stanford prison experiment details

32 Movies About Prison That Will Inspire You To Stay Out Of Jail

Stay out of jail!

Prison is a scary place. Even in the movies, it's the kind of place that is impossible to romanticize, and Hollywood can do that with a lot of other terrible places. Prisons are also a place where storytellers can find interesting characters and angles to bring humanity to life. There is nothing good in prison, but there is that, there is humanity. Still, as the movies on this list will prove, you never want to end up there. 

The Green Mile

If there is an even worse place to be than regular prison, it's death row. It's even worse if you were to find yourself on death row in Louisiana in the 1930s. That's where our story takes place in The Green Mile and while Tom Hanks ' character is somewhat kind, the rest of the guards are a nightmare and the experience looks miserable. Death might be a relief.

The Last Castle

Military prison is no joke, especially when the warden is one like the one James Gandolfini plays in The Last Castle . The movie plays out like a lot of prison movies, in the vein of Cool Hand Luke. One prisoner, unhappy with the unfair treatment of the warden and the guards takes them all on in a battle of wills.

Escape From Alcatraz

Escape From Alcatraz is an all-time classic and a fun adventure movie. It's not fun to see what life was really like on " The Rock ." Watching this movie it's easy to understand why people were desperate to escape the "escape-proof" prison.

Cool Hand Luke

A failure to communicate is not why Luke (Paul Newman) was the way he was in Cool Hand Luke . A mere existence on a chain gang in a prison work camp seems like it would be just the worst thing to ever go through. At least you get all the eggs you can eat though.

The Longest Yard

On its surface, The Longest Yard makes light of life in prison. They get to play football and make jokes all day. Dig a little deeper and think a little more and you realize that the only relief from the stress and the boredom of prison is the take desperate measures on the football field. No thanks.

Dead Man Walking

Dead Man Walking , starring Sean Penn as a condemned man on death row is a really hard movie to watch. There is nothing scarier than being in a situation where you know you're going to die and little can be done to save yourself. Instead, you can only hope to take solace in your death by meeting with a spiritual advisor and hope the afterlife is better than where you are.

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The Great Escape

Okay, okay, this really is a fun adventure movie, for the most part. Still, there are some dark moments in The Great Escape like Archie Ives (Angus Lennie) cracking and in a move of desperation trying to scale the fence only to be cut down by the guards. As fun, as this movie is, it's still prison.

In The Name Of The Father

The only thing worse than getting locked up for committing a crime is getting locked up as an innocent man. In the classic In The Name Of The Father , that's exactly what happens to a man and his father, played by Daniel Day-Lewis and Pete Postlethwaite, respectively. They spend years in prison fighting for their freedom, which eventually comes, but too late for the father. 

The Bridge On The River Kwai

World War II prison camps in the Pacific Theater were no joke. In one of the best movies of all-time, The Bridge On The River Kwai , the brutality of life in the camp is on display for the full run-time of the movie. It's impossible to understand how those soldiers kept their dignity like they did. 

The Shawshank Redeption

In one of, if not the best movie of the '90s , two men face life sentences in a brutal prison in Maine in The Shawshank Redemption . The fact that Andy ( Tim Robbins ) is an innocent man wrongly sent to jail makes it even more brutal. Still, this is the kind of movie where humanity shines through, it's just not how anyone would every choose to experience it. 

Bronson is a wild movie, about a wild guy dubbed "Great Britain's most dangerous prisoner." Tom Hardy plays the titular character, who is based on a real criminal, and one look at how he acts with those around him and you'll know you never want to deal with anyone like him. The best way to avoid that is to stay out of jail! 

Brokedown Palace

Smuggling illicit items into a foreign country is about the worst idea, ever. Starring Claire Danes as Alice Marano and Kate Beckinsale as Darlene Davis, Brokedown Palace tells the story of two young women who make one major mistake and pay the price in the worst way in a brutal women's prison in Thailand.

Escape From New York

Not every prison has walls guards, or even cells. Some, it turns out are just the burnt-out remains of one of the great cities of the world, New York City. In Escape from New York , Snake (Kurt Russell) must navigate an apocalyptic landscape in a chaotic, free-for-all prison on what was once the island of Manhattan. No thanks.

Midnight Express

"Have you ever been in a Turkish prison" is the question Captain Over asks a kid in the spoof movie Airplane! Lost on a modern audience is that the joke is in reference to a movie from 1978 called Midnight Express . It was a phenomenon at the time and really set the bar for just how scary and awful prison can be, 

Even though 25th Hour doesn't actually take place in a prison, it's almost worse. Edward Norton plays a convicted man headed to prison, navigating how to prepare. Sometimes the anticipation can be the worst part and there is no better example than this fantastic movie directed by Spike Lee. 

Once again, we're talking about a movie that while it's a ton of fun on the surface, it doesn't take much to look under the hood and see how terrifying the people in prison are. Just two of the passengers on Con Air, Cyrus the Virus (John Malkovich) and Garland Green (Steve Buscemi) are enough to convince anyone that prison is a bad place to be. 

The Hurricane

Yet another tragic tale of an innocent man rotting away in prison for decades trying to get someone, anyone, in the justice system to believe him. Ruben Carter was railroaded into a murder conviction in the 1970s and spent years trying to get out. Hurricane tells his story brilliantly, and the good news is that eventually he did get out and declared innocent. 

The Dark Knight Rises

There is an old saying about throwing the worst criminals down the deepest, darkest hole in the earth. In The Dark Knight Rises that's exactly where some of the worst of the worst end up, including both Bane and Batman at different times. Only a few have ever escaped, like Talia al Ghul (Joey King) and Bruce Wayne (Christian Bale)

Sometimes it's hard to tell the difference between prison and a mental facility. Especially in a dystopian future like the one in 12 Monkeys . In fact, the movie makes the latter look way worse than a simple prison. Either way, you hope to not end up in either one. 

Sadistic guards in movies have long been one of the reasons it's clear you don't end up in jail, even - or maybe especially - as a juvenile. Kevin Bacon's character in Sleepers is so evil, so sadistic, that even when the worst happens to him later, you can't help but cheer. And say a little prayer that you never had to go through what the kids in that movie went through. 

Even in a fun superhero movie like Deadpool 2 , you don't want to end up in prison like Wade (Ryan Reynolds) does. Not only do they block his power and allow the cancer to return, he can't be protected from Cable (Josh Brolin)

The Power of One

One of Morgan Freeman's most underrated movies has to be The Power of One. Ultimately it's an inspiring story, but it's not without the cautionary tale of avoiding prison, something his character sadly cannot do in apartheid South Africa. 

American History X

If there is one thing to learn about avoiding prison in American History X , it's that you never want to end up like Edward Norton's character. Ever. He is the personification of evil and prison only makes him better at being evil. Not only do want to avoid people like him, you would never want to be in a position to have to be more like him. 

This one is a little tricky. For one, prison for wise guys doesn't look that bad in Goodfellas . There is steak, lobster, and thinly sliced garlic. On the other hand, life in the witness relocation program, eating egg noodles with ketchup, sounds like a miserable existence, so its best to just avoid the whole situation and stay on the straight and narrow. 

Papillion (2017)

2017's Papillon is a remake of a movie from 1973 starring Steve McQueen about a condemned man sent to the notorious Devil's Island prison from France. Both movies are great, so it's hard to pick one over the other. Both will scare the pants off you and ensure you'll do anything to avoid something like that. 

Gene Wilder and Richard Pryor can make anything fun and that includes prison. So while Stir Crazy is of the few movies on this list that audiences laugh through, it still doesn't sell anyone on the idea that prison is the place to be. Quite the opposite, in fact. 

The Stanford Prison Experiment

The Stanford Prison Experiment isn't the best movie on the list, nor is it about an actual prison, but anyone who knows anything about the real experience this film is fictionalizing knows just how awful things got. The experiment was to show what happens when regular people are put under the stress of being prisoners and guards in a prison-like situation. The results may make you lose all faith in humanity. 

Violence is everywhere in prison and Starred Up makes sure that audiences feel all of it viscerally. It's not an easy movie to watch, and it makes you wonder how anyone could survive inside with the level of violence possible. It's an underrated movie, but not one you aspire to be like. 

Jailhouse Rock

One of the many low-budget, quick productions that starred Elvis early in his career was the prison movie Jailhouse Rock . While it doesn't seem like the worst prison on earth and there is singing and dancing, it's still a prison. Maybe the real prison would be having to watch this movie over and over in lockdown 23 hours a day. 

Even in the future, prison looks miserable. Maybe even more miserable when you are stuck on a prison planet with nothing but violent criminals and forced to shave your head to avoid lice. And then an alien gets involved. Nope! No, thank you! 

Law Abiding Citizen

Everyone want to root for the antihero and in Law Abiding Citizen, Gerard Butler's character is one that is easy to root for. The time he spends in jail, however, is not something anyone could root for. Just like all the movies on this list. It all just sounds awful. 

Hugh Scott is the Syndication Editor for CinemaBlend. Before CinemaBlend, he was the managing editor for Suggest.com and Gossipcop.com, covering celebrity news and debunking false gossip. He has been in the publishing industry for almost two decades, covering pop culture – movies and TV shows, especially – with a keen interest and love for Gen X culture, the older influences on it, and what it has since inspired. He graduated from Boston University with a degree in Political Science but cured himself of the desire to be a politician almost immediately after graduation.

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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

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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

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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 .

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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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Blum B. The lifespan of a lie . Medium .

Le Texier T. Debunking the Stanford Prison Experiment . Am Psychol . 2019;74(7):823-839. doi:10.1037/amp0000401

Stanford Prison Experiment. Philip Zimbardo's response to recent criticisms of the Stanford Prison Experiment .

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

The Stanford Prison Experiment 50 Years Later: A Conversation with Philip Zimbardo

In April 1971, a seemingly innocuous ad appeared in the classifieds of the Palo Alto Times : Male college students needed for psychological study of prison life. $15 per day for 1-2 weeks. In no time, more than 70 students volunteered, and 24 were chosen. Thus began the Stanford Prison Experiment (SPE), conducted inside Jordan Hall on the Stanford campus. Originally scheduled to last two weeks, it was ended early over concerns regarding the behavior of both “prisoners” and “guards.” Still today, the SPE spikes enormous interest. Movies and documentaries have been made, books published, and studies produced about those six days. It’s clear today the research would never be allowed, but it was motivated by genuine concern over the ethical issues surrounding prisons, compliance with authority, and the evil humans have proved capable of. What was learned and at what cost? What is still being learned?

The Stanford Historical Society sponsors a look back at the controversial study with its leader, social psychologist Philip Zimbardo , Stanford Professor Emeritus of Psychology. Zimbardo is joined in conversation by Paul Costello who served as the chief communications officer for the School of Medicine for 17 years. He retired from Stanford in January 2021.

This program is organized by the Stanford Historical Society and co-sponsored by the Department of Psychology at Stanford University.

Additional resources

Watch video

Image credit: Stanford Prison Experiment (Special Collections and University Archives, Stanford Libraries)

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

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The Real Lesson of the Stanford Prison Experiment

On the morning of August 17, 1971, nine young men in the Palo Alto area received visits from local police officers. While their neighbors looked on, the men were arrested for violating Penal Codes 211 and 459 (armed robbery and burglary), searched, handcuffed, and led into the rear of a waiting police car. The cars took them to a Palo Alto police station, where the men were booked, fingerprinted, moved to a holding cell, and blindfolded. Finally, they were transported to the Stanford County Prison—also known as the Stanford University psychology department.

They were willing participants in the Stanford Prison Experiment, one of the most controversial studies in the history of social psychology. (It’s the subject of a new film of the same name—a drama, not a documentary—starring Billy Crudup, of “Almost Famous,” as the lead investigator, Philip Zimbardo. It opens July 17th.) The study subjects, middle-class college students, had answered a questionnaire about their family backgrounds, physical- and mental-health histories, and social behavior, and had been deemed “normal”; a coin flip divided them into prisoners and guards. According to the lore that’s grown up around the experiment, the guards, with little to no instruction, began humiliating and psychologically abusing the prisoners within twenty-four hours of the study’s start. The prisoners, in turn, became submissive and depersonalized, taking the abuse and saying little in protest. The behavior of all involved was so extreme that the experiment, which was meant to last two weeks, was terminated after six days.

Less than a decade earlier, the Milgram obedience study had shown that ordinary people, if encouraged by an authority figure, were willing to shock their fellow-citizens with what they believed to be painful and potentially lethal levels of electricity. To many, the Stanford experiment underscored those findings, revealing the ease with which regular people, if given too much power, could transform into ruthless oppressors. Today, more than forty-five years later, many look to the study to make sense of events like the behavior of the guards at Abu Ghraib and America’s epidemic of police brutality. The Stanford Prison Experiment is cited as evidence of the atavistic impulses that lurk within us all; it’s said to show that, with a little nudge, we could all become tyrants.

And yet the lessons of the Stanford Prison Experiment aren’t so clear-cut. From the beginning, the study has been haunted by ambiguity. Even as it suggests that ordinary people harbor ugly potentialities, it also testifies to the way our circumstances shape our behavior. Was the study about our individual fallibility, or about broken institutions? Were its findings about prisons, specifically, or about life in general? What did the Stanford Prison Experiment really show?

The appeal of the experiment has a lot to do with its apparently simple setup: prisoners, guards, a fake jail, and some ground rules. But, in reality, the Stanford County Prison was a heavily manipulated environment, and the guards and prisoners acted in ways that were largely predetermined by how their roles were presented. To understand the meaning of the experiment, you have to understand that it wasn’t a blank slate; from the start, its goal was to evoke the experience of working and living in a brutal jail.

From the first, the guards’ priorities were set by Zimbardo. In a presentation to his Stanford colleagues shortly after the study’s conclusion, he described the procedures surrounding each prisoner’s arrival: each man was stripped and searched, “deloused,” and then given a uniform—a numbered gown, which Zimbardo called a “dress,” with a heavy bolted chain near the ankle, loose-fitting rubber sandals, and a cap made from a woman’s nylon stocking. “Real male prisoners don't wear dresses,” Zimbardo explained, “but real male prisoners, we have learned, do feel humiliated, do feel emasculated, and we thought we could produce the same effects very quickly by putting men in a dress without any underclothes.” The stocking caps were in lieu of shaving the prisoner’s heads. (The guards wore khaki uniforms and were given whistles, nightsticks, and mirrored sunglasses inspired by a prison guard in the movie “Cool Hand Luke.”)

Often, the guards operated without explicit, moment-to-moment instructions. But that didn’t mean that they were fully autonomous: Zimbardo himself took part in the experiment, playing the role of the prison superintendent. (The prison’s “warden” was also a researcher.) /Occasionally, disputes between prisoner and guards got out of hand, violating an explicit injunction against physical force that both prisoners and guards had read prior to enrolling in the study. When the “superintendent” and “warden” overlooked these incidents, the message to the guards was clear: all is well; keep going as you are. The participants knew that an audience was watching, and so a lack of feedback could be read as tacit approval. And the sense of being watched may also have encouraged them to perform. Dave Eshelman, one of the guards, recalled that he “consciously created” his guard persona. “I was in all kinds of drama productions in high school and college. It was something I was very familiar with: to take on another personality before you step out on the stage,” Eshelman said. In fact, he continued, “I was kind of running my own experiment in there, by saying, ‘How far can I push these things and how much abuse will these people take before they say, ‘Knock it off?’ ”

Other, more subtle factors also shaped the experiment. It’s often said that the study participants were ordinary guys—and they were, indeed, determined to be “normal” and healthy by a battery of tests. But they were also a self-selected group who responded to a newspaper advertisement seeking volunteers for “a psychological study of prison life.” In a 2007 study, the psychologists Thomas Carnahan and Sam McFarland asked whether that wording itself may have stacked the odds. They recreated the original ad, and then ran a separate ad omitting the phrase “prison life.” They found that the people who responded to the two ads scored differently on a set of psychological tests. Those who thought that they would be participating in a prison study had significantly higher levels of aggressiveness, authoritarianism, Machiavellianism, narcissism, and social dominance, and they scored lower on measures of empathy and altruism.

Moreover, even within that self-selected sample, behavioral patterns were far from homogeneous. Much of the study’s cachet depends on the idea that the students responded en masse, giving up their individual identities to become submissive “prisoners” and tyrannical “guards.” But, in fact, the participants responded to the prison environment in all sorts of ways. While some guard shifts were especially cruel, others remained humane. Many of the supposedly passive prisoners rebelled. Richard Yacco, a prisoner, remembered “resisting what one guard was telling me to do and being willing to go into solitary confinement. As prisoners, we developed solidarity—we realized that we could join together and do passive resistance and cause some problems.”

What emerges from these details isn’t a perfectly lucid photograph but an ambiguous watercolor. While it’s true that some guards and prisoners behaved in alarming ways, it’s also the case that their environment was designed to encourage—and, in some cases, to require—those behaviors. Zimbardo himself has always been forthcoming about the details and the nature of his prison experiment: he thoroughly explained the setup in his original study and, in an early write-up , in which the experiment was described in broad strokes only, he pointed out that only “about a third of the guards became tyrannical in their arbitrary use of power.” (That’s about four people in total.) So how did the myth of the Stanford Prison Experiment—“Lord of the Flies” in the psych lab—come to diverge so profoundly from the reality?

In part, Zimbardo’s earliest statements about the experiment are to blame. In October, 1971, soon after the study’s completion—and before a single methodologically and analytically rigorous result had been published—Zimbardo was asked to testify before Congress about prison reform. His dramatic testimony , even as it clearly explained how the experiment worked, also allowed listeners to overlook how coercive the environment really was. He described the study as “an attempt to understand just what it means psychologically to be a prisoner or a prison guard.” But he also emphasized that the students in the study had been “the cream of the crop of this generation,” and said that the guards were given no specific instructions, and left free to make “up their own rules for maintaining law, order, and respect.” In explaining the results, he said that the “majority” of participants found themselves “no longer able to clearly differentiate between role-playing and self,” and that, in the six days the study took to unfold, “the experience of imprisonment undid, although temporarily, a lifetime of learning; human values were suspended, self-concepts were challenged, and the ugliest, most base, pathological side of human nature surfaced.” In describing another, related study and its implications for prison life, he said that “the mere act of assigning labels to people, calling some people prisoners and others guards, is sufficient to elicit pathological behavior.”

Zimbardo released video to NBC, which ran a feature on November 26, 1971. An article ran in the Times Magazine in April of 1973. In various ways, these accounts reiterated the claim that relatively small changes in circumstances could turn the best and brightest into monsters or depersonalized serfs. By the time Zimbardo published a formal paper about the study , in a 1973 issue of the International Journal of Crim__i__nology and Penology , a streamlined and unequivocal version of events had become entrenched in the national consciousness—so much so that a 1975 methodological critique fell largely on deaf ears.

Forty years later, Zimbardo still doesn’t shy away from popular attention. He served as a consultant on the new film, which follows his original study in detail, relying on direct transcripts from the experimental recordings and taking few dramatic liberties. In many ways, the film is critical of the study: Crudup plays Zimbardo as an overzealous researcher overstepping his bounds, trying to create a very specific outcome among the students he observes. The filmmakers even underscore the flimsiness of the experimental design, inserting characters who point out that Zimbardo is not a disinterested observer. They highlight a real-life conversation in which another psychologist asks Zimbardo whether he has an “independent variable.” In describing the study to his Stanford colleagues shortly after it ended, Zimbardo recalled that conversation: “To my surprise, I got really angry at him,” he said. “The security of my men and the stability of my prison was at stake, and I have to contend with this bleeding-heart, liberal, academic, effete dingdong whose only concern was for a ridiculous thing like an independent variable. The next thing he’d be asking me about was rehabilitation programs, the dummy! It wasn’t until sometime later that I realized how far into the experiment I was at that point.”

In a broad sense, the film reaffirms the opinion of John Mark, one of the guards, who, looking back, has said that Zimbardo’s interpretation of events was too shaped by his expectations to be meaningful: “He wanted to be able to say that college students, people from middle-class backgrounds ... will turn on each other just because they’re given a role and given power. Based on my experience, and what I saw and what I felt, I think that was a real stretch.”

If the Stanford Prison Experiment had simulated a less brutal environment, would the prisoners and guards have acted differently? In December, 2001 , two psychologists, Stephen Reicher and Alexander Haslam, tried to find out. They worked with the documentaries unit of the BBC to partially recreate Zimbardo’s setup over the course of an eight-day experiment. Their guards also had uniforms, and were given latitude to dole out rewards and punishments; their prisoners were placed in three-person cells that followed the layout of the Stanford County Jail almost exactly. The main difference was that, in this prison, the preset expectations were gone. The guards were asked to come up with rules prior to the prisoners’ arrival, and were told only to make the prison run smoothly. (The BBC Prison Study, as it came to be called, differed from the Stanford experiment in a few other ways, including prisoner dress; for a while, moreover, the prisoners were told that they could become guards through good behavior, although, on the third day, that offer was revoked, and the roles were made permanent.)

Within the first few days of the BBC study, it became clear that the guards weren’t cohering as a group. “Several guards were wary of assuming and exerting their authority,” the researchers wrote. The prisoners, on the other hand, developed a collective identity. In a change from the Stanford study, the psychologists asked each participant to complete a daily survey that measured the degree to which he felt solidarity with his group; it showed that, as the guards grew further apart, the prisoners were growing closer together. On the fourth day, three cellmates decided to test their luck. At lunchtime, one threw his plate down and demanded better food, another asked to smoke, and the third asked for medical attention for a blister on his foot. The guards became disorganized; one even offered the smoker a cigarette. Reicher and Haslam reported that, after the prisoners returned to their cells, they “literally danced with joy.” (“That was fucking sweet,” one prisoner remarked.) Soon, more prisoners began to challenge the guards. They acted out during roll call, complained about the food, and talked back. At the end of the sixth day, the three insubordinate cellmates broke out and occupied the guards’ quarters. “At this point,” the researchers wrote, “the guards’ regime was seen by all to be unworkable and at an end.”

Taken together, these two studies don’t suggest that we all have an innate capacity for tyranny or victimhood. Instead, they suggest that our behavior largely conforms to our preconceived expectations. All else being equal, we act as we think we’re expected to act—especially if that expectation comes from above. Suggest, as the Stanford setup did, that we should behave in stereotypical tough-guard fashion, and we strive to fit that role. Tell us, as the BBC experimenters did, that we shouldn’t give up hope of social mobility, and we act accordingly.

This understanding might seem to diminish the power of the Stanford Prison Experiment. But, in fact, it sharpens and clarifies the study’s meaning. Last weekend brought the tragic news of Kalief Browder’s suicide . At sixteen, Browder was arrested, in the Bronx, for allegedly stealing a backpack; after the arrest, he was imprisoned at Rikers for three years without trial . (Ultimately, the case against him was dismissed.) While at Rikers, Browder was the object of violence from both prisoners and guards, some of which was captured on video . It’s possible to think that prisons are the way they are because human nature tends toward the pathological. But the Stanford Prison Experiment suggests that extreme behavior flows from extreme institutions. Prisons aren’t blank slates. Guards do indeed self-select into their jobs, as Zimbardo’s students self-selected into a study of prison life. Like Zimbardo’s men, they are bombarded with expectations from the first and shaped by preëxisting norms and patterns of behavior. The lesson of Stanford isn’t that any random human being is capable of descending into sadism and tyranny. It’s that certain institutions and environments demand those behaviors—and, perhaps, can change them.

the InMind blog

Bug or feature boredom feels aversive, and this is why it matters.

written by Wanja Wolff, Katja Rewitz & Dr. Maik Bieleke

Doing ill for ‘the greater good’: Understanding what really went on in the Stanford Prison Experiment

• written by Alex Haslam , Stephen Reicher & Jay Van Bavel

Just about every highschool and college psychology textbook offers extensive coverage of Zimbardo’s Stanford Prison Experiment (SPE). The meaning of the SPE seemed obvious — that when given roles with power , people naturally become brutal tyrants. This message has had lasting influence, not only in psychology but in the world at large. However, after researchers have recently gained access to the SPE archives, it has come to light that much of what we thought we knew about the study is inaccurate. We asked three experts to weigh in on these recent events, and the resulting discussion is one that offers valuable insights not only into the SPE but also into the role of debate in science and way that we engage with, and teach about, psychology’s classic studies.   

Few readers will be unfamiliar with the story of the Stanford Prison Experiment (SPE). Conducted in the summer of 1971, the study involved randomly assigning 18 college students to roles as Prisoners and Guards in a simulated prison that had been created in the basement of the Department of Psychology at Stanford University [ 1 , 2 ]. The researchers’ claim was that they simply stood back and watched what happened, and, in particular, that they provided no training to the Guards.

Their hypothesis was that the participants’ “behavioural scripts associated with the oppositional roles of Prisoner and Guard” — which were “the sole source of guidance” — would be sufficient for the prison to turn nasty [ 3 ]. There is little question that things did indeed turned nasty: after just six days the study had to be abandoned out of fear for the Prisoners’ welfare, such was the brutality of the Guards.

In the intervening 47 years this is a story that has been told by Zimbardo again and again, in media interviews, public lectures, and on the official website for the study. It was also a story that he retold in 2003 as he contributed to the legal defence of those who abused detainees at Abu Ghraib prison in Iraq. Here Zimbardo argued that the brutal acts that shocked the world were evidence of the power of roles to subvert perpetrators’ character and morality. He labelled this “The Lucifer Effect” — the title of his best-selling 2007 book [ 4 ] which also provided the basis for Kyle Alavarez’s eponymous film which faithfully and dramatically reenacted Zimbardo’s official version of events in the SPE [ 5 ]. This story is a staple of most of introductory psychology textbooks [ 6 ] and is retold to tens of thousands of college and high school students around the world every year [ 7 ].

In recent weeks, however, there has been another surge of interest in the SPE, rivalling any that have gone before. This time, though, the story is very different. It coincides with the digitization of material from the SPE in the Stanford University archives [ 8 ] which, for the first time, gives researchers (and anyone else who is interested) direct access to evidence from the study itself. In particular, it reveals hitherto unknown information about how Zimbardo and his colleagues conducted their research. Since the original paper was not published in a traditional peer-reviewed psychology journal, these critical methodological details have been hidden to scholars—and the public—for the past half century.

There is a wealth of such material in the archive, and researchers are now beginning to pore over it with interest. In this they have been guided by the exhaustive forensic work of the French researcher Thibault Le Texier [ 9 ], closely (and independently) followed by American journalist Ben Blum [ 10 ]. The title of Le Texier’s book —  Histoire D’Un Mensonge  [ Story of a Lie ] — gives a clear indication of his findings. Blum also uses the same word,  lie , to sum up his conclusion. The bottom line for both researchers is that many of the things we thought we knew about the SPE are flatly contradicted by the newly unearthed evidence.

Perhaps the most revealing piece of evidence in the archive is an 18-minute tape recording of a meeting between Zimbardo’s prison Warden, David Jaffe, and a reluctant Guard, John Mark [ 11 ]. This recording can be accessed at  https://purl.stanford.edu/wn708sg0050  (from 8:38 onwards).  Before you read on, we strongly recommend that you listen to this recording with your own ears and ask yourself: Is the guard conforming blindly to his role as a brutal guard or is he being pressured by the Warden to behave this way?

What you can hear on the tape is a Warden repeatedly cajoling the Guard to “toughen up”. He starts by saying “ We noticed this morning that you weren’t really lending a hand … but we really want to get you active and involved because the Guards have to know that every Guard is going to be what we call a tough Guard” . The Guard, John Mark, repeatedly resists this pressure from the Warden over the course of the meeting. Eventually, the Warden declares: “ When there’s a situation … [you have]  to have to go in there and shout if necessary. To be more  into  the action. ”

Far from being left to their own devices, it is thus clear that the Guards—or at least this one Guard—were told what they had to do, and then asked to account for themselves if they didn’t. It is not clear how many guards were exposed to pressure of this form, but it seems likely that even if only one Guard was told to behave this way, the message would have been shared among the Guards as the study progressed (noting that this was instruction directed at “every Guard”).  

This evidence blows Zimbardo’s role account out of the water. For what one sees in the meeting is that the Warden characterizes the Guard not as a research participant but as a confederate who is expected to act in ways defined by the Experimenters. Unsurprisingly, perhaps, no mention was made of such meetings in Zimbardo’s 2007 book, and they are conspicuously absent from Alvarez’s movie. While an early paper did allude to the fact that the Guards thought the Experimenters were primarily interested in the Prisoners’ behaviour [1, p.75], the significance of this point was never elaborated upon, and it was then dropped from later accounts.

This type of instruction is unheard of in psychology experiments. Indeed, Experimenters are expected to take steps to ensure that their actions, even subtle ones, do not unduly influence the behaviour of participants. But in this case, the Experimenters’ influence attempts were anything but subtle. In the face ongoing and stubborn resistance from the participant they took the form of explicit, repeated instructions to engage in patterns of behaviour that supported Zimbardo’s research goals.

Almost everyone we have shared this recording with has concluded that Zimbardo’s account of the SPE actually is deeply flawed. To ensure these intuitions had some validity, we conducted a Twitter poll asking people to listen to the tape and then evaluate Zimbardo’s account. This, of course, is not a scientific test. Nevertheless, just 4% of respondents felt that what happened in the meeting between Warden Jaffe and Guard Mark was consistent with the idea that the Guards in the SPE conformed “naturally” to role (the phrase used in the original article on the study [ 12 ]). In short, then, the received story about the Stanford Prison Experiment simply does not hold up in the face of the new evidence.

Although we were surprised to find such convincing evidence (evidence that, to be frank, we would have struggled to make up), its content was not wholly surprising to us. There had always been rumours that the SPE was not all that it seemed. Amongst other things, a number of letters published in the  Stanford Daily  over the years had suggested that the Experimenters had been more interventionist than they admitted. Thus, in 2007 the resistant Guard, John Mark, wrote that: “My opinion, based on my observations, was that Zimbardo began with a preformed blockbuster conclusion and designed an experiment to ‘prove’ that conclusion” [ 13 ].

Even before this, in 2006, we had noted that snippets of information that were already in the public  domain  — such as Zimbardo’s original briefing to his Guards which forms part of his film ‘Quiet Rage’ [ 14 ]  —   pointed to the importance of the Experimenter’s leadership in producing the toxicity of the SPE. But such evidence was limited in quantity and quality. It was hardly enough to topple what is possibly the single most famous study in social psychology. But the news from the archive and the Jaffe-Mark tape completely transform our understanding of this classic study. Now the evidence of the Experimenters’ intervention and leadership is simply undeniable.

Faced with this new evidence, one response has been to urge psychologists to wash their hands of the SPE. Tellingly, both Le Texier and Blum press for the study to be labelled as fraudulent and purged from classrooms and textbooks. We understand this response. Whether it will be successful is a quite different question. As Richard Griggs has noted [10], in the past, textbook authors have been reluctant to discuss the SPE’s shortcomings in favour of a simple compelling story.

But this new evidence is of a qualitatively different order. Moreover, it comes in the midst of greatly heightened concern about scientific fraud and misconduct. Certainly, it would be better to have the study expunged from the scientific record than to perpetuate a story which is strikingly inconsistent with the facts.

At the same time, we would urge against so sweeping a response. Certainly, the SPE is deeply flawed. The accounts we have been given omit crucial information, the degree of guard brutality is overemphasised, and Zimbardo’s explanation of the study is plainly untenable.

But it remains undeniable that  some  Guards did act in extreme ways.  So we still accept Zimbardo’s claim that the SPE is a powerful demonstration of the capacity for ordinary men to be turned to evil. But this needs to be properly explained. In this respect, at the same time as it discredits the old analysis, the information that has emerged from the archive is extremely helpful.

We were always concerned with what we saw as excessive interventionism with the SPE. That is why, when two of us ran our own prison study [ 15 ] we consciously declined to tell our participants what to do. In the absence of such direction, our Guards were very unwilling to take on their role and to impose discipline. This meant that they became increasingly unable to keep the Prisoners in order and eventually the system collapsed. It was only when a leader who promised to restore law and order in the prison came to the fore and cultivated a following among new Guards that the spectre of oppression akin to that seen in the SPE surfaced.

Over time, that experience motivated us to examine the role of leadership in toxic behaviour more generally, looking both at other studies that address how ordinary people can act with inhumanity (notably Milgram’s Obedience to Authority studies [ 16 ]) and real-world examples such as the Holocaust and the Rwandan genocide [ 17 , 18 ]. This work culminated in a model of ‘identity leadership’ which argues that brutality occurs to the extent that leaders are able to persuade people (1) that they are part of a common group, (2) that the group’s cause is worthy, and (3) that brutal acts are necessary for the achievement of group goals [ 19 , 20 ].

But although the SPE set us on the path towards an identity leadership analysis, we were unable to find clear evidence that such an analysis could explain what happened in the SPE. Until now. As we show in a paper we have just submitted for publication [ 21 ], the archives provide us with the critical evidence to complete our argument.

What we hear in Warden Jaffe’s cajoling of Guard Mark is precisely the hallmarks of identity leadership. First, the Warden repeatedly uses collective pronouns (“we”) to characterize their relationship, endeavoring to position the Experimenters and Guards as a team working toward a common goal . Second, Warden Jaffe does not tell Mark to be tough for its own sake. Rather he tries to persuade him that toughness is something  necessary  for the achievement of shared ingroup goals. And, third he presents that cause as one that is fundamentally  noble and worth y.

In this case, the cause was much-needed improvement to the U.S. correctional system.  “ Hopefully what will come out of this study”,  the Warden tells the Guard , “is some very serious recommendations for reform, at least reform, if not, you know, revolutionary-type reform”.  “We’re not doing this because we’re sadists” , he says, we’re doing it to make the world a better place. This, then, is the very essence of identity leadership.

The end of tyranny

For the past 10 years we have sought to engage Zimbardo in debate around the above ideas. Not least, we have done so through peer-reviewed publications in leading journals that address the broad range of issues that his and our work raises — those concerning not only the origins of tyranny and resistance [ 22 ], but also the nature of leadership and followership [ 23 , 24 ], and the social determinants of stress and mental health [ 25 ]. 

These efforts have failed. Zimbardo has responded by labelling our prison study ‘reality TV’ [ 26 ], as deplorable, shameful and fraudulent [ 27 , 28 ], and he describes us as mere ‘bloggers’ [ 29 ]. What is fascinating here is the way that Zimbardo — responding to us and his other critics — uses the very same rhetorical techniques to try and engage the audience on his side as his Warden, Jaffe, used to try and engage Mark in the SPE. That is, he insists that his work is a moral crusade, aimed at promoting social justice. And that therefore those who threaten to derail his position need to be swatted aside for the sake of the cause.

As Zimbardo himself is unwilling to reconsider the meaning of his study, then we ask you, the reader, to listen to the evidence with your own ears and tell us what you hear. If you share our concern that his story does not fit his data, then we encourage you to change how you talk about the SPE to your students, colleagues and members of the public at large.

Correspondence regarding this piece can be addressed to Alex Haslam, School of Psychology, University of Queensland, St. Lucia QLD 4072, Australia; e-mail: [email protected] ; Tel.: +61 (0)7 3346 9157

[1] Haney, C., Banks, C. & Zimbardo, P. (1973). A study of prisoners and guards in a simulated prison.  Naval Research Reviews . September (pp.1-17). Office of Naval Research: Washington, D.C.

[2] Haney, C., Banks, C., & Zimbardo, P. G. (1973). Interpersonal dynamics in a simulated prison.  International Journal of Criminology and Penology ,  1 , 69–97.

[3] Zimbardo, P. G. (2004). A situationist perspective on the psychology of evil: Understanding how good people are transformed into perpetrators. In A.Miller (Ed.),  The social psychology of good and evil  (pp.21–50).New York: Guilford. (p.39)

[4] Zimbardo, P. (2007).  The Lucifer Effect: How good people turn evil. London: Random House.

[5] Alvarez, K. P. (Dir.) (2015).  The Stanford Prison Experiment [Motion picture]. New York: IFC Films.

[6] Griggs, R. A. (2014). Coverage of the Stanford Prison Experiment in introductory psychology textbooks.  Teaching of Psychology ,  41 , 195-203.

[7] Bartels, J. M., Milovich, M. M., & Moussier, S. (2016). Coverage of the Stanford prison experiment in introductory psychology courses: A survey of introductory psychology instructors.  Teaching of Psychology ,  43 , 136-141.

[8] https://searchworks.stanford.edu/catalog?f%5Bcollection%5D%5B%5D=6022627

[9] Le Texier, T. (2018).  Histoire d’un mensonge: Enquête sur l’experience de Stanford . Editions la Découverte: Paris. 

[10] Blum, B. (2018). The lifespan of a lie.  Medium . https://medium.com/s/trustissues/the-lifespan-of-a-lie-d869212b1f62

[11] Accessible at:  http://purl.stanford.edu/wn708sg0050

[12] Haney, C., Banks, C. & Zimbardo, P. (1973). A study of prisoners and guards in a simulated prison.  Naval Research Reviews . September (pp.1-17). Office of Naval Research: Washington, D.C. (p.12)

[13] See: https://alumni.stanford.edu/get/page/magazine/article/?article_id=32561

[14] Zimbardo, P. (1989). Quiet rage  (video). Stanford, CA: Stanford University.

[15] Reicher, S. D., & Haslam, S. A. (2006). Rethinking the psychology of tyranny: The BBC Prison Experiment.  British Journal of Social Psychology ,  45 , 1-40.

[16] Milgram, S. (1974).  Obedience to authority: An experimental view.  New York: Harper & Row.

[17] Haslam, S. A., & Reicher, S. D. (2012). Contesting the “nature” of conformity: What Milgram and Zimbardo’s studies really show.  PLoS Biology ,  10 (11): e1001426.

[18] Reicher, S., Haslam, S. A., & Rath, R. (2008). Making a virtue of evil: A five‐step social identity model of the development of collective hate.  Social and Personality Psychology Compass ,  2 (3), 1313-1344.

[19] Haslam, S. A., & Reicher, S. D. (2007). Beyond the banality of evil: Three dynamics of an interactionist social psychology of tyranny.  Personality and Social Psychology Bulletin, 33 , 615-622.

[20] Haslam, S. A., & Reicher, S. D. (2017). 50 years of “obedience to authority”: From blind obedience to engaged followership.  Annual Review of Law and Social Science ,  13 , 59-78. e109015. doi:10.1146/annurev-lawsocsci-110316-113710

[21] Haslam, S. A., Reicher, S. D., Ranz-Schleifer, N., & Van Bavel. (2018).Rethinking the ‘nature’ of brutality: Uncovering the role of identity leadership in the Stanford Prison Experiment. Accessible at PsyArXiv Preprints: https://psyarxiv.com/b7crx

[22] Haslam, S. A., & Reicher, S. D. (2012a). When prisoners take over the prison: A social psychology of resistance.  Personality and Social Psychology Review ,  16 , 154-179.

[23] Reicher, S. D., Haslam, S. A., & Hopkins, N. (2005). Social identity and the dynamics of leadership: Leaders and followers as collaborative agents in the transformation of social reality.  Leadership Quarterly, 16 , 547-568.

[24] Haslam, S. A., & Reicher, S. D. (2007). Identity entrepreneurship and the consequences of identity failure: The dynamics of leadership in the BBC Prison Study.  Social Psychology Quarterly , 70 , 125-147. doi:10.1177/019027250707000204

[25] Haslam, S. A., & Reicher, S. D. (2006). Stressing the group: Social identity and the unfolding dynamics of responses to stress.  Journal of Applied Psychology, 91 , 1037-1052. doi:10.1037/0021-9010.91.5.1037

[26] See: http://www.prisonexp.org/response

[27] See: https://twitter.com/alexanderhaslam/status/1011876643927883776

[28] Zimbardo, P. (2006). On rethinking the psychology of tyranny: The BBC Prison Study.  British Journal of Social Psychology ,  45 , 47–53.

[29] See: https://www.vox.com/science-and-health/2018/6/28/17509470/stanford-priso...

article author(s)

Alex Haslam

Alex Haslam is Professor of Psychology and Australian Laureate Fellow at the University of Queensland. His research focuses on the study of group and... more

Stephen Reicher

Stephen Reicher is Wardlaw Professor of Psychology at the University of St. Andrews. His research is on social identity and group processes. Stephen is a... more

Jay Van Bavel

Jay Van Bavel is an Associate Professor of Psychology & Neural Science at New York University, an affiliate at the Stern School of Business in... more

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Table of Contents

Background and Objectives

In the 1960s and 70s, psychologist Philip Zimbardo conducted several notable social psychology experiments examining how social roles and situations can impact human behavior .

Zimbardo designed the Stanford Prison Experiment in 1971 to explore the psychology of imprisoning people. He aimed to study how participants reacted to being assigned randomized roles of prisoner and guard.

Zimbardo’s primary hypothesis was that the imposed social roles and environment of a prison would dominate the individual personalities of the participants, causing them to exhibit more extreme behaviors.

The experiment intended to demonstrate that situational variables can have a more powerful influence over behavior than inherent individual traits.

Zimbardo set up a simulated prison environment in the basement of Stanford University’s psychology building.

He recruited 18 male college students through a newspaper ad offering $15 per day to participate.

Although the participants had no abnormal psychological issues, Zimbardo hoped to provoke realistic responses by creating a believable mock prison.

The experiment planned to observe the participants’ interactions, emotions, and behaviors in this environment over a planned two-week study period.

Through this approach, Zimbardo sought to gain insight into the psychological mechanisms that make prisons dehumanizing environments.

Methodology

Zimbardo converted a corridor of the psychology department building into a simulated prison environment.

The experiment was monitored with video cameras and microphones. The participants were randomly assigned to be either “prisoners” or “guards” using a coin flip.

The “prisoners” were picked up by surprise at their homes by actual police officers, searched, handcuffed, and brought to the mock prison.

The prisoners were stripped naked, deloused, and given smocks and stocking caps to establish their powerless status.

Each prisoner was assigned an ID number to replace their name and lived in a small cell containing only a cot for sleeping.

The “guards” worked eight-hour shifts, with three guards working each shift. Guards wore military-style uniforms and reflector sunglasses to create an anonymous, authoritative appearance.

They carried handcuffs, whistles, and billy clubs. The guards followed protocols to maintain control, including bag searches, ID checks, and setting strict schedules.

However, they could otherwise run the prison however they wished and were told to demand total compliance from prisoners.

The study was scheduled to run for 14 days.

Zimbardo intended to observe how the participants interacted in these circumstances.

He took on the role of the prison superintendent, navigating how the study would proceed. Zimbardo encouraged the guards to create an oppressive atmosphere and break down the prisoners over time.

Findings and Analysis

The experiment quickly escalated out of control as the “guards” began ramping up their harassment and authoritarian measures, while the “prisoners” passively accepted the abuse.

On the second day of the experiment, the prisoners rebelled by barricading their cell doors and taunting the guards.

The guards responded by forcibly stripping the prisoners naked and removing their beds as punishment.

One prisoner developed acute emotional disturbance and had to be released after only 36 hours.

Over the next few days, the guards escalated their aggressive and dehumanizing tactics using psychological humiliation.

They set up privilege systems to make prisoners turn on each other.

Prisoners were forced to repeat their ID numbers and do meaningless chores and exercise.

Some prisoners began showing signs of depression and acute anxiety .

The guards and prisoner “#819” came into major conflict , with the prisoner launching a hunger strike.

Prisoner #819 was then subjected to further abuse.

Zimbardo interpreted the behavior results as arising from the assigned social roles and rules dominating over individual dispositions.

The prisoners became increasingly passive , depressed, and helpless as the study went on.

The phenomenon of one domineering guard nicknamed “John Wayne” emerged through the study procedures.

Zimbardo concluded the imposed prison environment crushed internal values and morals.

Criticisms and Ethical Concerns

The Stanford Prison Experiment has been widely criticized for being unscientific and unethical.

Critics point out there was no control group to compare against the prisoner and guard group.

The sample size of only 24 male participants was also too small to draw general conclusions about human behavior.

There are major ethical concerns about the amount of psychological distress inflicted on the participants.

The prisoners showed signs of anxiety, depression, and learned helplessness. Critics argue it was unethical to allow participants to continue suffering emotional harm.

The guards were encouraged to degrade the prisoners without oversight on their methods.

The experimenters became overinvolved as the study progressed rather than remaining neutral observers.

The experiment could not be conducted today with current ethical standards.

Today’s Institutional Review Boards would never allow vulnerable participants to be subjected to such dangerous psychological manipulation without proper informed consent.

Critics argue Zimbardo was irresponsible for encouraging aggression and abuse between participants.

The dramatic, uncontrolled nature of the study design would be prohibited by today’s more stringent safeguards.

Ultimately, the Stanford Prison Experiment revealed more about the problematic study procedures than any deep insights into human behavior.

While thought-provoking, the experiment is widely considered unethical and lacking in scientific rigor by today’s standards.

Legacy and Relevance Today

While the Stanford Prison Experiment faced deserved criticism, it left a legacy and continues to be referenced given the dramatics of the study.

Zimbardo’s experiment demonstrated how situational variables like social roles can override individual disposition to generate extreme behaviors.

The study shed light on how putting people in positions of power without oversight can lead to the abuse of authority.

The Stanford Prison Experiment is frequently cited when discussing the psychology of imprisonment.

The study showed how prisoners can become distressed and resigned in response to an oppressive environment.

It provided insight into how regimes like concentration camps can gain control through psychological manipulation.

However, the experiment’s scientific limitations mean its conclusions should be applied cautiously.

The study informed later research into prison conditions and supervisor/subordinate dynamics.

Modern replication attempts have used more rigorous methods and ethical standards.

However, the original experiment’s dramatic narrative keeps its themes relevant when examining topics like oppression, compliance, surveillance, and dehumanization.

Zimbardo’s prison study remains impactful despite its flaws, pioneering new areas of psychology research.

While controversial, it provided a warning about unconstrained authority that still resonates over 50 years later.

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The Stanford Prison Experiment

In 1971, twenty-four male students are selected to take on randomly assigned roles of prisoners and guards in a mock prison situated in the basement of the Stanford psychology building. In 1971, twenty-four male students are selected to take on randomly assigned roles of prisoners and guards in a mock prison situated in the basement of the Stanford psychology building. In 1971, twenty-four male students are selected to take on randomly assigned roles of prisoners and guards in a mock prison situated in the basement of the Stanford psychology building.

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• Trivia Although never mentioned in the movie, the real life experiment was funded by the U.S. Office of Naval Research and was of interest to both the U.S. Navy and Marine Corps as an investigation into the causes of conflict between military guards and prisoners.
• Goofs When Dr. Zimbardo speaks with his colleague, the colleague says that he will see him at the beginning of the semester. Stanford does not have semesters; rather, it has a quarter academic calendar.

Daniel Culp : I know you're a nice guy.

Christopher Archer : So why do you hate me?

Daniel Culp : Because I know what you can become.

• Connections Featured in WatchMojo: Top 10 Creepiest Historic Events That Are Scarier than Horror Movies (2020)

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• May 28, 2016
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• July 17, 2015 (United States)
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• Jul 19, 2015

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• Runtime 2 hours 2 minutes

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How the Stanford Prison Experiment Worked

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A Deeper Look at the Stanford Prison Experiment

Zimbardo has written extensively about the experiment, filling in major details about what happened. There were nine prisoners and nine active guards. The remaining three participants on each side were on standby in case they were needed. The guards operated in shifts, and the prisoners were always present. The guards were initially reluctant in their roles, the prisoners defiant. But on the second day, the prisoners united: They locked themselves in their cells, insulted the guards and ripped the prisoner numbers off their uniforms, rebelling against the guards' authority. The guards used the incoming shift and the standby guards as reinforcements to put down the rebellion, stripping the prisoners naked and taking away their beds [source: Zimbardo ]. This incident also marked the introduction of physical punishments like pushups (often with a guard placing his foot on a prisoner's back).

The guards even instituted a "privilege" cell, one with beds and good meals for the three best-behaved prisoners, and used it to turn the prisoners against each other. At the apex of the guards' brutality, they tried to keep a prisoner in solitary confinement , which was literally a tiny closet barely large enough to fit a person, for an entire night, only relenting when one of the researchers stepped in. And during the night shift, when the guards thought they were not being observed, their torment of the prisoners turned to more intense physical punishment, waking the prisoners throughout the night and forcing them to perform vaguely erotic acts (such as standing very close to each other).

But the guards were not all equally brutal. There was a "ringleader" guard, nicknamed John Wayne, who seemed especially vicious, as well as guards who did the prisoners favors and did not punish them severely. However, the "good" guards never objected to or complained about the behavior of the sadistic guards. The brutal guard, whose real name is Dave Eshelman, has claimed in interviews that he was acting the part he thought the researchers wanted to see. But he has noted that pretending didn't absolve him of his cruelty, since his actions obviously caused misery [source: Ratnesar ].

By the end of the experiment, the prisoners exhibited no solidarity, while the guards and even Zimbardo had grown to see the prisoners as a threat that needed to be subdued for the safety of the guards and the integrity of the prison [source: Stanford Prison Experiment ]. Everyone involved became so deeply immersed in the experiment's role-playing scenario that at one point the prisoners were offered "parole." That is, they could be released if they would forfeit any money they'd earned for participating. In a parole hearing, most of the prisoners said they would forfeit their money, and the parole board members (secretaries, students and the prison consultant) said they had to consider if they would allow parole for those prisoners who accepted the offer. The board sent the prisoners back to their cells, and the prisoners complied, even though they had the ability to walk away from the experiment (giving up the $15 per day) at any time [source: Haney et al. ].

The five prisoners who were released (no guards left the experiment) experienced irrational thinking, unstable emotions and severe anxiety. One even broke out in a psychosomatic rash. In fact, the prisoners either had breakdowns, faked breakdowns so they could leave or simply became "zombies," going along with whatever the guards made them do with little or no emotional reaction.

But on day six, Zimbardo called off the experiment, realizing it had quickly become problematic.

Zimbardo and his team went to astonishing lengths to make their prison seem realistic. During a visiting hour, parents and friends were subjected to arbitrary prison rules, such as being forced to wait to see an "inmate" and having a limited amount of time to speak to him. Also, a former prison chaplain who was brought in to speak to the prisoners suggested they get legal counsel if they wanted to get out of the prison. When some parents asked for a lawyer, a lawyer came in and played along as if it were a real prison. And when the first prisoner to emotionally break down asked to leave, he was convinced to stay when the researchers' prison consultant manipulated and browbeat him. When he went back to the other prisoners, he told them he'd learned they really couldn't leave.

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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

• What Is Shyness?
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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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Stanford Prison Experiment

The Stanford Prison Experiment (SPE) is a highly influential and controversial study run by Philip Zimbardo and his colleagues at Stanford University in 1971. The researchers originally set out to support the notion that situational forces are just as powerful and perhaps more powerful than dispositional forces in influencing prison behavior. In addition to providing support for their hypothesis, the study was heavily covered in the mainstream media and had far-reaching ethical implications. Regardless, and perhaps because of its controversial nature, the SPE remains one of the most well-known experiments in social psychology.

The Purpose of the Stanford Prison Experiment

Stanford Prison Experiment Methodology

To test their hypothesis, Zimbardo and colleagues created a realistic mock prison in the basement of Stanford University. The participants included 21 male college students, specifically chosen for their normal responses on a battery of background questionnaires. The participants were randomly assigned to be either a guard or a prisoner, with an undergraduate research assistant acting as warden and Zimbardo himself taking on the role of superintendent. The prisoners stayed in the prison 24 hours per day, while the guards worked 8-hour shifts. Aside from a restriction on physical violence, guards were given great latitude in how they could deal with prisoners, including the rules they could establish and punishments they could dole out.

The experimenters went to great lengths to establish realism. Prisoners were unexpectedly “arrested” at their houses by the local police department, were taken to the police station to be charged their “crime” and brought to the prison at Stanford. Prisoners were assigned a number and wore only a smock, which was designed to deindividuate the prisoners. Guards were fitted with a uniform, nightstick, and reflective sunglasses to establish power. The prison cells consisted of a 6- by 9-foot space furnished with only a cot. To further increase realism, a catholic priest and attorney were brought in and a parole board was established.

Once the participants had arrived at the prison, the situation escalated at a surprising rate. On the second day, a prisoner rebellion was quickly quelled by the guards, who punished the prisoners through means conceived without guidance from the experimenters. For example, prisoners were stripped naked, forced to do menial tasks, and in many cases were deprived of their cots, meals, and bathroom privileges. After the attempted revolt and subsequent punishment, five prisoners began to experience extreme emotional reactions and were eventually released. As the obedience tactics became more brutal and humiliating and prisoners displayed increasingly negative affectivity, Zimbardo eventually decided to end the study on the sixth day of what had been planned as a 2-week study.

Findings of the Stanford Prison Experiment

Zimbardo and colleagues construed the increasingly hostile behavior of the guards and increasingly passive behavior of the prisoners, each of which had started out as groups of normal young men, as evidence that the extreme nature of the prison situation breeds such volatile and desperate behavior. Indeed, the SPE is often cited as evidence for the strong role of the situation over individuals in ways in which they often do not predict. The researchers also compared their work to Stanley Milgram’s research on obedience in that both provide support for the notion that given an extreme situation, good people can be coerced into doing evil things. Despite these exciting findings, the SPE has been criticized from both a methodological and ethical standpoint.

Methodological Criticisms of the Stanford Prison Experiment

Methodologically, critics have argued that participants of the SPE never fully accepted the situation as real and were merely playing the stereotypic roles of prisoners and guards. In essence, it was argued that the results were driven by demand characteristics of the experimental situation. It did not help the original authors’ argument that Zimbardo himself played a prominent role in the experiment, sometimes guiding the way in which the study played out. Regardless, evidence suggests that participants did internalize the situation, as well as their roles in the situation. For instance, only one-tenth of the conversations between prisoners contained speech about life outside of the experiment.

Ethical Criticisms of the Stanford Prison Experiment

The SPE was likely more controversial from an ethical point of view. The ethical implications of the study, as well as Zimbardo’s dual role as investigator and superintendent of the Stanford prison were highly criticized at the time. Zimbardo himself admitted that his own acceptance of the prison situation and his desire to run a good prison clouded his judgment, suggesting that even he had internalized his role in the situation. Although the experiment did conform to the guidelines set forth by the ethics review board at the time, few would argue that the sadistic and humiliating acts performed during the study were ethical by today’s standards. Even Zimbardo admits that it was unethical for the study to continue after the first prisoner showed an extreme negative reaction.

Stanford Prison Experiment Replications

Stephen Reicher and S. Alexander Haslam attempted to replicate the SPE, skirting ethical guidelines through allowing the experiment to take place in the context of a British reality television show. The results of the SPE were not replicated; in Reicher and Haslam’s version, the guards never organized themselves and were eventually overthrown.

References:

• Adam, D. (2002). Reality TV show recreates famed social study. Nature, 417, 213.
• Haney, C., Banks, C., & Zimbardo, P. (1973). Interpersonal dynamics in a simulated prison. International Journal of Criminology and Penology, 1, 69-97.
• 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.

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What the Stanford Prison Experiment Taught Us

In August of 1971, Dr. Philip G. Zimbardo of Stanford University in California conducted what is widely considered one of the most influential experiments in social psychology to date. Made into a New York Times best seller in 2007 ( The Lucifer Effect ) and a major motion picture in 2015 ( The Stanford Prison Experiment ), the Stanford Prison Experiment has integrated itself not only into the psychology community but also popular culture. The events that occurred within this experiment, though disturbing, have given many people insight into just how much a situation can affect behavior. They have also caused many to ponder the nature of evil. How disturbing was it? Well, the proposed two-week experiment was terminated after just six days, due to alarming levels of mistreatment and brutality perpetrated on student “prisoners” by fellow student “guards.”

The study aimed to test the effects of prison life on behavior and wanted to tackle the effects of situational behavior rather than just those of disposition. After placing an ad in the newspaper, Zimbardo selected 24 mentally and physically healthy undergraduate students to participate in the study. The idea was to randomly assign nine boys to be prisoners, nine to be guards, and six to be extras should they need to make any replacements. After randomly assigning the boys, the nine deemed prisoners were “arrested” and promptly brought into a makeshift Stanford County Prison, which was really just the basement of the Stanford Psychology Department building. Upon arrival, the boys’ heads were shaved, and they were subjected to a strip search as well as delousing (measures taken to dehumanize the prisoners). Each prisoner was then issued a uniform and a number to increase anonymity. The guards who were to be in charge of the prisoners were not given any formal training; they were to make up their own set of rules as to how they would govern their prison.

Over the course of six days, a shocking set of events unfolded. While day one seemed to go by without issue, on the second day there was a rebellion, causing guards to spray prisoners with a fire extinguisher in order to force them further into their cells. The guards took the prisoners’ beds and even utilized solitary confinement. They also began to use psychological tactics, attempting to break prisoner solidarity by creating a privilege cell. With each member of the experiment, including Zimbardo, falling deeper into their roles, this “prison” life quickly became a real and threatening situation for many. Thirty-six hours into the experiment, prisoner #8612 was released on account of acute emotional distress, but only after (incorrectly) telling his prison-mates that they were trapped and not allowed to leave, insisting that it was no longer an experiment. This perpetuated a lot of the fears that many of the prisoners were already experiencing, which caused prisoner #819 to be released a day later after becoming hysterical in Dr. Zimbardo’s office.

The guards got even crueler and more unusual in their punishments as time progressed, forcing prisoners to participate in sexual situations such as leap-frogging each other’s partially naked bodies. They took food privileges away and forced the prisoners to insult one another. Even the prisoners fell victim to their roles of submission. At a fake parole board hearing, each of them was asked if they would forfeit all money earned should they be allowed to leave the prison immediately. Most of them said yes, then were upset when they were not granted parole, despite the fact that they were allowed to opt out of the experiment at any time. They had fallen too far into submissive roles to remember, or even consider, their rights.

On the sixth day, Dr. Zimbardo closed the experiment due to the continuing degradation of the prisoners’ emotional and mental states. While his findings were, at times, a terrifying glimpse into the capabilities of humanity, they also advanced the understanding of the psychological community. When it came to the torture done at Abu Ghraib or the Rape of Nanjing in China, Zimbardo’s findings allowed for psychologists to understand evil behavior as a situational occurrence and not always a dispositional one.

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