stanford prison experiment debriefing

Stanford Prison Experiment: Zimbardo’s Famous Study

Saul McLeod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

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Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

On This Page:

• The experiment was conducted in 1971 by psychologist Philip Zimbardo to examine situational forces versus dispositions in human behavior.
• 24 young, healthy, psychologically normal men were randomly assigned to be “prisoners” or “guards” in a simulated prison environment.
• The experiment had to be terminated after only 6 days due to the extreme, pathological behavior emerging in both groups. The situational forces overwhelmed the dispositions of the participants.
• Pacifist young men assigned as guards began behaving sadistically, inflicting humiliation and suffering on the prisoners. Prisoners became blindly obedient and allowed themselves to be dehumanized.
• The principal investigator, Zimbardo, was also transformed into a rigid authority figure as the Prison Superintendent.
• The experiment demonstrated the power of situations to alter human behavior dramatically. Even good, normal people can do evil things when situational forces push them in that direction.

Zimbardo and his colleagues (1973) were interested in finding out whether the brutality reported among guards in American prisons was due to the sadistic personalities of the guards (i.e., dispositional) or had more to do with the prison environment (i.e., situational).

For example, prisoners and guards may have personalities that make conflict inevitable, with prisoners lacking respect for law and order and guards being domineering and aggressive.

Alternatively, prisoners and guards may behave in a hostile manner due to the rigid power structure of the social environment in prisons.

Zimbardo predicted the situation made people act the way they do rather than their disposition (personality).

To study people’s roles in prison situations, Zimbardo converted a basement of the Stanford University psychology building into a mock prison.

He advertised asking for volunteers to participate in a study of the psychological effects of prison life.

The 75 applicants who answered the ad were given diagnostic interviews and personality tests to eliminate candidates with psychological problems, medical disabilities, or a history of crime or drug abuse.

24 men judged to be the most physically & mentally stable, the most mature, & the least involved in antisocial behaviors were chosen to participate.

The participants did not know each other prior to the study and were paid $15 per day to take part in the experiment.

Participants were randomly assigned to either the role of prisoner or guard in a simulated prison environment. There were two reserves, and one dropped out, finally leaving ten prisoners and 11 guards.

Prisoners were treated like every other criminal, being arrested at their own homes, without warning, and taken to the local police station. They were fingerprinted, photographed and ‘booked.’

Then they were blindfolded and driven to the psychology department of Stanford University, where Zimbardo had had the basement set out as a prison, with barred doors and windows, bare walls and small cells. Here the deindividuation process began.

When the prisoners arrived at the prison they were stripped naked, deloused, had all their personal possessions removed and locked away, and were given prison clothes and bedding. They were issued a uniform, and referred to by their number only.

The use of ID numbers was a way to make prisoners feel anonymous. Each prisoner had to be called only by his ID number and could only refer to himself and the other prisoners by number.

Their clothes comprised a smock with their number written on it, but no underclothes. They also had a tight nylon cap to cover their hair, and a locked chain around one ankle.

All guards were dressed in identical uniforms of khaki, and they carried a whistle around their neck and a billy club borrowed from the police. Guards also wore special sunglasses, to make eye contact with prisoners impossible.

Three guards worked shifts of eight hours each (the other guards remained on call). Guards were instructed to do whatever they thought was necessary to maintain law and order in the prison and to command the respect of the prisoners. No physical violence was permitted.

Zimbardo observed the behavior of the prisoners and guards (as a researcher), and also acted as a prison warden.

Within a very short time both guards and prisoners were settling into their new roles, with the guards adopting theirs quickly and easily.

Asserting Authority

Within hours of beginning the experiment, some guards began to harass prisoners. At 2:30 A.M. prisoners were awakened from sleep by blasting whistles for the first of many “counts.”

The counts served as a way to familiarize the prisoners with their numbers. More importantly, they provided a regular occasion for the guards to exercise control over the prisoners.

The prisoners soon adopted prisoner-like behavior too. They talked about prison issues a great deal of the time. They ‘told tales’ on each other to the guards.

They started taking the prison rules very seriously, as though they were there for the prisoners’ benefit and infringement would spell disaster for all of them. Some even began siding with the guards against prisoners who did not obey the rules.

Physical Punishment

The prisoners were taunted with insults and petty orders, they were given pointless and boring tasks to accomplish, and they were generally dehumanized.

Push-ups were a common form of physical punishment imposed by the guards. One of the guards stepped on the prisoners” backs while they did push-ups, or made other prisoners sit on the backs of fellow prisoners doing their push-ups.

Asserting Independence

Because the first day passed without incident, the guards were surprised and totally unprepared for the rebellion which broke out on the morning of the second day.

During the second day of the experiment, the prisoners removed their stocking caps, ripped off their numbers, and barricaded themselves inside the cells by putting their beds against the door.

The guards called in reinforcements. The three guards who were waiting on stand-by duty came in and the night shift guards voluntarily remained on duty.

Putting Down the Rebellion

The guards retaliated by using a fire extinguisher which shot a stream of skin-chilling carbon dioxide, and they forced the prisoners away from the doors. Next, the guards broke into each cell, stripped the prisoners naked and took the beds out.

The ringleaders of the prisoner rebellion were placed into solitary confinement. After this, the guards generally began to harass and intimidate the prisoners.

Special Privileges

One of the three cells was designated as a “privilege cell.” The three prisoners least involved in the rebellion were given special privileges. The guards gave them back their uniforms and beds and allowed them to wash their hair and brush their teeth.

Privileged prisoners also got to eat special food in the presence of the other prisoners who had temporarily lost the privilege of eating. The effect was to break the solidarity among prisoners.

Consequences of the Rebellion

Over the next few days, the relationships between the guards and the prisoners changed, with a change in one leading to a change in the other. Remember that the guards were firmly in control and the prisoners were totally dependent on them.

As the prisoners became more dependent, the guards became more derisive towards them. They held the prisoners in contempt and let the prisoners know it. As the guards’ contempt for them grew, the prisoners became more submissive.

As the prisoners became more submissive, the guards became more aggressive and assertive. They demanded ever greater obedience from the prisoners. The prisoners were dependent on the guards for everything, so tried to find ways to please the guards, such as telling tales on fellow prisoners.

Prisoner #8612

Less than 36 hours into the experiment, Prisoner #8612 began suffering from acute emotional disturbance, disorganized thinking, uncontrollable crying, and rage.

After a meeting with the guards where they told him he was weak, but offered him “informant” status, #8612 returned to the other prisoners and said “You can”t leave. You can’t quit.”

Soon #8612 “began to act ‘crazy,’ to scream, to curse, to go into a rage that seemed out of control.” It wasn’t until this point that the psychologists realized they had to let him out.

A Visit from Parents

The next day, the guards held a visiting hour for parents and friends. They were worried that when the parents saw the state of the jail, they might insist on taking their sons home. Guards washed the prisoners, had them clean and polish their cells, fed them a big dinner and played music on the intercom.

After the visit, rumors spread of a mass escape plan. Afraid that they would lose the prisoners, the guards and experimenters tried to enlist help and facilities of the Palo Alto police department.

The guards again escalated the level of harassment, forcing them to do menial, repetitive work such as cleaning toilets with their bare hands.

Catholic Priest

Zimbardo invited a Catholic priest who had been a prison chaplain to evaluate how realistic our prison situation was. Half of the prisoners introduced themselves by their number rather than name.

The chaplain interviewed each prisoner individually. The priest told them the only way they would get out was with the help of a lawyer.

Prisoner #819

Eventually, while talking to the priest, #819 broke down and began to cry hysterically, just like two previously released prisoners had.

The psychologists removed the chain from his foot, the cap off his head, and told him to go and rest in a room that was adjacent to the prison yard. They told him they would get him some food and then take him to see a doctor.

While this was going on, one of the guards lined up the other prisoners and had them chant aloud:

“Prisoner #819 is a bad prisoner. Because of what Prisoner #819 did, my cell is a mess, Mr. Correctional Officer.”

The psychologists realized #819 could hear the chanting and went back into the room where they found him sobbing uncontrollably. The psychologists tried to get him to agree to leave the experiment, but he said he could not leave because the others had labeled him a bad prisoner.

Back to Reality

At that point, Zimbardo said, “Listen, you are not #819. You are [his name], and my name is Dr. Zimbardo. I am a psychologist, not a prison superintendent, and this is not a real prison. This is just an experiment, and those are students, not prisoners, just like you. Let’s go.”

He stopped crying suddenly, looked up and replied, “Okay, let’s go,“ as if nothing had been wrong.

An End to the Experiment

Zimbardo (1973) had intended that the experiment should run for two weeks, but on the sixth day, it was terminated, due to the emotional breakdowns of prisoners, and excessive aggression of the guards.

Christina Maslach, a recent Stanford Ph.D. brought in to conduct interviews with the guards and prisoners, strongly objected when she saw the prisoners being abused by the guards.

Filled with outrage, she said, “It’s terrible what you are doing to these boys!” Out of 50 or more outsiders who had seen our prison, she was the only one who ever questioned its morality.

Zimbardo (2008) later noted, “It wasn’t until much later that I realized how far into my prison role I was at that point — that I was thinking like a prison superintendent rather than a research psychologist.“

This led him to prioritize maintaining the experiment’s structure over the well-being and ethics involved, thereby highlighting the blurring of roles and the profound impact of the situation on human behavior.

Here’s a quote that illustrates how Philip Zimbardo, initially the principal investigator, became deeply immersed in his role as the “Stanford Prison Superintendent (April 19, 2011):

“By the third day, when the second prisoner broke down, I had already slipped into or been transformed into the role of “Stanford Prison Superintendent.” And in that role, I was no longer the principal investigator, worried about ethics. When a prisoner broke down, what was my job? It was to replace him with somebody on our standby list. And that’s what I did. There was a weakness in the study in not separating those two roles. I should only have been the principal investigator, in charge of two graduate students and one undergraduate.”

According to Zimbardo and his colleagues, the Stanford Prison Experiment revealed how people will readily conform to the social roles they are expected to play, especially if the roles are as strongly stereotyped as those of the prison guards.

Because the guards were placed in a position of authority, they began to act in ways they would not usually behave in their normal lives.

The “prison” environment was an important factor in creating the guards’ brutal behavior (none of the participants who acted as guards showed sadistic tendencies before the study).

Therefore, the findings support the situational explanation of behavior rather than the dispositional one.

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

Deindividuation may explain the behavior of the participants; especially the guards. This is a state when you become so immersed in the norms of the group that you lose your sense of identity and personal responsibility.

The guards may have been so sadistic because they did not feel what happened was down to them personally – it was a group norm. They also may have lost their sense of personal identity because of the uniform they wore.

Also, learned helplessness could explain the prisoner’s submission to the guards. The prisoners learned that whatever they did had little effect on what happened to them. In the mock prison the unpredictable decisions of the guards led the prisoners to give up responding.

After the prison experiment was terminated, Zimbardo interviewed the participants. Here’s an excerpt:

‘Most of the participants said they had felt involved and committed. The research had felt “real” to them. One guard said, “I was surprised at myself. I made them call each other names and clean the toilets out with their bare hands. I practically considered the prisoners cattle and I kept thinking I had to watch out for them in case they tried something.” Another guard said “Acting authoritatively can be fun. Power can be a great pleasure.” And another: “… during the inspection I went to Cell Two to mess up a bed which a prisoner had just made and he grabbed me, screaming that he had just made it and that he was not going to let me mess it up. He grabbed me by the throat and although he was laughing I was pretty scared. I lashed out with my stick and hit him on the chin although not very hard, and when I freed myself I became angry.”’

Most of the guards found it difficult to believe that they had behaved in the brutal ways that they had. Many said they hadn’t known this side of them existed or that they were capable of such things.

The prisoners, too, couldn’t believe that they had responded in the submissive, cowering, dependent way they had. Several claimed to be assertive types normally.

When asked about the guards, they described the usual three stereotypes that can be found in any prison: some guards were good, some were tough but fair, and some were cruel.

A further explanation for the behavior of the participants can be described in terms of reinforcement.  The escalation of aggression and abuse by the guards could be seen as being due to the positive reinforcement they received both from fellow guards and intrinsically in terms of how good it made them feel to have so much power.

Similarly, the prisoners could have learned through negative reinforcement that if they kept their heads down and did as they were told, they could avoid further unpleasant experiences.

Critical Evaluation

Ecological validity.

The Stanford Prison Experiment is criticized for lacking ecological validity in its attempt to simulate a real prison environment. Specifically, the “prison” was merely a setup in the basement of Stanford University’s psychology department.

The student “guards” lacked professional training, and the experiment’s duration was much shorter than real prison sentences. Furthermore, the participants, who were college students, didn’t reflect the diverse backgrounds typically found in actual prisons in terms of ethnicity, education, and socioeconomic status.

None had prior prison experience, and they were chosen due to their mental stability and low antisocial tendencies. Additionally, the mock prison lacked spaces for exercise or rehabilitative activities.

Demand characteristics

Demand characteristics could explain the findings of the study. Most of the guards later claimed they were simply acting. Because the guards and prisoners were playing a role, their behavior may not be influenced by the same factors which affect behavior in real life. This means the study’s findings cannot be reasonably generalized to real life, such as prison settings. I.e, the study has low ecological validity.

One of the biggest criticisms is that strong demand characteristics confounded the study. Banuazizi and Movahedi (1975) found that the majority of respondents, when given a description of the study, were able to guess the hypothesis and predict how participants were expected to behave.

This suggests participants may have simply been playing out expected roles rather than genuinely conforming to their assigned identities.

In addition, revelations by Zimbardo (2007) indicate he actively encouraged the guards to be cruel and oppressive in his orientation instructions prior to the start of the study. For example, telling them “they [the prisoners] will be able to do nothing and say nothing that we don’t permit.”

He also tacitly approved of abusive behaviors as the study progressed. This deliberate cueing of how participants should act, rather than allowing behavior to unfold naturally, indicates the study findings were likely a result of strong demand characteristics rather than insightful revelations about human behavior.

However, there is considerable evidence that the participants did react to the situation as though it was real. For example, 90% of the prisoners’ private conversations, which were monitored by the researchers, were on the prison conditions, and only 10% of the time were their conversations about life outside of the prison.

The guards, too, rarely exchanged personal information during their relaxation breaks – they either talked about ‘problem prisoners,’ other prison topics, or did not talk at all. The guards were always on time and even worked overtime for no extra pay.

When the prisoners were introduced to a priest, they referred to themselves by their prison number, rather than their first name. Some even asked him to get a lawyer to help get them out.

Fourteen years after his experience as prisoner 8612 in the Stanford Prison Experiment, Douglas Korpi, now a prison psychologist, reflected on his time and stated (Musen and Zimbardo 1992):

“The Stanford Prison Experiment was a very benign prison situation and it promotes everything a normal prison promotes — the guard role promotes sadism, the prisoner role promotes confusion and shame”.

Sample bias

The study may also lack population validity as the sample comprised US male students. The study’s findings cannot be applied to female prisons or those from other countries. For example, America is an individualist culture (where people are generally less conforming), and the results may be different in collectivist cultures (such as Asian countries).

Carnahan and McFarland (2007) have questioned whether self-selection may have influenced the results – i.e., did certain personality traits or dispositions lead some individuals to volunteer for a study of “prison life” in the first place?

All participants completed personality measures assessing: aggression, authoritarianism, Machiavellianism, narcissism, social dominance, empathy, and altruism. Participants also answered questions on mental health and criminal history to screen out any issues as per the original SPE.

Results showed that volunteers for the prison study, compared to the control group, scored significantly higher on aggressiveness, authoritarianism, Machiavellianism, narcissism, and social dominance. They scored significantly lower on empathy and altruism.

A follow-up role-playing study found that self-presentation biases could not explain these differences. Overall, the findings suggest that volunteering for the prison study was influenced by personality traits associated with abusive tendencies.

Zimbardo’s conclusion may be wrong

While implications for the original SPE are speculative, this lends support to a person-situation interactionist perspective, rather than a purely situational account.

It implies that certain individuals are drawn to and selected into situations that fit their personality, and that group composition can shape behavior through mutual reinforcement.

Contributions to psychology

Another strength of the study is that the harmful treatment of participants led to the formal recognition of ethical  guidelines by the American Psychological Association. Studies must now undergo an extensive review by an institutional review board (US) or ethics committee (UK) before they are implemented.

Most institutions, such as universities, hospitals, and government agencies, require a review of research plans by a panel. These boards review whether the potential benefits of the research are justifiable in light of the possible risk of physical or psychological harm.

These boards may request researchers make changes to the study’s design or procedure, or, in extreme cases, deny approval of the study altogether.

Contribution to prison policy

A strength of the study is that it has altered the way US prisons are run. For example, juveniles accused of federal crimes are no longer housed before trial with adult prisoners (due to the risk of violence against them).

However, in the 25 years since the SPE, U.S. prison policy has transformed in ways counter to SPE insights (Haney & Zimbardo, 1995):

• Rehabilitation was abandoned in favor of punishment and containment. Prison is now seen as inflicting pain rather than enabling productive re-entry.
• Sentencing became rigid rather than accounting for inmates’ individual contexts. Mandatory minimums and “three strikes” laws over-incarcerate nonviolent crimes.
• Prison construction boomed, and populations soared, disproportionately affecting minorities. From 1925 to 1975, incarceration rates held steady at around 100 per 100,000. By 1995, rates tripled to over 600 per 100,000.
• Drug offenses account for an increasing proportion of prisoners. Nonviolent drug offenses make up a large share of the increased incarceration.
• Psychological perspectives have been ignored in policymaking. Legislators overlooked insights from social psychology on the power of contexts in shaping behavior.
• Oversight retreated, with courts deferring to prison officials and ending meaningful scrutiny of conditions. Standards like “evolving decency” gave way to “legitimate” pain.
• Supermax prisons proliferated, isolating prisoners in psychological trauma-inducing conditions.

The authors argue psychologists should reengage to:

• Limit the use of imprisonment and adopt humane alternatives based on the harmful effects of prison environments
• Assess prisons’ total environments, not just individual conditions, given situational forces interact
• Prepare inmates for release by transforming criminogenic post-release contexts
• Address socioeconomic risk factors, not just incarcerate individuals
• Develop contextual prediction models vs. focusing only on static traits
• Scrutinize prison systems independently, not just defer to officials shaped by those environments
• Generate creative, evidence-based reforms to counter over-punitive policies

Psychology once contributed to a more humane system and can again counter the U.S. “rage to punish” with contextual insights (Haney & Zimbardo, 1998).

Evidence for situational factors

Zimbardo (1995) further demonstrates the power of situations to elicit evil actions from ordinary, educated people who likely would never have done such things otherwise. It was another situation-induced “transformation of human character.”

• Unit 731 was a covert biological and chemical warfare research unit of the Japanese army during WWII.
• It was led by General Shiro Ishii and involved thousands of doctors and researchers.
• Unit 731 set up facilities near Harbin, China to conduct lethal human experimentation on prisoners, including Allied POWs.
• Experiments involved exposing prisoners to things like plague, anthrax, mustard gas, and bullets to test biological weapons. They infected prisoners with diseases and monitored their deaths.
• At least 3,000 prisoners died from these brutal experiments. Many were killed and dissected.
• The doctors in Unit 731 obeyed orders unquestioningly and conducted these experiments in the name of “medical science.”
• After the war, the vast majority of doctors who participated faced no punishment and went on to have prestigious careers. This was largely covered up by the U.S. in exchange for data.
• It shows how normal, intelligent professionals can be led by situational forces to systematically dehumanize victims and conduct incredibly cruel and lethal experiments on people.
• Even healers trained to preserve life used their expertise to destroy lives when the situational forces compelled obedience, nationalism, and wartime enmity.

Evidence for an interactionist approach

The results are also relevant for explaining abuses by American guards at Abu Ghraib prison in Iraq.

An interactionist perspective recognizes that volunteering for roles as prison guards attracts those already prone to abusive tendencies, which are intensified by the prison context.

This counters a solely situationist view of good people succumbing to evil situational forces.

Ethical Issues

The study has received many ethical criticisms, including lack of fully informed consent by participants as Zimbardo himself did not know what would happen in the experiment (it was unpredictable). Also, the prisoners did not consent to being “arrested” at home. The prisoners were not told partly because final approval from the police wasn’t given until minutes before the participants decided to participate, and partly because the researchers wanted the arrests to come as a surprise. However, this was a breach of the ethics of Zimbardo’s own contract that all of the participants had signed.

Protection of Participants

Participants playing the role of prisoners were not protected from psychological harm, experiencing incidents of humiliation and distress. For example, one prisoner had to be released after 36 hours because of uncontrollable bursts of screaming, crying, and anger.

Here’s a quote from Philip G. Zimbardo, taken from an interview on the Stanford Prison Experiment’s 40th anniversary (April 19, 2011):

“In the Stanford prison study, people were stressed, day and night, for 5 days, 24 hours a day. There’s no question that it was a high level of stress because five of the boys had emotional breakdowns, the first within 36 hours. Other boys that didn’t have emotional breakdowns were blindly obedient to corrupt authority by the guards and did terrible things to each other. And so it is no question that that was unethical. You can’t do research where you allow people to suffer at that level.”

“After the first one broke down, we didn’t believe it. We thought he was faking. There was actually a rumor he was faking to get out. He was going to bring his friends in to liberate the prison. And/or we believed our screening procedure was inadequate, [we believed] that he had some mental defect that we did not pick up. At that point, by the third day, when the second prisoner broke down, I had already slipped into or been transformed into the role of “Stanford Prison Superintendent.” And in that role, I was no longer the principal investigator, worried about ethics.”

However, in Zimbardo’s defense, the emotional distress experienced by the prisoners could not have been predicted from the outset.

Approval for the study was given by the Office of Naval Research, the Psychology Department, and the University Committee of Human Experimentation.

This Committee also did not anticipate the prisoners’ extreme reactions that were to follow. Alternative methodologies were looked at that would cause less distress to the participants but at the same time give the desired information, but nothing suitable could be found.

Withdrawal 

Although guards were explicitly instructed not to physically harm prisoners at the beginning of the Stanford Prison Experiment, they were allowed to induce feelings of boredom, frustration, arbitrariness, and powerlessness among the inmates.

This created a pervasive atmosphere where prisoners genuinely believed and even reinforced among each other, that they couldn’t leave the experiment until their “sentence” was completed, mirroring the inescapability of a real prison.

Even though two participants (8612 and 819) were released early, the impact of the environment was so profound that prisoner 416, reflecting on the experience two months later, described it as a “prison run by psychologists rather than by the state.”

Extensive group and individual debriefing sessions were held, and all participants returned post-experimental questionnaires several weeks, then several months later, and then at yearly intervals. Zimbardo concluded there were no lasting negative effects.

Zimbardo also strongly argues that the benefits gained from our understanding of human behavior and how we can improve society should outbalance the distress caused by the study.

However, it has been suggested that the US Navy was not so much interested in making prisons more human and were, in fact, more interested in using the study to train people in the armed services to cope with the stresses of captivity.

Discussion Questions

What are the effects of living in an environment with no clocks, no view of the outside world, and minimal sensory stimulation?

Consider the psychological consequences of stripping, delousing, and shaving the heads of prisoners or members of the military. Whattransformations take place when people go through an experience like this?

The prisoners could have left at any time, and yet, they didn’t. Why?

After the study, how do you think the prisoners and guards felt?

If you were the experimenter in charge, would you have done this study? Would you have terminated it earlier? Would you have conducted a follow-up study?

Frequently Asked Questions

What happened to prisoner 8612 after the experiment.

Douglas Korpi, as prisoner 8612, was the first to show signs of severe distress and demanded to be released from the experiment. He was released on the second day, and his reaction to the simulated prison environment highlighted the study’s ethical issues and the potential harm inflicted on participants.

After the experiment, Douglas Korpi graduated from Stanford University and earned a Ph.D. in clinical psychology. He pursued a career as a psychotherapist, helping others with their mental health struggles.

Why did Zimbardo not stop the experiment?

Zimbardo did not initially stop the experiment because he became too immersed in his dual role as the principal investigator and the prison superintendent, causing him to overlook the escalating abuse and distress among participants.

It was only after an external observer, Christina Maslach, raised concerns about the participants’ well-being that Zimbardo terminated the study.

What happened to the guards in the Stanford Prison Experiment?

In the Stanford Prison Experiment, the guards exhibited abusive and authoritarian behavior, using psychological manipulation, humiliation, and control tactics to assert dominance over the prisoners. This ultimately led to the study’s early termination due to ethical concerns.

What did Zimbardo want to find out?

Zimbardo aimed to investigate the impact of situational factors and power dynamics on human behavior, specifically how individuals would conform to the roles of prisoners and guards in a simulated prison environment.

He wanted to explore whether the behavior displayed in prisons was due to the inherent personalities of prisoners and guards or the result of the social structure and environment of the prison itself.

What were the results of the Stanford Prison Experiment?

The results of the Stanford Prison Experiment showed that situational factors and power dynamics played a significant role in shaping participants’ behavior. The guards became abusive and authoritarian, while the prisoners became submissive and emotionally distressed.

The experiment revealed how quickly ordinary individuals could adopt and internalize harmful behaviors due to their assigned roles and the environment.

Banuazizi, A., & Movahedi, S. (1975). Interpersonal dynamics in a simulated prison: A methodological analysis. American Psychologist, 30 , 152-160.

Carnahan, T., & McFarland, S. (2007). Revisiting the Stanford prison experiment: Could participant self-selection have led to the cruelty? Personality and Social Psychology Bulletin, 33, 603-614.

Drury, S., Hutchens, S. A., Shuttlesworth, D. E., & White, C. L. (2012). Philip G. Zimbardo on his career and the Stanford Prison Experiment’s 40th anniversary.  History of Psychology ,  15 (2), 161.

Griggs, R. A., & Whitehead, G. I., III. (2014). Coverage of the Stanford Prison Experiment in introductory social psychology textbooks. Teaching of Psychology, 41 , 318 –324.

Haney, C., Banks, W. C., & Zimbardo, P. G. (1973). A study of prisoners and guards in a simulated prison . Naval Research Review , 30, 4-17.

Haney, C., & Zimbardo, P. (1998). The past and future of U.S. prison policy: Twenty-five years after the Stanford Prison Experiment.  American Psychologist, 53 (7), 709–727.

Musen, K. & Zimbardo, P. (1992) (DVD) Quiet Rage: The Stanford Prison Experiment Documentary.

Zimbardo, P. G. (Consultant, On-Screen Performer), Goldstein, L. (Producer), & Utley, G. (Correspondent). (1971, November 26). Prisoner 819 did a bad thing: The Stanford Prison Experiment [Television series episode]. In L. Goldstein (Producer), Chronolog. New York, NY: NBC-TV.

Zimbardo, P. G. (1973). On the ethics of intervention in human psychological research: With special reference to the Stanford prison experiment.  Cognition ,  2 (2), 243-256.

Zimbardo, P. G. (1995). The psychology of evil: A situationist perspective on recruiting good people to engage in anti-social acts.  Japanese Journal of Social Psychology ,  11 (2), 125-133.

Zimbardo, P.G. (2007). The Lucifer effect: Understanding how good people turn evil . New York, NY: Random House.

Further Information

• Reicher, S., & Haslam, S. A. (2006). Rethinking the psychology of tyranny: The BBC prison study. The British Journal of Social Psychology, 45 , 1.
• Coverage of the Stanford Prison Experiment in introductory psychology textbooks
• The Stanford Prison Experiment Official Website

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Book Table of Contents

Chapter Contents

The Stanford Prison Experiment

In 1971, social psychologist Philip Zimbardo conducted an experiment that showed violent and aggressive behavior could be elicited from college students simply by asking them to play the role of prison guards. Zimbardo did this to prove that situations, rather than personal traits (dispositions), ruled behavior.

The situationist vs dispositionist controversy was at the heart of the Stanford Prison Experiment. We encountered this distinction in discus­sing Walter Mischel's famous criticism of the trait concept, in Chapter 11 (Personality).

A situationist believes environments and situations elicit certain beha­viors. A dispositionist believes individual traits or personality characteristics usually determine behaviors. (Disposition is a lasting personality orientation such as "temperament, character, nature, constitution, makeup, or mentality.")

What is disposition?

In Chapter 11 we saw how American social psychologists and personality psychologists invented the concept of authoritarian personality to explain Nazi behavior. The authoritarian personality was said to be a personality type with dispositions like these:

Blind allegiance to conventional beliefs about right and wrong

Respect for submission to acknowledged authority

Belief in aggression toward those who do not subscribe to conventional thinking, or who are different

A negative view of people in general - i.e. the belief that people would all lie, cheat or steal if given the opportunity

A need for strong leadership which displays uncompro­mising power (etc)

Dispositions come from inside, pre­sumably put there mostly by education and culture (or biology). By contrast, a "situationist" perspective emphasizes the power of the environment. Situations can over­ride individual dispositions.

Stanley Milgram, who conducted the obedience research, apparently wanted to see if the "German character" encouraged obedience, which would be predicted by dispositionism. If Americans resisted the demand to obey, but Germans obeyed, it might support the dispositional perspective.

Instead, Milgram found that his subjects, all Americans, mostly obeyed situational pressures to be cruel. Milgram never did repeat the experiment in Germany.

By the 1970s, a decade after Milgram showed the potential power of the situation, Zimbardo decided to see if ordinary college students could be similarly affected. He arranged an experiment to demonstrate the power of the situation to overpower individual personality, ethics and morals.

The Experiment

Male subjects were recruited through newspaper ads offering them $15 a day to participate. Seventy-five men applied to participate, and 19 were chosen.

Zimbardo said a battery of tests were employed to select those with the most stable personalities. Volunteers were randomly assigned to play prison guard or prisoner through the flip of a coin.

The preparation and execution of the study was thorough and realistic. It began on a Sunday morning as police swept through Palo Alto, the home of Stanford University, picking up students selected to be prisoners.

Sirens blared as students tapped to play the prisoner role were arrested, placed spread-eagled against a car, searched, handcuffed, and booked at the police station. After fingerprinting and paper­work, prisoners were transported to Stanford County Prison, actually the basement of the Stan­ford psychology building, unused for a few weeks after summer term.

The prisoners were stripped and their hair was sprayed to kill lice. They were required to stand naked and listen to the guards read a list of regulations.

One of the rules was that prisoners had to follow any order from a guard. Another rule was that they had to ask for permis­sion to do anything, even to go to the toilet. After this the prisoners were issued a simple uniform and a towel and each was assigned to a cell.

What elements helped make the prison study realistic?

The guards in the study were given khaki-colored uniforms and mirrored sun­glasses, giving them an anony­mous and sinister look. They wore billy clubs, keys, and handcuffs.

Zimbardo said the guards received no special instructions. That was not quite true, as later critics pointed out.

The guards may not have received explicit instructions to be cruel, but the demand characteristics of the experi­ment were obvious. Everything about the experiment made it clear the guards were expected to act like stereotyped prison guards.

How did the prison guards start to act?

Before long, the prison guards were acting mean. For example, they decided to call roll during the middle of the night and make the prisoners do pushups, with guards putting their feet on the middle of a prisoner's back.

On the second day of the experiment, the guards crushed a rebellion and became more verbally abusive. After a day and a half, one of the prisoners had to be re­leased because of uncontrolled crying, depression, fits of rage, and disorgan­ized thinking.

A few days later, the same thing hap­pened to three additional prisoners. By the fifth day, all the volunteer prisoners asked to be released. One subject developed a skin rash over his whole body after having his appeal rejected by a mock Parole Board.

On the sixth day the exper­iment was terminated. "The experience dramatically and painfully transformed most of the participants in ways we did not antici­pate, prepare for, or expect" (Haney & Zimbardo, 1998).

Over 30 years after the research, Zim­bardo added details about how the experiment happened to be called off.

About halfway through the study, I had invited some psycho­logists who knew little about the experiment to interview the staff and participants, to get an outsiders' evaluation of how it was going. A former doctoral student of mine, Christina Maslach, a new assistant professor at the University of California at Berkeley, came down late Thursday night to have dinner with me.

We had started dating recently and were becoming romantically in­volved. When she saw the prisoners lined up with bags over their heads, their legs chained, and guards shouting abuses at them while herding them to the toilet, she got upset and refused my suggestion to observe what was happening in this "crucible of human nature."

Instead she ran out of the basement, and I followed, berating her for being overly sensitive and not realizing the important lessons taking place here. "It is terrible what YOU are doing to those boys!" she yelled at me.

Christina made evident in that one statement that human beings were suffering, not prisoners, not experi­mental subjects, not paid volunteers. And further, I was the one who was personally responsible for the hor­rors she had witnessed (and which she assumed were even worse when no outsider was looking).

She also made clear that if this per­son I had become—the heartless superintendent of the Stanford pri­son—was the real me, not the car­ing, generous person she had come to like, she wanted nothing more to do with me. That powerful jolt of reality snapped me back to my senses.

I agreed that we had gone too far, that whatever was to be learned about situational power was already indelibly etched on our videos, data logs, and minds; there was no need to continue. (Zimbardo, 2007)

What story did Zimbardo tell later, about why the experiment was terminated?

Every single student playing the guard role became authoritarian and abusive at least once, and many of them seemed to enjoy the role. Although Zimbardo did not explicitly tell the guards to act aggres­sive, evidently they felt this was part of the prison guard role or stereotype.

The Zimbardo prison study resembled the Milgram obedience study in several ways. It put ordinary citizens in the role of torturers or bullies, in part by appearing to remove their personal responsibility for their actions.

Like the Milgram study, the Stanford prison experiment led to protests about abusive treatment of experi­mental subjects. Like Milgram, Zimbardo claimed he exercised extraordinary care in debriefing his subjects and conducting follow-up interviews to make sure none suffered lasting harm.

The Milgram Connection

The parallels between Zimbardo's experiment and Milgram's experiment were clear from the start, and Zimbardo gave Milgram credit for inspiring the Stanford prison experiment. However, few psychologists knew about the deeper connections between Zimbardo and Milgram until years later.

Zimbardo and Milgram were class­mates at a Bronx high school. Milgram was "considered the smartest kid" and Zimbardo was voted most popular (Zimbardo, Maslach, and Haney, 1999). Zimbardo said they had an early bias toward the situational perspective

We sometimes talked about the reasons for seemingly strange or irrational behavior by teachers, peers, or people in the real world that violated our expectations. Not coming from well-to-do homes, we gravitated toward situational ex­planations and away from disposi­tional ones to make sense of such anomalies.

The rich and powerful want to take personal credit for their success and to blame the faults of the poor on their defects. But we knew better; it was usually the situation that mat­tered, by our account. (Zimbardo, Maslach, and Haney, 1999)

Both went to Yale and were influenced by some of the same professors. They stayed in touch afterwards. Milgram's study was published about a decade before Zimbardo's.

How were Milgram and Zimbardo connected by their past histories?

Milgram's research contributed to a strong tilt, in social psychology, toward situationist perspectives. You might say they showed lasting dispositions. Milgrim (the "smart one") did his research first. Zimbardo (the "popular one") tagged along and re-affirmed Milgram's discovery that situations could dominate behavior.

Criticisms of the Stanford Prison Experiment

Criticisms of Zimbardo's experiment concentrated on the demand charact­eristics of the study. The concept of demand characteristics came from Martin Orne.

Orne did research about hypnosis, among other things. He saw demand characteristics as similar to hypnosis except implicit (unspoken). They were a form of suggestion that could induce unusual displays of behavior.

Demand characteristics were found in the context or framing of an experiment, which implicitly conveyed how a parti­cipant was expected to act. Subjects will usually try to please the experimenter and do what they think is expected.

How did Orne apply the concept of suggestion to experimental settings?

Orne (1962) found that experimental subjects were "willing to tolerate a considerable degree of discomfort, boredom, or actual pain, if required to do so by the experimenter." In one famous experiment, Orne tried to find tasks so boring or frustrating that subjects would quit an experiment, such as tearing a piece of paper into smaller pieces and repeating this for hours.

But subjects did not quit; they did what they were asked to do, without complaint. Orne wrote:

Just about any request which could conceivably be asked of the subject by a reputable investigator is legitimized by the quasi-magical phrase (or cognition) "This is an experiment" [p. 777].

Banuazizi and Movahedi (1975) pointed out that Zimbardo's experiment had set up obvious demand characteristics.

(a) The subjects entered the experi­ment carrying strong social stereo­types of how guards and prisoners act and relate to one another in a real prison.

(b) In the experimental context itself, there were numerous cues pointing to the experimental hypothesis, the experimenters' expectations, and possibly, the experimenters' ideolo­gical commitment.

(c) Complying with the actual or perceived demands in the experi­mental situation, and acting on the basis of their own role-related expectancies, the subjects produced data highly in accord with the experimental hypothesis.

To test the demand characteristics of the Stanford prison experiment, Banuazizi and Movahedi gave 185 students a questionnaires with a brief description of the Stanford prison experiment, and added this:

Suppose you decide to participate, and you sign the proper release forms. On a subsequent Sunday morning, a police officer knocks on your apartment door and arrests you.

He charges you with a felony, warns you of your constitutional rights, searches you, handcuffs you, and in the back of his car, takes you to the police station for booking. You are then fingerprinted, and left in an isolated detention cell.

After a while, you are blindfolded and sent to a prison. There, you are stripped naked, skin searched, deloused, and issued a uniform, bedding, soap, towel, toothpaste, and toothbrush. And all this time you have been pushed around, put down, and humiliated. (Banuazizi and Movahedi, 1975)

After reading that, students were asked to guess the experimental hypothesis and their expectancies about the outcome of the experiment. 35 of the 185 students already knew about the Stanford prison experiment, so their responses were excluded.

How did Banuazizi and Movahedi test the demand characteristics of Zimbardo's study?

81% of the remaining 150 respondents "were able to articulate quite accurately the intent of the experiment." Here are some of their questionnaire responses.

S1014: Experimenter is trying to prove the contention that he has about jails. He believes that people are pushed about, put down, and humiliated in jails and other correctional institutions.

S1029: Testing endurance–to see how far you go before fighting back, I think they are trying to find out what causes prison riots

S1053: He is trying to find out if any­body would fit into either of the two roles. That is, figuring that everyone is equal, a person selected as a guard will behave, act, and become like a guard; if a person is selected to be a prisoner, he will act, behave, and become like a prisoner.

Next the students receiving the ques­tionnaire were asked to guess the outcome of the research. 85% of males and 94% of females guessed that parti­cipants assigned to be guards would be oppressive and hostile.

In other words, the demand character­istics of the experiment were obvious. Banuazizi and Movahedi note, "when experimental subjects are asked to play highly stereotyped and emotion-laden roles, they bring to the experimental situation "mental sets," or dispositions, which could decisively influence their behavior.

Zimbardo (following Milgram) saw his research as demonstrating the power of situations over dispositions. In Banuzizi and Movahedi's re-interpretation, Zim­bardo was using dispositions in the experimental subjects, namely their stereotyped, pre-existing ideas about prison-guard roles.

How did Banuazizi and Movahedi portray Zimbardo as using dispositions in addition to situations?

As a separate issue, was it ethical for Zimbardo to put student participants in this situation? Again, present-day criticisms of the prison experiment echo criticisms of Milgram's experiment.

You might recall the concept of engag­ed followership raised in connection with the obedience experiment. Mil­gram's subjects were engaged followers (because they bought into their role as participants in scientific research) and Milgram's research associates were engaged followers (for the same reason; they knew they were participating in research).

All parties therefore justified what they did. Milgram's assistants (such as the man playing the role of experimenter in the famous video) no doubt felt their make-believe roles justified their cruelty in urging subjects to continue even when they were distressed. The participants who continued to shock the learner felt similarly justified in their role as research subjects.

Everybody involved (not just subjects) was engaged in what they considered a worthy enterprise: scientific research. According to Milgram and Zimbardo, the experiments were unpleasant, but they were justified by the lessons they taught us about human behavior. Zimbardo made this argument explicitly, writing:

The value of the Stanford Prison Experiment (SPE) resides in demonstrating the evil that good people can be readily induced into doing to other good people within the context of socially approved roles, rules, and norms, a legitimizing ideology, and institutional support that transcends individual agency. (Zimbardo, Maslach, and Haney, 1999)

The "engaged followership" critique turns this rationalization on its ear. The researchers were excusing unjustifiable abusive behavior toward the participants, by portraying the research as valuable.

What is the "engaged followership" analysis of both Milgram and Zimbardo's research?

Ironically, the critics would agree with Zimbardo, Maslach, and Haney's point. Good people can be readily induced to do bad things by putting bad things in a socially approved context. The actual researchers (Milgram and Zimbardo) as well as the make-believe experimenter and prison guards engaged in cruelty, justifying their activity by portraying it as a worthy scientific endeavor.

--------------------- References:

Banuazizi A. & Movahedi S. (1975). Interpersonal dynamics in a simulated prison: A methodological analysis. American Psychologist, 30 , 152-160. https://dx.doi.org/ 10.1037/h0076835

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

Kompa, J. S. (2012, July) Analysis of the Stanford Prison Experiment. Retrieved from: https://joanakompa.files.wordpress.com/ 2012/07/the-stanford-prison-experiment-an-analysis-by-joana-stella-kompa.pdf

Orne, M. T. (1962) On the social psychology of the psychological experiment: With particular reference to demand characteristics and their implications. American Psychologist, 17 ,776-783.

Zimbardo P. G., Maslach C., & Haney C. (1999). Reflections on the Stanford Prison Experiment: Genesis, transformations, consequences. In Blass T. (Ed.), Obedience to Authority: Current Perspectives on the Milgram Paradigm (pp. 193-237). Mahwah, NJ: Lawrence Erlbaum.

Zimbardo, P. G. (2007) Revisiting the Stanford prison experiment: A lesson in the power of situation. Chronicle of Higher Education, 53, p.B6.

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Demonstrating the Power of Social Situations via a Simulated Prison Experiment

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

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

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

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

Significance

Practical application.

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

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

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

Cited Research

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

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

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

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

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

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

Zimbardo, P. G., Maslach, C., & Haney, C. (1999). Reflections on the Stanford Prison Experiment: Genesis, transformations, consequences. In T. Blass (Ed.), Obedience to Authority: Current Perspectives on the Milgram Paradigm. (pp. 193-237). Mahwah, NJ: Erlbaum.

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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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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: The Power of the Situation

• First Online: 20 January 2024

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Part of the book series: Clinical Sociology: Research and Practice ((CSRP))

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Philip Zimbardo is best known for his 1971 Stanford Prison Experiment (SPE). Early in his career, he conducted experiments in the psychology of deindividualization, in which a person in a group or crowd no longer acts as a responsible individual but is swept along and participates in antisocial actions. After moving to Stanford University, he began to focus on institutional power over the individual in group settings, such as long-term care facilities for the elderly and prisons. His research proposal for a simulated prison was approved by the Stanford University Human Subjects Research Review Committee in July 1971. He built a mock prison in the basement of the University’s psychology building and recruited college-aged male subjects to play prisoners and guards. The study began on Sunday, August 8th, and was to run for 2 weeks but ended on Friday morning August 13th. In less than a week, several of the mock guards hazed and brutalized the mock prisoners, some of whom found ways of coping, while others exhibited symptoms of mental breakdown.

The degree of civilization in a society can be judged by entering its prisons. — attributed to Fyodor Dostoevsky, The House of the Dead

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Acknowledgments

I wish to thank Chris Herrera, Jonathan K. Rosen, David Segal and Ruth Spivak for their comments on this chapter.

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Perlstadt, H. (2023). The Stanford Prison Experiment: The Power of the Situation. In: Assessing Social Science Research Ethics and Integrity. Clinical Sociology: Research and Practice. Springer, Cham. https://doi.org/10.1007/978-3-031-34538-8_8

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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?
• Take our Social Anxiety Test
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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

• Quiet Rage: The Stanford Prison Experiment

About the Stanford Prison Experiment

Carried out August 15-21, 1971 in the basement of Jordan Hall, the Stanford Prison Experiment set out to examine the psychological effects of authority and powerlessness in a prison environment. The study, led by psychology professor Philip G. Zimbardo, recruited Stanford students using a local newspaper ad. Twenty-four students were carefully screened and randomly assigned into groups of prisoners and guards. The experiment, which was scheduled to last 1-2 weeks, ultimately had to be terminated on only the 6th day as the experiment escalated out of hand when the prisoners were forced to endure cruel and dehumanizing abuse at the hands of their peers. The experiment showed, in Dr. Zimbardo’s words, how “ordinary college students could do terrible things.”

This exhibit includes documentation of the experiment, including images and audiovisual recordings, that some viewers may find disturbing. Viewer discretion is advised.

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How to Get Out of The Stanford Prison Experiment Revisiting Social Science Research Ethics?

Harry Perlstadt

1 Department of Sociology, Michigan State University, East Lansing, MI USA .

DOI: http://dx.doi.org/10.12944/CRJSSH.1.2.01

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Perlstadt H. 2018 “How to Get Out of the Stanford Prison Experiment: Revisiting Social Science Research Ethics” Current Research Journal of Social Sciences and Humanities 1(2). DOI: http://dx.doi.org/10.12944/CRJSSH.1.2.01

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Article Review / Publishing History

Introduction Philip Zimbardo’s 1971 Stanford Prison Experiment randomly assigned young male volunteers to the roles of guards or prisoners for a two-week period. Zimbardo was interested in how an individual adapts to a new environment and role. In 1971 he set up a mock prison in the basement of the Stanford University psychology building. The guards soon dehumanized and abused the prisoners to the extent that many of the prisoners wished to withdraw from the experiment and he had to call off and shut down the experiment after only six days. The simulation raised philosophical and social science questions about the nature and source of evil, whether humans can liberate themselves from the constraints and alienation of society, and the capability of the social sciences to answer the question of what makes people do what they do. It also started a debate over human nature, the social sciences, and research ethics that has lasted almost 50 years. The widely used tutorial website Collaborative Institutional Training Initiative (CITI) module on history and ethics identified the ethical problems with the Zimbardo study as harm to participants and a degree of detachment on the part of the researcher: “This landmark psychological study of the human response to captivity and, in particular, prison life, involved assigning roles to normal male student volunteers to create groups of ‘prisoners’ and ‘guards.’ The research became so intense, as physical and psychological abuse of ‘prisoners’ by ‘guards’ escalated, that several of the subjects experienced distress less than 36 hours after the study began. Dr Philip Zimbardo, the researcher, did not stop the experiment/simulation until six days had passed.” 1 The simulation was enhanced by the role-playing of five participants. 8612 became a rebellious political prisoner and Arnett, a sociology grad student, became one of the most sadistic/ extremely authoritarian guards. 2  In response to a request by prisoners for religious services, Zimbardo recruited a priest to play prison chaplain, had an ex-convict advise him on prisons and serve as chair of the parole board, and allowed a public defender to hold official lawyer’s visits with prisoners. All three acted as they would with real prisoners. In general, investigators file a conflict of interest form when submitting their application to their Institutional Review (IRB) board for approval to carry out their proposed research. While most research conflict of interest statements focus on financial interests or personal and family member gains, some non-financial considerations may influence or compromise professional judgment in a clinical trial or research experiment. In Zimbardo’s case, he had a conflict of professional interest in his dual role of Principle Investigator and Prison Superintendent. He finally ended the experiment when confronted by Christina Maslach, his former teaching assistant and current girlfriend, whom he asked to come to the mock prison on the fifth day. She was shocked by what she saw and, as a result, he ended the experiment the next morning. In April 2018, Thibault Le Texier, a Ph.D. economist and associate researcher at Nice Sophia Antipolis University in France, published Historie d’un mensonge Enquéte sur l’expérience de Stanford (History of a Lie: Investigation of the Stanford experience) which he called “one of the greatest scientific deceptions of the 20th century.” 3  Le Texier found a conversation taped on day three of the simulation in Zimbardo’s archives at Stanford University in which Zimbardo told his staff that two prisoners had come in the day before and said they wanted to leave. Zimbardo had told them “no,” and informed them that the only way they could leave was a medical or psychiatric reason. Zimbardo added that he thought the prisoners really believed they can’t get out. Le Texier noted that the informed consent form that Zimbardo’s subjects signed, which is available online from Zimbardo’s own website, contain no mention of the safe phrase “I quit the experiment.” 4,5 Under today’s guidelines, this would violate research ethics since investigators are required to inform participants that they are free to quit the experiment at any time and may or may not require a safe phrase. After interviewing Zimbardo, science reporter Brian Resnick 6  thought that the results of the prison experiment seemed unscientific and untrustworthy and doubted that it should be the basis for enduring lessons in psychology. The Rise of Policy to Protect Human Subjects The experiment was carried out in August 1971. This was just before the Institutional Guide to DHEW Policy on Protection of Human Subjects, 7  known as ‘The Yellow Book,’ was published on December 1, 1971. The Guide reflected several years’ experience with an earlier public health service policy. It was designed to be flexible on what can or should be done and depended upon common sense and sound professional judgment. It explicitly stated that one basic element of informed consent is an instruction that the subject is free to withdraw his consent and to discontinue participation in the project or activity at any time. It mentioned that compensation to volunteers should never be such as to constitute an undue inducement. However, Zimbardo’s simulation was funded by the Office of Naval Research, Department of Defense which, at the time, was not a signatory to the DHEW policy. The simulation was approved by a Stanford University Human Subjects Research Review Committee, the Stanford Psychology Department, and the Group Effectiveness Branch of the Office of Naval Research. In 1973 the American Psychological Association concluded that all existing ethical guidelines had been followed. 8 Congress passed the National Research Act (PL 93-348) in July 1974, officially giving DHEW the authority to establish regulations in this area. The law specifically limited the scope of the regulations to biomedical and behavioural research. This was followed by the 1979  Belmont Report 9  which established the ethical principles of respect for persons, beneficence, and justice and provided guidelines for research involving human subjects. Like Stanley Milgram’s Obedience to Authority, 10  Zimbardo’s Stanford Prison Experiment found that systemic and group forces can influence an individual’s behaviour to violate a social norm or commit a crime, often without her or his personal awareness at the time. These studies, then, implant fear or anxiety and, like a cautionary tale, warn us of danger and use the Holocaust or Abu Ghraib prison as real-life examples of what might happen to good people who find themselves in an evil place. When Zimbardo first spoke publicly about the Stanford Prison Experiment, Milgram told him, “I would soon be diffusing some of the critical heat off him regarding the ethics of such ‘dark side of human nature’ research.” 11 Human behaviour is almost always a function of the interaction of person and social context, and Zimbardo’s prison environment encouraged several participants and groups to intentionally or unintentionally take on specific roles and behaviours. Rather than focusing on a person-centred analysis which starts with the dispositional factors of individuals to explain their behaviour, this paper will examine group dynamics and the situational factors in which individual participants are embedded. It will review how the experiment was conceived and developed, describe the then existing ethics review process, and focus on how participants attempted to get out of the experiment or developed coping mechanisms and behaviours to endure their painful or difficult situation. Zimbardo’s Review Application Zimbardo’s experiment grew out of a class project. In the spring of 1971, he asked students in his Social Psychology in Action class to investigate the changes an individual undergoes in the process of adapting to a new environment and role. Options included seniors entering retirement homes, people joining cults, and prisoners and guards socializing into their roles. Several students ran a mock prison in their dormitory over a weekend. While Zimbardo was aware this had taken place, he did not know what had happened until the students gave their in-class report. The report revealed participants experienced intense feelings of anger, frustration, shame, and confusion about their behaviour during the project. Zimbardo held a debriefing with all of them. He realized that only a random assignment to the roles of guards and prisoners could separate dispositional factors, that is, behaviour-based primarily on participants’ attitudes and personalities, from situational factors, that is, behaviour resulting from the institutional rules and role expectations in a new environment. 12 Zimbardo had previously studied deindividuation, a concept developed by Festinger  et al., 13  that refers to the psychological state of group members who lose their individualism because they are treated uniformly within their group. Deindividuated persons may become unrestrained, and the group may generate antisocial acts. Zimbardo had found that participants who were deindividuated were more likely to inflict pain on others than those who felt more individuated. 14 While a fellow at the Center for Advanced Study in Behavioral Science at Stanford, Zimbardo had several contracts with the Office of Naval Research. The US Navy and Marine Corps were concerned about conflicts between guards and prisoners in naval prisons. Zimbardo proposed to demonstrate that prison conditions were not the result of the type of individuals working and incarcerated in them, but rather emerged from the prison environment, rules, and role expectations. If successful, he hoped to help the Navy develop training programs to eliminate conditions which elicit counter-productive conflict. 15  The Office of Naval Research agreed to a no-cost extension to pay for the prison experiment.  Zimbardo completed his application for “Role Playing in a Simulated Prison” to the Stanford University Human Subjects Research Review Committee on July 31, 1971. Within two weeks the review committee approved the application, Zimbardo set up the mock prison, and the experiment began on Sunday, August 15 th . It was an exploratory study to document as completely as possible the emergence of a prison environment with respect to roles and behaviour. This meant that his application did not have research hypotheses, but rather identified a few basic parameters for the simulation and then proposed to observe and document how it evolved. The Stanford Review Committee had many of the same concerns that would be addressed in regulations first published by the Department of Health Education and Welfare in 1974 and subsequently incorporated in the 1991 Federal Policy for the Protection of Human Subjects, known as the Common Rule (45 CFR 46) 16  adopted by 15 federal departments and agencies including the Department of Defense. Part C §46.306(a)(2)(ii) requires Institutional Review Board (IRB) approval for a study of prisons as institutional structures or of prisoners as incarcerated persons, provided that the study presents no more than minimal risk and no more than an inconvenience to the subjects. On his application, Zimbardo wrote: “There may be some potential emotional stress created by this temporary loss of freedom among the prisoners and by the need for surveillance and control among the guards. We will maintain careful observation of both groups, with professional staff living in [rooms] adjacent to the experimental ‘prison cells.’ Subjects will be notified of the potential stressfulness of the experience and, during a preliminary interview, will be encouraged not to participate if they are at all anxious.” 17  In addition, the project would require physical activity, including exercise, cleaning rooms and halls, and number counts.  Zimbardo answered “No” to the questions “Is deception to be used at any point?” and “Does deception affect the informed consent?” The application then asked if the participants would be submitted to humiliation, harassment, irritation, or public or private embarrassment. Zimbardo answered “Yes,” the prisoners’ privacy will be minimized, they will have to wear prison uniforms, and have to follow orders and rules. Zimbardo also indicated that a background questionnaire and personality inventory would probably be used in the selection of participants to exclude extreme responders and deviants since he wanted the guards and prisoners to be as homogeneous and “normal” as possible. With respect to confidentiality, Zimbardo promised that all information would be coded, with a master list available only to the principal investigators, and that release forms for any film footage would be obtained from each participant before such films were shown. Ads were placed in The Stanford Daily (the student-run independent newspaper) and The Palo Alto Times seeking male college students for a psychological study of prison life. Those who responded were sent an information sheet. 18  They were to be paid $15 a day and would be randomly assigned to play the roles of either prisoners or guards for the duration of the study. Those selected would remain in the study from five days to two weeks, depending on the prisoner’s ‘sentence,’ and the guards would continue based on their work ‘effectiveness.’ Food and accommodations would meet minimal standard nutrition, health, and sanitation requirements. Medical and psychiatric facilities would be accessible should any of the participants desire or require such services. Participants would agree to have their behaviour observed, to be interviewed, and take psychological tests and that films of the study could be taken and shown, assuming the content had scientific value. The information sheet, which was not the informed consent form, stated that “It is obviously essential that no prisoner can leave once jailed.” 18  Zimbardo’s justification was presumably that, like real prisoners, those in the Stanford simulation ought not to have been given an easy way out. The concept of bail did not come up until Wednesday. The guards were told they must report for their eight-hour shifts promptly and that failure to fulfil the contract would result in partial loss of salary accumulated. Finally, the applicants were told that two of the problems to be studied were (a) the development of norms which govern behaviour in a novel situation, and (b) the differential perceptions of “the prison experience” from participants who are initially comparable but arbitrarily assigned to play different roles.  Respondents completed a questionnaire and were interviewed in depth by two psychology graduate students. The final 24 applicants, who ranged from 18 to 24, were judged to be the most physically and mentally stable, most mature, and least involved in antisocial behaviours. The participants did not know each other, save for two brothers who became guards but were assigned to different shifts. The applicants were randomly assigned to be either prisoners or guards, although none of the volunteers wanted to be a guard. The nine initial prisoners were then randomly assigned to one of three cells. Creating a Total Institution Zimbardo constructed a mock prison out of a hallway, several offices, and a closet in the basement of the psychology building at Stanford. The closet would become solitary confinement or Hole for disobedient prisoners. The prisoners’ uniforms would consist of a smock-like tan muslin dress with numbers on front and back, a woman’s nylon stocking to cover the participants’ hair (a substitute for head shaving), and clogs. He obtained guard uniforms at the local army surplus store. The guards wore reflective sunglasses and had no name tags. He ordered food for the prisoners from the student union, set up videotaping facilities, and bugged the prisoners’ cells. He also contacted Stanford University’s health, legal, fire, and police departments. 19 Zimbardo based his experimental set-up in part on what he’d learned about prisons. One of the students in the spring social psychology class had invited ex-convict Carlo Prescott to talk to the class about his experiences in San Quentin State Prison. 20  Prescott described prisoners having bags placed over their heads, inmates being bound together with chains, and buckets being used in place of toilets in cells. 21  Under Prescott’s mentoring, Zimbardo was able to bring a kind of situational savvy to his experiment. 22  Prescott would become the chair of the parole board. Sociologist Erving Goffman 23  wrote that total institutions are those in which the daily activities of members, such as eating, sleeping, working, and recreation, are collectively regimented, scheduled, and carried out in the immediate presence of many others. Everyone is treated alike and expected to follow a system of explicit formal rules enforced by the staff. Examples of total institutions were prisons, concentration and prisoner of war camps, mental hospitals, military barracks, and monasteries.  To make his simulation as realistic as possible, Zimbardo created a total institution de novo with a rigid schedule, explicit rules, and strict obedience to authority. In some ways, the start-up of the Stanford County Jail resembled a prisoner of war camp where captured soldiers and military police were brought together for the first time, as compared to the start-up of a prison, where many inmates and guards are transferred in and have already been socialized into a prison environment. Zimbardo held an orientation meeting with the guards, where he discussed the purpose of the experiment, gave them their assignments, and suggested means of keeping the prisoners under control without using physical punishment. Zimbardo explained that he wanted to understand the psychological barriers that prisons create between people.  The guards were told that the prisoners knew that the guards could not physically abuse the prisoners in any way. The guards, however, could act arbitrarily. Once during each of the three shifts, the guards could line up the prisoners for a “count” using their prison ID number to establish that all prisoners were present and to test them on their knowledge of prison rules. Zimbardo informed the guards that one research question was, “What will the prisoners do to try to gain power, to gain some degree of individuality, to gain some freedom, to gain some privacy?” 24 The guards then met with “Warden” David Jaffe, the undergraduate student who had led the prison project in the social psychology class that spring. Jaffe and the guards reviewed the set of rules developed by the class and agreed on a list of 17 that the prisoners would memorize and follow. These rules covered regulation of daily activities, respect for property, privileges controlled by the guards and staff, respect for authority, and taboo or forbidden words. In Goffman’s view, house rules are a formal set of prescriptions that lay out the main requirements of inmate conduct. 25  The rules governing daily activities at the Stanford County Jail. Rule 1 required that prisoners must remain silent during rest periods, after lights out, during meals, and whenever they were outside the prison Yard (the long, narrow basement corridor). They were only to eat at mealtimes, participate in all prison activities and keep their cells clean at all times. The prisoners were not to move, tamper with, deface or damage walls, ceilings, windows, doors, or other prison property; and were never to operate ceiling lights. The rules stated that prisoners had to address each other by number (and the guards would address them by number as well), and address the guards as “Mr Correctional Officer” and the warden as “Mr Chief Correctional Officer,” and, they had to stand whenever the warden, the prison superintendent, or any other visitor arrived and wait for orders to be seated or to resume activities. Rule 9 specified: “Prisoners must never refer to their condition as an experiment or simulation. They are imprisoned until paroled.” 26  Ironically, that which must not be said became the safe phrase to get out of prison. Privileges controlled by the guards, warden and superintendent included the three supervised toilet visits, which were limited to five minutes, and smoking after meals. As in real-world jails, mail would be inspected and censored, visitations would be supervised and terminated by a guard, and failure to obey any of the rules could result in punishment.  The prisoners were “arrested” at their homes on Sunday morning by the local police and taken to the Stanford County Jail. Upon arriving at the jail, each prisoner went through dehumanization procedures similar to those in some prisons and concentration camps. They were blindfolded, ordered to strip naked and sprayed with powder to delouse them. They then put on a smock-like dress but no underwear, and a cap made of a woman’s nylon stocking to cover the long hair of many of these prisoners. 27 When all the prisoners had arrived, the rules were read slowly and authoritatively by Guard Arnett. The warden told them that a copy of the rules would be posted in each cell and that they were expected to know them and recite them by number. The prisoners were then sent to their cells to memorize the rules. The prisoners were later instructed to sing the rules, and after many repetitions, Zimbardo noted that they had obviously learned them all. Within 24 hours of their incarceration, the prisoners had internalized the rules as part of their prison mindset. The behaviour of both prisoners and guards would be governed by these rules — the guards enforcing them and the prisoners breaking them. Escalating Confrontations Zimbardo’s previous research on deindividuation 13  suggested that sleep deprivation and altered time schedules could lower the threshold of behaviour restraint. He set up three eight-hour shifts for the guards: day from 10 a.m. to 6 p.m., night from 6 p.m. to 2 a.m., and morning from 2 a.m. to 10 a.m. The prisoners did not have a good night sleep Sunday night. They were awakened around 2:30 a.m. Monday by the incoming morning shift for the “count” and then allowed less than four hours of sleep prior to an early morning wakeup call at 6:10 a.m. By that time, they were frustrated with how the guards were treating them. Before breakfast, the prisoners were tested on the rules and required to do morning exercises. 819 refused to do sit-ups as commanded and was put in the Hole. The guards then conducted a bed inspection with the prisoners standing by their beds. One of the guards told 8612 that his bed was a mess and ripped off the blanket and sheets. 8612 lunged at the guard who called for reinforcements and they put 8612 in the Hole with 819 where the two remained through breakfast. 28 After breakfast 5704, who had been denied his after-dinner smoke the night before, convinced his two cellmates (7258 and 3401) to do something to protest their living conditions. 3401 suggested that they push their beds against the door of cell #1, cover the door opening with blankets, and shut off the lights—a clear violation of Rule 6, which forbade operating the ceiling lights. When the guards could not break into cell #1, they rushed into cell #2, which, in Zimbardo’s opinion, held the top of the line troublemakers. One guard grabbed a big fire extinguisher and sprayed it into cell #2. The guards grabbed the three cots and hauled them out into the hall corridor that served as the prison Yard. A struggle ensued, with much pushing, shoving and shouting. 819 screamed, “No, no, no! This is an experiment. Leave me alone!” His cellmate 8612 added, “A fucking simulation. It’s a fucking simulated experiment. It’s no prison.” 29 During the struggle, 8612 ended up naked and shouted that in real prisons they don’t take your clothes and bed away. This produced a sudden silence. But then another prisoner tells him that they do. Zimbardo noted that in order for the simulation to work, everyone had to agree to act as if it were a prison and impose communal self-censorship. 30  After that everyone avoided mentioning the obvious truth, that it was, in fact, a simulation that was getting out of control. Following the Monday rebellion, Zimbardo created a grievance committee, with the prisoners electing its members. The committee met with Zimbardo and demanded less physical and verbal abuse and harassment, complained about the food and requested books and more than one visiting night. They asked that medicines be administered, wanted their glasses returned, and requested religious services. Zimbardo then contacted a Catholic priest to play prison chaplain. As it turned out, Father McDermott had actually served as one in Washington, DC. He agreed to talk with some of the prisoners and then give Zimbardo his honest evaluation of how realistic the prison experience seemed.7 On Wednesday, the priest met with eight of the nine prisoners one at a time, but Zimbardo pulled up a chair and sat next to the priest so he could listen in. Father McDermott asked some of the prisoners whether they have seen the public defender. In response, 7258 gives him his mother’s name and phone number, explaining that his cousin is in the local public defender’s office and might be able to bail him out. Unexpectedly, 5848, an undemonstrative good prisoner, told the priest that what was going on was an experiment which, in his estimation, was getting out of control. Father McDermott thought that all the prisoners he had met with were naïve and didn’t know anything about prison or what it is for. In his opinion, the study was working as a real prison, and what he saw was the typical first-offender syndrome. The prisoners exhibited confusion, irritability, rage, depression, and over-emotionalization. He assured Zimbardo that such reactions would change after a week or so. 32 Get Out of Jail Free In the board game Monopoly, players can use the “Get out of Jail Free” card and not have to roll doubles or pay the $50 fine. But the rules for getting out of the Stanford County Jail were ambiguous at best, and some were improvised, including asking prisoners if they were willing to forfeit their pay to be paroled. Exactly what did those prisoners who wanted to leave have to do in order to get out of the study? The Stanford Prison Experiment informed consent form 33  stated that participants would only be released from the simulation for reasons of health deemed adequate by the medical advisors to the research project or for other reasons deemed appropriate by Zimbardo. Once in the study, the prisoners learned Rule 9 that prisoners must never refer to their condition as an experiment or simulation. To utter the words that must not be spoken would threaten the illusion vital to the success of the study. Participants had to maintain the fiction that supported their assigned roles as prisoners or guards. Rule 9 was broken several times. The first was on Monday morning, in the midst of the “rebellion” when 819 and 8612 said it was an experiment and simulation. The second was on Wednesday when 5486 told the priest that it was an experiment which was getting out of control. Goffman 34  identified four types of adaptation to total institutions: (a) withdrawal, where the inmate drastically curtails his involvement and interactions with both staff and fellow inmates; (b) intransigence or rebellion, where the inmate intentionally refuses to cooperate with the staff in any way; (c) colonization, where the inmate carves out a personal niche within the institution to make life more bearable, and may be accused by fellow inmates of never having it so good, and (d) conversion, where the inmate identifies with and assists the staff in dealing with fellow inmates. Four of the original nine prisoners were in jail until the end of the experiment on Friday morning. Two were “good” prisoners, or colonizers, from the start, while the other two converted and became “good” prisoners after the Monday rebellion. This suggests that those who adjusted most rapidly to the experimental conditions of prison life were able to minimize the degradation and harassment meted out by the guards. The remaining five original prisoners used different tactics to get out of jail early. The first to be released was the rebel in 8612. As described above, during the struggle on Monday he screamed it was a simulated experiment. That afternoon, he reported feeling sick and met with Warden Jaffe and complained about the arbitrary and sadistic behaviour of the guards. The warden assured him that he would see to it that the guards eased up. The warden went to Zimbardo and reported that 8612 was really distraught, wanted out, and insisted on seeing him. When 8612 told Zimbardo that he couldn’t take it anymore, Zimbardo replied that he was the most rebellious, insubordinate prisoner. But 8612 responded that Zimbardo had violated the contract and that he hadn’t expected to be treated so poorly. Zimbardo made 8612 an offer: the guards would not hassle him, and he could stay and earn his money if he cooperated and provided information—in essence, if he became an informer or snitch. 8612 appeared to capitulate by replying, “Well, all right.” Zimbardo later contended that “At that moment, if he had insisted on being released, I would have allowed him that option.” 35 Not to be deterred, 8162 managed to unlock his cell door and almost escaped around dinnertime. He was captured and allowed to eat dinner by himself. But he suddenly got up from dinner, raced across the room and ripped down the black scrim hiding the video camera. The guards caught him and put him back in the Hole. He then began complaining about headaches. When he was released from solitary at lights out, 8612 screamed that he was burning up inside. He had a second meeting with the warden and insisted that he wanted to get out and that he couldn’t stand another night. He also asked if he had the right to ask for a lawyer. When Craig Haney, one of the graduate assistants, returned from his late dinner on Monday, he met with 8612 to determine if he should be released immediately based on severe emotional distress. Haney realized that an early release could compromise the study design and that this was an unexpected turn of events. But 8612 was obviously disturbed. Haney, therefore, decided on his own to release him on ethical/humanitarian considerations over experimental ones. 36  Haney contacted 8612’s girlfriend who quickly came and picked him up. Haney told them that if the distress continued, he should visit Student Health on Tuesday morning where arrangements had been made with staff to deal with such reactions. He was released on Monday night approximately 36 hours after the experiment began. Prisoner 819 was the next to get out of jail. His tactics, like 8612, followed what Goffman termed “rebellion.” He refused to cooperate and, as in the movies The Great Escape(1963) and Cool Hand Luke (1967), got put in the Hole time and was left alone. On Monday morning, after having his sleep interrupted for the 2 a.m. and 6 a.m. counts, he quit the exercises and refused to continue for which he is sent to the Hole. Later that morning, when the guards rushed into his cell and pulled the cots into the Yard, Prisoner 819 screamed, “This is an experiment! Leave me alone!” When Prisoner 819 started to tell his visiting parents, brother, and sister on Tuesday evening about the Hole and his problems with the guards, one of the guards overheard him and stopped him from saying more. On Wednesday, Prisoner 819 locked himself in his cell and ripped his pillow apart. After another stay in the Hole, he reluctantly consented to meet with Father McDermott. At the meeting, he was not wearing his stocking cap and his hair was a mess. After telling the chaplain what he had been going through, Father McDermott told him that he needed to be less emotional. Later Zimbardo asked 819 if he wanted to be released immediately, but the prisoner insisted he was willing to continue and promised not to try any funny business. However, when he heard guard Arnett having the other prisoners shout over and over“  Because of the bad things that Prisoner 819 did, your cells are a mess, 37  he began shaking. This is an instance where an authority figure orders or encourages subordinate group members to exert peer pressure on a deviant or cowardly member, who then agrees to conform and behave properly. He told Zimbardo that he still did not want to leave and had to go back in, but Zimbardo called him by his first name, told him it was just an experiment, and that it was time for him to go home. The third was 1037 who joined the Monday morning rebellion by urging the occupants of cell #3 to barricade themselves in, but later withdrew and refused to come out of his cell. Three guards entered his cell, handcuffed his ankles and dragged him by his feet through the Yard and into the Hole. He was subsequently elected to the Grievance Committee which Zimbardo created on Monday after the rebellion. The committee met with Zimbardo, but 1037 was not convinced that any changes would be made. 1037’s mother wrote a letter to Zimbardo after visiting her son on Tuesday evening. She said her son looked haggard and had not been well sleeping because of the middle of the night “counts.” Her son was sorry he had volunteered, had gone through several moods, and was now resigned. Following the advice of the prison chaplain, FMcDermott, she indicated that she was going to secure legal counsel for her son. Zimbardo considered the Stanford County Jail as one holding a group of adolescents in pretrial detention following their Sunday-morning arrests. Obviously, no trial date had yet been set for any of them and none of them had legal representation. However, after a full staff meeting, a parole process was quickly improvised. 38  Parole was not mentioned in the informed consent form, although Rule 9, which forbade saying experiment or simulation, mentioned the possibility of parole. The parole board consisted of Prescott as chair, Haney, a department secretary and a graduate student. The latter two had little prior knowledge of the experiment. The research staff met and identified prisoners, including 1037, whom they considered eligible, and invited them to write formal requests explaining why they thought they deserved parole. They also asked the guards to prepare written reasons for denying parole to each of the four prisoners. However, the guards insisted that 416 not be granted such an opportunity because of his persistent violation of Rule 2 that prisoners must eat at mealtimes and only meal times. 416 was brought in to replace 8612 who was released on Monday night. He was horrified by what he saw and believed that quitting was impossible. 416 decided to go on a nonviolent Gandhi hunger strike. 39  When he refused to eat, the guards put him in the Hole for three hours, although the rules stated was one hour was the limit. He would remain in the experiment until it ended on Friday. In his parole petition, 1037 stated he had rebelled, but that evening realized that he was unworthy of better treatment. Since then he did his best to cooperate and no longer cause problems, or, in Goffman’s typology, converted. During his hearing on Wednesday, 1037 told the parole board that he would consider parole even if it meant forfeiting his salary. On Thursday, Zimbardo told him that he would be paroled and would get full pay for the entire experiment after the study and final surveys were completed. His parents picked him up during visiting hours that evening. The last of the original prisoners to be released was 4325. He had been a good prisoner and had been elected from cell #3 to the Grievance Committee. In Goffman’s terms, he adopted the role of the colonizer. After his appearance before the parole board, he was hopeful that he would be released soon, for the board had agreed that he should be the first of the four to be let out. But when he learned that 1037’s parents had come to pick him up, 4325 became depressed and “broke” as a result. 40  Zimbardo saw this and had him released. Following up on his promise, Father McDermott called7258’s mother, who called her nephew, an attorney in the local public defender’s office, who, in turn, called Zimbardo. Zimbardo reluctantly agreed to schedule an official lawyer’s visit for the prisoners on Friday morning as one more realistic element in the study. The public defender was curious and sceptical about the whole situation. Zimbardo briefed him on the study, how serious it had become, and invited the lawyer to treat the matter exactly as if he were working with a group of real prisoners.  Although Zimbardo had already decided to end the study, he raised the final curtain on Friday morning meetings between the public defender and several prisoners. The public defender told Prisoner 7258 (his cousin) that if he was willing to forfeit that his pay, then the contract would be null and void. Prisoner 7258 replied that he had told the parole board that he was willing to give up his compensation to get out of prison, but it did no good. The public defender heard complaints from the other prisoners about physical harassment by guards and inadequate supervision by the senior staff. 41  When he told the prisoners he would file a formal report on Monday and try to arrange their bail, his cousin begged to be bailed out immediately because the prisoners couldn’t take another week or even a weekend. The lawyer replied that he could help them but was powerless to do anything right then and there. This brought the remaining prisoners to a new low. As soon as the public defender left, Zimbardo told them that the study was in fact over and that they were free to leave. Ethical Issue: Ability to Leave at Will The primary research ethics issues of interest are the inability of the volunteers to readily exit the study and the contention that the experiment was continued too long as physical and psychological abuse of the prisoners escalated. On the question of quitting the experiment, Zimbardo 42  noted that the student volunteers could have elected to quit at any time, but they had promised to do their best to last the full two weeks. The students assumed that they could leave whenever they chose not to continue. But this changed when 8612 told the prisoners after his meeting with Zimbardo that he would not be let out and that they couldn’t get out either. The other prisoners came to believe that if this rebellious leader couldn’t get out, they, too, were helplessly stuck in jail for the duration of the experiment. 43 This is an example of how a subordinate group legitimizes the authority and rules of an organization and supports those with power over them. Max Weber 44  wrote that voluntary submission is a basic criterion of authority, and Peter Blau 45  noted that authority rests on the acceptance of social norms that a collectivity of subordinates can enforce on its individual members. That is, peer pressure obliges individuals to comply. The failure of the prisoner rebellion and the capitulation of its leader sent a powerful message to the other study participants that resistance was futile, and it was in their best interest to recognize the legitimacy of the prison guards. When a prisoner did in fact attempt to say, “I quit,” his plea was either ignored or met with delaying tactics. Years later, Prisoner 8612 told the media that the prisoners had only been pretending to go crazy. 46  It appeared that those participants who wanted out of the study either made a conscious choice to playact medical/psychological symptoms, adopt role models like Gandhi, Steve McQueen in The Great Escape or Paul Newman in Cool Hand Luke, or genuinely succumbed to the stressful conditions. Certainly, for 8612, who was stripped naked and complained about the arbitrary and sadistic behaviour of the guards, the severity of harm had reached a point on Monday evening that Hanley released him from the experiment. Zimbardo’s study was a simulation rather than a traditional experiment with testable hypotheses and a control group, although participants were randomly assigned to the roles of guard and prisoner. He thought of it as a demonstration of a phenomenon, like Milgram’s obedience study.8A simulation is designed and carried out when one wants to understand the natural dynamics and relationships in a social situation, but it is not feasible to conduct the study in a real-world setting. Good simulations are interactive, and researchers may adjust the ongoing scenario. Zimbardo made the simulation more realistic by bringing in a prison chaplain, creating a parole board and finally allowing the prisoners to meet with a public defender.  In his application to the Stanford Human Subjects Research Review Committee, Zimbardo had explicitly stated that those playing prisoners would be discouraged from quitting. At the parole board hearings, 7258, admitted he had attempted to escape with a former cellmate but that he had since pretty much followed all the rules. When parole board chair Prescott, asked what he did to get in here, 7258 truthfully answered, “Nothing, sir, but to sign up for an experiment.” On hearing the words that must not be spoken, Prescott quickly responded, “So wise guy, you think this is just an experiment.” But a few minutes later, Prescott noted, “You tell us you’d even be willing to forfeit compensation to get out of prison.” 48  Upon hearing this, Zimbardo had each of the four prisoners return and told Prescott to ask them if they would forfeit their pay if paroled. Zimbardo thereby sent a message that only the parole board could give the participants permission to leave, and then only if they were willing to forfeit the money they had earned. Of the four, only 3401, who really needed the money, said he would continue rather than take the offer to leave immediately without pay. He also told the parole board that he had a rash that’s going to break out, but Prescott dismissed his concern. He subsequently developed what appeared to be a full-body rash, perhaps psychosomatically induced, and was released on medical grounds. 49 Many of the critiques of the Stanford Prison experiment fail to mention that five of the original nine prisoners, either through playacting, rule-breaking, forfeiting pay, or experiencing extreme stress, were able to be released early. Although approximately half were able to get out, this still supports the current requirement that participants should be free to withdraw from a study at any time without penalty or loss of compensation. Ethical Concern: Lack of Oversight The second ethical concern was that the experiment continued too long which allowed the physical and psychological abuse of the prisoners to escalate. Haney 50  reported that after the experiment had ended, an analysis of the data revealed that, in fact, total guard aggression showed a daily escalation even after most prisoners had ceased resisting. This not only happened on camera in the Yard but also when an individual guard was alone with a single prisoner out of range of the cameras on their way to the toilet. Zimbardo acknowledged that he did not provide sufficient oversight and training for the guards. 51  He told them they could not physically abuse or torture the prisoners but could instil a sense of fear and treat them arbitrarily. Zimbardo and the research team did not respond to prisoner complaints by reprimanding those guards who physically abused the prisoners or kept them in the Hole for over an hour. He admitted “failing to intervene more often, which had thereby given them implicit permission to go to the extremes they did. They might have avoided their abuses had they had better top-down surveillance.” 52  Apparently, Zimbardo wanted to see how far the guards would go and did not release any prisoners unless they threatened the integrity of the simulation, became extremely uncooperative, or were clearly suffering from extreme stress.  Given Zimbardo’s dual role of Principle Investigator and Prison Superintendent, and his determination to see the simulation play itself out, no one was in an official position of authority to force him to end the study early. The person who persuaded him was Christine Maslach, Zimbardo’s former teaching assistant who had collaborated with him on other research projects. She recently completed her PhD at Stanford and was about to become an assistant professor in the psychology department at the University of California, Berkeley. She was also romantically involved with Zimbardo — a year after the prison study ended, they married.  Zimbardo had not told her how the study was evolving because she was part of a team that was scheduled to do a thorough evaluation of staff, prisoners, and guards on Friday, near the end of the first full week of the experiment. On Thursday, she unexpectedly was asked to serve on the parole board as a replacement for Haney, who left to deal with a family emergency. That evening, she came down to the prison to meet Zimbardo for a late dinner. On her way in, Maslach stopped to talk with one of the guards, whom she described as being “very pleasant, polite and friendly.” 53  Later on, she was told by one of the research staff that she should take a look at the meanest, toughest guard, who had just come on duty. When she looked through the observation point, she was stunned to discover it was the same guard she had chatted with earlier, but now he moved and talked differently, cursing with a southern accent, and swinging his club. This was guard Hellman, who was nicknamed John Wayne. When Zimbardo told her to look at the prisoners chained together by the ankles and with paper bags over their heads, she said that she had already seen them and averted her gaze. She began to cry and told Zimbardo that she was leaving and to forget about dinner. He ran after her and told her no one else had reacted as she just had. 54  She replied that she didn’t care if everyone in the world thought that what was going on was okay, she thought it was simply wrong, and that Zimbardo was personally responsible for the prisoners’ suffering. The argument was intense, unlike any they had had before. He acknowledged his responsibility and decided he would end the experiment on Friday morning.  Someone, who was not part of the research team, should have provided oversight and made decisions about when participants could leave the experiment. Zimbardo 55  later admitted that he had a serious conflict of interest as Principal Investigator and Prison Superintendent. He thought that if someone else had been acting as superintendent, he would have seen the light and ended the experiment earlier. But, more to the point, he also acknowledged that the study required oversight and that someone should have had authority over him to end it. The Common Rule §46.111(a)(6) states that “when appropriate, the research plan makes adequate provision for monitoring the data collected to ensure the safety of subjects.” These Data Safety and Monitoring Plans (DSMP) may assign the responsibility to the principal investigator, the sponsoring entity, or a data-safety monitoring committee or board. If the research is not a clinical trial but does involve greater-than-minimal risks to participants, IRB approval of a data-safety monitoring plan is required which may include an observational study monitoring board. 56 Because the Stanford Prison study was scheduled to last only two weeks and the data would not be available until much later, safety monitoring would depend on ongoing observation. This could have been carried out if the IRB appointed an individual to serve as both safety monitor and Prison Superintendent, thereby eliminating Zimbardo’s conflict of interest. As Prison Superintendent, the safety monitor would have attended research staff meetings, been able to observe from the behind the one-way screen, had the authority to reprimand the guards for excessive abuse, and report adverse events directly to the IRB. The safety monitor could have met with Zimbardo to discuss the possibility of releasing specific study participants, most likely those that, in fact, did leave early. Maslach’s source of authority was her personal relationship with Zimbardo: that is, referent power, as opposed to the organizational and regulatory status of an IRB safety monitor who would have held legitimate power over Zimbardo as Principal Investigator. 57 To his credit, Zimbardo had scheduled an evaluation of the study on Friday of the first full week and ended the study that morning. He later held group and individual debriefing sessions and regularly collected post-experimental questionnaires over the next months and years. He concluded that the suffering the participants experienced did not extend beyond the confines of the basement prison. 58 Zimbardo let the simulation evolve until he was finally persuaded to end it. While the original class simulation could be considered exempt from current IRB review since it was designed to enable students to develop experiments to investigate how individuals adapt to a new environment and role, the standalone Stanford Prison Experiment would require IRB review since Zimbardo intended to publish and publicize the results. Discussion At the onset of the experiment, Zimbardo had informed the participants that he wanted to study the development of norms that govern behaviour in novel situations and how people who are initially comparable but arbitrarily assigned to play specific roles would differentially perceive the same situation. The Stanford Prison Experiment demonstrated that the behaviours of guards and prisoners were not a result of their personality types but rather of values, norms, and behaviour generated by the prison environment, rules, and role expectations. Individuals will vary in their role adaptations to specific situations. The focus, then, should not be on individual psychological characteristics or moral fortitude, but rather on group dynamics and role socialization which transfer norms, values, beliefs, and behaviours to incoming group members. The simulation gave Zimbardo valuable insights into prison behaviour, riots, and abuses, specifically the retaking of the Attica New York Prison after the September 1971 riot and abuses by the 372nd Military Police Company of the US Army Reserves at the Abu Ghraib detention centre in Iraq in 2003-2004. Ashley Rubin, who studies penal change, thought that Zimbardo got a lot right. Although rare, Attica Prison and Abu Ghraib are real-world examples of “how prison can unleash the worst of human nature with terrible consequences.” 59  The Stanford Prison Experiment showed how quickly a prison-like an environment can morally degenerate when guards are left to their own devices. For the most part, Zimbardo followed the ethical procedures in place at the time. The consent form stated that participation in the research project will involve a loss of privacy, that release from participation would only be for reasons for health determined by the medical advisers or by Zimbardo, and that participants were expected to follow directions from staff members of the project or from other participants. They have not informed the type of prison clothing they would be wearing, or the degree of harassment and humiliation they might experience. Because it was a simulation, Zimbardo and his research team could not anticipate many of the events that emerged over the five days. He did not have a safety monitor who might have spotted the escalating violence, but relied on and followed the advice of his graduate research assistants, ex-convict Prescott, and Father McDermott who believed the simulation was realistic and the students slowly becoming socialized to their new roles as prisoners. Lessons Learned Fyodor Dostoyevsky, who spent who spent four years of hard labour in a Siberian prison camp, wrote that “The degree of civilization in a society can be judged by entering its prisons.” 60  To be sure, Zimbardo’s prison simulation was not normal paradigm science in which formal theories generate hypotheses and variables that can be tested using established experimental methods. Zimbardo’s controversial methods and findings triggered an ongoing debate on human nature, the social sciences, and research ethics that has lasted almost 50 years. The Stanford Prison Experiment showed how good people can do bad things in a prison environment if oversight and safeguards are not in place. It justified the need for social science research ethics and practices that protect participants and, when necessary, closely monitor studies in which the IRB determines that the probability and the magnitude of possible harm or discomfort anticipated is greater than those ordinarily encountered in daily life or during the performance of routine physical or psychological examination or tests. These are lessons that should be included in textbooks with a discussion of what happened, how the participants behaved and reacted to the situation, and the implications for real-world prisons and detention centers. Acknowledgments No Funding source Conflict of Interest None References

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• Toppo, G. (2018). Time to Dismiss the Stanford Prison Experiment? Inside Higher Ed. (June 20, 2018). Available at https://www.insidehighered.com/news/2018/06/20/new-stanford-prison-experiment-revelations-question-findings.
• Resnick, B. (2018). Philip Zimbardo defends the Stanford Prison Experiment, his most famous work.  Vox, (Jun 28, 2018). Available at: https://www.vox.com/science-and-health/2018/6/28/17509470/stanford-prison-experiment-zimbardo-interview.
• Department of Health Education and Welfare. (1971). Institutional guide to DHEW policy on protection of human subjects (NIH 72-102) Washington, D.C. 20402. Available at: https://archive.org/stream/institutionalgui00nati/institutionalgui00nati_djvu.txt.
• Zimbardo, P. (2008). Ibid. pp 235-236.
• National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research. (1978).  The Belmont report: Ethical principles and guidelines for the protection of human subjects of research.  Bethesda, MD: The Commission.
• Milgram, S. (1974).  Obedience to Authority: An Experimental View . New York: Harper and Row.
• Zimbardo, P.G, Maslach, C., and Haney, C. (2000). Reflections on the Stanford Prison Experiment: Genesis, Transformations, p 3. Available at:zimbardo.com/downloads/Publications.pdf.
• Zimbardo, P.G.(2008). Ibid, pp 32, 494, 495.
• Festinger, L., Pepitone, A., and Newcombe, T. (1952). Some Consequences of Deindividuation in a Group.  Journal of Abnormal and Social Psychology  47:382–89. CrossRef
• Zimbardo, P. (1969). The Human Choice: Individuation, Reason, and Order versus Deindividuation, Impulse, and Chaos.In W. J. Arnold, & D. Levine, D (Eds).  Nebraska Symposium on Motivation  (vol 17:237-307). Lincoln, NB: University of Nebraska Press,
• Haney, C., Banks, C., & Zimbardo, P. (1973) A Study of Prisoners and Guards in a Simulated Prison.  Naval Research Reviews. p1. Available at: www.zimbardo.com/downloads/1973%20A%20Study%20of%20Prisoners%20and%20Guards,%20Naval%20Research%20Reviews.pdf.
• Federal Policy for the Protection of Human Subjects 45 C.F.R. 46 §306. (1991).
• Zimbardo, P. G. 1971a). Application for Institutional Approval of Research Involving Human Subjects. Available at: http://www.prisonexp.org/pdf/humansubjects.pdf.
• Zimbardo, P.G. (1971b). Participant information sheet. Available at: http://www.prisonexp.org/pdf/geninfo.pdf.
• Zimbardo, P.G. (2008). Ibid. pp. 28, 40.
• Zimbardo, P.G, Maslach, C., and Haney, C. (2000). Ibid. p 23.
• Prescott, C. (2005). The Lie of the Stanford Prison Experiment,  The Stanford Daily . (April 28, 2005).
• Zimbardo, P.G. (2008). Ibid. p 68.
• Goffman, E. (1961).  Asylums. Essays on the Social Situation of Mental Patients and Other Inmates . New York: Doubleday Anchor. p. 5-6.
• Zimbardo, P.G. (2008). Ibid. p 55.
• Goffman, E. (1961.). Ibid. p.48.
• Zimbardo, P.G. (2008). Ibid. p 44-45.
• Zimbardo, P.G. (2008). Ibid. p 40.
• Zimbardo, P.G. (2008). Ibid. p58-59.
• Zimbardo, P.G. (2008). Ibid. p 61.
• Zimbardo, P.G. (2008). Ibid. p 496.
• Zimbardo, P.G. (2008). Ibid. p 100-104.
• Zimbardo, P.G. (2008). Ibid. p 104-106.
• Zimbardo, P.G. (1971c) Informed Consent Form. Available at: http://pdf.prisonexp.org/consent.pdf.
• Goffman, E. (1961). Ibid. p.61-63.
• Zimbardo, P.G. (2008). Ibid. p 71.
• Zimbardo, P.G. (2008). Ibid. p 77.
• Zimbardo, P.G. (2008). Ibid. p 105-107.
• Zimbardo, P.G. (2008). Ibid. p 130-131.
• Zimbardo, P.G. (2008). Ibid. pp.115,116, 131.
• Zimbardo, P.G. (2008). Ibid. p 161-162.
• Zimbardo, P.G. (2008). Ibid. p. 177-178.
• Zimbardo, P.G. (2008). Ibid. p. 222.
• Zimbardo, P.G. (2008). Ibid. p.70-71.
• Weber, M. (1947).  The Theory of Social and Economic Organization , NY: Oxford University Press. p.324.
• Blau, P. (1964).  Exchange and Power in Social Life .  New York: John Wiley and Sons. p. 200.
• Zimbardo, P.G. (2008). Ibid. p.361.
• Zimbardo, P.G. (2008). Ibid. p.197.
• Zimbardo, P.G. (2008). Ibid. p.139-140.
• Zimbardo, P.G. (2008). Ibid. p.135, 143.
• Haney, C., Banks, C., & Zimbardo, P., (1973). Ibid. p.12.
• Zimbardo, P.G. (2008). Ibid. pp. 4, 55, 166.
• Zimbardo, P.G. (2008). Ibid. p. 183.
• Zimbardo, P.G. (2008). Ibid. p. 169.
• Zimbardo, P.G. (2008). Ibid. p. 170.
• Zimbardo, P.G. (2008). Ibid. p. 234-235.
• National Heart Lung and Blood Institute. (2008).  Data and Safety Monitoring Policy . Available at: http://www.nhlbi.nih.gov/funding/policies/dsmpolicy.htm.
• French, J.R.P., & Raven, B. (1959). The Bases of Social Power. In D. Cartwright (Ed.), Studies in Social Power, (pp:150-167). Ann Arbor: MI: Institute for Social Research.
• 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. CrossRef
• Rubin, A. (2018). What a widely attacked experiment got right on the harmful effects of prisons.  The Conversation . (October 2, 2018). Available at: http://theconversation.com/what-a-widely-attacked-experiment-got-right-on-the-harmful-effects-of-prisons-103967.
• Dostoyevsky, F. (1862).  The House of the Dead . C. Garnett (trans). New York: Macmillan Co., 1950. In F. R. Shapiro (Ed.). (2006).  The Yale Book of Quotations (p. 210). New Haven, CT: Yale University Press.

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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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Debunking the Stanford Prison Experiment

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• 1 Université de Nice Sophia Antipolis.
• PMID: 31380664
• DOI: 10.1037/amp0000401

The Stanford Prison Experiment (SPE) is one of psychology's most famous studies. It has been criticized on many grounds, and yet a majority of textbook authors have ignored these criticisms in their discussions of the SPE, thereby misleading both students and the general public about the study's questionable scientific validity. Data collected from a thorough investigation of the SPE archives and interviews with 15 of the participants in the experiment further question the study's scientific merit. These data are not only supportive of previous criticisms of the SPE, such as the presence of demand characteristics, but provide new criticisms of the SPE based on heretofore unknown information. These new criticisms include the biased and incomplete collection of data, the extent to which the SPE drew on a prison experiment devised and conducted by students in one of Zimbardo's classes 3 months earlier, the fact that the guards received precise instructions regarding the treatment of the prisoners, the fact that the guards were not told they were subjects, and the fact that participants were almost never completely immersed by the situation. Possible explanations of the inaccurate textbook portrayal and general misperception of the SPE's scientific validity over the past 5 decades, in spite of its flaws and shortcomings, are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

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• Continuing to acknowledge the power of dehumanizing environments: Comment on Haslam et al. (2019) and Le Texier (2019). Zimbardo PG, Haney C. Zimbardo PG, et al. Am Psychol. 2020 Apr;75(3):400-402. doi: 10.1037/amp0000593. Am Psychol. 2020. PMID: 32250143

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• Revisiting the Stanford prison experiment, again: Examining demand characteristics in the guard orientation. Bartels J. Bartels J. J Soc Psychol. 2019;159(6):780-790. doi: 10.1080/00224545.2019.1596058. Epub 2019 Apr 8. J Soc Psychol. 2019. PMID: 30961456
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The Stanford Prison Experiment was massively influential. We just learned it was a fraud.

The most famous psychological studies are often wrong, fraudulent, or outdated. Textbooks need to catch up.

by Brian Resnick

The Stanford Prison Experiment, one of the most famous and compelling psychological studies of all time, told us a tantalizingly simple story about human nature.

The study took paid participants and assigned them to be “inmates” or “guards” in a mock prison at Stanford University. Soon after the experiment began, the “guards” began mistreating the “prisoners,” implying evil is brought out by circumstance. The authors, in their conclusions, suggested innocent people, thrown into a situation where they have power over others, will begin to abuse that power. And people who are put into a situation where they are powerless will be driven to submission, even madness.

The Stanford Prison Experiment has been included in many, many introductory psychology textbooks and is often cited uncritically . It’s the subject of movies, documentaries, books, television shows, and congressional testimony .

But its findings were wrong. Very wrong. And not just due to its questionable ethics or lack of concrete data — but because of deceit.

• Philip Zimbardo defends the Stanford Prison Experiment, his most famous work 

A new exposé published by Medium based on previously unpublished recordings of Philip Zimbardo, the Stanford psychologist who ran the study, and interviews with his participants, offers convincing evidence that the guards in the experiment were coached to be cruel. It also shows that the experiment’s most memorable moment — of a prisoner descending into a screaming fit, proclaiming, “I’m burning up inside!” — was the result of the prisoner acting. “I took it as a kind of an improv exercise,” one of the guards told reporter Ben Blum . “I believed that I was doing what the researchers wanted me to do.”

The findings have long been subject to scrutiny — many think of them as more of a dramatic demonstration , a sort-of academic reality show, than a serious bit of science. But these new revelations incited an immediate response. “We must stop celebrating this work,” personality psychologist Simine Vazire tweeted , in response to the article . “It’s anti-scientific. Get it out of textbooks.” Many other psychologists have expressed similar sentiments.

( Update : Since this article published, the journal American Psychologist has published a thorough debunking of the Stanford Prison Experiment that goes beyond what Blum found in his piece. There’s even more evidence that the “guards” knew the results that Zimbardo wanted to produce, and were trained to meet his goals. It also provides evidence that the conclusions of the experiment were predetermined.)

Many of the classic show-stopping experiments in psychology have lately turned out to be wrong, fraudulent, or outdated. And in recent years, social scientists have begun to reckon with the truth that their old work needs a redo, the “ replication crisis .” But there’s been a lag — in the popular consciousness and in how psychology is taught by teachers and textbooks. It’s time to catch up.

Many classic findings in psychology have been reevaluated recently

The Zimbardo prison experiment is not the only classic study that has been recently scrutinized, reevaluated, or outright exposed as a fraud. Recently, science journalist Gina Perry found that the infamous “Robbers Cave“ experiment in the 1950s — in which young boys at summer camp were essentially manipulated into joining warring factions — was a do-over from a failed previous version of an experiment, which the scientists never mentioned in an academic paper. That’s a glaring omission. It’s wrong to throw out data that refutes your hypothesis and only publicize data that supports it.

Perry has also revealed inconsistencies in another major early work in psychology: the Milgram electroshock test, in which participants were told by an authority figure to deliver seemingly lethal doses of electricity to an unseen hapless soul. Her investigations show some evidence of researchers going off the study script and possibly coercing participants to deliver the desired results. (Somewhat ironically, the new revelations about the prison experiment also show the power an authority figure — in this case Zimbardo himself and his “warden” — has in manipulating others to be cruel.)

• The Stanford Prison Experiment is based on lies. Hear them for yourself.

Other studies have been reevaluated for more honest, methodological snafus. Recently, I wrote about the “marshmallow test,” a series of studies from the early ’90s that suggested the ability to delay gratification at a young age is correlated with success later in life . New research finds that if the original marshmallow test authors had a larger sample size, and greater research controls, their results would not have been the showstoppers they were in the ’90s. I can list so many more textbook psychology findings that have either not replicated, or are currently in the midst of a serious reevaluation.

• Social priming: People who read “old”-sounding words (like “nursing home”) were more likely to walk slowly — showing how our brains can be subtly “primed” with thoughts and actions.
• The facial feedback hypothesis: Merely activating muscles around the mouth caused people to become happier — demonstrating how our bodies tell our brains what emotions to feel.
• Stereotype threat: Minorities and maligned social groups don’t perform as well on tests due to anxieties about becoming a stereotype themselves.
• Ego depletion: The idea that willpower is a finite mental resource.

Alas, the past few years have brought about a reckoning for these ideas and social psychology as a whole.

Many psychological theories have been debunked or diminished in rigorous replication attempts. Psychologists are now realizing it’s more likely that false positives will make it through to publication than inconclusive results. And they’ve realized that experimental methods commonly used just a few years ago aren’t rigorous enough. For instance, it used to be commonplace for scientists to publish experiments that sampled about 50 undergraduate students. Today, scientists realize this is a recipe for false positives , and strive for sample sizes in the hundreds and ideally from a more representative subject pool.

Nevertheless, in so many of these cases, scientists have moved on and corrected errors, and are still doing well-intentioned work to understand the heart of humanity. For instance, work on one of psychology’s oldest fixations — dehumanization, the ability to see another as less than human — continues with methodological rigor, helping us understand the modern-day maltreatment of Muslims and immigrants in America.

In some cases, time has shown that flawed original experiments offer worthwhile reexamination. The original Milgram experiment was flawed. But at least its study design — which brings in participants to administer shocks (not actually carried out) to punish others for failing at a memory test — is basically repeatable today with some ethical tweaks.

And it seems like Milgram’s conclusions may hold up: In a recent study, many people found demands from an authority figure to be a compelling reason to shock another. However, it’s possible, due to something known as the file-drawer effect, that failed replications of the Milgram experiment have not been published. Replication attempts at the Stanford prison study, on the other hand, have been a mess .

In science, too often, the first demonstration of an idea becomes the lasting one — in both pop culture and academia. But this isn’t how science is supposed to work at all!

Science is a frustrating, iterative process. When we communicate it, we need to get beyond the idea that a single, stunning study ought to last the test of time. Scientists know this as well, but their institutions have often discouraged them from replicating old work, instead of the pursuit of new and exciting, attention-grabbing studies. (Journalists are part of the problem too , imbuing small, insignificant studies with more importance and meaning than they’re due.)

Thankfully, there are researchers thinking very hard, and very earnestly, on trying to make psychology a more replicable, robust science. There’s even a whole Society for the Improvement of Psychological Science devoted to these issues.

Follow-up results tend to be less dramatic than original findings , but they are more useful in helping discover the truth. And it’s not that the Stanford Prison Experiment has no place in a classroom. It’s interesting as history. Psychologists like Zimbardo and Milgram were highly influenced by World War II. Their experiments were, in part, an attempt to figure out why ordinary people would fall for Nazism. That’s an important question, one that set the agenda for a huge amount of research in psychological science, and is still echoed in papers today.

Textbooks need to catch up

Psychology has changed tremendously over the past few years. Many studies used to teach the next generation of psychologists have been intensely scrutinized, and found to be in error. But troublingly, the textbooks have not been updated accordingly .

That’s the conclusion of a 2016 study in Current Psychology. “ By and large,” the study explains (emphasis mine):

introductory textbooks have difficulty accurately portraying controversial topics with care or, in some cases, simply avoid covering them at all. ... readers of introductory textbooks may be unintentionally misinformed on these topics.

The study authors — from Texas A&M and Stetson universities — gathered a stack of 24 popular introductory psych textbooks and began looking for coverage of 12 contested ideas or myths in psychology.

The ideas — like stereotype threat, the Mozart effect , and whether there’s a “narcissism epidemic” among millennials — have not necessarily been disproven. Nevertheless, there are credible and noteworthy studies that cast doubt on them. The list of ideas also included some urban legends — like the one about the brain only using 10 percent of its potential at any given time, and a debunked story about how bystanders refused to help a woman named Kitty Genovese while she was being murdered.

The researchers then rated the texts on how they handled these contested ideas. The results found a troubling amount of “biased” coverage on many of the topic areas.

But why wouldn’t these textbooks include more doubt? Replication, after all, is a cornerstone of any science.

One idea is that textbooks, in the pursuit of covering a wide range of topics, aren’t meant to be authoritative on these individual controversies. But something else might be going on. The study authors suggest these textbook authors are trying to “oversell” psychology as a discipline, to get more undergraduates to study it full time. (I have to admit that it might have worked on me back when I was an undeclared undergraduate.)

There are some caveats to mention with the study: One is that the 12 topics the authors chose to scrutinize are completely arbitrary. “And many other potential issues were left out of our analysis,” they note. Also, the textbooks included were printed in the spring of 2012; it’s possible they have been updated since then.

Recently, I asked on Twitter how intro psychology professors deal with inconsistencies in their textbooks. Their answers were simple. Some say they decided to get rid of textbooks (which save students money) and focus on teaching individual articles. Others have another solution that’s just as simple: “You point out the wrong, outdated, and less-than-replicable sections,” Daniël Lakens , a professor at Eindhoven University of Technology in the Netherlands, said. He offered a useful example of one of the slides he uses in class.

Anecdotally, Illinois State University professor Joe Hilgard said he thinks his students appreciate “the ‘cutting-edge’ feeling from knowing something that the textbook didn’t.” (Also, who really, earnestly reads the textbook in an introductory college course?)

And it seems this type of teaching is catching on. A (not perfectly representative) recent survey of 262 psychology professors found more than half said replication issues impacted their teaching . On the other hand, 40 percent said they hadn’t. So whether students are exposed to the recent reckoning is all up to the teachers they have.

If it’s true that textbooks and teachers are still neglecting to cover replication issues, then I’d argue they are actually underselling the science. To teach the “replication crisis” is to teach students that science strives to be self-correcting. It would instill in them the value that science ought to be reproducible.

Understanding human behavior is a hard problem. Finding out the answers shouldn’t be easy. If anything, that should give students more motivation to become the generation of scientists who get it right.

“Textbooks may be missing an opportunity for myth busting,” the Current Psychology study’s authors write. That’s, ideally, what young scientist ought to learn: how to bust myths and find the truth.

Further reading: Psychology’s “replication crisis”

• The replication crisis, explained. Psychology is currently undergoing a painful period of introspection. It will emerge stronger than before.
• The “marshmallow test” said patience was a key to success. A new replication tells us s’more.
• The 7 biggest problems facing science, according to 270 scientists
• What a nerdy debate about p-values shows about science — and how to fix it
• Science is often flawed. It’s time we embraced that.

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