stanford prison experiment trauma

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.

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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

danny dutch

The stanford prison experiment: a dark exploration into the human psyche.

The Stanford Prison Experiment (SPE) remains one of the most controversial and frequently cited psychological studies in the history of behavioural science. Conducted in 1971 by psychologist Philip Zimbardo at Stanford University, the experiment sought to explore the psychological effects of perceived power, focusing on the struggle between prisoners and prison guards. It quickly spiralled out of control, leading to serious ethical concerns and raising troubling questions about human nature, authority, and morality.

Let's take a look at the background, methodology, results, and long-term implications of the Stanford Prison Experiment.

Background and Theoretical Foundations

In the late 1960s and early 1970s, American society was deeply divided by issues like civil rights, the Vietnam War, and distrust in government institutions.

These social fractures created an atmosphere ripe for exploring questions of authority, conformity, and rebellion.

Influenced by the atrocities of the Holocaust , the My Lai Massacre in Vietnam, and the increasingly heavy-handed nature of the police and military, social psychologists began probing how ordinary people could commit extreme acts of cruelty under certain conditions.

Philip Zimbardo, a psychology professor at Stanford University, was one such researcher. He had been particularly influenced by Stanley Milgram’s experiment in 1963, which demonstrated that people could be led to administer what they believed to be fatal electric shocks to others simply because they were ordered to by an authority figure. Zimbardo’s interest lay in understanding how systemic roles and structures, rather than direct orders, could cause individuals to abandon their personal morals and adopt abusive behaviour.

Zimbardo theorised that people were not inherently good or evil, but that situations could exert powerful forces on behaviour. The Stanford Prison Experiment was designed to test this hypothesis by simulating a prison environment and observing the ways in which ordinary individuals would adapt to roles of guards and prisoners.

The Experiment: Methodology and Setup

The SPE began on 14th August 1971, with 24 male college students from the Palo Alto area who had volunteered in response to an advertisement. These volunteers were screened to ensure they were psychologically stable and healthy, with no history of mental illness, criminal behaviour, or substance abuse. They were randomly assigned to play the role of either a prisoner or a guard in a simulated prison environment that was set up in the basement of the Stanford Psychology Department.

The basement was converted to resemble a prison as closely as possible. It included three small cells, each housing three prisoners, a guard’s room, a solitary confinement cell (called “The Hole”), and a warden’s office. There were hidden cameras and microphones placed in the cells and corridors, allowing Zimbardo and his team to observe the experiment continuously. The prisoners were given identical uniforms and referred to by numbers rather than names, dehumanising them and stripping them of their individuality. The guards wore khaki uniforms, reflective sunglasses to avoid eye contact, and carried batons, enhancing their authority and intimidation.

The prisoners were informed that they would be subjected to a series of conditions designed to simulate imprisonment, but not told the specific forms that these would take. The guards were given no explicit instructions on how to behave, apart from being told to maintain order and respect the rights of the prisoners, which gave them significant discretion in their actions. Zimbardo himself played the role of prison superintendent, which further blurred the lines between researcher and participant.

The experiment was originally planned to last two weeks, but it was abruptly terminated after just six days due to the extreme and disturbing behaviour exhibited by both guards and prisoners.

The Descent into Dehumanisation

From the outset, the participants quickly conformed to their assigned roles. The prisoners, who had been “arrested” from their homes by real police officers to add to the realism, were stripped, deloused, and dressed in smocks with chains placed around their ankles. This process was designed to create feelings of humiliation and helplessness. Meanwhile, the guards, imbued with their authority, soon began to exhibit increasingly authoritarian and abusive behaviours.

Within a day, the guards had adopted a regime of psychological harassment. They would wake the prisoners in the middle of the night for roll calls and forced physical exercises. They began to insult the prisoners, taunt them, and devise arbitrary rules to maintain control. One guard, referred to as “John Wayne” in later interviews, became particularly sadistic, adopting a southern accent and treating the prisoners with extreme cruelty.

As time progressed, the guards’ behaviour escalated. They enforced strict punishments for disobedience, such as confinement in “The Hole” for hours on end, forced public humiliations, and the withdrawal of basic privileges like food and bedding. Prisoners were made to clean toilets with their bare hands, and some were stripped naked to further degrade them.

The prisoners, in turn, began to exhibit signs of severe stress and trauma. By the second day, they attempted to rebel by barricading themselves in their cells, refusing to follow orders. In response, the guards retaliated with fire extinguishers, stripping the prisoners of their beds and clothing, and isolating the ringleaders. Over time, the prisoners became increasingly passive and submissive. Some prisoners had emotional breakdowns and had to be removed from the experiment early. One prisoner, identified only as “8612”, had to be released after just 36 hours when he began exhibiting signs of acute distress and uncontrollable crying.

Interestingly, the guards became more cohesive and bonded over their shared authority, while the prisoners became increasingly alienated from one another. This reflected the deindividuation and groupthink phenomena common in real-world prison environments, where people’s identities are suppressed, and group dynamics become a driving force in behaviour.

Ethical Concerns and the Termination of the Experiment

By the sixth day, the situation had deteriorated to such an extent that Zimbardo’s colleagues and outside observers began to voice serious concerns about the ethics of the experiment. Zimbardo himself, deeply immersed in his role as prison superintendent, failed to recognise how out of control the situation had become.

The experiment was finally ended when Christina Maslach, a graduate student who was Zimbardo’s girlfriend at the time, visited the site and was horrified by what she saw. She confronted Zimbardo, questioning the morality of continuing an experiment that was clearly causing harm to its participants. This external perspective was enough to break the spell, prompting Zimbardo to halt the experiment prematurely on 20th August 1971.

The decision to stop the experiment was a wake-up call for Zimbardo and his team. Although the guards and prisoners were simply role-playing, the lines between reality and simulation had blurred to such an extent that both groups had internalised their roles. The prisoners were showing signs of severe psychological trauma, while the guards had become sadistic in their exercise of power.

Criticisms and Legacy

The Stanford Prison Experiment has faced intense criticism over the years, particularly regarding its ethics and the validity of its findings. Many have argued that the experiment should never have been allowed to proceed, as the researchers failed to provide adequate protections for the well-being of participants. Critics also questioned whether Zimbardo’s dual role as researcher and prison superintendent created a conflict of interest that compromised the integrity of the experiment. By taking on an active role in the simulation, Zimbardo may have unintentionally encouraged or shaped the guards’ behaviour rather than merely observing it.

Another criticism is that the participants may have been influenced by demand characteristics—psychological cues that guide participants to behave in ways that align with what they believe the experimenter expects. Some of the guards later admitted that they had behaved in a sadistic manner because they believed that this was what Zimbardo wanted to observe.

Despite these criticisms, the Stanford Prison Experiment remains one of the most frequently cited studies in psychology. Its findings have been used to explain phenomena such as prison riots, police brutality, and even atrocities like those committed by American soldiers at Abu Ghraib prison in Iraq in 2004. Zimbardo himself has continued to explore the darker aspects of human nature, writing extensively about the conditions that lead ordinary people to commit acts of evil.

The SPE also led to significant changes in the ethical guidelines governing psychological research. Today, experiments that involve such extreme manipulation of participants’ psychological states are heavily scrutinised, with institutional review boards required to ensure the safety and well-being of participants.

A Cautionary Tale

The Stanford Prison Experiment stands as a chilling reminder of the power that social roles, authority, and situational pressures can have on human behaviour. While its ethical shortcomings are undeniable, it continues to offer valuable insights into the potential for ordinary people to commit extraordinary acts of cruelty when placed in positions of power. The SPE serves as a cautionary tale, urging us to consider how systems, rather than individuals, can create environments where immorality flourishes.

Though conducted over 50 years ago, the Stanford Prison Experiment remains a critical point of reference for debates on human nature, ethical research practices, and the often-frightening effects of unchecked authority.

The Stanford Prison Experiment

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

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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."

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Chapter 4: Understanding and Influencing Others

Back to chapter, the stanford prison experiment, previous video 4.2: fundamental attribution error, next video 4.4: conformity.

There’s a dark side to the summer of 1971. Police “arrested” a number of college students who responded to an ad seeking volunteers for a psychological study of prison life.

Little did they know, in the basement of the Stanford Psychology Department, they were about to embark upon one of the most famous and controversial psychological studies: The Stanford Prison Experiment, led by Philip Zimbardo and colleagues.

After filling out an informational questionnaire, participants were randomly assigned to one of two groups: Prisoners—who were realistically picked up and booked by police—or Guards, who were in direct control of the inmates.

Depending on the assignment, they were dressed to fit their role —a set of expectations defining how those in the social position should behave.

For example, each guard was given a nightstick and whistle, along with mirrored aviator glasses, to emphasize their status and authority.

In addition, two researchers were present and oversaw the day-to-day operations: the lead experimenter, Zimbardo, acted as the prison superintendent, while another researcher, David Jaffe, was the Warden.

During one orientation session for the guards, Zimbardo vaguely outlined behaviors that they should conform with, like limiting the prisoners’ freedom and using their power to evoke fear and dominate non-violently.

In a follow-up session, the Warden provided more explicit directions to encourage the creation of a prison environment, for the collective good of the experiment.

With the correctional authorities in place, the prisoners entered the mock jail, which contained three cells and a closet for solitary confinement. They were stripped down, immediately degraded, and blindfolded to confuse them. Also, as part of their assigned role, they were outfitted in numbered gowns and nylon-stocking caps to depersonalize them.

On the second day, the prisoners started to rebel by blockading the cell door with the bed. As punishment, the ring leader was placed in confinement. This event precipitated the guards now turning on the other inmates, and the level of cruelty escalated.

Several guards… but not all …upped their performance to act tough—to fit the preconceived expectations of their label—all under the watchful eyes of the Warden and Superintendent. These leaders promoted toughness as a shared attribute of conforming to the in-group to achieve the goal of exposing the toxicity of the penal system.

Due to the increased and creative oppression placed on the prisoners, the experiment was terminated early, after six days instead of two weeks.

Ultimately, the guards behaved in a stereotypical tough-guy manner, striving to fit the normative guidance they were given. Sometimes, toxic situations can bring out the worst in someone, especially in cases where the individual identifies with a leader and the group’s collective cause.

The famous and controversial Stanford Prison Experiment , conducted by social psychologist Philip Zimbardo and his colleagues at Stanford University, demonstrated the power of social roles, social norms, and scripts.

Social Roles

One major social determinant of human behavior is our social role— a pattern of behavior that is expected of a person in a given setting or group (Hare, 2003). Each one of us has several social roles. You may be, at the same time, a student, a parent, an aspiring teacher, a son or daughter, a spouse, and a lifeguard. How do these social roles influence your behavior? Social roles are defined by culturally shared knowledge. That is, nearly everyone in a given culture knows what behavior is expected of a person in a given role. For example, what is the social role for a student? If you look around a college classroom you will likely see students engaging in studious behavior, taking notes, listening to the professor, reading the textbook, and sitting quietly at their desks. Of course, you may see students deviating from the expected studious behavior such as texting on their phones or using Facebook on their laptops, but in all cases, the students that you observe are attending class—a part of the social role of students.

Social roles, and our related behavior, can vary across different settings. How do you behave when you are engaging in the role of son or daughter and attending a family function? Now imagine how you behave when you are engaged in the role of employee at your workplace. It is very likely that your behavior will be different. Perhaps you are more relaxed and outgoing with your family, making jokes and doing silly things. But at your workplace you might speak more professionally, and although you may be friendly, you are also serious and focused on getting the work completed. These are examples of how our social roles influence and often dictate our behavior to the extent that identity and personality can vary with context (that is, in different social groups; Malloy, Albright, Kenny, Agatstein, & Winquist, 1997).

Social Norms

As discussed previously, social roles are defined by a culture’s shared knowledge of what is expected behavior of an individual in a specific role. This shared knowledge comes from social norms—a group’s expectations of what is appropriate and acceptable behavior for its members—how they are supposed to behave and think (Deutsch & Gerard, 1955; Berkowitz, 2004). How are we expected to act? What are we expected to talk about? What are we expected to wear? In our discussion of social roles, we noted that colleges have social norms for students’ behavior in the role of student and workplaces have social norms for employees’ behaviors in the role of employee. Social norms are everywhere including in families, gangs, and on social media outlets.

Because of social roles, people tend to know what behavior is expected of them in specific, familiar settings. A script is a person’s knowledge about the sequence of events expected in a specific setting (Schank & Abelson, 1977). How do you act on the first day of school, when you walk into an elevator, or are at a restaurant? For example, at a restaurant in the United States, if we want the server’s attention, we try to make eye contact. In Brazil, you would make the sound “psst” to get the server’s attention. You can see the cultural differences in scripts. To an American, saying “psst” to a server might seem rude, yet to a Brazilian, trying to make eye contact might not seem an effective strategy. Scripts are important sources of information to guide behavior in given situations. Can you imagine being in an unfamiliar situation and not having a script for how to behave? This could be uncomfortable and confusing. How could you find out about social norms in an unfamiliar culture?

Zimbardo’s Stanford Prison Experiment

In the summer of 1971, an advertisement was placed in a California newspaper asking for male volunteers to participate in a study about the psychological effects of prison life. More than 70 men volunteered, and these volunteers then underwent psychological testing to eliminate candidates who had underlying psychiatric issues, medical issues, or a history of crime or drug abuse. The pool of volunteers was whittled down to 24 healthy male college students. Each student was paid $15 per day and was randomly assigned to play the role of either a prisoner or a guard in the study. Based on what you have learned about research methods, why is it important that participants were randomly assigned?

A mock prison was constructed in the basement of the psychology building at Stanford. Participants assigned to play the role of prisoners were “arrested” at their homes by Palo Alto police officers, booked at a police station, and subsequently taken to the mock prison. The experiment was scheduled to run for several weeks. To the surprise of the researchers, both the “prisoners” and “guards” assumed their roles with zeal. In fact, on day 2, some of the prisoners revolted, and the guards quelled the rebellion by threatening the prisoners with night sticks. In a relatively short time, the guards came to harass the prisoners in an increasingly sadistic manner, through a complete lack of privacy, lack of basic comforts such as mattresses to sleep on, and through degrading chores and late-night counts.

The prisoners, in turn, began to show signs of severe anxiety and hopelessness—they began tolerating the guards’ abuse. Even the Stanford professor who designed the study and was the head researcher, Philip Zimbardo, found himself acting as if the prison was real and his role, as prison supervisor, was real as well. After only six days, the experiment had to be ended due to the participants’ deteriorating behavior.

The Stanford prison experiment demonstrated the power of social roles, norms, and scripts in affecting human behavior. The guards and prisoners enacted their social roles by engaging in behaviors appropriate to the roles: The guards gave orders and the prisoners followed orders. Social norms require guards to be authoritarian (such behavior was reinforced; see Haslam, Reicher, & Van Bavel, 2018) and prisoners to be submissive. When prisoners rebelled, they violated these social norms, which led to upheaval. The specific acts engaged by the guards and the prisoners derived from scripts. For example, guards degraded the prisoners by forcing them do push-ups and by removing all privacy. Prisoners rebelled by throwing pillows and trashing their cells. Some prisoners became so immersed in their roles that they exhibited symptoms of mental breakdown; however, according to Zimbardo, none of the participants suffered long term harm (Alexander, 2001).

This text is adapted from OpenStax, Psychology. OpenStax CNX.

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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. However, mistreatment of prisoners escalated so alarmingly that principal investigator Philip G. Zimbardo terminated the experiment after only six days.

More than 70 young men responded to an advertisement about a “psychological study of prison life,” and experimenters selected 24 applicants who were judged to be physically and mentally healthy. The paid subjects—they received $15 a day—were divided randomly into equal numbers of guards and prisoners. Guards were ordered not to physically abuse prisoners and were issued mirrored sunglasses that prevented any eye contact. Prisoners were “arrested” by actual police and handed over to the experimenters in a mock prison in the basement of a campus building. Prisoners were then subjected to indignities that were intended to simulate the environment of a real-life prison. In keeping with Zimbardo’s intention to create very quickly an “atmosphere of oppression,” each prisoner was made to wear a “dress” as a uniform and to carry a chain padlocked around one ankle. All participants were observed and videotaped by the experimenters.

On only the second day the prisoners staged a rebellion. Guards then worked out a system of rewards and punishments to manage the prisoners. Within the first four days, three prisoners had become so traumatized that they were released. Over the course of the experiment, some of the guards became cruel and tyrannical, while a number of the prisoners became depressed and disoriented. However, only after an outside observer came upon the scene and registered shock did Zimbardo conclude the experiment, less than a week after it had started.

The Stanford Prison Experiment immediately came under attack on methodological and ethical grounds. Zimbardo admitted that during the experiment he had sometimes felt more like a prison superintendent than a research psychologist. Later on, he claimed that the experiment’s “social forces and environmental contingencies” had led the guards to behave badly. However, others claimed that the original advertisement attracted people who were predisposed to authoritarianism . The most conspicuous challenge to the Stanford findings came decades later in the form of the BBC Prison Study, a differently organized experiment documented in a British Broadcasting Corporation series called The Experiment (2002). The BBC’s mock prisoners turned out to be more assertive than Zimbardo’s. The British experimenters called the Stanford experiment “a study of what happens when a powerful authority figure (Zimbardo) imposes tyranny.”

The Stanford Prison Experiment became widely known outside academia . It was the acknowledged inspiration for Das Experiment (2001), a German movie that was remade in the United States as the direct-to-video film The Experiment (2010). The Stanford Prison Experiment (2015) was created with Zimbardo’s active participation; the dramatic film more closely followed actual events.

The Shocking Truth Behind the Stanford Prison Experiment: A Psychology Study Gone Wrong

The Stanford Prison Experiment is one of history’s most famous and controversial psychological experiments. Conducted in the summer of 1971 by psychology professor Philip Zimbardo and his team of researchers, the experiment aimed to investigate the effects of situational variables on participants’ reactions and behaviors. The study simulated a prison environment and recruited college students to play the roles of prisoners and guards.

During the two-week experiment, the participants quickly became immersed in their roles, with the guards exhibiting abusive and authoritarian behavior towards the prisoners. The study was intended to last for two weeks, but it was terminated after only six days due to the extreme and dangerous behavior of the participants. The experiment has been widely criticized for its ethical implications, as well as its scientific validity.

Despite the controversy surrounding the Stanford Prison Experiment, it remains a significant case study in psychology. The study’s findings have been used to inform research on the effects of power and authority on human behavior and the role of situational variables in shaping our actions and attitudes. In this article, we will explore the history and significance of the Stanford Prison Experiment and examine its lasting impact on psychology.

Background of the Experiment

We are going to discuss the background of the infamous Stanford Prison Experiment. It is a well-known psychological study in August 1971 at Stanford University. The experiment was designed to investigate the psychological effects of power and authority on individuals in a prison environment.

Philip Zimbardo, a psychology professor at Stanford University, led the study. The U.S. Office of Naval Research funded the experiment, which was conducted in Jordan Hall’s basement. The participants were recruited through a local newspaper ad, and they were all college students who were paid $15 per day to participate.

The study examined the psychological effects of power and authority on individuals in a prison environment. The participants were randomly assigned to be either prisoners or guards. The prisoners were stripped of their identities and given a uniform, while the guards were given a uniform and a nightstick.

The experiment was supposed to last for two weeks, but it was terminated after only six days due to the extreme and abusive behavior of the guards toward the prisoners. The guards became increasingly brutal and sadistic towards the prisoners, and the prisoners began to show signs of extreme stress and emotional distress.

The study has been highly controversial and criticized for its lack of ethical considerations and for the harm it caused to the participants. However, it has also contributed to our understanding of the power dynamics in institutions and how they can affect the behavior of individuals.

The following section will discuss the experiment’s procedure in more detail.

Aim and Hypothesis

The Stanford Prison Experiment (SPE) was conducted in 1971 by Philip Zimbardo and his colleagues. The study aimed to investigate the influence of situational factors on human behavior. Specifically, the researchers wanted to examine whether the brutality reported among guards in American prisons was due to the sadistic personalities of the guards or had more to do with the prison environment.

The study hypothesized that their assigned roles would determine the participants’ behavior. The researchers expected that the participants assigned to the role of guards would become more aggressive and authoritarian. In contrast, those who were assigned to the role of prisoners would become more passive and submissive.

To test this hypothesis, Zimbardo and his colleagues recruited 24 male participants from a pool of volunteers. The participants were randomly assigned to the roles of either guards or prisoners. The guards were instructed to maintain order within the prison, while the prisoners were asked to follow the rules and regulations of the prison.

The study was designed to last for two weeks, but it was terminated after only six days due to the extreme behavior of the participants. The guards became increasingly abusive and authoritarian, while the prisoners became more passive and submissive. The study demonstrated the power of situational factors in influencing human behavior and has had a lasting impact on psychology.

Methodology

To conduct our study on the Stanford Prison Experiment, we followed the same methodology used by Philip Zimbardo in 1971. The experiment explored how people’s behavior changes in a simulated prison environment. The study involved selecting college students to play the roles of prisoners and guards in a mock prison.

The participants were randomly assigned to play the role of either a prisoner or a guard. The guards were instructed to maintain order in the prison, while the prisoners were told to follow the rules and regulations set by the guards. The roles were assigned to create a power dynamic between the two groups, with the guards having more authority over the prisoners.

Environment Setup

A basement in the Stanford University psychology building was converted into a mock prison to simulate a prison environment. The environment was set up to resemble a real prison, with cells, a cafeteria, and a yard. The cells were small, with no windows, and had only a bed and a toilet. The environment was designed to be uncomfortable and oppressive, to create a sense of confinement and isolation.

Subject Selection

The participants were selected through an advertisement that asked for volunteers to participate in a study of the psychological effects of prison life. The study received more than 70 responses, and 24 participants were selected based on their physical and mental health. The participants were all male and were paid $15 per day for their participation.

The methodology used in the Stanford Prison Experiment aimed to create a simulated prison environment to explore how people’s behavior changes when placed in a position of power. The study involved selecting college students to play the roles of prisoners and guards in a mock prison, and the environment was designed to be uncomfortable and oppressive. The study received more than 70 responses, and 24 participants were selected based on their physical and mental health.

Results and Findings

In the Stanford Prison Experiment, the participants were randomly assigned roles of prisoners or guards. The experiment was expected to last two weeks. Still, it was terminated after only six days due to the extreme behavior of the guards and the emotional distress of the prisoners.

The results showed that the guards became increasingly abusive towards the prisoners, using physical and psychological tactics to assert their authority. Conversely, the prisoners became passive and submissive, showing signs of depression and anxiety.

The experiment demonstrated the powerful influence of social roles and situational factors on human behavior. It also revealed the potential for abuse of power in institutional settings, such as prisons.

Furthermore, the study challenged the dispositional hypothesis, which suggests that individual personality traits are the primary determinants of behavior. Instead, it supported the situational hypothesis, which suggests that the context in which behavior occurs is more important than individual differences.

Ethical Considerations

When discussing the Stanford Prison Experiment, it is impossible to ignore the ethical considerations raised by the study. The experiment was highly controversial, and its findings have been criticized for being unethical and inhumane.

One of the study’s main ethical concerns was the participants’ treatment. The prisoners were subjected to psychological and physical abuse by the guards, which caused some of them to experience significant psychological distress. This raises questions about the researchers’ responsibility for their participants’ well-being.

Another ethical issue raised by the study was the lack of informed consent. The participants needed to be fully informed of the nature of the experiment, and some may have been coerced into participating. This raises concerns about the validity of the results and the ethical implications of using human subjects in research.

Furthermore, the use of deception in the study has also been criticized. The participants needed to be made aware of the true nature of the experiment, which raised concerns about the ethical implications of using deception in research.

Impact and Influence

The Stanford Prison Experiment has significantly impacted psychology, and its influence can still be seen today. Here are some of how the experiment has impacted the field:

Ethics in research: The experiment raised essential questions about research ethics and researchers’ responsibilities to their subjects. The unethical treatment of the participants in the experiment has led to stricter guidelines for research involving human subjects.
Social psychology: The experiment demonstrated the powerful influence of social roles and situational factors on human behavior. It has been cited as evidence for the social identity theory and the power of conformity.
Media and popular culture: The experiment has been the subject of numerous books, documentaries, and movies, including “The Stanford Prison Experiment” (2015). It has become a cultural touchstone, often referenced in power dynamics and authority discussions.
Criminal justice system: The experiment has been used to inform discussions about the criminal justice system and the treatment of prisoners. It has been cited in debates about using solitary confinement and the psychological effects of imprisonment.

Despite its impact, the experiment has also been the subject of controversy. Critics have pointed out that the experiment needed more scientific rigor and that the results may not be generalizable to other contexts. Additionally, the unethical treatment of the participants has raised questions about the validity of the findings.

Criticism and Controversy

The Stanford Prison Experiment has been the subject of much criticism and controversy since its inception. Many have questioned the ethics of the experiment, as well as its scientific rigor. Some have even gone so far as to call it a fraud.

One of the main criticisms of the experiment is that it needed proper controls. Critics have argued that the participants were not randomly assigned to their roles as prisoners or guards and that the experiment was not adequately blinded. This means that the participants may have been influenced by the experimenters’ expectations rather than the experiment’s actual conditions.

Another criticism of the experiment is that it was unethical. Participants were subjected to psychological stress and trauma, and many of them suffered from long-term psychological effects as a result. Additionally, the experimenters did not adequately debrief the participants, which may have contributed to their negative experiences.

Despite these criticisms, the Stanford Prison Experiment remains an essential landmark in psychology. It has inspired numerous follow-up studies and has helped to shed light on the nature of authority and power in human relationships. However, it is essential to remember that the experiment had flaws and that its findings should be interpreted cautiously.

Replications and Follow-Up Studies

We know that the Stanford Prison Experiment is one of the most famous and controversial studies in psychology. It has been replicated in various forms over the years, with mixed results. Let’s take a look at some of the notable replications and follow-up studies.

BBC Prison Study

The BBC Prison Study was a partial replication of the Stanford Prison Experiment conducted with the assistance of the BBC. The study was broadcast in a documentary series called The Experiment. The results and conclusions differed from Zimbardo’s, leading to several publications on tyranny, stress, and leadership.

Stanford Prison Experiment: A Simulation Study of the Psychology of Imprisonment

This replication was conducted by Haney, Banks, and Zimbardo in 1973. The study was similar to the original but with some modifications. The results were consistent with the original experiment, which suggested that the findings were not due to chance.

Standford Prison Experiment: Reactions to the Study

This study was conducted by Zimbardo and his colleagues in 1973. The study examined the reactions of participants to the original experiment. The results showed that the participants had mixed reactions to the experiment. Some participants felt the experiment was valuable, while others felt it was unethical.

Criticisms and Controversies

Critics of the Stanford Prison Experiment have pointed out several flaws in the study. For example, some have argued that the study needed ecological validity, meaning the findings may not apply to real-world situations. Others have criticized the study’s methodology, suggesting that demand characteristics may have influenced the results.

While the Stanford Prison Experiment remains a highly influential study in psychology, it is essential to consider its limitations and the mixed results of replications and follow-up studies.

Legacy of the Experiment

The Stanford Prison Experiment significantly impacted psychology and our understanding of human behavior. The study demonstrated the power of social roles and situational factors in shaping individual behavior. It also highlighted the importance of ethical considerations in research, mainly when conducting studies involving human subjects.

One of the most significant legacies of the experiment was the recognition of the potential harm that can result from the abuse of power. The study showed how individuals in positions of authority can become abusive when given unchecked power over others. This finding has important implications for understanding the dynamics of abusive relationships, workplace harassment, and other forms of power-based violence.

The experiment also demonstrated the importance of deindividuation in shaping behavior. When individuals are stripped of their identities and placed in group settings, they may be more likely to engage in behaviors they would not normally engage in. This phenomenon has important implications for understanding group dynamics, mob behavior, and other forms of collective action.

Moreover, the study significantly impacted social psychology, leading to the development of new research areas. The study’s lead researcher, Philip Zimbardo, developed new lines of research on topics such as good and evil, time perspective, and shyness.

Despite the many contributions of the Stanford Prison Experiment, the study has also been subject to criticism. Some have argued that the study needed more scientific rigor and that the findings may not be generalizable to other contexts. Others have raised ethical concerns about the study, particularly regarding the well-being of the participants.

The legacy of the Stanford Prison Experiment has been a mixed one. While the study has contributed significantly to our understanding of human behavior, it has also raised important questions about the ethics of research and the responsibility of researchers to protect their participants. As such, the study serves as a cautionary tale for researchers and underscores the importance of ethical considerations in all forms of scientific inquiry.

Frequently Asked Questions

What were the ethical issues surrounding the stanford prison experiment.

The Stanford Prison Experiment was heavily criticized for its ethical issues. The participants were subjected to psychological and emotional stress, which could have caused long-term harm. The experiment lacked informed consent, as the participants were not fully aware of what they were signing up for. Additionally, the researchers did not intervene when the situation became abusive, which violated the ethical principle of beneficence.

What was the hypothesis of the Stanford Prison Experiment?

The hypothesis of the Stanford Prison Experiment was to test the effects of power and authority on human behavior. The researchers wanted to see how people would react when placed in a simulated prison environment, with some acting as prisoners and others as guards. They hypothesized that the guards would become abusive and the prisoners would become passive and helpless.

What happened during the Stanford Prison Experiment?

During the Stanford Prison Experiment, participants were randomly assigned to be either prisoners or guards. The guards were given complete control over the prisoners, and they quickly became abusive. The prisoners were subjected to psychological and emotional stress and some even developed mental health issues. The experiment was cut short after just six days due to the increasingly disturbing behavior of the guards.

Why was the Stanford Prison Experiment considered disturbing?

The Stanford Prison Experiment was considered disturbing because of the extreme psychological and emotional stress that the participants were subjected to. The guards became increasingly abusive, and the prisoners became passive and helpless. The experiment highlighted the dangers of power and authority and raised questions about the ethics of conducting such experiments.

Were any legal actions taken against the Stanford Prison Experiment?

No legal actions were taken against the Stanford Prison Experiment. However, the experiment did lead to changes in the way that psychological experiments are conducted. Ethical guidelines were put in place to ensure that participants are fully informed and protected from harm.

What were the long-term effects on the participants of the Stanford Prison Experiment?

The long-term effects of the Stanford Prison Experiment on the participants are not fully known. However, some participants reported experiencing psychological and emotional trauma as a result of their participation in the experiment. The experiment highlighted the importance of protecting participants in psychological experiments and raised questions about the ethics of conducting such experiments in the future.

Inside the prison experiment that claimed to show the roots of evil

The Stanford prison experiment was the classic demonstration of how power can bring out the worst in us. But now it seems it was more about showbiz than science

By Gina Perry

10 October 2018

Philip Zimbardo in 1971. He is now 85 and still gives talks

Duke Downey/Polaris/eyevine

IN A darkened auditorium in September 2008, I sat in the audience awaiting the start of a presentation entitled “The psychology of evil” by social psychologist Philip Zimbardo. Suddenly, the doors at the back of the theatre burst open, lights flashed and Santana’s song Evil Ways blared from the speakers. A man with slicked-back black hair and a devilish pointy beard danced up the aisle towards the stage, snapping his fingers in time with the music. Zimbardo’s flamboyant entrance was startling, given the nature of the talk.

I shouldn’t have been surprised. Zimbardo’s knack for performance is one of the reasons his Stanford prison experiment is one of the most famous psychological studies of the 20th century, alongside research into obedience carried out by his high-school classmate, Stanley Milgram .

Eschewing conventional academic reporting, Zimbardo’s first account of the experiment was a sensational piece that appeared in a supplement of The New York Times , showcasing his skill as a storyteller. The article kicked off by detailing how, one sunny morning in Palo Alto, California, in 1971, police swooped on the homes of nine young men. They were bundled into squad cars, taken to the police station, charged, then blindfolded and transported to the Stanford County Jail, where they met their guards.

The “jail” was actually a set-up in the basement of a building at Stanford University. The prisoners were one half of a group of volunteers, the other half being assigned the role of guards. In what Zimbardo described as “a gradual Kafkaesque metamorphosis of good into evil”, these seemingly well-adjusted young men became increasingly brutal as guards. They “repeatedly stripped their prisoners naked, hooded them, chained them, denied them food or bedding privileges, put them into solitary confinement, and made them clean toilet bowls with their bare hands”, Zimbardo wrote. “Over time, these amusements took a sexual turn, such as having the prisoners simulate sodomy on each other.” The prisoners, humiliated and victimised, suffered such emotional distress that Zimbardo, playing the role of all-powerful prison superintendent, terminated the two-week experiment after just six days.

The experience made the key players famous – not least because Zimbardo captured some of the experiment on film and in now-familiar photos. The images showed aggressive-looking guards in tinted aviator shades, clutching police batons, and cowed, shackled prisoners sitting in line with bags over their heads.

The Stanford prison experiment in 1971 started with lifelike arrests of volunteers

Philip G. Zimbardo

The experiment led Zimbardo to conclude that normal people could be transformed into sadistic tyrants or passive slaves, not because of any inherent personality flaws but through finding themselves in a dehumanising environment: context was king. And suddenly, so was Zimbardo. Overnight, he became the go-to expert on prison reform, and over the following decade he appeared at a series of Congressional hearings and advisory panels on the US prison system.

The Stanford experiment might have started as a psychological exploration of incarceration, but Zimbardo and countless media commentators since have reached for it to illuminate an ever-widening range of behaviours – police brutality, corporate fraud, domestic abuse, genocide. Every invocation of the experiment has cemented it in the public imagination. The experiment has become enshrined in the psychology curriculum for its simple and compelling conclusion, that corrupt environments can turn good people evil. And of course it has made the leap to popular culture, inspiring documentaries, books and dramatisations. The most recent feature film based on it was 2015’s The Stanford Prison Experiment , for which Zimbardo was a consultant.

Battered credibility

Zimbardo was elected president of the American Psychological Association in 2002 and in 2012 received the American Psychological Foundation’s gold medal for lifetime achievement. Despite Zimbardo’s recognition and career honours, and his experiment being in all the textbooks, academic psychology is ambivalent about it. Not surprising, given that the experiment’s scientific credibility has taken a battering.

On the one hand, with his high profile and media know-how, Zimbardo has done much to promote social psychology. On the other, the experiment’s ethics, methodology and conclusions have long troubled colleagues. The first published criticism, in 1973, attacked the ethics of the study and questioned whether the apparent degradation of the young men was justified, given the experiment’s unsurprising result. By 1975, the methodology of the experiment was also under fire. Zimbardo’s claims that the results support the view that behaviour is determined by circumstances, not personality have also been robustly challenged by a growing number of researchers since then. After all, critics argued, the guards’ behaviour was hardly spontaneous: they knew they were expected to behave like tyrants and were encouraged to do so. And by Zimbardo’s own admission, two-thirds of them did not act sadistically, undermining his claim that the situation had an overpowering influence on their actions.

How did a study so flawed become so famous? First, there’s the powerful idea that evil lurks inside us all, waiting for the right – or wrong – circumstances to be called forth. The experiment itself may be shocking, but the way it echoes archetypal stories of sinfulness make it hard to shake off.

Then there is Zimbardo himself, a compelling narrator who inserts himself front-and-centre in the drama. In that first published account, Zimbardo admitted to a growing sense of unease over his role as architect of an experiment of such cruelty. His epiphany – helped along by a visit from his then girlfriend, who was appalled at his behaviour – that he too had been corrupted by power was what prompted him to call the experiment off. This acceptance of blame both disarms critics of the ethics of the experiment and suggests that we can trust him to give an unvarnished account of the research. There are echoes of biblical conversion stories; Zimbardo’s subsequent involvement in prison reform and more recently in a project to train ordinary people to become “heroes” are a form of atonement. “I want to be remembered not as Dr Evil,” Zimbardo tells me, “but as Dr Good.”

His public performances, TV appearances and TED talks have an evangelical flavour . Let’s face it, “good vs evil” sells, and it circumvents the hassle of trying to understand the subtleties of human psychology.

Zimbardo also has a talent for reframing the “lessons” of the Stanford experiment to capture the prevailing zeitgeist. In 2004, the study made the headlines when it emerged that American military police had abused and tortured prisoners inside Iraq’s Abu Ghraib prison . The public debate about how US soldiers could behave so appallingly raised comparisons with the experiment, rekindling Zimbardo’s career as a government-appointed expert. In a Boston Globe editorial, he wrote, “ The terrible things my guards [at Stanford] did to their prisoners were comparable to the horrors inflicted on the Iraqi detainees .” In reality, the terrifying and degrading acts of physical, psychological and sexual abuse meted out at Abu Ghraib were way beyond anything experienced by Zimbardo’s prisoners.

Philip Zimbardo captured the degradation of prisoners in his experiment on film

Chuck Painter/Stanford News Service

But this fresh attention sparked a more critical examination by journalists, who bypassed Zimbardo and sought out the people who took part. Cracks soon appeared in Zimbardo’s tightly controlled narrative.

In interviews with researchers and participants, an alternative story emerged. In a 2004 article in the Los Angeles Times , journa list Alan Zarembo reported that “prisoner” Douglas Korpi was disgusted with the experiment and Zimbardo’s exploitation of it. Both Korpi and Dave Eshelman, who was often depicted as one of the more sadistic guards , spoke of a staged “experiment”, and that they had behaved in order to fulfil their role as paid participants. That undermined Zimbardo’s insistence that his participants unquestioningly accepted the reality of the dramatic situation.

In 2011, Zimbardo admitted the study’s limitations . “It wasn’t a formal experiment. My colleagues probably never thought much of it,” he told an interviewer. In a high-profile blog post in 2013, textbook author Peter Gray decried the inclusion of the experiment in the teaching of psychology, and later called it “an embarrassment to the field”.

In April this year, French author Thibault Le Texier published the book Histoire d’un Mensonge (“History of a Lie”). Le Texier compared archival records with Zimbardo’s published accounts, listened to audio recordings and video footage of the experiment that had been edited out of public presentations, and interviewed research staff, former “guards” and “prisoners”. He concluded that Zimbardo’s claims were overblown and his findings hollow.

In a subsequent article on the Medium website , journalist Ben Blum confronted Zimbardo with the contradictions Le Texier had uncovered. Zimbardo pointed to the fame of the experiment as his defence. He later published a rebuttal on his website, infuriating critics of his research by dismissing them as “bloggers” and labelling their findings “differences in interpretation”. Only time will tell if these recent revelations will diminish the experiment in the public imagination.

If social psychology can be said to have attained the status of religious teachings, then Zimbardo is one of the field’s best-known preachers. And like a good preacher, Zimbardo represents the story of the experiment as a timeless parable. “Famous studies like Milgram’s obedience to authority, Mischel’s marshmallow test, the Stanford prison experiment, they raise moral issues and offer lessons about the psychology of temptation,” Zimbardo tells me. “Think about the Lord’s prayer. What is the key line? ‘Lead us not into temptation, but deliver us from evil.’ There are temptations all around us, and who gives in and who resists, this is a fundamental thing about human nature. This is what all these experiments explore and that gives them great public appeal.”

“I want to be remembered not as Doctor Evil, but as Doctor Good”

In his 2007 bestseller The Lucifer Effect , Zimbardo appealed to readers to look inwards. “Could we, like God’s favourite angel, Lucifer, ever be led into the temptation to do the unthinkable to others?” He promised readers a journey that will take in “genocide in Rwanda, the mass suicide and murder of People’s Temple followers in the jungles of Guyana, the My Lai massacre in Vietnam, the horrors of Nazi concentration camps, the torture by military and civilian police around the world, and the sexual abuse of parishioners by Catholic priests…” Then he adds that the “one… thread tying these atrocities together” comes from “the Stanford Prison Experiment”.

Through his story of a descent into the basement hell, the suffering, the epiphany, the ascent, transformation and redemption, Zimbardo offers a powerful message of hope about human nature: we all have the potential to be saints rather than sinners. It’s seductive to think that in the fight between good and evil we can all be winners through the redemptive power of psychological knowledge. Shame that, as far the Stanford prison experiment is concerned, it’s more showbiz than science.

This article appeared in print under the headline “The evil inside us all”

psychology /

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Lessons from the Stanford Prison Experiment: fifty years later

A Plaque in Jordan Hall (Building 420) marking the location of the Stanford Prison Experiment (Photo: Eric. E. Castro)

On an August morning in 1971, police officers drove around Palo Alto to arrest nine college boys for violations of Penal Codes 211, Armed Robbery, and Burglary, a 459 PC violation. The officers read them their Miranda rights and conducted a search, having the suspects spread-eagled against the police car. They were handcuffed and driven to the station. This marked the beginning of the famed Stanford Prison Experiment conducted by Professor Zimbardo, attempting to investigate the psychological effects of perceived power.

Recently I’ve been thinking about how we have gotten to a state in which our cops comfortably kill Black people, and I suspect the answer in part relates to the power of institutions to influence individual behavior—the very question Zimbardo posed fifty years ago. Here I am likening the student prison guards to real police officers, and the student prisoners to real Black people. While the comparison may seem drastic, so do the statistics of police brutality, such that it is a leading cause of death for young men in the United States. Over one’s life course, about one in every 1,000 Black men can expect to be killed by police. These statistics are uniquely American, separating our police force’s use of violence and racial profiling from that of any other nation. The demand to defund the police may seem radical given their international ubiquity, appearing to be a necessary part of any lawful society. Yet it is the positioning of this organization in America that makes our police uniquely vicious, which is why activists across America are calling for its defunding.

In the Stanford Prison Experiment, 18 participants were randomly split into nine prison guards and nine prisoners. Despite the elaborate set-up including a real arrest, steel bars, cell numbers and costumes, within the experiment the only thing that differentiated the prisoners from the guards was the perception of power. Taking place over a week, theoretically the participants could have existed amicably: prisoners socializing within their office-turned-cells, and guards within the corridor. Yet to the shock of Zimbardo and his team, the guards rapidly abused their power, using a fire extinguisher to shoot a stream of “skin-chilling carbon dioxide,” forcing prisoners to defecate in a bucket which caused the prison to smell of urine and feces, and utilizing various modes of psychological abuse. In a sense, the experiment was about the extraordinary evil that results from the magnification of power imbalance.

While this imbalance inherently exists between any nation’s police and citizens, it is especially trenchant in America due to its history of Black derogation. While the founding of our nation can be told through the narrative of freedom and democracy, it was built on the vigorous exploitation of Black people beginning from chattel slavery to lynchings and Jim Crow, all the way to our current systems of mass incarceration, private prisons, and racist, unaccountable policing practices. A history of racial genocide is not unique to America—what is unique is how the history is undealt with.

In Germany, it is impossible to walk two-hundred feet without seeing a reminder of the Holocaust; swastikas have been banned; the country has and continues to pay reparations. While the conversation about slavery reparations has been broached time and again, most elected American officials have never seriously considered it. Instead, Black Americans get thrown phrases such as “reverse racism” and “all lives matter,” in a culture that extols celebrities stealing from and profiting off Black culture. As long as our country refuses to face and address its history of racial trauma, there will always be a disproportionate power imbalance between police officers and Black people, which is among the many reasons it has become necessary to defund the police.

The Stanford Prison Experiment has been partially invalidated, most prominently on the grounds that the guards were instructed to be cruel. Yet their decision to actually carry out the violence may even more accurately reflect the realities of police brutality. A large reason why George Floyd’s murder has caused such an uproar is because it was not an isolated incident, but part of a pattern. In observing prior police murders of black men, Floyd’s officers were being primed—yet it was still their decision to not only accept, but to execute that same behavior. As such, the experiment’s findings may more accurately be that, once permitted, authority figures are willing to carry out violence, which can still be used to cite many of the inherent problems with the police force.

The guards’ attire included mirror sunglasses which, by hiding their eyes, personified anonymity, allowing them to conflate themselves with capital Authority, thus deindividuating their personal crimes by sourcing it back to their larger team. In our real police force, this herd immunity is pillared by for-profit policy-making companies such as Lexipol, which is designed to help police officers navigate laws in ways that will make them less liable to be charged of any crime.

Another telling aspect of the experiment is the specific punishments the guards decided to use on the prisoners. In addition to the examples already listed, the guards imposed solitary confinement, forced menial work such as cleaning toilet bowls with their bare hands, and physical work such as sustaining push-ups or jumping jacks for hours. The participants were college boys, and those arbitrarily chosen to be guards were given no specific training. Naturally, the punishments they enacted could have only been extracted from what they had consumed in the media throughout their lives, whether that be from television, news reports, etc, punishments that they were raised to believe were justified. Humane treatment of prisoners is a subjective matter, and the fact that these boys believed these actions to be humane speaks to the values of the culture they were raised in, which is the same culture that cultivates our police officers. The murders of George Floyd, Breonna Taylor, Ahmaud Arbery, Tony McDade and countless others could have only been committed if the police officers believed their actions to be socially acceptable. These officers believed their racist and violent acts to be acceptable within our current policing system.

When society moves forward, we instinctively look outward to the world we don’t know in order to inform ourselves. Yet it is often true that we do so without even sufficiently examining parts of ourselves, of our institutions, that already contain the knowledge we need. Much of the inherent faults of the police and criminal justice system were evidenced fifty years ago on our very campus, thus demonstrating yet another reason why history cannot be relegated to relics, but rather that it must stay afloat in our psyches.

Stanford is a historically practical institution, prioritizing technology and innovation, demonstrated today by the near half of students receiving degrees from the School of Engineering. While these studies are important, it is times like these in America, when we are confronted with the genocide of Black people by our own “peacekeepers,” that we must consider if innovation is the thing our nation currently requires. It is in asking the right questions and insisting on being thoughtful about our education that we keep Stanford close, even from afar.

— Chloe Cay Kim ’21

Contact Chloe Cay Kim at cay ‘at’ stanford.edu

The Daily is committed to publishing a diversity of op-eds and letters to the editor. We’d love to hear your thoughts. Email letters to the editor to eic ‘at’ stanforddaily.com and op-ed submissions to opinions ‘at’ stanforddaily.com.

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Stanford Prison Experiment

In 2015, The Stanford Prison Experiment was released in theaters. The movie detailed an infamous 1971 experiment in which 24 college students were “put in prison.” While the “experiment” was supposed to last for two weeks, it was terminated after just six days due to the psychological effects it was having on both the “guards” and “prisoners.”

So what actually happened during the Stanford Prison Experiment? Why is it so infamous? Does the movie get everything right, or is it just a dramatization? Find out for yourself.

What Was the Stanford Prison Experiment?

After Stanley Milgram’s experiment rocked the world of psychology, many people were left with questions about obedience, power dynamics, and the abuse of power. Philip Zimbardo, a professor at Stanford, wanted to explore these questions further. With a grant from the Navy, Zimbardo set up the Stanford Prison Experiment.

Could a person’s role influence their behavior? This is the question Philip Zimbardo wanted to answer.

How Was the Stanford Prison Experiment Conducted?

Zimbardo and his team interviewed 70 applicants at Stanford who were willing to participate in the study for 14 days and receive $15 a day. They wanted to make sure that they chose the brightest and most mentally sound participants. After narrowing their applicants down to 24, the researchers flipped a coin and assigned the roles. Half of the participants would be prisoners and half would be guards.

The researchers then set up a basement at Stanford to look like a real prison. They were very serious about treating the experiment like a simulation. Prisoners were “arrested” in public and taken into the prison. (They were even booked, fingerprinted, and strip searched.)

Zimbardo’s team also gave prisoners numbers that they were meant to use instead of their real name. They claimed that it would help give the prisoners a sense of anonymity and help the experiment.

Guards had pretty much free reign on how they could treat the prisoner, although they had two main rules:

Guards could not hit the prisoners
Guards could not put prisoners in solitary confinement (“the hole”) for more than an hour

Zimbardo played the role of prison superintendent. His graduate students and research partners also played roles as members of the “parole board” and the prison warden.

Prisoners were tasked with certain activities like writing a letter home to their “visitors” and making a case to the parole board about why they should be let off. Guards also subjected the prisoners to “counts” in which they forced the prisoners to do jumping jacks, push-ups, and degrading tasks.

How Long Did the Stanford Prison Experiment Last?

It did not take long for the guards to abuse their power. Within one day, a guard hit one of the prisoners with his nightstick.

On the second day, the prisoners tried to rebel and their beds were taken away. To punish the prisoners, the guards shot a fire extinguisher into the cell. Guards used physical and psychological abuse, including sleep deprivation, to punish and intimidate the prisoners throughout the study.

The prisoners were forced to wear dressings and stocking caps the whole time. At some points, guards would put bags over the prisoners’ heads. Since the study has ended, it has been compared to actions at the Abu Ghraib detention center - Zimbardo has written about the case and its parallels to the prison experiment since.

Why Did It Get Shut Down?

Very quickly, the guards started to abuse their power. The prisoners started to spiral. On the third day, Prisoner #8612 started to cry and scream uncontrollably. He threatened to harm himself and call a lawyer. To avoid potential psychological damage or a lawsuit, he was let go. Two other prisoners were let go in the next two days. One had refused to eat.

On the fifth day, Zimbardo’s girlfriend (and former student) came to visit the experiment. Zimbardo and his team had been monitoring the experiment, and playing their roles in it, 24/7. When she saw the horrors of what was going on in the prison, she asked Zimbardo to end the “experiment” immediately. She even threatened to break up with him.

On the sixth day, Zimbardo ended the experiment.

Stanford Prison Experiment Movie

In 2015, a movie about the Stanford Prison Experiment was released on Netflix. The movie is no longer streaming on Netflix, but you can order the DVD version if you want to watch it. Although all movies based on true events are seen through a specific point of view, critics say that this is a very accurate portrayal of what happened during the experiment.

Why Was the Stanford Prison Experiment Unethical?

This experiment showed the world just how quickly people can abuse power when it’s given to them. But it remains as one of the most controversial experiments in the world of social psychology . There are a few reasons why.

The first obvious one is the psychological abuse that the prisoners endured during the study. Is it ethical to put human subjects through that kind of distress and trauma, so much so that many couldn’t endure the experiment?

(Zimbardo claims that none of the participants have suffered long-term psychological consequences from their participation.)

Was The Stanford Prison Experiment Fake?

In more recent years, critics have also come forward to say that the results were not as “natural” as Zimbardo and his team may want you to think. Transcripts and audio recordings from the Stanford Prison Experiment show that Zimbardo’s team “coached” guards. They told them to be “tough” for the sake of the experiment.

Even the prisoners may have been “faking” their responses. Prisoner #8612, who is most well-known for his blood-curdling “I’m burning up inside!” has come forward to say that his time in the Stanford County Jail was more of an “improv exercise.” Many critics have likened the experiment to a drama rather than a legitimate psychology experiment.

Carlo Prescott, the experiment’s prison consultant, has also come forward to say that the experiment’s more cruel treatments were not naturally thought up and executed by the guards alone. He wrote the following in an op-ed:

“Ideas such as bags being placed over the heads of prisoners, inmates being bound together with chains and buckets being used in place of toilets in their cells were all experiences of mine at the old "Spanish Jail" section of San Quentin and which I dutifully shared with the Stanford Prison Experiment braintrust months before the experiment started. To allege that all these carefully tested, psychologically solid, upper-middle-class Caucasian "guards" dreamed this up on their own is absurd.”

The Lasting Effect of the Stanford Prison Experiment

The Stanford Prison Experiment seems to have raised more questions than it answered. Where should psychologists draw the line when it comes to subjecting participants to distress? How easily can psychologists blur the lines of “experiment” vs. “simulation” or “drama?” And if the Stanford Prison Experiment didn’t exactly answer its original questions about power dynamics and obedience , what similar experiments can? How can the Stanford Prison experiment be improved?

These are just some of the questions that psychologists face today. Maybe your work can help to figure out the answers!

Philip Zimbardo (Biography + Experiments)
The Monster Study (Summary, Results, and Ethical Issues)
Beck’s Depression Inventory (BDI Test)
40+ Famous Psychologists (Images + Biographies)
Human Experimentation List (in Psychology)

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Demonstrating the Power of Social Situations via a Simulated Prison Experiment

A person-centered analysis of human behavior attributes most behavior change, in positive or negative directions, to internal, dispositional features of individuals. The factors commonly believed to direct behavior are to be found in the operation of genes, temperament, personality traits, personal pathologies and virtues. A situation-centered approach, in contrast, focuses on factors external to the person, to the behavioral context in which individuals are functioning. Although human behavior is almost always a function of the interaction of person and situation, social psychologists have called attention to the attributional biases in much of psychology and among the general public that overestimates the importance of dispositional factors while underestimating situational factors. This "fundamental attribution error" they argue, leads to a misrepresentation of both causal determinants and means for modifying undesirable behavior patterns. Research by social psychologist Stanley Milgram, PhD, (1974; see also Blass, 1999) was one of the earliest demonstrations of the extent to which a large sample of ordinary American citizens could be led to blindly obey unjust authority in delivering extreme levels of shock to an innocent "victim."

The Stanford Prison Experiment extended that analysis to demonstrate the surprisingly profound impact of institutional forces on the behavior of normal, healthy participants. Philip Zimbardo, PhD, and his research team of Craig Haney, Curtis Banks, David Jaffe, and ex convict consultant, Carlo Prescott (Zimbardo, Haney, Banks, & Jaffe, 1973) designed a study that separated the usual dispositional factors among correctional personnel and prisoners from the situational factors that characterize many prisons. They wanted to determine what prison-like settings bring out in people that are not confounded by what people bring into prisons. They sought to discover to what extent the violence and anti-social behaviors often found in prisons can be traced to the "bad apples" that go into prisons or to the "bad barrels" (the prisons themselves) that can corrupt behavior of even ordinary, good people.

The study was conducted this way: College students from all over the United States who answered a city newspaper ad for participants in a study of prison life were personally interviewed, given a battery of personality tests, and completed background surveys that enabled the researchers to pre-select only those who were mentally and physically healthy, normal and well adjusted. They were randomly assigned to role-play either prisoners or guards in the simulated prison setting constructed in the basement of Stanford University's Psychology Department. The prison setting was designed as functional simulation of the central features present in the psychology of imprisonment (Zimbardo, Maslach, & Haney, 1999). Read a full description of the methodology, chronology of daily events and transformations of human character that were revealed.

The major results of the study can be summarized as: many of the normal, healthy mock prisoners suffered such intense emotional stress reactions that they had to be released in a matter of days; most of the other prisoners acted like zombies totally obeying the demeaning orders of the guards; the distress of the prisoners was caused by their sense of powerlessness induced by the guards who began acting in cruel, dehumanizing and even sadistic ways. The study was terminated prematurely because it was getting out of control in the extent of degrading actions being perpetrated by the guards against the prisoners - all of whom had been normal, healthy, ordinary young college students less than a week before.

Significance

Practical application.

The lessons of the Stanford Prison Experiment have gone well beyond the classroom (Haney & Zimbardo, 1998). Zimbardo was invited to give testimony to a Congressional Committee investigating the causes of prison riots (Zimbardo, 1971), and to a Senate Judiciary Committee on crime and prisons focused on detention of juveniles (Zimbardo, 1974). Its chair, Senator Birch Bayh, prepared a new law for federal prisons requiring juveniles in pre-trial detention to be housed separately from adult inmates (to prevent their being abused), based on the abuse reported in the Stanford Prison Experiment of its juveniles in the pre-trial detention facility of the Stanford jail.

A video documentary of the study, "Quiet Rage: the Stanford Prison Experiment," has been used extensively by many agencies within the civilian and military criminal justice system, as well as in shelters for abused women. It is also used to educate role-playing military interrogators in the Navy SEAR program (SURVIVAL, EVASION, and RESISTANCE) on the potential dangers of abusing their power against others who role-playing pretend spies and terrorists (Zimbardo, Personal communication, fall, 2003, Annapolis Naval College psychology staff).

The eerily direct parallels between the sadistic acts perpetrator by the Stanford Prison Experiment guard and the Abu Ghraib Prison guards, as well as the conclusions about situational forces dominating dispositional aspects of the guards' abusive behavior have propelled this research into the national dialogue. It is seen as a relevant contribution to understanding the multiple situational causes of such aberrant behavior. The situational analysis of the Stanford Prison Experiment redirects the search for blame from an exclusive focus on the character of an alleged "few bad apples" to systemic abuses that were inherent in the "bad barrel" of that corrupting prison environment.

Cited Research

Blass, T. (Ed.) ( 1999). Obedience to Authority: Current Perspectives on the Milgram Paradigm. Mahwah, NJ: Erlbaum.

Haney, C. & Zimbardo, P.G., (1998). The Past and Future of U.S. Prison Policy. Twenty-Five Years After the Stanford Prison Experiment. American Psychologist, Vol. 53, No. 7, pp. 709-727.

Milgram, S. (1974). Obedience to Authority. New York: Harper & Row.

Zimbardo, P. G. (1971). The power and pathology of imprisonment. Congressional Record. (Serial No. 15, October 25, 1971). Hearings before Subcommittee No. 3, of the Committee on the Judiciary, House of Representatives, Ninety-Second Congress, First Session on Corrections, Part II, Prisons, Prison Reform and Prisoner's Rights: California. Washington, DC: U.S. Government Printing Office.

Zimbardo, P. G. (1974). The detention and jailing of juveniles (Hearings before U. S. Senate Committee on the Judiciary Subcommittee to Investigate Juvenile Delinquency, 10, 11, 17, September, 1973). Washington, DC: U.S. Government Printing Office, 141-161.

Zimbardo, P. G., Haney, C., Banks, W. C., & Jaffe, D. (1973, April 8). The mind is a formidable jailer: A Pirandellian prison. The New York Times Magazine, Section 6, pp. 38, ff.

Zimbardo, P. G., Maslach, C., & Haney, C. (1999). 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). Mahwah, NJ: Erlbaum.

American Psychological Association, June 8, 2004

The Harms of Being Subjugated and Doing the Subjugation

A formerly incarcerated psychologist looks at incarceration through the lens of learned helplessness, the Stanford Prison Experiment, synapses, and power.

An illustration from Anarchist Black Dragon, Volume 1, Issue 5

Research shows that the criminal justice system leaves an imprint not just on the body, but on the psyche. The effects linger long beyond release for the incarcerated person or the end of a shift for those working in prisons. One of those effects that’s well-documented is learned helplessness.

Martin Seligman first observed learned helplessness when he was doing experiments on dogs . When dogs had been conditioned through exposure to believe that electric shocks were preventing their escape, they no longer even attempted it, instead remaining confined. They had learned they were helpless and acted as if they were, even when they were no longer. This 50-year-old theory has been used to explain a wide swath of human behaviors that seem counterintuitive, often resulting from either confinement or trauma.

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It was this theory that loomed heaviest in my mind the day a federal judge sentenced me to 52 months in federal prison. Already a practicing therapist, I was in the first year of my doctoral education in psychology the day I was sentenced. I feared becoming the dogs, conditioned to accept shocks, abuses, and injustices without attempting to escape. I feared losing my mind—not in a bout of madness, but rather losing the ability to use my mind to freely exert choices over my behaviors and circumstances.

In addition to learned helplessness, the infamous Stanford Prison Experiment research also helps explain the lasting psychological effects of incarceration not only for prisoners but for guards as well. Conceived to study prison life, the Stanford Prison Experiment began with an average group of healthy, intelligent, middle-class college men. The researchers assigned one half of the men to be prisoners and the other half to be guards based on a coin flip. Their social contexts and backgrounds were similar.

This similarity reflects the reality inside prisons. While people that are incarcerated are often depicted as fundamentally different than the correctional officers tasked with overseeing them, they have more similar backgrounds than many realize. Being a correctional officer is a low-prestige job, with pay that varies between low and median depending on the jurisdiction. Moreover, thirty-eight percent of Federal Bureau of Prisons staff are BIPOC and 42% of the people incarcerated within their prisons are, as well.

There was even less difference in the real-life socioeconomic and cultural backgrounds among the participants of the Stanford Prison Experiment. And yet, the participants’ outcomes in the study varied wildly and were heavily dependent on which role they were assigned to play: prisoner or guard. One of the key takeaways of the short-lived experiment was just how readily people conform to social roles they are expected to play, especially when said roles are as heavily stereotyped as those of prison guards. The Stanford Prison Experiment has been heavily criticized in recent years, but it is one piece of research in a large body that shows how group dynamics and internalizing roles, even when simply to obediently comply with authority, can lead people that are kind as individuals to perpetuate harms within a group.

I saw correctional officers—and other prisoners—behave in ways that can only be understood through these theories. The roles had been defined for us, with decades of pop culture references and deeply engrained stereotypes reinforcing each other. As if we had been randomly selected by the flip of a coin instead of a judge’s gavel, the people assigned to the role of correctional officer seemed to internalize it. They were told, through external cues, that they had power over other human beings. For those of us in prison khakis, others had power over us . Situation after situation confirmed that we were helpless to effectuate change in our lives, and needed to fully subjugate ourselves to those who held the power.

In prolonged confinement, much like the dogs who were conditioned to accept the shocks in Seligman’s study, people instinctively internalize a learned sense of inferiority, helplessness, and weakened ego strength. Meanwhile, correctional officers internalize having power over human beings, however artificial. Philip Zimbardo, the researcher behind the Stanford Prison Experiment, even predicted this outcome. He said that circumstance motivates people to act in the way that they do more so than their baseline personality.

I witnessed this “power over” dynamic daily while incarcerated. I used to walk around the track during my free time, which was one of the few recreational activities available to me. This was an attempt daily to mindfully keep my ego strength in order—I was referred to as “inmate Lipton” and had to remind myself that was only a construct, not a reality.

One of the most salient experiences of my incarceration occurred on that track. A group of “inmate workers” had unfortunately crossed paths with a correctional officer not known for his compassion, Mr. West. He had seized one of the women’s MP3 players—that belonged to her and was bought off commissary—under a false pretense of her not being allowed to have it during work hours. He told her she could get it back on one condition. “ Lay on the ground and put your legs in the air like a cockroach ,” he demanded, without a trace of irony. Without the psychological framework of his “power over” us having permeated his mind and actions, I’m unsure there’s an explanation for exposing another human being to such humiliation.

The pervasive culture of the prison and its environment promotes correctional officers to adopt the prison identity . Once that identity has been adopted, so has the violent culture that can accompany it. Yet our minds cannot cleanly be divided in two distinct halves, the “work half” and the “life half.” Internalizations about power and authority over others bleeds through a correctional officer’s whole life, even as they cycle “inside” and “outside” of prison as their shifts come and go.

Research into domestic violence offers some insight into the behaviors of correctional officers. They have disproportionately high rates of intimate partner violence, suicide , substance use issues, and alcohol use disorder. Research suggests that it this is more likely a result of the psychological impact of their chosen career than a result of the personalities of those who go into the profession.

Studies into the psychology and circumstances of domestic violence provide surprising insights into this behavior. Evan Stark, author of the book Coercive Control: How Men Entrap Women in Personal Life provides an analysis of domestic violence far more nuanced—and according to Cheryl Hanna who reviewed it for the journal Signs , “arguably more accurate,”—than is common in society. While intimate partner violence is often attributed to men who have poor impulse control (i.e., they are a bad character/person) and strike their partners because they can, Stark argues that the abuser’s behavior is better understood as preventing the other from attaining freedom and autonomy (i.e, in relation to others).

Hanna’s summation of Stark’s theory proves informative in analyses of correctional officers’ behavior. “Stark advocates redefining abuse from specific acts to ‘an ongoing and gender-specific pattern of coercive and controlling behaviors that cause a range of harms in addition to injury’ (99–100).” The physical violence is but the most visible system of an interlocking web of harmful behaviors, all designed to subjugate. How does it affect your psyche when the primary function of your job duty is to subjugate others?

A core duty of any corrections employee is to impose coercive systems of control on the people confined to their institution. And yet it is that very concept that may form the basis for later incidents of domestic violence in their homes. As their workplace role of dominator or controller of people gets internalized more and more deeply, it seeps into the other aspects of their personal life.

Humans are born with nearly 100 billion neurons. Synapses are brain structures that allow neurons to transmit an electrical or chemical signal to other neurons. Through synaptic pruning that occurs in childhood and early adolescence, the brain destroys extra synapses . People lose up to 50% of their synaptic connections during adolescence . The main change is that unused connections in the thinking and processing part of children’s brain (called the grey matter) are ‘pruned’ away. At the same time, other connections are strengthened. This is the brain’s way of becoming more efficient, based on the ‘use it or lose it’ principle . This process occurs throughout our life and explains some of the brain changes that occur during long-term incarceration.

The process of neural plasticity (changes in the neural nets), designed to optimize our brain structure to suit the needs of our circumstance, will therefore optimize to embrace the circumstance of either being the “incarcerated person” or the “correctional officer.” Unlike leaving prison—which is an utter binary, in/out—neural plasticity (the brain being shaped by our experiences) occurs gradually and over time. This plasticity reinforces the power differentials projected upon us.

During my time in prison, despite concerted efforts at resisting it, I internalized my subjugation. I became conditioned to eat exactly what was given to me, without question or complaint. Upon release, I found myself at restaurants and adopting the implicit pattern of accepting what I was given. Despite the fact I was a paying customer, I couldn’t bear to complain when my meal showed up and was not what I ordered. I simply ate it, even when it was a food that disgusted me; I didn’t even perceive an alternative. My neural net changed, my powerlessness internalized, I had become the helpless prisoner they told me that I was.

Problems arise when there is a mismatch between the synaptic structure and the situation in which someone currently find themselves. Whether an officer has left work after their shift or a person has been released after serving their sentence, their mind does not suddenly revert to the pre-prison state. Their neural network continues to be primed for the role imposed upon them. Whether they have been conditioned to exert dominance, or conditioned to expect subjugation, both states manifest in behaviors that follow the person far beyond the gates of prison.

Mismatches also occur between how we present to the world and how we feel inside. Correctional officers often feel the need to present as “tough,” encapsulated within a 2015 Guardian article titled, “‘Prison guards can never be weak’: the hidden PTSD crisis in America’s jails.” If inside they feel afraid, or plagued by insecurities, the mismatch alone can cause psychological discord.

The rate of PTSD in correctional officers is double that of military veterans. Their suicide rate is double the national average. Incidents of domestic violence are grossly elevated. And yet, receiving psychological treatment is heavily stigmatized within law enforcement communities. And they must keep returning to work, no matter what has occurred the shift before. Correctional officers at the infamously violent jail Rikers Island were recently embroiled in a scandal for abusing sick leave and general absenteeism . The jail is also infamous for suicides of currently and formerly incarcerated people, typified by the suicide of Kalief Browder .

Research shows that re-entering society after incarceration is challenging and rife with barriers . People coming out of incarceration usually lack housing, employment, money, and health insurance. Depending on how long they were incarcerated, they could have severely hampered technological skills in what is increasingly a tech-dependent society. The learned helplessness they were forced to acquire throughout their incarceration is exactly the opposite of what is needed to surmount barriers. (PTSD, it should be noted, is dramatically over-represented in the incarcerated population, too, many of whom are exposed to violence and have disproportional rates of sexual trauma. It also contributes to diminished functioning, making people more susceptible to succumb to hurdles.)

The extreme power differential perpetuated by US prison systems could be one reason the recidivism rate is so high. It could also explain why correctional officers experience so many negative health outcomes. Humans cannot rapidly toggle modes in their mind to align their psyche with their circumstance.

Dr. Kaia Stern is the co-founder of the Prison Studies Project who stumbled almost accidentally onto the connection between poor outcomes for people sent to prison and poor outcomes for those who work in prisons. In her piece, “ The Keeper and the Kept ,” she quotes a “self-described U.S. Marine and Black man” who worked as correctional line officer for 11 years:

I’m slowly being poisoned over a 35-year period and no one tells me. You think it is you when it manifests in your life: obesity domestic violence, suicide, alcoholism… we don’t have a name for trauma because there’s no training, so people associate [their own trauma] with deviant behavior. And then the [state] agency tells you that the injury you suffer can’t be solely identified to work… If the public really knew the kind of disconnect for humanity.

Unlike military veterans exposed to trauma who can then later be compensated by the VA , correctional officers and incarcerated people are less likely to even be diagnosed and treated, with compensation exceedingly rare.

These negative psychological effects of incarceration are not inevitable. Norway ’s Halden prison offers a model for prisons where power differentials are lessened, the emphasis is on education and rehabilitation, and all people no matter their crimes are treated with basic levels of human dignity, in compliance with the United Nations Standard Minimum Rules for the Treatment of Prisoners. As the punitiveness of their prison environment decreased, so did their recidivism. As less recidivism means less crime and less need for further incarceration, states from North Dakota to Oregon have sent delegations to Norway to learn their model of corrections and attempt to implement it back home.

As the Norway model sets the precedent for treatment of people in prison, they greatly improve the mental health of the staff, too. In the officers’ training school, the governor (warden) of Halden prison Are Høidal explains, guards are taught that treating inmates humanely is something they should do not for the prisons but for themselves. The theory is that if officers are taught to be harsh, domineering, and suspicious, it will ripple outward in their lives, affecting their self-image, their families, and even Norway as a whole. Høidal stated a line that is usually attributed to Dostoyevsky: “The degree of civilization in a society can be judged by entering its prisons.

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What were the long-term effects on the participants of the Stanford Prison Experiment?

It has been maintained by Dr. Philip Zimbardo that the experiment has had no long-term harm on the participants. However, one out of the 24 initial participants , who had suffered a breakdown within 36 hours of starting, later went on to become a prison psychologist and has been in the profession for at least 14 years.

While the experiment may not have had any "harm" on the participants, the fact that it had such a huge impact on one participant (as the person himself claims in the experiment documentary ), calls into question the fact that how much did the experiment end up altering or affecting the participant's lives.

So, were long term effects (not just "harm") of the experiment tracked and documented by the team or anybody else? If tracked, has this been published at any point of time?

Secondly, in most of the popular literature and even on the official website, I do not find any discussion of the experiment in terms of long term effects. Are long-term effects of psychological studies on participants' not considered worth recording? Why?

social-psychology
methodology

$\begingroup$ Note that Stanford Prison was not an experiment, but a role-play and simulation, or demo, or at best, a pilot. Thus, its participants were more like actors than subjects, warranting little need for follow-up. Some were interviewed long after the study, in case you're interested. $\endgroup$ – Arnon Weinberg ♦ Commented Jan 4, 2022 at 5:47

I found this snippet from Quora: Whatever happened to the participants in the Stanford Prison Experiment?

"They performed extensive follow-ups by bringing all the subjects back individually or in groups over a period of the first year and then for the next ten years they have surveyed them by mail and phone and the consensus is that they did suffer during that week of the experiment, but they learned a great deal about themselves and about human nature that most of them say was quite valuable."

Perhaps within the first decade after the experiment they found constancy in how the participants were affected and felt there was no longer a need for further analysis / recording.

$\begingroup$ I am aware of this. I was asking specifically about long term effects not limited to negative effects (harm) . Moreover, this is exactly what is mentioned in Quiet Rage. In fact, IIRC the Quora answer has changed the wording of the statement. $\endgroup$ – asheeshr Commented Aug 23, 2013 at 17:20

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Rosemary K.M. Sword and Philip Zimbardo Ph.D.

50 Years On: What We've Learned From the Stanford Prison Experiment

The experiment generated important research into unexplored territories..

Posted August 16, 2021 | Reviewed by Tyler Woods

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I developed 3 new areas of research after the Stanford prison experiment (SPE): good and evil, time perspective, and shyness.
The SPE was closed down after 6 days because the "guards" became so brutal and as Superintendent, I was too caught up in my role.
The Heroic Imagination Project teaches people how to be Everyday Heroes and take effective actions in challenging situations.

Fifty years ago this month I conducted a research experiment that could have been a blight to my career . Instead, what has become known as the Stanford prison experiment (SPE) drove me to extensively pursue the question: Why do good people do evil things? After three decades of research on this subject, I recorded my findings in The Lucifer Effect: Understanding How Good People Turn Evil (Random House, 2007).

But the SPE also led me to research three new topics that hadn’t previously been studied:

1) Heroism: Why, in difficult situations, some people heroically step forward to help others, oftentimes complete strangers, while others stand by and watch.

2) Time Perspective: The psychological time warp experienced by participants of the SPE—not knowing if it was day or night or what day it was—led to my research in people’s individual time perspectives and how these affect our lives.

3) Shyness : Rethinking shyness as a self-imposed psychological prison led me to conduct research on shyness in adults, and then create a clinic in the community designed to cure shyness.

The Experiment in a Nutshell

In August 1971, I led a team of researchers at Stanford University to determine the psychological effects of being a guard or a prisoner. The study was funded by the US Office of Naval Research as both the US Navy and the US Marine Corps were interested in the causes of conflict between military guards and prisoners. In the study, 24 normal college students were randomly assigned to play the role of guard or inmate for two weeks in a simulated prison located in the basement of the Stanford Psychology Department building. But the guards quickly became so brutal, and I had become so caught up in my role as Superintendent, that I shut down the experiment after only six days.

Challenging the Truth

There seem to be powerful silent barriers to dealing with new truths emanating from psychological laboratories and field experiments that tell us things about how the mind works, which challenge our basic assumptions. We want to believe our decisions are wisely informed, that our actions are rational, that our personal conscience buffers us against tyrannical authorities. Moreover, we want to believe in the dominating influence of our good character despite social circumstances. Yes, those personal beliefs are sometimes true, but often they are not, and rigidly defending them can get us in trouble individually and collectively. Let’s see how.

Denial and Finger Pointing

When we discover two or three ordinary American citizens administered extreme electric shocks to an innocent victim on the relentless commands of a heartless authority, we say, “no way, not me.” Yale University psychologist Stanley Milgram’s obedience to authority research has been in the public arena for decades, yet we ignore its message of the power of unjust authority in undercutting our moral conscience. Similarly, the SPE research made vivid the power of hostile situational forces in overwhelming dispositional tendencies toward compassion and human dignity. Still, many who insist on honoring the dominance of character over circumstance reject its situational power message.

In 2004, people around the world witnessed online photos of horrific actions of American Military Police guards in Iraq’s Abu Ghraib Prison against prisoners in their charge. It was portrayed as the work of a “few bad apples” according to military brass and Bush administration spokespeople. I publicly challenged this traditional focus on individual dispositions by portraying American servicemen as good apples that were forced to operate in a Bad Barrel (the Situation) created by Bad Barrel Makers (the System).

I became an expert witness in the defense of the Staff Sergeant in charge of the night shift, where all the abuses took place. In that capacity, I had personal access to the defendant, to all 1,000 photos and videos, to all dozen military investigations, and more. It was sufficient to validate my view of that prison as a replica of the Stanford prison experiment on steroids, and of my defendant, Chip Frederick, as really a Good Apple corrupted by being forced to function for 12 hours every night for many months in the worst barrel imaginable. My situation-based testimony to the military Court Martial hearings helped reduce the severity of his sentence from 15 years down to only four years.

The January 6, 2021 insurrection is a recent example of some Good Apples being corrupted by a Bad Barrel. In this case, the Bad Barrel is the insidiousness of fascism led by the former president and other fraudulent politicians as well as media personalities. These “leaders” have been generously dumping poison in the Barrel and over the Apples with lies that feed the Apples’ deepest fears.

“The Stanford Prison Experiment” Film

In 2015, The Stanford Prison Experiment was made into a film starring Billy Crudup as me and Olivia Thrilby as Christina Maslach, the whistle-blowing graduate student (whom I later married) who pointed out the experiment had gone awry and had changed me to such a degree that she didn’t know who I was anymore. Her personal challenge led me to end the study the next day. The film received two awards at the Sundance Film Festival: best screenwriting and best science feature.

The Stanford Prison Experiment movie enables viewers to look through the observation window as if they were part of the prison staff watching this remarkable drama slowly unfold, and simultaneously observe those observers as well. They are witnesses to the gradual transformations taking place, hour by hour, day by day, and guard shift by guard shift. Viewers see what readers of The Lucifer Effect book account can only imagine. As these young students become the characters inhabited in their roles and dressed in their costumes, as prisoners or guards, a Pirandellian drama emerges.

The fixed line between Good, like us, and Evil, like them, is relentlessly blurred as it becomes ever more permeable. Ordinary people soon slip into doing extraordinarily bad things to other people, who are actually just like them except for a random coin flip. Other healthy people soon get sick mentally, being unable to cope with the learned helplessness imposed on them in that unique, unfamiliar setting. They do not offer comfort to their buddies as they break down, nor do those who adopt a “good guard” persona ever do anything to limit the sadistic excesses of the cruel guards heading their shifts.

Finally, the movie also tracks the emotional changes in the lead character (me) as his compassion and intellectual curiosity get distilled and submerged over time. The initial roles of research creator and objective observer are dominated by power and insensitivity to prisoners' suffering in the new role of Prison Superintendent.

Visit the official Stanford Prison Experiment website to learn more about the experiment.

Heroic Imagination

I should add that, along with continuing research in time perspectives and time perspective therapy , my new mission in life has been to empower everyone to wisely resist negative situational forces and evil by becoming Everyday Heroes in Training. Our non-profit Heroic Imagination Project (HIP) teaches ordinary people how to stand up, speak out and take effective actions in challenging situations in their lives.

Rosemary K.M. Sword and Philip Zimbardo are authors, along with Richard M. Sword, of The Time Cure: Overcoming PTSD with the New Psychology of Time Perspective Therapy.

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Exploring Zimbardo’s Stanford Prison Experiment

What happens when ordinary people become in charge? Does human nature make them act brutally, or is it the setting that pushes them to do wrong?

The Stanford Prison Experiment, led by Philip Zimbardo in 1971, showed us how fast people can change under power. It was meant to last two weeks but ended after six days due to chaos. Twenty-four male college students played the roles of guards and prisoners, showing us how quickly authority can change behavior.

This study made us think about how situations affect us and the tough questions it raises about research ethics.

Table of Contents

Key Takeaways

The experiment involved 24 young, healthy men selected from 75 applicants.
Each participant was compensated $15 a day for their involvement.
The study was intended to last 14 days but was terminated after just six.
Multiple ethical issues arose, including lack of informed consent and participant abuse.
Results showed alarming impacts of power dynamics on behavior.
The sample was predominantly from a specific demographic, limiting generalizability.
Critiques surfaced regarding the scientific merit of the findings in 2019.

Introduction to Zimbardo’s Stanford Prison Experiment

The Stanford Prison Experiment is a key study in social psychology . It aimed to understand human behavior in a prison setting. In 1971, Philip Zimbardo led the study with over 70 volunteers, each earning $15 a day.

After a careful selection, 24 college students were chosen. They were randomly put into roles as guards and prisoners. This setup was meant to study how power affects people.

The study was meant to last two weeks but ended after six days. The results were shocking. Guards acted with extreme cruelty, while prisoners felt deep anxiety and hopelessness.

Zimbardo’s study sparked a big debate on research ethics. It made people think about the limits of scientific studies, the safety of participants, and the duties of researchers. Today, it reminds us of the fine line between research and respecting human dignity.

Background of Philip Zimbardo and the Study

Philip Zimbardo was born on March 23, 1933, in New York City. He is a well-known name in psychology. His education and academic roles laid the groundwork for his big contributions to social psychology .

Zimbardo’s name became famous with the Stanford Prison Experiment in 1971. This study looked at how situations affect human behavior. It was a key moment in understanding authority, following the crowd, and morality in people.

The experiment took place in the basement of Stanford University’s psychology building. Zimbardo set up a mock prison to see how people would act in certain roles. The study had 24 male college students, randomly put as guards or prisoners. It was meant to last two weeks but ended early due to the guards’ harsh behavior.

Zimbardo’s study showed how roles and power can change people’s behavior. The experiment was cut short because of the guards’ aggression and the prisoners’ distress. His work didn’t stop there. He wrote “The Lucifer Effect: Understanding How Good People Turn Evil” and other books on morality and human behavior.

Zimbardo was a big name in psychology, even serving as president of the American Psychological Association in 2002. He stayed active in academia until he retired from Stanford in 2003. His work on how situations influence us is still widely discussed.

Year	Event
1933	Birth of Philip Zimbardo in New York City
1971	Conducted the Stanford Prison Experiment
2002	Elected president of the American Psychological Association
2003	Retired from teaching at Stanford University
2007	Published “The Lucifer Effect”

Aim of the Stanford Prison Experiment

The main goal of the Stanford Prison Experiment was to see how power affects people in a fake prison. Zimbardo wanted to know if guards in prisons act violently because of who they are or because of the prison setting. He wanted to show how situations can change people, especially when it comes to authority.

Over 70 men applied for the study, and Zimbardo picked 24 for two groups: guards and prisoners. They got $15 a day. The plan was to run it for two weeks. But, the situation got intense fast. After just four days, three people had to stop because they were too stressed.

The results were shocking and made people question the ethics of such studies. Zimbardo found that the situation and roles given to people can change their behavior a lot. This study showed how important it is to understand group dynamics and the risks of too much power.

Aspect	Details
Participants	24 selected from over 70 applicants
Roles	12 guards and 12 prisoners
Payment	$15 per day
Duration	Intended: 2 weeks; Actual: 6 days
Emotional Impact	3 prisoners released due to trauma
Funding	US Office of Naval Research

Methodology of the Experiment

The experiment’s design aimed to study how assigned roles change behavior. It used the basement of the Stanford psychology building to mimic a prison. This setup helped researchers study power dynamics .

Setting Up the Mock Prison

Creating a realistic prison was key. The team built cells and a guard station. They used surveillance cameras and control systems to make it feel like a real prison.

This setup helped focus on how guards and prisoners interacted. It was all about observing their behaviors closely.

Participant Selection and Assignment

They picked 24 male college students from different backgrounds. These students went through personality tests and interviews. This made sure they were mentally fit and got along well with others.

Then, they randomly put the students into guard or prisoner roles. This was done to avoid bias and keep the experiment fair.

Aspect	Details
Number of Participants	24 male college students
Duration of Study	Originally planned for 14 days, terminated after 6 days
Roles Assigned	Guards and Prisoners (randomly assigned)
Rules Enforced	16 rules regulating prisoners’ daily routines
Punitive Measures	Guards implemented punishments, including solitary confinement
Early Releases	5 participants released early due to psychological distress

This experiment showed how roles and environments change behavior quickly. It led to deep talks on ethics in research with humans.

Findings and Observations During the Experiment

The Stanford Prison Experiment showed us how people act when given certain roles. It was shocking to see how quickly everyone fell into their parts. The guards and prisoners showed us the dark side of human nature.

Behavior of Guards and Prisoners

Guards quickly became mean and bossy. Some even acted sadistically. About one-third of them treated the prisoners badly, making them feel low.

Prisoners, on the other hand, felt trapped and helpless. They started to see each other as less human. Some got so stressed, they had to leave the experiment early.

One prisoner tried to stand up for himself but failed. He was ignored by others who just wanted to stay safe.

The experiment showed us some scary things. Prisoners didn’t fight back even when they could. One prisoner tried to protest by fasting, but his friends didn’t support him.

Guard Behavior	Prisoner Behavior
Adoption of sadistic tendencies	Exhibited submissiveness and dehumanization
Hostile actions towards inmates	Three prisoners released due to trauma
Coaching and instructions encouraged harshness	Obedience to directives despite personal costs
Intimidation and humiliation techniques used	Participation in rebellion met with group

The study showed us how power and obedience are linked. It made us think about why people act the way they do in places like prisons. It’s not just about what’s in their hearts, but also the situation they’re in.

The Unethical Nature of the Research

The Stanford Prison Experiment is a key example of unethical research in psychology. Dr. Philip Zimbardo led the study in 1971. He took 24 male college students and made them prisoners and guards in a fake prison. The plan was to run it for two weeks, but it ended after six days because of the harm it caused.

This research had many ethical problems. The participants lost their belongings and wore prison clothes. They were also treated in ways that were very humiliating. This was done without fully telling them about the experiment, which is a big ethical issue.

The guards had a lot of power but no rules to follow. They were told to keep control but not to use physical force. This led to some guards treating the prisoners very badly. The situation got worse as time went on, causing a lot of emotional pain.

During visits from parents, the prison setting was made to seem even more real. This made things worse for the participants. The researchers focused on the success of the study over the well-being of the people taking part. Zimbardo later said the study would help train law enforcement, showing he didn’t care about the harm caused.

The Stanford Prison Experiment shows how important it is to have ethics in research. It reminds us that keeping people safe and treating them with respect is more important than any research goal.

Moral Implications and Psychological Insights

The Stanford Prison Experiment shows us the dangers of unchecked power. It tells us how ordinary people can turn bad when given authority. This study gives us deep insights into how people act under pressure.

It shows how easy it is for people to treat others as less than human when they’re in a certain role. Guards in the study acted out in ways that were shocking. This shows us how quickly we can lose our sense of right and wrong when we have power.

The prisoners in the study also suffered a lot. They felt anxiety, depression, and trauma. This shows how fast people can fall apart when they lose control and face harsh conditions. The study ended after just six days, showing how fragile our dignity is when faced with authority.

This study has big lessons for today’s world. It talks about ethics in research, stress in prisons, and how power affects us. Understanding this study helps us think about how to act better in situations where power matters.

Aspect	Moral Implications	Psychological Insights	Social Behavior
Authority Impact	People can become corrupt when given power.	Individuals may act against their morals under duress.	Social roles shape behavior significantly.
Participant Distress	Informed consent was inadequate.	Severe trauma responses were noted.	Isolation led to emotional breakdowns.
Ethical Oversight	Need for stricter ethical guidelines.	can silence .	Public awareness is crucial for oversight.

The Impact of Power Dynamics in the Experiment

The Stanford Prison Experiment showed us how power changes human behavior. When the guards took on their roles, everything changed. They used authority influence by humiliating and intimidating others. This control changed how people acted, showing how situational forces can make us act differently than we normally would.

As the experiment went on, the guards became more abusive. The prisoners got more anxious. This shows how easily morality can break down in power situations. The power dynamics led to a loss of empathy and moral values, making the guards forget who they were outside their roles.

When we compare it to the BBC Prison Study, we see more about these dynamics. The BBC study lasted longer and showed different results. It found that changing power dynamics can affect how people identify with their groups and how effective they are. In contrast, prisoners in the study bonded more with each other and challenged the guards’ authority.

Learning from the Stanford Prison Experiment helps us understand power in places like the military and prisons. It teaches us how to deal with authority and follow rules in real life. These lessons are important for tackling challenges related to power and obedience.

The Stanford Prison Experiment showed us a lot about human behavior. It found that some people can become very mean when given power. This shows how easily ordinary people can act out of character.

This study is still important today. It helps us understand how power and authority affect us. It also reminds us of the need to think about ethics in research.

The study was stopped early because it was too intense. This shows how important it is to treat people right in research. The prisoners showed different ways of coping, making us think about how we handle power.

Zimbardo’s experiment changed how we see prisons and society. It teaches us to think about ethics in research. It also warns us about the bad things people can do when put in certain situations.

The eSoft Editorial Team, a blend of experienced professionals, leaders, and academics, specializes in soft skills, leadership, management, and personal and professional development. Committed to delivering thoroughly researched, high-quality, and reliable content, they abide by strict editorial guidelines ensuring accuracy and currency. Each article crafted is not merely informative but serves as a catalyst for growth, empowering individuals and organizations. As enablers, their trusted insights shape the leaders and organizations of tomorrow.

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One of Psychology's Most Famous Experiments Was Deeply Flawed

The Stanford Prison Experiment — the infamous 1971 exercise in which regular college students placed in a mock prison suddenly transformed into aggressive guards and hysterical prisoners — was deeply flawed, a new investigation reveals.

The participants in the experiment, who were male college students, didn't just organically become abusive guards, reporter Ben Blum wrote in Medium . Rather, Philip Zimbardo, who led the experiment and is now a professor emeritus of psychology at Stanford University, encouraged the guards to act "tough," according to newfound audio from the Stanford archive .

Moreover, some of the outbursts from the so-called prisoners weren't triggered by the trauma of prison, Blum found. One student prisoner, Douglas Korpi, told Blum that he faked a breakdown so that he could get out of the experiment early to study for a graduate school exam. [ 7 Absolutely Evil Medical Experiments ]

"Anybody who is a clinician would know that I was faking," Korpi told Blum. "I'm not that good at acting. I mean, I think I do a fairly good job, but I'm more hysterical than psychotic."

In the experiment, Zimbardo paid nine student participants to act as prisoners and another nine to assume the role of prison guards. The experiment, housed in a mock jail built in the basement at Stanford, was supposed to last two weeks. But Zimbardo's girlfriend convinced him to shut it down after six days when she saw the bad conditions, Blum reported.

Since then, results from the Stanford Prison Experiment have been used to show that unique situations and social roles can bring out the worst in people. The experiment has informed psychologists and historians trying to understand how humans could act so brutally in events ranging from the Holocaust to Abu Ghraib prison (now called the Baghdad Central Prison) in Iraq. Many psychology textbooks in universities across the country also describe the experiment.

But the new discoveries could change all that.

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For instance, in a series of June 12 tweets , Jay Van Bavel, an associate professor of psychology and neural science at New York University, wrote, "The bottom line is that conformity isn't natural, blind or inevitable. Zimbardo was not only deeply wrong about this — but his public comments misled millions of people into accepting this false narrative about the Stanford Prison Experiment."

Rather, scientists "have been arguing for years that conformity often emerges when leaders cultivate a sense of shared identity. This is an active, engaged process — very different from automatic and mindless conformity," Van Bavel tweeted .

Zimbardo initially denied some of the charges but agreed to talk with Blum again when Thibault Le Texier, a French academic and filmmaker, published "History of a Lie" (Histoire d’un Mensonge) in April, which took a deep dive into newly released documents from Stanford's archives. When Blum asked if he thought Le Texier's book would change the way people saw the experiment, Zimbardo said, "In a sense, I don't really care. At this point, the big problem is, I don't want to waste any more of my time. After my talk with you, I'm not going to do any interviews about it."

The hullabaloo over the experiment might have been avoided if the scientific community and media had been more skeptical back in the 1970s, other psychologists said. For instance, the results weren't published in a reputable peer-reviewed psychology journal but rather the obscure journal Naval Research Reviews . Given that respected, mainstream journals tend to have rigorous publication standards, "apparently, peer review did its job [in this case]," David Amodio, an associate professor of psychology and neural science social at New York Univeristy, wrote on Twitter .

In addition, other researchers failed to replicate Zimbardo's results, Blum reported. But the notion that people's behavior is largely dictated by their environment and social positions has lingered in the scientific and popular domains for years, possibly because the idea removes some of the blame for despicable acts from the people who commit them, he said.

"The appeal of the Stanford Prison Experiment [SPE] seems to go deeper than its scientific validity, perhaps because it tells us a story about ourselves that we desperately want to believe: that we, as individuals, cannot really be held accountable for the sometimes-reprehensible things we do," Blum wrote.

"As troubling as it might seem to accept Zimbardo's fallen vision of human nature, it is also profoundly liberating," Blum continued. "It means we're off the hook. Our actions are determined by circumstance. Our fallibility is situational. Just as the Gospel promised to absolve us of our sins if we would only believe, the SPE offered a form of redemption tailor-made for a scientific era, and we embraced it."

Original article on Live Science .

Laura is the archaeology and Life's Little Mysteries editor at Live Science. She also reports on general science, including paleontology. Her work has appeared in The New York Times, Scholastic, Popular Science and Spectrum, a site on autism research. She has won multiple awards from the Society of Professional Journalists and the Washington Newspaper Publishers Association for her reporting at a weekly newspaper near Seattle. Laura holds a bachelor's degree in English literature and psychology from Washington University in St. Louis and a master's degree in science writing from NYU.

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COMMENTS

Stanford Prison Experiment: Zimbardo's Famous Study
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. ... Supermax prisons proliferated, isolating prisoners in psychological trauma-inducing conditions ...
The Stanford Prison Experiment: A Dark Exploration into the Human Psyche
The Stanford Prison Experiment (SPE) remains one of the most controversial and frequently cited psychological studies in the history of behavioural science. Conducted in 1971 by psychologist Philip Zimbardo at Stanford University, the experiment sought to explore the psychological effects of perceived power, focusing on the struggle between prisoners and prison guards. It quickly spiralled out ...
The Stanford Prison Experiment
The Stanford prison experiment was conducted in the 1970s as a way to assess how individual and institutional factors impact psychology within a prison setting. Although it's considered a ...
Stanford prison experiment
The Stanford prison experiment (SPE) was a psychological experiment conducted in 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 led the research team who administered the study. [1] ...
Stanford Prison Experiment: Zimbardo's Famous Study
Stanford Prison Experiment: Zimbardo's Famous Study
The Stanford Prison Experiment: Effect of Social Roles, Norms on ...
The Stanford Prison Experiment: Effect of Social Roles ...
Stanford Prison Experiment
Stanford Prison Experiment | History & Facts
50 Years On: What We've Learned From the Stanford Prison Experiment
The Experiment in a Nutshell. In August 1971, I led a team of researchers at Stanford University to determine the psychological effects of being a guard or a prisoner. The study was funded by the ...
The dirty work of the Stanford Prison Experiment: Re-reading the
Almost 50 years on, the Stanford Prison Experiment of 1971 remains one of the most notorious and controversial psychology studies ever devised. It has often been treated as a cautionary tale about what can happen in prison situations if there is inadequate staff training or safeguarding, given the inherent power differentials between staff and ...
The Shocking Truth Behind the Stanford Prison Experiment: A Psychology
The Stanford Prison Experiment is one of history's most famous and controversial psychological experiments. Conducted in the summer of 1971 by psychology professor Philip Zimbardo and his team of researchers, the experiment aimed to investigate the effects of situational variables on participants' reactions and behaviors. The study simulated a prison environment and recruited college ...
The Controversial True Story Behind the Infamous Study
The Stanford Prison Experiment, conducted in 1971 by psychologist Philip Zimbardo, aimed to explore the impact of situational forces on human behavior. This study, which simulated a prison environment using student volunteers as guards and prisoners, quickly gained notoriety for its shocking results and ethical concerns.
Inside the prison experiment that claimed to show the roots of evil
Inside the prison experiment that claimed to show the roots of evil. The Stanford prison experiment was the classic demonstration of how power can bring out the worst in us. But now it seems it ...
More Information
A: Although the Stanford Prison Experiment movie was inspired by the classic 1971 experiment, there are key differences between the two. In the actual experiment, guards and prisoners were prevented from carrying out acts of physical violence such as those shown in the movie. In addition, the study ended differently than the movie.
Lessons from the Stanford Prison Experiment: fifty years later
June 16, 2020, 9:31 p.m. On an August morning in 1971, police officers drove around Palo Alto to arrest nine college boys for violations of Penal Codes 211, Armed Robbery, and Burglary, a 459 PC ...
Stanford Prison Experiment
Practical Psychology. on October 2, 2023. In 2015, The Stanford Prison Experiment was released in theaters. The movie detailed an infamous 1971 experiment in which 24 college students were "put in prison.". While the "experiment" was supposed to last for two weeks, it was terminated after just six days due to the psychological effects ...
Demonstrating the Power of Social Situations via a Simulated Prison
Demonstrating the Power of Social Situations via a ...
The Harms of Being Subjugated and Doing the Subjugation
In addition to learned helplessness, the infamous Stanford Prison Experiment research also helps explain the lasting psychological effects of incarceration not only for prisoners but for guards as well. Conceived to study prison life, the Stanford Prison Experiment began with an average group of healthy, intelligent, middle-class college men.
What were the long-term effects on the participants of the Stanford
It has been maintained by Dr. Philip Zimbardo that the experiment has had no long-term harm on the participants. However, one out of the 24 initial participants, who had suffered a breakdown within 36 hours of starting, later went on to become a prison psychologist and has been in the profession for at least 14 years. While the experiment may not have had any "harm" on the participants, the ...
6. Grievances
The First Prisoner Released. Less than 36 hours into the experiment, Prisoner #8612 began suffering from acute emotional disturbance, disorganized thinking, uncontrollable crying, and rage. In spite of all of this, we had already come to think so much like prison authorities that we thought he was trying to "con" us - to fool us into ...
50 Years On: What We've Learned From the Stanford Prison Experiment
The Experiment in a Nutshell. In August 1971, I led a team of researchers at Stanford University to determine the psychological effects of being a guard or a prisoner. The study was funded by the ...
Exploring Zimbardo's Stanford Prison Experiment
Introduction to Zimbardo's Stanford Prison Experiment. The Stanford Prison Experiment is a key study in social psychology. It aimed to understand human behavior in a prison setting. In 1971, Philip Zimbardo led the study with over 70 volunteers, each earning $15 a day. After a careful selection, 24 college students were chosen.
One of Psychology's Most Famous Experiments Was Deeply Flawed
The Stanford Prison Experiment — the infamous 1971 exercise in which regular college students placed in a mock prison suddenly transformed into aggressive guards and hysterical prisoners — was ...
stanford prison experiment: Topics by Science.gov
Zimbardo's 1971 Stanford Prison Experiment (SPE), one of the most famous studies in psychology, is discussed in most introductory textbooks. The present study is concerned with the nature of this coverage, given that there have been myriad criticisms, especially recently, of the SPE. These criticisms concern both Zimbardo's situationistâ€¦.

Stanford Prison Experiment: Zimbardo’s Famous Study

Asserting Authority

Physical Punishment

Asserting Independence

Putting Down the Rebellion

Special Privileges

Consequences of the Rebellion

Prisoner #8612

A Visit from Parents

Catholic Priest

Prisoner #819

Back to Reality

An End to the Experiment

Zimbardo proposed that two processes can explain the prisoner’s “final submission.”

Critical Evaluation

Demand characteristics

Sample bias

Zimbardo’s conclusion may be wrong

Contributions to psychology

Contribution to prison policy

Evidence for situational factors

Evidence for an interactionist approach

Ethical Issues

Protection of Participants

Withdrawal

Discussion Questions

Frequently Asked Questions

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Purpose of the Stanford Prison Experiment

Participants in the Stanford Prison Experiment

Setting and Procedures

Results of the Stanford Prison Experiment

Impact of the Zimbardo Prison Experiment

Criticisms of the Stanford Prison Experiment

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Why was Zimbardo's experiment unethical?

Lack of Generalizability

Lack of Realism

Recent Criticisms

Chapter 4: Understanding and Influencing Others

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Stanford Prison Experiment

The Shocking Truth Behind the Stanford Prison Experiment: A Psychology Study Gone Wrong

Background of the Experiment

Aim and Hypothesis

Methodology

Environment Setup

Subject Selection

Results and Findings

Ethical Considerations

Impact and Influence

Criticism and Controversy

Replications and Follow-Up Studies

BBC Prison Study

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Standford Prison Experiment: Reactions to the Study

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