchers were attempting to show that prison roles would cause changes in psychology.

Did they prove their hypothesis? Explain. — Within the context of this experiment, the researchers did prove their hypothesis because behavior and psychology did incur change from being assigned prison roles. However, this success is based on the simulated prison environment, not an actual prison environment.

Findings — Researchers characterized the guards as:
approximately 30% of the guards as ‘cruel and tough’;
about 50% were ‘tough but fair’;
and less than 20% were ‘good guards’ (generally helpful and kind to the prisoners) (Haney, Banks, & Zimbardo, 1973).
Prisoners were depressed and were 90% focused on the prison conditions.
Power was found to be the overarching factor that was causal to behavioral changes.

Extraneous Variables — Important concepts to consider in this experiment would be a small sample size, sample size not matching the demographics of real prisoners, and a short time of the experiment (6 days).

Research Flaws — The major flaws in the experiment were the undersized sample, validity issues, and unethical behavior. The sample of 22 participants is not large enough to create statistical significance. There are also validity issues with the experiment such as demographics of the simulated environment, not matching a real-world prison. There are many validity issues in question such as the ratio of guards to prisoners and lack of violence that is indicative of a simulation, not a real world prison. As well, the experiment was fraught with ethical violations from the beginning such as exposing people to maltreatment and researchers becoming too involved in the scenarios.

What could have been done more efficiently? This experiment could not have been done more efficiently due to ethical issues. The experiment needed to take place in a real prison in order to have been more efficient and effective. Observing a simulated environment created conditions that allowed for efficiency but reduced realism.

Could the study be replicated? This study cannot be replicated due to it being considered unethical.

Does more research need to be done? Explain. Despite the ethical implications of the experiment, more research needs to be done in this area because the experiment was successful in showing that when people are placed in either role of prisoner or guard in a prison environment their behavior and psychology are impacted. What is in question is the degree of this impact and how the differences in demographics of real prisons would impact these outcomes.

What directions should later research take in this area? New research should be committed in this area but within the prison system with willing participants. Perhaps participants having video cameras in cells or by using interview methods.

Generalizability — Can the research be generalized to the entire population or a smaller group? Because the SPE was cut short and was not designed well, one must be careful of making generalizations. It would be safe at this point to consider the fact that prison environments are forces for change both psychologically and behaviorally. However, specific behavioral generalizations cannot be made at this time because SPE was not a close enough approximation of a real prison environment.

What did you think of the study design? This study, despite being unethical and poorly designed, was a strong example for future prison studies. The changes that occurred in the college male demographic was surprising. Despite the fact that these participants were chosen for the lack of violent pathologies, they became dangerously close to physical violence. This warrants closer study.

What did you think of the findings? The research team credits authority or power with the primary causes of changes in behavior and psychology. In the terms of the researchers:

The use of power was self-aggrandizing and self-perpetuating. The guard power derived initially from an arbitrary and randomly assigned label, was intensified whenever there was any perceived threat by the prisoners and this new level subsequently became the baseline from which further hostility and harassment would begin. The most hostile guards on each shift moved spontaneously into the leadership roles of giving orders and deciding on punishments. They became role models whose behavior was emulated by other members of the shift.

While power appears to be the culprit, this appears to be an oversimplification of human behavior. For example, rather than power being the sole cause, limits of educational understanding of prisoners and how to manage them would also be a likely factor. If it were true that power alone was constantly self corrupting it, then one would expect that everyone in power would eventually become corrupt. This does not happen which tends to show that there are more complex variables at work such as psychological factors, like violent upbringing, poverty, lack of education, and many other elements that may impact one's perception of power and use.

What might you have done differently? A replication of the experiment would really necessitate a larger sample and more validity. This would not be possible in a simulated environment so instead, a long-term observation of a prison environment would be needed. A 5-year study that follows the incarceration of many different real prisoners from their entrance to the prison to the end of the study.


Haney, C., Banks, C., & Zimbardo, P. (1973, September). A Study of Prisoners and Guards in a Simulated Prison. Naval Research Reviews, 1–17.

Photo by Eric Ward on Unsplash


Vincent Triola. Wed, Jan 06, 2021. Review: A Study of Prisoners and Guards in a Simulated Prison Retrieved from

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