Stanford Prison Experiment: Zimbardo’s Famous Study
Saul McLeod, PhD
Editor-in-Chief for Simply Psychology
BSc (Hons) Psychology, MRes, PhD, University of Manchester
Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.
Learn about our Editorial Process
Olivia Guy-Evans, MSc
Associate Editor for Simply Psychology
BSc (Hons) Psychology, MSc Psychology of Education
Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.
On This Page:
- The experiment was conducted in 1971 by psychologist Philip Zimbardo to examine situational forces versus dispositions in human behavior.
- 24 young, healthy, psychologically normal men were randomly assigned to be “prisoners” or “guards” in a simulated prison environment.
- The experiment had to be terminated after only 6 days due to the extreme, pathological behavior emerging in both groups. The situational forces overwhelmed the dispositions of the participants.
- Pacifist young men assigned as guards began behaving sadistically, inflicting humiliation and suffering on the prisoners. Prisoners became blindly obedient and allowed themselves to be dehumanized.
- The principal investigator, Zimbardo, was also transformed into a rigid authority figure as the Prison Superintendent.
- The experiment demonstrated the power of situations to alter human behavior dramatically. Even good, normal people can do evil things when situational forces push them in that direction.
Zimbardo and his colleagues (1973) were interested in finding out whether the brutality reported among guards in American prisons was due to the sadistic personalities of the guards (i.e., dispositional) or had more to do with the prison environment (i.e., situational).
For example, prisoners and guards may have personalities that make conflict inevitable, with prisoners lacking respect for law and order and guards being domineering and aggressive.
Alternatively, prisoners and guards may behave in a hostile manner due to the rigid power structure of the social environment in prisons.
Zimbardo predicted the situation made people act the way they do rather than their disposition (personality).
To study people’s roles in prison situations, Zimbardo converted a basement of the Stanford University psychology building into a mock prison.
He advertised asking for volunteers to participate in a study of the psychological effects of prison life.
The 75 applicants who answered the ad were given diagnostic interviews and personality tests to eliminate candidates with psychological problems, medical disabilities, or a history of crime or drug abuse.
24 men judged to be the most physically & mentally stable, the most mature, & the least involved in antisocial behaviors were chosen to participate.
The participants did not know each other prior to the study and were paid $15 per day to take part in the experiment.
Participants were randomly assigned to either the role of prisoner or guard in a simulated prison environment. There were two reserves, and one dropped out, finally leaving ten prisoners and 11 guards.
Prisoners were treated like every other criminal, being arrested at their own homes, without warning, and taken to the local police station. They were fingerprinted, photographed and ‘booked.’
Then they were blindfolded and driven to the psychology department of Stanford University, where Zimbardo had had the basement set out as a prison, with barred doors and windows, bare walls and small cells. Here the deindividuation process began.
When the prisoners arrived at the prison they were stripped naked, deloused, had all their personal possessions removed and locked away, and were given prison clothes and bedding. They were issued a uniform, and referred to by their number only.
The use of ID numbers was a way to make prisoners feel anonymous. Each prisoner had to be called only by his ID number and could only refer to himself and the other prisoners by number.
Their clothes comprised a smock with their number written on it, but no underclothes. They also had a tight nylon cap to cover their hair, and a locked chain around one ankle.
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 sunglasses, to make eye contact with prisoners impossible.
Three guards worked shifts of eight hours each (the other guards remained on call). Guards were instructed to do whatever they thought was necessary to maintain law and order in the prison and to command the respect of the prisoners. No physical violence was permitted.
Zimbardo observed the behavior of the prisoners and guards (as a researcher), and also acted as a prison warden.
Within a very short time both guards and prisoners were settling into their new roles, with the guards adopting theirs quickly and easily.
Asserting Authority
Within hours of beginning the experiment, some guards began to harass prisoners. At 2:30 A.M. prisoners were awakened from sleep by blasting whistles for the first of many “counts.”
The counts served as a way to familiarize the prisoners with their numbers. More importantly, they provided a regular occasion for the guards to exercise control over the prisoners.
The prisoners soon adopted prisoner-like behavior too. They talked about prison issues a great deal of the time. They ‘told tales’ on each other to the guards.
They started taking the prison rules very seriously, as though they were there for the prisoners’ benefit and infringement would spell disaster for all of them. Some even began siding with the guards against prisoners who did not obey the rules.
Physical Punishment
The prisoners were taunted with insults and petty orders, they were given pointless and boring tasks to accomplish, and they were generally dehumanized.
Push-ups were a common form of physical punishment imposed by the guards. One of the guards stepped on the prisoners” backs while they did push-ups, or made other prisoners sit on the backs of fellow prisoners doing their push-ups.
Asserting Independence
Because the first day passed without incident, the guards were surprised and totally unprepared for the rebellion which broke out on the morning of the second day.
During the second day of the experiment, 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 called in reinforcements. The three guards who were waiting on stand-by duty came in and the night shift guards voluntarily remained on duty.
Putting Down the Rebellion
The guards retaliated by using a fire extinguisher which shot a stream of skin-chilling carbon dioxide, and they forced the prisoners away from the doors. Next, the guards broke into each cell, stripped the prisoners naked and took the beds out.
The ringleaders of the prisoner rebellion were placed into solitary confinement. After this, the guards generally began to harass and intimidate the prisoners.
Special Privileges
One of the three cells was designated as a “privilege cell.” The three prisoners least involved in the rebellion were given special privileges. The guards gave them back their uniforms and beds and allowed them to wash their hair and brush their teeth.
Privileged prisoners also got to eat special food in the presence of the other prisoners who had temporarily lost the privilege of eating. The effect was to break the solidarity among prisoners.
Consequences of the Rebellion
Over the next few days, the relationships between the guards and the prisoners changed, with a change in one leading to a change in the other. Remember that the guards were firmly in control and the prisoners were totally dependent on them.
As the prisoners became more dependent, the guards became more derisive towards them. They held the prisoners in contempt and let the prisoners know it. As the guards’ contempt for them grew, the prisoners became more submissive.
As the prisoners became more submissive, the guards became more aggressive and assertive. They demanded ever greater obedience from the prisoners. The prisoners were dependent on the guards for everything, so tried to find ways to please the guards, such as telling tales on fellow prisoners.
Prisoner #8612
Less than 36 hours into the experiment, Prisoner #8612 began suffering from acute emotional disturbance, disorganized thinking, uncontrollable crying, and rage.
After a meeting with the guards where they told him he was weak, but offered him “informant” status, #8612 returned to the other prisoners and said “You can”t leave. You can’t quit.”
Soon #8612 “began to act ‘crazy,’ to scream, to curse, to go into a rage that seemed out of control.” It wasn’t until this point that the psychologists realized they had to let him out.
A Visit from Parents
The next day, the guards held a visiting hour for parents and friends. They were worried that when the parents saw the state of the jail, they might insist on taking their sons home. Guards washed the prisoners, had them clean and polish their cells, fed them a big dinner and played music on the intercom.
After the visit, rumors spread of a mass escape plan. Afraid that they would lose the prisoners, the guards and experimenters tried to enlist help and facilities of the Palo Alto police department.
The guards again escalated the level of harassment, forcing them to do menial, repetitive work such as cleaning toilets with their bare hands.
Catholic Priest
Zimbardo invited a Catholic priest who had been a prison chaplain to evaluate how realistic our prison situation was. Half of the prisoners introduced themselves by their number rather than name.
The chaplain interviewed each prisoner individually. The priest told them the only way they would get out was with the help of a lawyer.
Prisoner #819
Eventually, while talking to the priest, #819 broke down and began to cry hysterically, just like two previously released prisoners had.
The psychologists removed the chain from his foot, the cap off his head, and told him to go and rest in a room that was adjacent to the prison yard. They told him they would get him some food and then take him to see a doctor.
While this was going on, one of the guards lined up the other prisoners and had them chant aloud:
“Prisoner #819 is a bad prisoner. Because of what Prisoner #819 did, my cell is a mess, Mr. Correctional Officer.”
The psychologists realized #819 could hear the chanting and went back into the room where they found him sobbing uncontrollably. The psychologists tried to get him to agree to leave the experiment, but he said he could not leave because the others had labeled him a bad prisoner.
Back to Reality
At that point, Zimbardo said, “Listen, you are not #819. You are [his name], and my name is Dr. Zimbardo. I am a psychologist, not a prison superintendent, and this is not a real prison. This is just an experiment, and those are students, not prisoners, just like you. Let’s go.”
He stopped crying suddenly, looked up and replied, “Okay, let’s go,“ as if nothing had been wrong.
An End to the Experiment
Zimbardo (1973) had intended that the experiment should run for two weeks, but on the sixth day, it was terminated, due to the emotional breakdowns of prisoners, and excessive aggression of the guards.
Christina Maslach, a recent Stanford Ph.D. brought in to conduct interviews with the guards and prisoners, strongly objected when she saw the prisoners being abused by the guards.
Filled with outrage, she said, “It’s terrible what you are doing to these boys!” Out of 50 or more outsiders who had seen our prison, she was the only one who ever questioned its morality.
Zimbardo (2008) later noted, “It wasn’t until much later that I realized how far into my prison role I was at that point — that I was thinking like a prison superintendent rather than a research psychologist.“
This led him to prioritize maintaining the experiment’s structure over the well-being and ethics involved, thereby highlighting the blurring of roles and the profound impact of the situation on human behavior.
Here’s a quote that illustrates how Philip Zimbardo, initially the principal investigator, became deeply immersed in his role as the “Stanford Prison Superintendent (April 19, 2011):
“By the third day, when the second prisoner broke down, I had already slipped into or been transformed into the role of “Stanford Prison Superintendent.” And in that role, I was no longer the principal investigator, worried about ethics. When a prisoner broke down, what was my job? It was to replace him with somebody on our standby list. And that’s what I did. There was a weakness in the study in not separating those two roles. I should only have been the principal investigator, in charge of two graduate students and one undergraduate.”
According to Zimbardo and his colleagues, the Stanford Prison Experiment revealed how people will readily conform to the social roles they are expected to play, especially if the roles are as strongly stereotyped as those of the prison guards.
Because the guards were placed in a position of authority, they began to act in ways they would not usually behave in their normal lives.
The “prison” environment was an important factor in creating the guards’ brutal behavior (none of the participants who acted as guards showed sadistic tendencies before the study).
Therefore, the findings support the situational explanation of behavior rather than the dispositional one.
Zimbardo proposed that two processes can explain the prisoner’s “final submission.”
Deindividuation may explain the behavior of the participants; especially the guards. This is a state when you become so immersed in the norms of the group that you lose your sense of identity and personal responsibility.
The guards may have been so sadistic because they did not feel what happened was down to them personally – it was a group norm. They also may have lost their sense of personal identity because of the uniform they wore.
Also, learned helplessness could explain the prisoner’s submission to the guards. The prisoners learned that whatever they did had little effect on what happened to them. In the mock prison the unpredictable decisions of the guards led the prisoners to give up responding.
After the prison experiment was terminated, Zimbardo interviewed the participants. Here’s an excerpt:
‘Most of the participants said they had felt involved and committed. The research had felt “real” to them. One guard said, “I was surprised at myself. I made them call each other names and clean the toilets out with their bare hands. I practically considered the prisoners cattle and I kept thinking I had to watch out for them in case they tried something.” Another guard said “Acting authoritatively can be fun. Power can be a great pleasure.” And another: “… during the inspection I went to Cell Two to mess up a bed which a prisoner had just made and he grabbed me, screaming that he had just made it and that he was not going to let me mess it up. He grabbed me by the throat and although he was laughing I was pretty scared. I lashed out with my stick and hit him on the chin although not very hard, and when I freed myself I became angry.”’
Most of the guards found it difficult to believe that they had behaved in the brutal ways that they had. Many said they hadn’t known this side of them existed or that they were capable of such things.
The prisoners, too, couldn’t believe that they had responded in the submissive, cowering, dependent way they had. Several claimed to be assertive types normally.
When asked about the guards, they described the usual three stereotypes that can be found in any prison: some guards were good, some were tough but fair, and some were cruel.
A further explanation for the behavior of the participants can be described in terms of reinforcement. The escalation of aggression and abuse by the guards could be seen as being due to the positive reinforcement they received both from fellow guards and intrinsically in terms of how good it made them feel to have so much power.
Similarly, the prisoners could have learned through negative reinforcement that if they kept their heads down and did as they were told, they could avoid further unpleasant experiences.
Critical Evaluation
Ecological validity.
The Stanford Prison Experiment is criticized for lacking ecological validity in its attempt to simulate a real prison environment. Specifically, the “prison” was merely a setup in the basement of Stanford University’s psychology department.
The student “guards” lacked professional training, and the experiment’s duration was much shorter than real prison sentences. Furthermore, the participants, who were college students, didn’t reflect the diverse backgrounds typically found in actual prisons in terms of ethnicity, education, and socioeconomic status.
None had prior prison experience, and they were chosen due to their mental stability and low antisocial tendencies. Additionally, the mock prison lacked spaces for exercise or rehabilitative activities.
Demand characteristics
Demand characteristics could explain the findings of the study. Most of the guards later claimed they were simply acting. Because the guards and prisoners were playing a role, their behavior may not be influenced by the same factors which affect behavior in real life. This means the study’s findings cannot be reasonably generalized to real life, such as prison settings. I.e, the study has low ecological validity.
One of the biggest criticisms is that strong demand characteristics confounded the study. Banuazizi and Movahedi (1975) found that the majority of respondents, when given a description of the study, were able to guess the hypothesis and predict how participants were expected to behave.
This suggests participants may have simply been playing out expected roles rather than genuinely conforming to their assigned identities.
In addition, revelations by Zimbardo (2007) indicate he actively encouraged the guards to be cruel and oppressive in his orientation instructions prior to the start of the study. For example, telling them “they [the prisoners] will be able to do nothing and say nothing that we don’t permit.”
He also tacitly approved of abusive behaviors as the study progressed. This deliberate cueing of how participants should act, rather than allowing behavior to unfold naturally, indicates the study findings were likely a result of strong demand characteristics rather than insightful revelations about human behavior.
However, there is considerable evidence that the participants did react to the situation as though it was real. For example, 90% of the prisoners’ private conversations, which were monitored by the researchers, were on the prison conditions, and only 10% of the time were their conversations about life outside of the prison.
The guards, too, rarely exchanged personal information during their relaxation breaks – they either talked about ‘problem prisoners,’ other prison topics, or did not talk at all. The guards were always on time and even worked overtime for no extra pay.
When the prisoners were introduced to a priest, they referred to themselves by their prison number, rather than their first name. Some even asked him to get a lawyer to help get them out.
Fourteen years after his experience as prisoner 8612 in the Stanford Prison Experiment, Douglas Korpi, now a prison psychologist, reflected on his time and stated (Musen and Zimbardo 1992):
“The Stanford Prison Experiment was a very benign prison situation and it promotes everything a normal prison promotes — the guard role promotes sadism, the prisoner role promotes confusion and shame”.
Sample bias
The study may also lack population validity as the sample comprised US male students. The study’s findings cannot be applied to female prisons or those from other countries. For example, America is an individualist culture (where people are generally less conforming), and the results may be different in collectivist cultures (such as Asian countries).
Carnahan and McFarland (2007) have questioned whether self-selection may have influenced the results – i.e., did certain personality traits or dispositions lead some individuals to volunteer for a study of “prison life” in the first place?
All participants completed personality measures assessing: aggression, authoritarianism, Machiavellianism, narcissism, social dominance, empathy, and altruism. Participants also answered questions on mental health and criminal history to screen out any issues as per the original SPE.
Results showed that volunteers for the prison study, compared to the control group, scored significantly higher on aggressiveness, authoritarianism, Machiavellianism, narcissism, and social dominance. They scored significantly lower on empathy and altruism.
A follow-up role-playing study found that self-presentation biases could not explain these differences. Overall, the findings suggest that volunteering for the prison study was influenced by personality traits associated with abusive tendencies.
Zimbardo’s conclusion may be wrong
While implications for the original SPE are speculative, this lends support to a person-situation interactionist perspective, rather than a purely situational account.
It implies that certain individuals are drawn to and selected into situations that fit their personality, and that group composition can shape behavior through mutual reinforcement.
Contributions to psychology
Another strength of the study is that the harmful treatment of participants led to the formal recognition of ethical guidelines by the American Psychological Association. Studies must now undergo an extensive review by an institutional review board (US) or ethics committee (UK) before they are implemented.
Most institutions, such as universities, hospitals, and government agencies, require a review of research plans by a panel. These boards review whether the potential benefits of the research are justifiable in light of the possible risk of physical or psychological harm.
These boards may request researchers make changes to the study’s design or procedure, or, in extreme cases, deny approval of the study altogether.
Contribution to prison policy
A strength of the study is that it has altered the way US prisons are run. For example, juveniles accused of federal crimes are no longer housed before trial with adult prisoners (due to the risk of violence against them).
However, in the 25 years since the SPE, U.S. prison policy has transformed in ways counter to SPE insights (Haney & Zimbardo, 1995):
- Rehabilitation was abandoned in favor of punishment and containment. Prison is now seen as inflicting pain rather than enabling productive re-entry.
- Sentencing became rigid rather than accounting for inmates’ individual contexts. Mandatory minimums and “three strikes” laws over-incarcerate nonviolent crimes.
- Prison construction boomed, and populations soared, disproportionately affecting minorities. From 1925 to 1975, incarceration rates held steady at around 100 per 100,000. By 1995, rates tripled to over 600 per 100,000.
- Drug offenses account for an increasing proportion of prisoners. Nonviolent drug offenses make up a large share of the increased incarceration.
- Psychological perspectives have been ignored in policymaking. Legislators overlooked insights from social psychology on the power of contexts in shaping behavior.
- Oversight retreated, with courts deferring to prison officials and ending meaningful scrutiny of conditions. Standards like “evolving decency” gave way to “legitimate” pain.
- Supermax prisons proliferated, isolating prisoners in psychological trauma-inducing conditions.
The authors argue psychologists should reengage to:
- Limit the use of imprisonment and adopt humane alternatives based on the harmful effects of prison environments
- Assess prisons’ total environments, not just individual conditions, given situational forces interact
- Prepare inmates for release by transforming criminogenic post-release contexts
- Address socioeconomic risk factors, not just incarcerate individuals
- Develop contextual prediction models vs. focusing only on static traits
- Scrutinize prison systems independently, not just defer to officials shaped by those environments
- Generate creative, evidence-based reforms to counter over-punitive policies
Psychology once contributed to a more humane system and can again counter the U.S. “rage to punish” with contextual insights (Haney & Zimbardo, 1998).
Evidence for situational factors
Zimbardo (1995) further demonstrates the power of situations to elicit evil actions from ordinary, educated people who likely would never have done such things otherwise. It was another situation-induced “transformation of human character.”
- Unit 731 was a covert biological and chemical warfare research unit of the Japanese army during WWII.
- It was led by General Shiro Ishii and involved thousands of doctors and researchers.
- Unit 731 set up facilities near Harbin, China to conduct lethal human experimentation on prisoners, including Allied POWs.
- Experiments involved exposing prisoners to things like plague, anthrax, mustard gas, and bullets to test biological weapons. They infected prisoners with diseases and monitored their deaths.
- At least 3,000 prisoners died from these brutal experiments. Many were killed and dissected.
- The doctors in Unit 731 obeyed orders unquestioningly and conducted these experiments in the name of “medical science.”
- After the war, the vast majority of doctors who participated faced no punishment and went on to have prestigious careers. This was largely covered up by the U.S. in exchange for data.
- It shows how normal, intelligent professionals can be led by situational forces to systematically dehumanize victims and conduct incredibly cruel and lethal experiments on people.
- Even healers trained to preserve life used their expertise to destroy lives when the situational forces compelled obedience, nationalism, and wartime enmity.
Evidence for an interactionist approach
The results are also relevant for explaining abuses by American guards at Abu Ghraib prison in Iraq.
An interactionist perspective recognizes that volunteering for roles as prison guards attracts those already prone to abusive tendencies, which are intensified by the prison context.
This counters a solely situationist view of good people succumbing to evil situational forces.
Ethical Issues
The study has received many ethical criticisms, including lack of fully informed consent by participants as Zimbardo himself did not know what would happen in the experiment (it was unpredictable). Also, the prisoners did not consent to being “arrested” at home. The prisoners were not told partly because final approval from the police wasn’t given until minutes before the participants decided to participate, and partly because the researchers wanted the arrests to come as a surprise. However, this was a breach of the ethics of Zimbardo’s own contract that all of the participants had signed.
Protection of Participants
Participants playing the role of prisoners were not protected from psychological harm, experiencing incidents of humiliation and distress. For example, one prisoner had to be released after 36 hours because of uncontrollable bursts of screaming, crying, and anger.
Here’s a quote from Philip G. Zimbardo, taken from an interview on the Stanford Prison Experiment’s 40th anniversary (April 19, 2011):
“In the Stanford prison study, people were stressed, day and night, for 5 days, 24 hours a day. There’s no question that it was a high level of stress because five of the boys had emotional breakdowns, the first within 36 hours. Other boys that didn’t have emotional breakdowns were blindly obedient to corrupt authority by the guards and did terrible things to each other. And so it is no question that that was unethical. You can’t do research where you allow people to suffer at that level.”
“After the first one broke down, we didn’t believe it. We thought he was faking. There was actually a rumor he was faking to get out. He was going to bring his friends in to liberate the prison. And/or we believed our screening procedure was inadequate, [we believed] that he had some mental defect that we did not pick up. At that point, by the third day, when the second prisoner broke down, I had already slipped into or been transformed into the role of “Stanford Prison Superintendent.” And in that role, I was no longer the principal investigator, worried about ethics.”
However, in Zimbardo’s defense, the emotional distress experienced by the prisoners could not have been predicted from the outset.
Approval for the study was given by the Office of Naval Research, the Psychology Department, and the University Committee of Human Experimentation.
This Committee also did not anticipate the prisoners’ extreme reactions that were to follow. Alternative methodologies were looked at that would cause less distress to the participants but at the same time give the desired information, but nothing suitable could be found.
Withdrawal
Although guards were explicitly instructed not to physically harm prisoners at the beginning of the Stanford Prison Experiment, they were allowed to induce feelings of boredom, frustration, arbitrariness, and powerlessness among the inmates.
This created a pervasive atmosphere where prisoners genuinely believed and even reinforced among each other, that they couldn’t leave the experiment until their “sentence” was completed, mirroring the inescapability of a real prison.
Even though two participants (8612 and 819) were released early, the impact of the environment was so profound that prisoner 416, reflecting on the experience two months later, described it as a “prison run by psychologists rather than by the state.”
Extensive group and individual debriefing sessions were held, and all participants returned post-experimental questionnaires several weeks, then several months later, and then at yearly intervals. Zimbardo concluded there were no lasting negative effects.
Zimbardo also strongly argues that the benefits gained from our understanding of human behavior and how we can improve society should outbalance the distress caused by the study.
However, it has been suggested that the US Navy was not so much interested in making prisons more human and were, in fact, more interested in using the study to train people in the armed services to cope with the stresses of captivity.
Discussion Questions
What are the effects of living in an environment with no clocks, no view of the outside world, and minimal sensory stimulation?
Consider the psychological consequences of stripping, delousing, and shaving the heads of prisoners or members of the military. Whattransformations take place when people go through an experience like this?
The prisoners could have left at any time, and yet, they didn’t. Why?
After the study, how do you think the prisoners and guards felt?
If you were the experimenter in charge, would you have done this study? Would you have terminated it earlier? Would you have conducted a follow-up study?
Frequently Asked Questions
What happened to prisoner 8612 after the experiment.
Douglas Korpi, as prisoner 8612, was the first to show signs of severe distress and demanded to be released from the experiment. He was released on the second day, and his reaction to the simulated prison environment highlighted the study’s ethical issues and the potential harm inflicted on participants.
After the experiment, Douglas Korpi graduated from Stanford University and earned a Ph.D. in clinical psychology. He pursued a career as a psychotherapist, helping others with their mental health struggles.
Why did Zimbardo not stop the experiment?
Zimbardo did not initially stop the experiment because he became too immersed in his dual role as the principal investigator and the prison superintendent, causing him to overlook the escalating abuse and distress among participants.
It was only after an external observer, Christina Maslach, raised concerns about the participants’ well-being that Zimbardo terminated the study.
What happened to the guards in the Stanford Prison Experiment?
In the Stanford Prison Experiment, the guards exhibited abusive and authoritarian behavior, using psychological manipulation, humiliation, and control tactics to assert dominance over the prisoners. This ultimately led to the study’s early termination due to ethical concerns.
What did Zimbardo want to find out?
Zimbardo aimed to investigate the impact of situational factors and power dynamics on human behavior, specifically how individuals would conform to the roles of prisoners and guards in a simulated prison environment.
He wanted to explore whether the behavior displayed in prisons was due to the inherent personalities of prisoners and guards or the result of the social structure and environment of the prison itself.
What were the results of the Stanford Prison Experiment?
The results of the Stanford Prison Experiment showed that situational factors and power dynamics played a significant role in shaping participants’ behavior. The guards became abusive and authoritarian, while the prisoners became submissive and emotionally distressed.
The experiment revealed how quickly ordinary individuals could adopt and internalize harmful behaviors due to their assigned roles and the environment.
Banuazizi, A., & Movahedi, S. (1975). Interpersonal dynamics in a simulated prison: A methodological analysis. American Psychologist, 30 , 152-160.
Carnahan, T., & McFarland, S. (2007). Revisiting the Stanford prison experiment: Could participant self-selection have led to the cruelty? Personality and Social Psychology Bulletin, 33, 603-614.
Drury, S., Hutchens, S. A., Shuttlesworth, D. E., & White, C. L. (2012). Philip G. Zimbardo on his career and the Stanford Prison Experiment’s 40th anniversary. History of Psychology , 15 (2), 161.
Griggs, R. A., & Whitehead, G. I., III. (2014). Coverage of the Stanford Prison Experiment in introductory social psychology textbooks. Teaching of Psychology, 41 , 318 –324.
Haney, C., Banks, W. C., & Zimbardo, P. G. (1973). A study of prisoners and guards in a simulated prison . Naval Research Review , 30, 4-17.
Haney, C., & Zimbardo, P. (1998). The past and future of U.S. prison policy: Twenty-five years after the Stanford Prison Experiment. American Psychologist, 53 (7), 709–727.
Musen, K. & Zimbardo, P. (1992) (DVD) Quiet Rage: The Stanford Prison Experiment Documentary.
Zimbardo, P. G. (Consultant, On-Screen Performer), Goldstein, L. (Producer), & Utley, G. (Correspondent). (1971, November 26). Prisoner 819 did a bad thing: The Stanford Prison Experiment [Television series episode]. In L. Goldstein (Producer), Chronolog. New York, NY: NBC-TV.
Zimbardo, P. G. (1973). On the ethics of intervention in human psychological research: With special reference to the Stanford prison experiment. Cognition , 2 (2), 243-256.
Zimbardo, P. G. (1995). The psychology of evil: A situationist perspective on recruiting good people to engage in anti-social acts. Japanese Journal of Social Psychology , 11 (2), 125-133.
Zimbardo, P.G. (2007). The Lucifer effect: Understanding how good people turn evil . New York, NY: Random House.
Further Information
- Reicher, S., & Haslam, S. A. (2006). Rethinking the psychology of tyranny: The BBC prison study. The British Journal of Social Psychology, 45 , 1.
- Coverage of the Stanford Prison Experiment in introductory psychology textbooks
- The Stanford Prison Experiment Official Website
- Bipolar Disorder
- Therapy Center
- When To See a Therapist
- Types of Therapy
- Best Online Therapy
- Best Couples Therapy
- Managing Stress
- Sleep and Dreaming
- Understanding Emotions
- Self-Improvement
- Healthy Relationships
- Student Resources
- Personality Types
- Guided Meditations
- Verywell Mind Insights
- 2024 Verywell Mind 25
- Mental Health in the Classroom
- Editorial Process
- Meet Our Review Board
- Crisis Support
The Stanford Prison Experiment
Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."
Cara Lustik is a fact-checker and copywriter.
- Participants
- Setting and Procedure
In August of 1971, psychologist Philip Zimbardo and his colleagues created an experiment to determine the impacts of being a prisoner or prison guard. The Stanford Prison Experiment, also known as the Zimbardo Prison Experiment, went on to become one of the best-known studies in psychology's history —and one of the most controversial.
This study has long been a staple in textbooks, articles, psychology classes, and even movies. Learn what it entailed, what was learned, and the criticisms that have called the experiment's scientific merits and value into question.
Purpose of the Stanford Prison Experiment
Zimbardo was a former classmate of the psychologist Stanley Milgram . Milgram is best known for his famous obedience experiment , and Zimbardo was interested in expanding upon Milgram's research. He wanted to further investigate the impact of situational variables on human behavior.
Specifically, the researchers wanted to know how participants would react when placed in a simulated prison environment. They wondered if physically and psychologically healthy people who knew they were participating in an experiment would change their behavior in a prison-like setting.
Participants in the Stanford Prison Experiment
To carry out the experiment, researchers set up a mock prison in the basement of Stanford University's psychology building. They then selected 24 undergraduate students to play the roles of both prisoners and guards.
Participants were chosen from a larger group of 70 volunteers based on having no criminal background, no psychological issues , and no significant medical conditions. Each volunteer agreed to participate in the Stanford Prison Experiment for one to two weeks in exchange for $15 a day.
Setting and Procedures
The simulated prison included three six-by-nine-foot prison cells. Each cell held three prisoners and included three cots. Other rooms across from the cells were utilized for the jail guards and warden. One tiny space was designated as the solitary confinement room, and yet another small room served as the prison yard.
The 24 volunteers were randomly assigned to either the prisoner or guard group. Prisoners were to remain in the mock prison 24 hours a day during the study. Guards were assigned to work in three-man teams for eight-hour shifts. After each shift, they were allowed to return to their homes until their next shift.
Researchers were able to observe the behavior of the prisoners and guards using hidden cameras and microphones.
Results of the Stanford Prison Experiment
So what happened in the Zimbardo experiment? While originally slated to last 14 days, it had to be stopped after just six due to what was happening to the student participants. The guards became abusive and the prisoners began to show signs of extreme stress and anxiety .
It was noted that:
- While the prisoners and guards were allowed to interact in any way they wanted, the interactions were hostile or even dehumanizing.
- The guards began to become aggressive and abusive toward the prisoners while the prisoners became passive and depressed.
- Five of the prisoners began to experience severe negative emotions , including crying and acute anxiety, and had to be released from the study early.
Even the researchers themselves began to lose sight of the reality of the situation. Zimbardo, who acted as the prison warden, overlooked the abusive behavior of the jail guards until graduate student Christina Maslach voiced objections to the conditions in the simulated prison and the morality of continuing the experiment.
One possible explanation for the results of this experiment is the idea of deindividuation , which states that being part of a large group can make us more likely to perform behaviors we would otherwise not do on our own.
Impact of the Zimbardo Prison Experiment
The experiment became famous and was widely cited in textbooks and other publications. According to Zimbardo and his colleagues, the Stanford Prison Experiment demonstrated the powerful role that the situation can play in human behavior.
Because the guards were placed in a position of power, they began to behave in ways they would not usually act in their everyday lives or other situations. The prisoners, placed in a situation where they had no real control , became submissive and depressed.
In 2011, the Stanford Alumni Magazine featured a retrospective of the Stanford Prison Experiment in honor of the experiment’s 40th anniversary. The article contained interviews with several people involved, including Zimbardo and other researchers as well as some of the participants.
In the interviews, Richard Yacco, one of the prisoners in the experiment, suggested that the experiment demonstrated the power that societal roles and expectations can play in a person's behavior.
In 2015, the experiment became the topic of a feature film titled The Stanford Prison Experiment that dramatized the events of the 1971 study.
Criticisms of the Stanford Prison Experiment
In the years since the experiment was conducted, there have been a number of critiques of the study. Some of these include:
Ethical Issues
The Stanford Prison Experiment is frequently cited as an example of unethical research. It could not be replicated by researchers today because it fails to meet the standards established by numerous ethical codes, including the Code of Ethics of the American Psychological Association .
Why was Zimbardo's experiment unethical?
Zimbardo's experiment was unethical due to a lack of fully informed consent, abuse of participants, and lack of appropriate debriefings. More recent findings suggest there were other significant ethical issues that compromise the experiment's scientific standing, including the fact that experimenters may have encouraged abusive behaviors.
Lack of Generalizability
Other critics suggest that the study lacks generalizability due to a variety of factors. The unrepresentative sample of participants (mostly white and middle-class males) makes it difficult to apply the results to a wider population.
Lack of Realism
The Zimbardo Prison Experiment is also criticized for its lack of ecological validity. Ecological validity refers to the degree of realism with which a simulated experimental setup matches the real-world situation it seeks to emulate.
While the researchers did their best to recreate a prison setting, it is simply not possible to perfectly mimic all the environmental and situational variables of prison life. Because there may have been factors related to the setting and situation that influenced how the participants behaved, it may not truly represent what might happen outside of the lab.
Recent Criticisms
More recent examination of the experiment's archives and interviews with participants have revealed major issues with the research method , design, and procedures used. Together, these call the study's validity, value, and even authenticity into question.
These reports, including examinations of the study's records and new interviews with participants, have also cast doubt on some of its key findings and assumptions.
Among the issues described:
- One participant suggested that he faked a breakdown so he could leave the experiment because he was worried about failing his classes.
- Other participants also reported altering their behavior in a way designed to "help" the experiment .
- Evidence suggests that the experimenters encouraged the guards' behavior and played a role in fostering the abusive actions of the guards.
In 2019, the journal American Psychologist published an article debunking the famed experiment. It detailed the study's lack of scientific merit and concluded that the Stanford Prison Experiment was "an incredibly flawed study that should have died an early death."
In a statement posted on the experiment's official website, Zimbardo maintains that these criticisms do not undermine the main conclusion of the study—that situational forces can alter individual actions both in positive and negative ways.
The Stanford Prison Experiment is well known both inside and outside the field of psychology . While the study has long been criticized for many reasons, more recent criticisms of the study's procedures shine a brighter light on the experiment's scientific shortcomings.
Stanford University. About the Stanford Prison Experiment .
Stanford Prison Experiment. 2. Setting up .
Sommers T. An interview with Philip Zimbardo . The Believer.
Ratnesar R. The menace within . Stanford Magazine.
Jabbar A, Muazzam A, Sadaqat S. An unveiling the ethical quandaries: A critical analysis of the Stanford Prison Experiment as a mirror of Pakistani society . J Bus Manage Res . 2024;3(1):629-638.
Horn S. Landmark Stanford Prison Experiment criticized as a sham . Prison Legal News .
Bartels JM. The Stanford Prison Experiment in introductory psychology textbooks: A content analysis . Psychol Learn Teach . 2015;14(1):36-50. doi:10.1177/1475725714568007
American Psychological Association. Ecological validity .
Blum B. The lifespan of a lie . Medium .
Le Texier T. Debunking the Stanford Prison Experiment . Am Psychol . 2019;74(7):823-839. doi:10.1037/amp0000401
Stanford Prison Experiment. Philip Zimbardo's response to recent criticisms of the Stanford Prison Experiment .
By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."
Learn More Psychology
Zimbardo's stanford prison experiment, zimbardo's stanford prison experiment revealed how social roles can influence our behavior. we look at how it was conducted and what we can learn from it..
Permalink Print |
- Asch: Social Influence, Conforming in Groups
- Social Influence
- Minority Influence
Subjects were randomly assigned to play the role of "prisoner" or "guard". Those assigned to play the role of guard were given sticks and sunglasses; those assigned to play the prisoner role were arrested by the Palo Alto police department, deloused, forced to wear chains and prison garments, and transported to the basement of the Stanford psychology department, which had been converted into a makeshift jail.
Several of the guards became progressively more sadistic - particularly at night when they thought the cameras were off, despite being picked by chance out of the same pool as the prisoners.
The experiment very quickly got out of hand. A riot broke out on day two. One prisoner developed a psychosomatic rash all over his body upon finding out that his "parole" had been turned down. After only 6 days (of a planned two weeks), the experiment was shut down, for fear that one of the prisoners would be seriously hurt.
Although the intent of the experiment was to examine captivity, its result has been used to demonstrate the impressionability and obedience of people when provided with a legitimizing ideology and social and institutional support. It is also used to illustrate cognitive dissonance theory and the power of seniority/authority.
It can be argued that the conclusions that Professor Zimbardo and others have drawn from the Stanford Prison Experiment are not valid. Professor Zimbardo acknowleges that he was not merely an observer in the experiment but an active participant and in some cases it is clear he was influencing the direction the experiment went.
For example, Professor Zimbardo cites the fact that all of the "guards" wore sunglasses as an example of their dehumanization. However, the sunglasses were not spontaneously chosen as apparel by the students; they were given to them by Professor Zimbardo. The student "guards" were also issued batons by Professor Zimbardo on their first day, which may have predisposed them to consider physical force as an acceptable means of running the "prison".
Professor Zimbardo also acknowleges initiating several procedures that do not occur in actual prisons, such as blindfolding incoming "prisoners", making them wear women's clothing, not allowing them to wear underwear, not allowing them to look out windows, and not allowing them to use their names. Professor Zimbardo justifies this by stating that prison is a confusing and dehumanizing experience and it was necessary to enact these procedures to put the "prisoners" in the proper frame of mind. However, it opens the question of whether Professor Zimbardo's simulation is an accurate reflection of the reality of incarceration or a reflection of Professor Zimbardo's preconceived opinions of what actual incarceration is like.
Does Zimbardo's study explain Abu Ghraib abuse?
The human rights abuses that occurred at the Abu Ghraib prison under the authority of the American armed forces in the aftermath of the 2003 Iraq war may be a recent example of what happened in the experiment in real life. Soldiers were thrust into the role of prison guards and began to sadistically torment prisoners there and at other detention sites in Afghanistan and Iraq. Many of the specific acts of humiliation were similar to those that occurred in the Stanford Prison Experiment, according to Zimbardo.
This theory has been challenged by allegations by Seymour Hersh in the New Yorker that these soldiers were in fact acting under direct orders of their superiors as part of a top secret Pentagon intelligence gathering program authorized by Secretary of Defense Donald Rumsfeld.
Continue Reading
- Source: https://en.wikipedia.org/wiki/Stanford_Prison_Experiment
Which Archetype Are You?
Are You Angry?
Windows to the Soul
Are You Stressed?
Attachment & Relationships
Memory Like A Goldfish?
31 Defense Mechanisms
Slave To Your Role?
Are You Fixated?
Interpret Your Dreams
How to Read Body Language
How to Beat Stress and Succeed in Exams
More on Influence
Are You Authoritarian?
How Theodor Adorno's F-scale aimed to identify fascism and authoritarian...
Authoritarian Personality
False Memories
How false memories are created and can affect our ability to recall events.
Brainwashed
Brainwashing, its origins and its use in cults and media.
Psychology Of Influence
What causes us to obey to authority figures such as police, teachers and...
Influenced By Stories?
A study reveals how the Big Five personality dimensions influence audiences'...
Sign Up for Unlimited Access
- Psychology approaches, theories and studies explained
- Body Language Reading Guide
- How to Interpret Your Dreams Guide
- Self Hypnosis Downloads
- Plus More Member Benefits
You May Also Like...
Making conversation, persuasion with ingratiation, nap for performance, why do we dream, master body language, dark sense of humor linked to intelligence, psychology of color, psychology guides.
Learn Body Language Reading
How To Interpret Your Dreams
Overcome Your Fears and Phobias
Psychology topics, learn psychology.
- Access 2,200+ insightful pages of psychology explanations & theories
- Insights into the way we think and behave
- Body Language & Dream Interpretation guides
- Self hypnosis MP3 downloads and more
- Behavioral Approach
- Eye Reading
- Stress Test
- Cognitive Approach
- Fight-or-Flight Response
- Neuroticism Test
© 2024 Psychologist World. Parts licensed under GNU FDL . Home About Contact Us Terms of Use Privacy & Cookies Hypnosis Scripts Sign Up
Learning Materials
- Business Studies
- Combined Science
- Computer Science
- Engineering
- English Literature
- Environmental Science
- Human Geography
- Macroeconomics
- Microeconomics
- Stanford Prison Experiment
Simple acts such as wearing a uniform to school or choosing one of your parents’ careers as your own career path can be interpreted as conformity by psychologists. The truth is that humans are likely to conform to others’ beliefs and ideas to make them our own. Conformity has great social implications and given how often humans engage in it. Psychological research has aimed to explain conformity for the last decades. One of the most famous psychological experiments on the topic was the Stanford prison study conducted by Zimbardo in 1971.
Millions of flashcards designed to help you ace your studies
- Cell Biology
When we switch to the autonomous state, we no longer feel personally responsible for our actions.
Were guards allowed to harm the prisoners during Zimbardo's study?
What percentage of the guards acted abusively, as noted by Erich Fromm (1973)?
Participants in Zimbardo's study were debriefed and had an opportunity to talk about their experience.
How long did the Zimbardo's experiment last?
Haslam and Reicher (2002) replicated the findings of the Stanford Prison experiment and found that ‘guards’ and ‘prisoners’ automatically conformed to their roles.
Participants could choose which role they were assigned in Zimbardo's experiment.
Zimbardo’s experiment is an example of __________
Zimbardo protected participants from physical and psychological harm.
Achieve better grades quicker with Premium
Geld-zurück-Garantie, wenn du durch die Prüfung fällst
Review generated flashcards
to start learning or create your own AI flashcards
Start learning or create your own AI flashcards
StudySmarter Editorial Team
Team Stanford Prison Experiment Teachers
- 9 minutes reading time
- Checked by StudySmarter Editorial Team
- Approaches in Psychology
- Basic Psychology
- Ainsworth's Strange Situation
- Alternatives To The Medical Model
- Animal Studies of Attachment
- Attachment Figures
- Attachment and Later Relationships
- Auditory Attention
- BBC Prison Study
- Behaviour Strategies For Autism
- Biological Explanations for Autism
- Bowlby Theory of Maternal Deprivation
- Bowlby’s Monotropic Theory
- Caregiver Infant Interactions
- Categorising Mental Disorders
- Classic and Contemporary Research into Memory
- Classic and Contemporary Research into Obedience
- Cognitive Approach to Depression
- Cognitive Interview
- Conformity to Social Roles
- Contemporary Research Language Of Psychopaths
- Context-Dependent Memory
- Cross-Cultural Altruism
- Cue-Dependent Forgetting
- Cultural Variations in Attachment
- Definitions of Abnormality
- Deprivation Privation and Separation
- Developmental Pattern of Digit Span
- Developmental Psychology in Memory
- Developmental Psychology in Obedience/Prejudice
- Disobedience and Whistle-Blowing
- Dispositional Factors Social Influence
- Explanations for Prejudice
- Explanations of Attachment
- Eyewitness Identification under Stress
- Eyewitness Testimony
- Features of Memory
- Forgetting in Psychology
- Gould Bias in IQ Testing
- Hazan and Shaver
- History of Mental Health
- Inattentional Blindness
- Individual Differences In Autism
- Individual Differences In Ideological Attitudes And Prejudice
- Individual Differences In Memory
- Informational Social Influence
- Issues and Debates in the Context of Obedience/Prejudice
- Learning Theory
- Long-Term Memory
- Measuring Individual Differences
- Medical Model
- Milgram Experiment
- Milgram’s Variation Studies
- Minority Influence and Social Change
- Multi-Store Model of Memory
- Normative Social Influence
- Phobia Treatment
- Piliavin Subway Study
- Prosocial Behaviour And Altruism
- Psychopathology
- Realistic Conflict Theory
- Reconstruction From Memory In Naturalistic Environments
- Reconstructive Memory
- Resistance to Social Influence
- Rethinking the Psychology of Tyranny
- Romanian Orphan Studies
- Schema Theory
- Semantic Knowledge in Patient HM
- Short-Term Memory
- Situational Influence
- Social Identity Theory
- Social Impact Theory
- Social Influence
- Stages of Attachment
- Studies on Interference
- The Robbers Cave Experiment
- Theories of Autism
- Working Memory Model
- Biological Bases of Behavior
- Biopsychology
- Careers in Psychology
- Clinical Psychology
- Cognition and Development
- Cognitive Psychology
- Data Handling and Analysis
- Developmental Psychology
- Eating Behaviour
- Emotion and Motivation
- Famous Psychologists
- Forensic Psychology
- Health Psychology
- Individual Differences Psychology
- Issues and Debates in Psychology
- Personality in Psychology
- Psychological Treatment
- Psychology and Environment
- Relationships
- Research Methods in Psychology
- Schizophrenia
- Scientific Foundations of Psychology
- Scientific Investigation
- Sensation and Perception
- Social Context of Behaviour
- Social Psychology
Jump to a key chapter
- This explanation reviews the Stanford prison experiment by Zimbardo (1971). First, some background information is provided.
- Second, the explanation explores the Standford prison experiment variables .
- Moving on from this, the Standford prison experiment is described.
- The Standford prison experiment results are presented.
- Then, the significance of the Standford prison experiment is reviewed.
- The explanation closes with a presentation of the Standford prison experiment's ethical issues.
Stanford Prison Experiment: Background
Historically there have been many instances of people perpetrating human rights abuses when they are in a position of authority such as soldiers, guards, police officers or teachers. This is why finding out why authority figures become abusive is an important topic of research in social psychology .
One of the most famous and controversial experiments regarding social conformity was Phillip Zimbardo’s (1971) Stanford Prison Experiment, which investigated the power of social norms and roles and the influence of authority figures. During the 1970s in the USA, there was a lot of public debate about the rapidly growing prison population and police brutality. This prompted Zimbardo to investigate the extent to which a person’s behaviour would change depending on the role they take on.
Zimbardo showed that the temporary situations that surround an individual could influence anyone to act negatively ( situational influence ) more so than their personality ( dispositional influence ). By creating a realistic environment and power dynamic between the two groups, Zimbardo created pressure to conform to specific group roles.
Stanford Prison Experiment Variables
The Standford prison experiments divided participants into two groups: 'prisoners' and 'guards'. This reflects the independent variable of the study. Participants were randomly assigned to the two groups, and there was no control group. Zimbardo’s team gave the different groups clothing and accessories that matched their role. The ‘guards’ received uniforms, sunglasses and batons and the ‘prisoners’ wore a robe with a number and shackles. The ‘prisoners’ were confined day and night, whereas the ‘guards’ could go home.
The study’s dependent variable was the effect that the role assignation had on individuals’ behaviour. The study has been criticised for not having a clearly defined dependent variable since Zimbardo wanted to see what would happen. This lack of dependent variables sets the study as an observational study with no experimental design.
Participants in the Stanford prison experiment
Twenty-four subjects were recruited through a local newspaper advertisement, where participants would be given a reward of $15 per day to participate in a study about ‘prison life’. They were mostly white, middle-class male university students. None of them had been in prison before. Participants were tested for any pre-existing psychological or medical conditions. After Zimbardo tested and briefed the candidates, he sent them home.
Stanford Prison Experiment: Description
During the summer break at Stanford University, Zimbardo built a mock prison in the hallways of the psychology department. After having randomly assigned the role of either prisoner or guard to the subjects, he had the ‘prisoners’ arrested by the actual local Palo Alto police without warning. They were blindfolded and brought to a real police station to have their fingerprints and picture taken, then ‘charged’ with assault and brought to the mock prison.
Here the guards made the ‘prisoners’ get undressed and put on shackles and robes, then confined them in the mock ‘cells’ that had no amenities except for a mattress. They stayed in the prison day and night, whereas ‘guards’ worked in shifts and could return home when they were not on duty. The guards were told not to harm the ‘prisoners’ or withhold food or drink from them. However, throughout the study, violence started to escalate:
Day 1 : Uneventful.
Day 2 : The prisoners barricaded themselves in a room with their mattresses. A cycle of retaliation between the two groups began. One ‘prisoner’ has a nervous breakdown.
Days 3-5 : The ‘guards’ found increasingly extreme methods to establish control over the ‘prisoners’ by:
- Locking those who didn’t comply in a cupboard.
- Waking ‘prisoners’ up in the middle of the night for headcounts.
- Stripping ‘prisoners’ naked and using a fire extinguisher on them.
- Verbally assaulting and humiliating them.
- Making ‘prisoners’ defecate in a bucket and not allowing them to empty it.
- Withholding mattresses.
Day 6 : The study was cut short by Zimbardo.
This experiment is considered to be an example of conformity to social roles because there was a difference between the participants’ behaviour while they were in the ‘prison’ context and outside of it. During the study, the more extreme ‘guards’ encouraged the peaceful ones to use more force. They admitted to acting in ways that they afterwards said were different from their normal behaviour outside of the study. Subsequently, the ‘prisoners’ became more depressed and submissive over time, to the point where they reported thinking they deserved to be in prison, even though they had done nothing wrong.
Stanford Prison Experiment Results
Zimbardo’s experiment is an example of normative social influence and situational influence . All of the participants started as part of the same group but, when randomly assigned new social roles, started to identify and behave without explicit prompting.
Zimbardo suggests that there was a degree of cognitive dissonance, meaning participants behaved in ways they didn’t want to behave and started to identify with their roles.
Nobody died during the experiment, as Zimbardo cut it short when the behaviour of the guards started to get out of hand. All participants were debriefed by Zimbardo’s team, giving them the opportunity to discuss the events of the study. Surprisingly, Zimbardo never faced legal charges despite endangering the participants under his care.
Significance of the Stanford Prison Experiment
Although Zimbardo’s study was so influential that it determined policy in the USA prison system, Zimbardo’s study and his interpretation of the results have been extensively criticised.
Researchers Banuazizi and Mohavedi (1975) claimed that the participants in the study were only playing up to stereotypes and not to actual societal roles, hence, limiting the validity of the study. Another researcher, Peter Gray (2013), commented that the guards were encouraged to act in a psychologically oppressive manner, suggesting that in some way, Zimbardo may have produced the results through the instructions he gave the ‘guards’.
This is called a demand characteristic, as participants may have subconsciously acted in the way that is expected of them.
Erich Fromm (1973) criticised Zimbardo’s experiment for exaggerating the results of the study; specifically, two-thirds of the guards did not act abusively, as opposed to the one-third who did. Additionally, Haslam and Reicher (2002) aimed to replicate the experiment in the BBC prison study. In this study, the ‘guards’ and ‘prisoners’ did not automatically conform to their roles and this led to a collapse of the prison system in the study.
The possibility of Zimbardo’s recruitment process having produced a biased sample was investigated by Carnahan (2007) in a replication study where he repeated the original recruitment process but also recruited a control group by putting out an ad for a ‘psychological study. In the subsequent personality tests of the candidates, it was found that those candidates who had responded to the ‘prison life’ had scored higher in tests of aggression and social dominance and lower in empathy than the control group.
Despite the limitations that the study presents, the observed behaviour is of significance in societies. The study provided evidence that people adapt to certain situations they find themselves in. This effect is bigger when individuals adapt to highly stereotypical roles. Further, the study showed that individuals would continue with their roles to the point that they would exert physical punishments on others.
These types of behaviours have been detected across history. During the holocaust, over 6 million Jews were murdered by the german absolutist regiment during World War II. Although these days many people will argue that they would have helped the Jews, the reality was that many individuals conformed with the regiment and engage in very destructive behaviours.
This is evidence of the relevance and significance that the Standford prison experiment.
Stanford Prison Experiment Ethical Issues
The Stanford Prison Experiment shaped ethical standards for psychological experiments because it was such a cautionary example of what not to do. Although the participants reported distress and mental trauma throughout the study, Zimbardo did not listen to them. His objectivity was compromised because he had taken on the role of the prison warden. Based on this, future research started to be controlled and tracked by ethical committees. These committees ensure that ethical standards are met.
Today, the experiment would not have been possible because of two reasons:
- The study did not protect participants from harm since they were humiliated and mistreated.
- The study did not ask for written informed consent.
These points reflect the ethical standards that studies need to comply with today to be accepted by ethics commissions.
Stanford Prison Experiment - Key takeaways
- Zimbardo (1971) investigated conformity to social roles in his Stanford Prison Experiment.
- The Stanford Prison Experiment demonstrates situational influence.
- The Stanford Prison Experiment used questionable research practices that led to stricter ethics regulations in the field of psychology.
- Additional studies have shown that dispositional factors also determine whether or to which extent people conform to social roles.
- Some criticisms of the Stanford Prison Experiment are that it is possible that the sample was biased and that the situation did not produce real behaviour.
Flashcards in Stanford Prison Experiment 9
Haslam and Reicher (2002) replicated the findings of the Stanford Prison experiment and found that ‘guards’ and ‘prisoners’ automatically conformed to their roles.
Learn faster with the 9 flashcards about Stanford Prison Experiment
Sign up for free to gain access to all our flashcards.
Already have an account? Log in
Frequently Asked Questions about Stanford Prison Experiment
What was the Stanford prison experiment?
One of the most famous and controversial experiments regarding social conformity was Phillip Zimbardo’s (1971) Stanford prison experiment, which investigated the power of social norms and roles and the influence of authority figures.
When was the Stanford prison experiment?
What was the aim of the Stanford prison experiment?
Zimbardo showed that the temporary situations that surround an individual can influence anyone to act negatively (situational influence), more so than their personality (dispositional influence). By creating a realistic environment and power dynamic between two groups, Zimbardo created pressure to conform to specific group roles.
Why was the stanford prison experiment unethical?
The Stanford Prison Experiment shaped ethical standards for psychological experiments because it was such a cautionary example of what not to do. Although the participants reported distress and mental trauma through the study, Zimbardo did not listen to them. His objectivity was compromised because he had taken on the role of the prison warden. This created conflict with his responsibility as the lead researcher to safeguard the physical and mental health of his subjects. When a participant asked to leave the study, Zimbardo denied his request and kept him confined against his will. Since the Stanford Prison Experiment, ethics commissions have been established in the UK and USA to pre-approve all psychological research.
What type of experiment was the Sanford prison study?
The Stanford prison study was an observational experiment with no experimental design, due to the lack of a dependent variable.
Test your knowledge with multiple choice flashcards
Were guards allowed to harm the prisoners during Zimbardo's study?
That was a fantastic start!
You can do better, sign up to create your own flashcards.
Access over 700 million learning materials
Study more efficiently with flashcards
Get better grades with AI
Already have an account? Log in
Keep learning, you are doing great.
Discover learning materials with the free StudySmarter app
About StudySmarter
StudySmarter is a globally recognized educational technology company, offering a holistic learning platform designed for students of all ages and educational levels. Our platform provides learning support for a wide range of subjects, including STEM, Social Sciences, and Languages and also helps students to successfully master various tests and exams worldwide, such as GCSE, A Level, SAT, ACT, Abitur, and more. We offer an extensive library of learning materials, including interactive flashcards, comprehensive textbook solutions, and detailed explanations. The cutting-edge technology and tools we provide help students create their own learning materials. StudySmarter’s content is not only expert-verified but also regularly updated to ensure accuracy and relevance.
Team Psychology Teachers
Study anywhere. Anytime.Across all devices.
Create a free account to save this explanation..
Save explanations to your personalised space and access them anytime, anywhere!
By signing up, you agree to the Terms and Conditions and the Privacy Policy of StudySmarter.
Sign up to highlight and take notes. It’s 100% free.
Join over 22 million students in learning with our StudySmarter App
The first learning app that truly has everything you need to ace your exams in one place
- Flashcards & Quizzes
- AI Study Assistant
- Study Planner
- Smart Note-Taking
Advertisement
How the Stanford Prison Experiment Worked
- Share Content on Facebook
- Share Content on LinkedIn
- Share Content on Flipboard
- Share Content on Reddit
- Share Content via Email
The Takeaways
Zimbardo realized that rather than a neutral scenario, he created a prison much like real prisons, where corrupt and cruel behavior didn't occur in a vacuum, but flowed from the rules and principles of the institution to the people who carried out those principles. The behavior of the guards and prisoners wasn't dictated by some inherent internal trait, but by the situation they were in. The theory that external circumstances are the primary drivers of human behavior is known as situationist theory . Zimbardo didn't form the theory, but his experiment and later writings helped popularize it.
Experimental ethics are also an issue to consider. The Stanford Human Subjects Review Committee and Zimbardo's superiors approved the experiment — another layer of authority complicit in the experiment's outcome (it's like situationist "Inception") — but experimental ethics are more rigorous today. A modern institutional review board would likely never approve such an experiment without major modifications. Zimbardo has said that he feels the initial experiment was ethical (all the participants understood what they'd signed up for and consented), but that he suffered an ethical lapse when he allowed it to continue beyond the first emotional breakdown of a prisoner [source: Stanford Prison Experiment ].
The idea that humans have an inherent tendency toward abuse of authority and submission to authority is not ruled out by the experiment, however. The Stanford Prison Experiment is closely related to another psychological experiment that's as infamous: Stanley Milgram's obedience to authority experiment . In fact, Zimbardo and Milgram were high school classmates and colleagues at Yale University. In the obedience experiment, volunteers were directed to press buttons delivering increasingly powerful, and eventually fake lethal shocks to another person at the direction of a researcher. A large percentage of volunteers went along with the researcher's demands. However, like the Stanford Prison Experiment, the ethics, methodology and conclusions of Milgram's experiment have been called into question recently . And both experiments influenced changes in the regulation and ethical guidelines of studies with human subjects [sources: Zimbardo et al. , Defiesta ].
Zimbardo's conclusion was that we are not so much inherently "evil," but that we will commit heinous acts if encouraged to do so by systems that enable or encourage them. He took his results to the U.S. House of Representatives shortly after the experiment ended, testifying before a subcommittee on prison reform. His primary argument was that given the power institutions have to dictate the behavior of the people within them, it's necessary to reform those institutions to avoid those abuses. He suggested better training and pay for guards, better protection for prisoners' human rights , and specific training programs that could include role-playing scenarios to help guards learn to deal humanely with prisoners (and weed out the most sadistic among guards) [source: House of Representatives ]. The 2003 scandal surrounding prisoner treatment at the Iraqi prison Abu Ghraib, which mirrored the actions of Zimbardo's guards in disturbing ways, suggests that the experiment is not a relic of the past but still relevant to the way people are treated in modern civilian and military prisons.
Zimbardo's testimony also reflected his belief that researchers should not remain impartial observers, but should engage in social and political ways to act on the discoveries they make and seek ways to improve the world [source: Zimbardo et al. ].
Remember that part about Zimbardo's experiment lacking a control group? In 2002, the BBC broadcasted a similar experiment, one that conformed with modern ethics and removed many of the initial biases, such as dehumanizing the prisoners and giving the guards implements of authority. In many ways it could be seen as a control group for the Stanford Prison Experiment. The outcome? The prisoners stuck together, and the guards became disorganized. Like the Stanford Prison Experiment, this one ended early, because a group of participants planned to take over the prison, and the researchers anticipated violence [source: Reicher & Haslam ].
Author's Note: How the Stanford Prison Experiment Worked
Much of the appeal of the Stanford Prison Experiment, aside from the dark, voyeuristic thrill of learning how the subjects acted, is how easily it lets you insert yourself into the narrative Zimbardo created. What kind of guard would you be? How would you react when another guard did something sadistic? How would you react as a prisoner? Would you organize your fellow prisoners, or work against them to gain favor with the guards? Or maybe you envision yourself in Zimbardo's position, pulling the strings in your scenario. How would you have changed the conditions to alter the subjects' behavior? Could you redesign the experiment to be more ethical?
Related Articles
- How Prisons Work
- 'Made in the USA' Behind Bars: Is Prison Labor Really 'Slave Labor'?
- How Solitary Confinement Works
- Ramen Replacing Smokes as Preferred Prison Currency?
- California Released Thousands of Prisoners Early — Guess How That Turned Out
More Great Links
- The Milgram Experiment
- Carnahan, Thomas et al. "Revisiting the Stanford Prison Experiment: Could Participant Self-Selection Have Led to the Cruelty?" Personality and Social Psychology Bulletin. Vol. 33, issue 5. May 1, 2007. (June 22, 2017) http://journals.sagepub.com/doi/abs/10.1177/0146167206292689
- Defiesta, Nick. "When Psychologists 'Go Wrong.'" Yale Daily News. Sept. 28, 2011. (July 14, 2017) http://yaledailynews.com/blog/2011/09/28/when-psychologists-go-wrong/
- Haney, Craig et al. "Interpersonal Dynamics in a Simulated Prison." International Journal of Criminology and Penology. 1973. (June 10, 2017) http://pdf.prisonexp.org/ijcp1973.pdf
- House of Representatives. "Hearings Before Subcommittee No. 3 of the Committee on the Judiciary, House of Representatives, Ninety-Second Congress, First Session on Corrections Part 2, Prisons, Prison Reform, and Prisoner Rights: California." Oct. 25, 1971. (June 12, 2017) http://pdf.prisonexp.org/congress.pdf
- Konnikova, Maria. "The Real Lesson of the Stanford Prison Experiment." The New Yorker. June 12, 2015. (June 12, 2017) http://www.newyorker.com/science/maria-konnikova/the-real-lesson-of-the-stanford-prison-experiment
- Ratnesar, Romesh. "The Menace Within." Stanford Magazine. July/August 2011. (July 14, 2017) https://alumni.stanford.edu/get/page/magazine/article/?article_id=40741
- Reicher, Stephen & S. Alexander Haslam. "Rethinking the psychology of tyranny: The BBC prison study." British Journal of Social Psychology. 2006. (June 12, 2017) http://www.bbcprisonstudy.org/pdfs/BJSP(2006)Tyrannny.pdf
- Sedacca, Matthew. "The Man Who Played With Absolute Power." Feb. 16, 2017. (July 6, 2017) http://nautil.us/issue/45/power/the-man-who-played-with-absolute-power
- Stanford Prison Experiment. "The Story." (June 12, 2017) http://www.prisonexp.org/the-story
- Zimbardo, Philip G. "A Situationist Perspective on the Psychlogy of Evil." "The Social Psychology of Good and Evil," Gilford Press. 2004. (June 12, 2017) http://pdf.prisonexp.org/evil.pdf
- Zimbardo, Philip G. et al. "Reflections on the Stanford Prison Experiment: Genesis, Transformations, Consequences." In T. Blass (Ed.),"Obedience to Authority: Current Perspectives on the Milgram Paradigm" (pp. 193-237). Lawrence Erlbaum Assoc. 2000. (June 12, 2017) http://pdf.prisonexp.org/blass.pdf
Please copy/paste the following text to properly cite this HowStuffWorks.com article:
study guides for every class
That actually explain what's on your next test, stanford prison experiment, from class:, social psychology.
The Stanford Prison Experiment was a psychological study conducted in 1971 by Philip Zimbardo, which investigated the effects of perceived power and authority on human behavior. The experiment assigned college students to play the roles of guards and prisoners in a simulated prison environment, revealing how quickly individuals could conform to their assigned roles and exhibit extreme behaviors. This study is crucial for understanding social influence and obedience, as it showcases how situational factors can drive individuals to act in ways that are inconsistent with their personal morals.
congrats on reading the definition of Stanford Prison Experiment . now let's actually learn it.
5 Must Know Facts For Your Next Test
- The experiment was conducted at Stanford University and involved 24 male students who were randomly assigned to either the role of guard or prisoner.
- The study was intended to last two weeks but was terminated after just six days due to the extreme and distressing behavior exhibited by participants.
- Participants assigned to the role of guards became increasingly abusive and authoritarian, while those assigned as prisoners experienced psychological distress and emotional breakdowns.
- Zimbardo himself played the role of the prison superintendent, which contributed to the ethical concerns raised about his lack of oversight and intervention.
- The results highlighted the power of situational factors over personality traits, suggesting that ordinary people can engage in harmful behaviors when placed in certain environments.
Review Questions
- The Stanford Prison Experiment vividly demonstrated how social roles can dictate behavior by showing that participants quickly adopted their assigned roles as guards or prisoners. Those assigned as guards exhibited authoritarian behavior and aggression, while prisoners displayed submissiveness and emotional distress. This shift occurred even without prior training or explicit instructions, highlighting how strong situational forces can override personal morals and values.
- The ethical implications of the Stanford Prison Experiment are significant, particularly concerning participant welfare and informed consent. Participants were subjected to severe psychological stress and humiliation without adequate safeguards or debriefing. Zimbardo's dual role as researcher and prison superintendent blurred lines between oversight and experimentation, leading to criticisms that participants did not fully understand the risks involved. These concerns have prompted stricter ethical guidelines in psychological research today.
- The findings from the Stanford Prison Experiment provide critical insights into conformity and obedience by demonstrating that individuals may engage in harmful behaviors when influenced by authority figures or group dynamics. The rapid transformation of normal college students into abusive guards underscores how situational pressures can lead to actions that contradict personal ethics. This experiment contributes to our broader understanding of how social environments can shape behavior, emphasizing that ordinary individuals are capable of extreme actions under certain conditions.
Related terms
Social Roles : Social roles are the expectations and behaviors associated with a specific position or status within a social group, influencing how individuals behave in different contexts.
Deindividuation : Deindividuation is a psychological state characterized by a loss of self-awareness and individual accountability, often occurring in group settings where individuals feel anonymous.
Authority refers to the legitimate power or right to make decisions, command obedience, and enforce rules within a given context, impacting how people behave and conform.
" Stanford Prison Experiment " also found in:
Subjects ( 3 ).
- AP Psychology
- Intro to Brain and Behavior
- Intro to Psychology
© 2024 Fiveable Inc. All rights reserved.
Ap® and sat® are trademarks registered by the college board, which is not affiliated with, and does not endorse this website..
COMMENTS
In Zimbardo's Stanford Prison experiment, participants were randomly assigned to one of two groups, guards or prisoners. after a few days, the prisoners staged a failed revolt and were consequently punished and humiliated by the guards. ... Therefore, the findings support the situational explanation of behavior rather than the dispositional one.
A prisoner is being arrested for the experiment. Prisoners in a cell A prisoner breaks down. The Stanford Prison Experiment (SPE) was a psychology experiment to see the effects of becoming a prisoner or a prison guard on human behaviour and psychology. [1] The experiment ran from 15 to 21 August 1971. It was led by Dr Philip Zimbardo at Stanford University.
Stanford Prison Experiment, a social psychology study in which college students became prisoners or guards in a simulated prison environment.The experiment, funded by the U.S. Office of Naval Research, took place at Stanford University in August 1971. It was intended to measure the effect of role-playing, labeling, and social expectations on behaviour over a period of two weeks.
Guards walk through the prison "yard," the school hallway. It didn't take long for the experiment to spiral out of control. PrisonExp.org. The Stanford Prison Experiment is so well-known that even people who've never taken a course in psychology have heard of it, and anyone who does study psychology learns about it in introductory courses. The events of the experiment are told and retold among ...
An unveiling the ethical quandaries: A critical analysis of the Stanford Prison Experiment as a mirror of Pakistani society. J Bus Manage Res. 2024;3(1):629-638. Horn S. Landmark Stanford Prison Experiment criticized as a sham. Prison Legal News. Bartels JM. The Stanford Prison Experiment in introductory psychology textbooks: A content analysis.
Subjects were randomly assigned to play the role of "prisoner" or "guard". Those assigned to play the role of guard were given sticks and sunglasses; those assigned to play the prisoner role were arrested by the Palo Alto police department, deloused, forced to wear chains and prison garments, and transported to the basement of the Stanford psychology department, which had been converted into a ...
The Stanford prison experiment (SPE) was a psychological experiment performed during August 1971.It was a two-week simulation of a prison environment that examined the effects of situational variables on participants' reactions and behaviors. Stanford University psychology professor Philip Zimbardo managed the research team who administered the study. [1] ...
This explanation reviews the Stanford prison experiment by Zimbardo (1971). First, some background information is provided. Second, the explanation explores the Standford prison experiment variables. Moving on from this, the Standford prison experiment is described. The Standford prison experiment results are presented.
The Stanford Prison Experiment is closely related to another psychological experiment that's as infamous: Stanley Milgram's obedience to authority experiment. In fact, Zimbardo and Milgram were high school classmates and colleagues at Yale University. In the obedience experiment, volunteers were directed to press buttons delivering increasingly ...
The Stanford Prison Experiment was a psychological study conducted in 1971 by Philip Zimbardo, which investigated the effects of perceived power and authority on human behavior. The experiment assigned college students to play the roles of guards and prisoners in a simulated prison environment, revealing how quickly individuals could conform to their assigned roles and exhibit extreme behaviors.