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{{Short description|Controversial 1971 psychological experiment}}
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| title                    = Stanford prison experiment
| image                    = Plaque Dedicated to the Location of the Stanford Prison Experiment.jpg
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| image_alt                = Plaque with the text: "Site of the Standford Prison Experiment, 1971, conducted by Dr. Philip G. Zimbardo"
| caption                  = [[Commemorative plaque|Plaque]] at the location of the Stanford prison experiment
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| date                     = {{start and end dates|1971|08|14|1971|08|21}}
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| location                 = Single corridor in the basement of the [[Stanford University]]'s [[psychology]] building
| coordinates              = {{coord|37.4286304|-122.1729957|region:US-CA_type:event|display=inline,title}}
| also_known_as            = [[Philip Zimbardo|Zimbardo]] prison experiment<br />SPE<br />ZPE
| type                     = [[Psychological experiment]]
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<!--[[File:Plaque Dedicated to the Location of the Stanford Prison Experiment.jpg|thumb|Plaque at the location of the Stanford prison experiment|alt=Plaque with the text: "Site of the Standford Prison Experiment, 1971, conducted by Dr. Philip G. Zimbardo".]]-->

The '''Stanford prison experiment''' ('''SPE'''), also referred to as the ''' Zimbardo prison experiment''' ('''ZPE'''), was a controversial [[psychological experiment]] performed in August 1971 at [[Stanford University]]. It was designed to be a two-week [[simulation]] of a [[prison]] environment that examined the effects of [[Variable and attribute (research)|situational variables]] on participants' reactions and behaviors. [[Stanford University]] psychology professor [[Philip Zimbardo]] managed the research team who administered the study.<ref>{{Cite web|first=Victoria|last=Bekiempis|date=August 4, 2015|title=What Philip Zimbardo and the Stanford Prison Experiment Tell Us About Abuse of Power|url=https://www.newsweek.com/stanford-prison-experiment-age-justice-reform-359247|website=Newsweek}}</ref> Zimbardo ended the experiment early after realizing the guard participants'  abuse of the prisoners had gone too far. 

Participants were recruited from the local community through an advertisement in the newspapers offering $15 per day ($119.41 in 2025) to male students who wanted to participate in a "psychological study of prison life". 24 participants were chosen after assessments of psychological stability and then assigned randomly to the role of prisoners or prison guards.<ref>{{Cite web|title=2. Setting up|url=https://www.prisonexp.org/setting-up|access-date=2021-08-19|website=Stanford Prison Experiment|language=en-US}}</ref> Critics have questioned the validity of these methods.<ref name=LeTexier/>
Those volunteers selected to be "[[Prison guard|guards]]" were given uniforms designed specifically to de-individuate them, and they were instructed to prevent prisoners from escaping. The experiment started officially when "[[prisoner]]s" were arrested by the real police of [[Palo Alto]]. During the next five days, [[psychological abuse]] of the prisoners by the "guards" became increasingly brutal. After psychologist [[Christina Maslach]] visited to evaluate the conditions, she was troubled to see how study participants were behaving and she confronted Zimbardo. He ended the experiment on the sixth day.<ref>{{Cite web|title=8. Conclusion|url=https://www.prisonexp.org/conclusion|access-date=2021-08-19|website=Stanford Prison Experiment|language=en-US}}</ref>

The experiment has been referenced and critiqued as an example of an unethical psychological experiment, and the harm inflicted on the participants in this and other experiments during the post-World War II era prompted American universities to improve their ethical requirements and [[Institutional review board|institutional review]] for human experiment subjects in order to prevent them from being similarly harmed. Other researchers have found it difficult to reproduce the study, especially given those constraints.<ref>{{cite web|url=http://www.psypost.org/2014/09/intro-psychology-textbooks-gloss-criticisms-zimbardos-stanford-prison-experiment-27970|title=Intro to psychology textbooks gloss over criticisms of Zimbardo's Stanford Prison Experiment|date=September 7, 2014}}</ref>

Certain critics have described the study as unscientific and fraudulent.<ref name=LeTexier/><ref>{{cite web |last=Resnick |first=Brian |date=June 13, 2018 |title=The Stanford Prison Experiment was massively influential. We just learned it was a fraud. |url=https://www.vox.com/2018/6/13/17449118/stanford-prison-experiment-fraud-psychology-replication |website=Vox}}</ref> In particular, Thibault Le Texier has established that the guards were asked directly to behave in certain ways in order to confirm Zimbardo's conclusions, which were largely written in advance of the experiment. Zimbardo claimed that Le Texier's article was mostly ''[[ad hominem]]'' and ignored available data that contradicts his counterarguments, but the original participants, who were interviewed for the National Geographic documentary ''The Stanford Prison Experiment: Unlocking the Truth'', have largely confirmed many of Le Texier's claims.<ref>{{Cite web |last=Ouellette |first=Jennifer |date=2024-11-13 |title=Revisiting the Stanford Prison Experiment 50 years later |url=https://arstechnica.com/science/2024/11/revisting-the-stanford-prison-experiment-50-years-later/ |access-date=2025-03-09 |website=Ars Technica |language=en-US}}</ref>

== Funding and methodology==
Philip Zimbardo's official website described the experiment goal as follows:

{{blockquote|text=We wanted to see what the psychological effects were of becoming a prisoner or prison guard. To do this, we decided to set up a simulated prison and then carefully note the effects of this institution on the behavior of all those within its walls.<ref name="ArchivedOfficial">{{cite web|title=Slideshow on official site|url=http://www.prisonexp.org/slide-4.htm|archive-url=https://web.archive.org/web/20000512020449/http://www.prisonexp.org/slide-4.htm|archive-date=May 12, 2000|website=Prisonexp.org|page=Slide 4}}</ref>}}

A 1996 article from the Stanford News Service described the experiment goal in a more detailed way:

{{blockquote|text=Zimbardo's primary reason for conducting the experiment was to focus on the power of roles, rules, symbols, group identity and situational validation of behavior that generally would repulse ordinary individuals. "I had been conducting research for some years on deindividuation, vandalism and dehumanization that illustrated the ease with which ordinary people could be led to engage in anti-social acts by putting them in situations where they felt anonymous, or they could perceive of others in ways that made them less than human, as enemies or objects," Zimbardo told the Toronto symposium in the summer of 1996.<ref name="spespa">{{cite web|url=http://news.stanford.edu/pr/97/970108prisonexp.html|title=The Stanford Prison Experiment: Still powerful after all these years (1/97)|date=August 12, 1996|publisher=News.stanford.edu|access-date=July 12, 2018|quote=In the prison-conscious autumn of 1971, when George Jackson was killed at San Quentin and Attica erupted in even more deadly rebellion and retribution, the Stanford Prison Experiment made news in a big way. It offered the world a videotaped demonstration of how ordinary people, middle-class college students, and adult film stars can do things they would have never believed they were capable of doing. It seemed to say, as Hannah Arendt said of Adolf Eichmann, that normal people can take ghastly actions.|archive-date=November 18, 2011|archive-url=https://web.archive.org/web/20111118040323/http://news.stanford.edu/pr/97/970108prisonexp.html}}</ref>}}

The study was funded by the [[US Office of Naval Research]] to understand [[anti-social behaviour|antisocial behavior]].<ref>{{Cite web|title=More Information|url=https://www.prisonexp.org/faq|access-date=August 19, 2021|website=Stanford Prison Experiment|language=en-US}}</ref> The [[United States Navy]] and the [[United States Marine Corps]] wanted to investigate conflict between military guards and prisoners.<ref>{{Cite web|title=The Stanford Prison Experiment|url=https://www.psychologytoday.com/us/blog/the-time-cure/201507/the-stanford-prison-experiment|access-date=August 19, 2021|website=Psychology Today|language=en}}</ref>

Criticism of the SPE still continues today. Many researchers have critiqued Zimbardo's Stanford Prison Experiment for its method, whether it meets the criteria to be a scientific [[experiment]], and whether the guard orientation created a [[Demand characteristics|demand bias]].

== Publishing ==
Before publishing in [[American Psychologist]] and other [[Academic journal|peer-reviewed journals]], the researchers reported the findings in ''Naval Research Reviews'',<ref name="auto2">{{cite journal |last1=Haney |first1=C. |last2=Banks |first2=C. |last3=Zimbardo |first3=P. |date=September 1973|title=A study of prisoners and guards in a simulated prison|journal=Naval Research Reviews |url=https://babel.hathitrust.org/cgi/pt?id=nyp.33433016863114&view=1up&seq=313 |via=HathiTrust }}</ref> ''[[International Journal of Law, Crime and Justice|International Journal of Criminology and Penology]]'' (IJCP),<ref name="Haney Banks Zimbardo 1973" /> and the ''[[The New York Times Magazine|New York Times Magazine]]''.<ref>{{Cite news|last=Zimbardo|first=P.|date=April 8, 1973|title=The mind is a formidable jailer|language=en-US|page=38|work=The New York Times|issue=|url=https://www.nytimes.com/1973/04/08/archives/a-pirandellian-prison-the-mind-is-a-formidable-jailer.html|access-date=November 9, 2021|issn=0362-4331}}</ref> [[David Amodio]], psychology instructor at both [[New York University]] and the [[University of Amsterdam]], dismissed Zimbardo's study, stating that releasing the article to an "obscure journal" demonstrated that Zimbardo was unable to convince fellow psychologists of the validity and reliability of his study. This action by Zimbardo violated the tradition of scientific dissemination by publishing in other journals before publishing in a scientific peer-reviewed journal.<ref>{{cite tweet|number=1006958012756561920|user=david_m_amodio|title=Btw, the effects of the SPE fraud are far more devastating than any Stapel finding; it's given leaders cover for hu…<!-- full text of tweet that Twitter returned to the bot (excluding links) added by TweetCiteBot. This may be better truncated or may need expanding (TW limits responses to 140 characters) or case changes. --> |date=June 13, 2018}}</ref>{{better source needed|reason=[[WP:SPS]] on Twitter|date=November 2024}}

Zimbardo has stated that the grant agreement with the [[Office of Naval Research]] included a requirement to publish data in their journal, ''Naval Research Reviews''. He states that the ''International Journal of Criminology and Penology'' invited Zimbardo to write about his study in their journal, and he then wrote an article with the ''New York Times Magazine'' to share the findings with a broad audience. He states that the article still needed to pass through the very strict requirements of the American Psychologist, the official journal of the [[American Psychological Association]], in order to be published. After publishing the article in the American Psychologist, the findings were also reported in other peer-reviewed journals and books.<ref name="auto"/>

==Preparation==
===Recruitment and selection===
[[File:SPE1971-newspaper-ad cropped.jpg|thumb|Newspaper clipping of recruitment advertisement|alt=Photo of newspaper clipping reading: Male college students needed for psychological study of prison life. $15 per day for 1–2 weeks beginning Aug 15. For further information & applications, come to Room 248, Jordan Hall, Stanford U.]]

After Zimbardo received approval from the university to perform the experiment, study participants were recruited using an advertisement in the "help wanted" section of the ''Palo Alto Times'' and ''The Stanford Daily'' newspapers in August 1971:

{{blockquote|text=Male college students needed for psychological study of prison life. $15 per day for 1–2 weeks beginning Aug. 14. For further information and applications, come to Room 248, Jordan Hall, Stanford U.}}[[File:SPE1971-screening_applicants.jpg|thumb|Screening applicants|alt=Photo of a seminar room with a large table. Eight white male people are sitting at the table filling out papers spread out on the table. Another white male is standing at the side observing them.|left]]

75 men applied, and, after screening assessments and interviews, 24 were selected to participate in a two-week prison simulation.<ref name="Haney Banks Zimbardo 1973" /> The applicants were predominantly white, middle-class, and appeared to be stable psychologically and healthy.<ref name="Haney Banks Zimbardo 1973" /> The group of subjects was selected intentionally to exclude those with criminal backgrounds, psychological impairments, or medical problems.<ref name="Haney Banks Zimbardo 1973" />

On a random basis, half of the subjects were assigned the role of guard (nine plus three potential substitutes), and half were assigned to the role of prisoner (also nine plus three potential substitutes).<ref name="Haney Banks Zimbardo 1973" /> They agreed to participate for a 7- to 14-day period for $15 per day (roughly equivalent to $116.18 {{as of|alt=in 2025|2025}}<!-- Is a citation really needed for this? I don't think this usually has warranted a citation on other articles.
Edit: Removed C template. Be bold like ~~~~JayCubby -->).<ref name="Haney Banks Zimbardo 1973">{{cite journal |last1=Haney |first1=C. |last2=Banks |first2= C. |last3=Zimbardo |first3=P. |title=Interpersonal Dynamics in a simulated prison |journal=International Journal of Criminology and Penology |date=1973 |volume=1 |issue=1 |pages=69–77 |doi=10.21236/AD0751041 |pmid= |language=en |s2cid=143041401 |s2cid-access=free |issn= |pmc= |oclc= |bibcode= |id=[[PsycNET]] [https://psycnet.apa.org/record/1974-32677-001 1974-32677-001] {{NCJ|64810}}}}</ref>

{{Clear}}

=== Prison environment ===
[[File:SPE1971-prisoners_in_bed_in-cell.jpg|thumb|Prisoners in bed in cell|alt=Photo taken through iron bars. Behind the bars, three people are lying on beds side by side, wearing identical white smocks with numbers on the chest.]]

The day before the experiment began, small mock prison cells were rearranged to hold three prisoners each. There was a small corridor for the prison yard, a closet for solitary confinement, and a bigger room across from the prisoners for the guards and [[Prison warden|warden]].<ref name=":4" />{{rp|1–2}}

The experiment was performed in a {{convert|35|ft|m|abbr=on}} section of the basement of Jordan Hall, Stanford's psychology building. The prison had two fabricated walls: one at the entrance and one at the cell wall to block observation. Each cell ({{convert|7|x|10|ft|m|abbr=on|disp=or}}) was unlit, was intended to house 3 prisoners and had a cot (with mattress, sheet, and pillow) for each prisoner.<ref name=":12">{{Cite web|title=Index of /downloads|url=http://www.zimbardo.com/downloads|archive-url=https://web.archive.org/web/20150120225935/http://www.zimbardo.com/downloads/|archive-date=January 20, 2015|access-date=November 11, 2015|website=zimbardo.com}}</ref> Prisoners were confined and were to stay in their cells and the yard all day and night until the study was finished.<ref name=":4" />{{rp|1–2}} In contrast, the guards were to stay in a different environment, separate from the prisoners. The guards were given access to special areas for rest and relaxation, were told to work in teams of three for eight-hour shifts, and were not required to stay on-site after their shift.<ref name=":4" />{{rp|1–2}}

=== Roles ===
Zimbardo assumed the role of Superintendent, and an undergraduate [[research assistant]], David Jaffe, assumed the role of  Warden.<ref name=":4">{{Cite web |title=A Simulation Study of the Psychology of Imprisonment |url=https://web.stanford.edu/dept/spec_coll/uarch/exhibits/spe/Narration.pdf |archive-url=https://web.archive.org/web/20150906035518/https://web.stanford.edu/dept/spec_coll/uarch/exhibits/spe/Narration.pdf |archive-date=September 6, 2015 |access-date=August 19, 2021 |website=Stanford University |language=en}}</ref>

Digitized recordings available on the official SPE website were widely discussed in 2017, particularly one where warden David Jaffe tried to influence the behavior of one of the guards by encouraging him to participate more and be more "tough" for the benefit of the experiment.<ref name="Cosmos2018">{{Cite web|last=Masterson|first=Andrew|date=July 9, 2018|title=New evidence shows Stanford Prison Experiment conclusions "untenable"|url=https://cosmosmagazine.com/social-sciences/new-evidence-shows-stanford-prison-experiment-conclusions-untenable|access-date=July 13, 2018|work=Cosmos|quote=Archival recordings show one of the world's most famous psychology experiments was poorly designed – and its use to justify brutality baseless.}}</ref>

==== Orientation ====
The researchers had an orientation session for the guards the day before the experiment began, during which the guards were instructed not to harm the prisoners physically or withhold food or drink, but to maintain law and order. The researchers provided the guards with wooden [[Club (weapon)|batons]] to establish their status, deindividuating clothing similar to that of an actual prison guard (khaki shirt and pants from a local [[military surplus store]]), and [[mirrored sunglasses]] to prevent [[eye contact]] and create anonymity.<ref name=":4" />{{rp|1–2}}

Based on recordings from the experiment, guards were instructed by the researchers to refer to prisoners by number rather than by name. This, according to Zimbardo, was intended to diminish the prisoners' individuality.<ref>Zimbardo (2007), ''[[The Lucifer Effect]] '', p.54.</ref> With no control, prisoners learned they had little effect on what happened to them, ultimately causing them to stop responding and give up.<ref name=":12"/>

Zimbardo has explained that guard orientations in the prison system instructed the guards to exert power over the prisoners. Further, Zimbardo asserts that his fellow researcher explicitly instructed the guards not to inflict physical harm on the prisoners, but at the same time make the prisoners feel that they were in an actual prison.<ref>{{cite web|author=Zimbardo, P. G.|date=1971|title=Audio transcript—orientation of guards, 1971. ''Philip G Zimbardo Papers (SC0750)''|url=https://purl.stanford.edu/tn064kr9767|publisher=Department of Special Collections and University Archives, Stanford University Libraries}}</ref>

{{blockquote|Asking a person role-playing a guard in a prison simulation to be "firm" and "in the action" is mild compared to the pressure exerted by actual wardens and superior officers in real-life prison and military settings, where guards failing to participate fully can face disciplinary hearings, demotion, or dismissal.<ref name="auto"/>}}

== Critiques of scientific validity ==
In 1975, [[Ali Banuazizi]] and Siamak Movahedi argued that the behavior of the participants in the SPE was a result of [[demand characteristics]] and not the prison environment, that there is no single definition of prisoner behavior, and that participants were simply acting in the role in which they had been cast.<ref name=":1">{{cite journal|author1=Benuazizi, A.|author2=Movahedi, S.|date=February 1975|title="Interpersonal dynamics in a simulated prison: A methodological analysis"|url=http://www.faculty.umb.edu/siamak_movahedi/Library/zimbardo.pdf|journal=[[The American Psychologist]]|volume=30|issue=2|pages=152–160|doi=10.1037/h0076835}}</ref> Participants' behavior may have also been influenced by knowing that they were watched ([[Hawthorne effect]]).<ref name=":0">{{Cite web|title = Zimbardo – Stanford Prison Experiment|url = http://www.simplypsychology.org/zimbardo.html|website = www.simplypsychology.org|access-date = November 11, 2015|quote=Zimbardo (1973) was 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).}}</ref> Instead of being restrained by fear of an observer, guards may have behaved more aggressively when supervisors observing them did not restrain them.<ref name="NewYorker"/> The study was also criticized for demand characteristics in 2012 by psychologist [[Peter Gray (psychologist)|Peter Gray]], who argued that participants in psychological experiments are more likely to do what they believe the researchers want them to do, and specifically in the case of the SPE, "to act out their stereotyped views of what prisoners and guards do."<ref>{{cite news|author=Gray, Peter|date=2013|title=Why Zimbardo's Prison Experiment Isn't in My Textbook|work=Freedom to Learn blog|url=http://www.psychologytoday.com/blog/freedom-learn/201310/why-zimbardo-s-prison-experiment-isn-t-in-my-textbook}}</ref>

In 2007, Thomas Carnahan and Sam McFarland argued that the experiment suffers from [[selection bias]], as the recruiting posters for SPE specifically advertised participation in a study about prison life. Carnahan and McFarland argued that those who applied to participate with the SPE thus likely already had traits associated with abusiveness, [[aggression]], [[authoritarianism]], [[Machiavellianism (psychology)|Machiavellianism]], [[social dominance orientation]], and [[narcissism]]. Further, low dispositional [[empathy]] and [[altruism]] would also be indicators of someone who would volunteer.<ref name="revisitingSPE">{{Cite journal|last1=Carnahan|first1=Thomas|last2=McFarland|first2=Sam|date=April 17, 2007|title=Revisiting the Stanford prison experiment: could participant self-selection have led to the cruelty?|url=http://www.pitt.edu/~bertsch/Carnahan.pdf|journal=[[Personality and Social Psychology Bulletin]]|language=en|volume=33|issue=5|pages=603–14|doi=10.1177/0146167206292689|issn=0146-1672|pmid=17440210|s2cid=15946975}}</ref>

In 2018 Thibault Le Texier, a French researcher, in his book, {{lang|fr|Histoire d'un Mensonge}} (''The History of a Lie''), questions the scientific validity and merit of the SPE.<ref name="auto1">{{cite book|last=Le Texier|first=Thibault|title=Histoire d'un mensonge: enquête sur l'expérience de Stanford|publisher=Zones|year=2018|isbn=978-2-35522-120-0|publication-place=Paris|page=|language=fr|trans-title=The History of a Lie|oclc=1034777209}}</ref> He further discussed his critiques in an article published by the APA in 2019. Le Texier asserts his arguments using testimonies of those participants who were assigned as guards. In his opinion, the sadism and submission displayed in the SPE was directly caused by Zimbardo's instructions to the guards and the guards' desire to please the researchers. In particular, he has established that the guards were asked directly to behave in certain ways in order to confirm Zimbardo's conclusions, which were largely written in advance of the experiment.<ref name=LeTexier>{{cite journal|last=Le Texier |first=Thibault |date=2019 |title=Debunking the Stanford Prison Experiment |journal=[[American Psychologist]] |volume=74 |issue=7 |pages=823–839 |doi=10.1037/amp0000401 |pmid=31380664 |s2cid=199437070 |issn=1935-990X |url=https://psyarxiv.com/mjhnp/ |id=[[PsycNET]] [https://psycnet.apa.org/record/2019-45337-001 2019-45337-001]}}</ref><ref name="auto1" /> Zimbardo and colleagues contend that Le Texier's critiques were mostly [[ad hominem]] and ignored available data that contradicts his counterarguments.<ref>{{Cite journal |last1=Zimbardo |first1=Philip G. |last2=Haney |first2=Craig |date=April 2020 |title=Continuing to acknowledge the power of dehumanizing environments: Comment on Haslam et al. (2019) and Le Texier (2019) |journal=The American Psychologist |volume=75 |issue=3 |pages=400–402 |doi=10.1037/amp0000593 |issn=1935-990X |pmid=32250143|s2cid=214811340 }}</ref>

In 2020, Dutch historian [[Rutger Bregman]] claimed the experiment to be dubious. He states that the guards were urged to act aggressively towards the prisoners. In his book ''[[Humankind: A Hopeful History]]'', he is of the opinion that in similar experiments, researchers intentionally created hostility between groups and then interpreted the findings to suit their needs.<ref>{{cite book|last=Bregman|first=Rutger|title=Humankind: a hopeful history|publisher=Bloomsbury Publishing|year=2020|isbn=978-1-4088-9893-2|publication-place=London|page=|oclc=1119596186}}</ref>

Participant guard David Eshelman acknowledged that his theater background lent itself well to his role as guard, that he purposely thought of new ways to demean the prisoners – on one shift, Eshelman instructed the prisoners to simulate sodomy.<ref>"'John Wayne' (name withheld) Interview: 'The Science of Evil'". ''Primetime: Basic Instincts''. KATU. January 3, 2007</ref> Zimbardo has responded to this argument by stating that other guards acted similarly or engaged with Eshelman in the treatment of prisoners. While it is possible that one guard adopted his behavior from a movie (Eshelman identified with the warden in ''[[Cool Hand Luke]]''), others did not. Also, guards on a different shift than Eshelman exacted similar acts of emotional and mental brutality. Zimbardo further argues that the behaviors of the participant guards were not unlike those of real-world prison atrocities or the actions taken by American soldiers in the Abu Ghraib prison.<ref name="auto" /> Most of the guards have stated since the SPE that they were intentionally acting.<ref name=":0" />

The [[#BBC prison study|BBC prison study]] has indicated the importance of direction, of the form displayed by Zimbardo when briefing guards in the Stanford experiment, in the emergence of tyranny.<ref name=":3">{{Cite news|date=2005-10-31|author= John Sutherland 
|title=The ideas interview: Alex Haslam|language=en-GB|work=The Guardian|url=https://www.theguardian.com/education/2005/oct/31/highereducation.uk1|access-date=2023-03-16|issn=0261-3077}}</ref><ref name=":5">{{cite interview|last=Reicher|first=Steve|interviewer=Briggs, Pam|title=''Learning from the Experiment''|last2=Haslam|first2=Alex|url=http://www.offthetelly.co.uk/interviews/experiment.htm|archive-url=https://web.archive.org/web/20090221194634/http://www.offthetelly.co.uk/interviews/experiment.htm|archive-date=February 21, 2009|work=The Psychologist|author-link=Steve Reicher|author-link2=Alex Haslam}}</ref>

=== Carlo Prescott as a prison consultant ===

In 2005, an article was published by Carlo Prescott in ''[[The Stanford Daily]]'', explaining that the antagonistic tactics used by the guards were ones that he experienced during his time spent in [[San Quentin Rehabilitation Center|San Quentin]]. He shared each one in detail with the researchers prior to the experiment. In Prescott's opinion, the participants with the experiment, having no experience as prison guards, could not have acted in the ways they did unless they had been told of the explicit details of the actions they took.<ref>{{Cite web|last=Prescott|first=C.|date=2005|title=The lie of the Stanford Prison Experiment|url=https://archives.stanforddaily.com/2005/04/28?page=4&section=MODSMD_ARTICLE21#article|website=archives.stanforddaily.com|publisher=The Stanford Daily|access-date=November 9, 2021}}</ref>

Zimbardo has stated that he believed that the article was not written by Prescott, but rather by the screenwriter and producer [[Michael Lazarou]], who had attempted unsuccessfully to get the movie rights to the story of the SPE. In Zimbardo's opinion, Prescott would not have written in such a legalistic way, and Zimbardo claims that, in telephone records and emails obtained by Brett Emory, the SPE movie's producer asserted Prescott was not the author.<ref name="auto">Zimbardo, P., Hardwick, D. (2021). Zimbardo My Life Revealed. Giunti Psychometrics</ref>

== Events ==

=== Saturday, August 14: Set up ===
The small mock prison cells were set up, and the participants who had been assigned a guard role attended an orientation where they were briefed and given uniforms.<ref name=":4" />

===Sunday, August 15: Day 1===
[[File:SPE1971-arrest-of-prisoner-8612.jpg|thumb|Arrest of prisoners|alt=Photo of a person being arrested in the street by a policeman. The policeman is fixing the person's arms behind his back and pushing him towards a police car. One person kneeling at the side of the car is taking pictures. Two children in the foreground are watching the scene.]]

The participants who had been assigned a prisoner role were mock-arrested by the local [[Palo Alto]] police at their homes or assigned sites.<ref name=":4" />{{rp|2–5}} The participants were intentionally not informed that they would be arrested, as the researchers wanted it to come as a surprise.<ref name=":0" /> This was a breach of the ethics of Zimbardo's own contract that all of the participants had signed.<ref name=":0" /> The arrest involved charging them with armed robbery and burglary, Penal Codes 211 and 459, respectively. The Palo Alto police department assisted Zimbardo's team with the simulated arrests and performed full booking procedures on the prisoners at the Palo Alto City police headquarters, which included warning of Miranda rights, [[fingerprint]]ing, and taking of [[mug shot]]s. All of these actions were video-documented by a local San Francisco television station reporter using Zimbardo's car. Meanwhile, three guards prepared for the arrival of the inmates. The prisoners were then transported to the mock prison from the police station, sirens wailing. In the "Stanford County Jail" they were systematically [[strip search]]ed and given their new identities (inmate identification number) and uniform.<ref name=":4"/>{{rp|2–5}}

Prisoners wore uncomfortable, ill-fitting smocks without any underwear and stocking caps, as well as a chain around one ankle. Guards were instructed to call prisoners by their assigned numbers, sewn on their uniforms, instead of by name, thereby dehumanizing prisoners. The prisoners were then greeted by the warden, who conveyed the seriousness of their offence and their new status as prisoners. With the rules of the prison presented to them, the inmates retired to their cells for the rest of the first day of the experiment.<ref name=":4" />{{rp|2–5}}

===Monday, August 16: Day 2===
[[File:SPE1971_prisoner_lineup.jpg|thumb|Prisoners lineup|alt=Several white male people lined up along a white wall. They are wearing identical white smocks with numbertags on their chests. Their hair is covered by nylon and cotton bonnets.]]Guards referred to prisoners by their identification numbers and confined them to their small cells. At 2:30 am the prisoners rebelled against guards' wake up calls of whistles and clanging of batons. Prisoners refused to leave their cells to eat in the yard, ripped off their inmate number tags, took off their stocking caps and insulted the guards.

[[File:SPE1971-parole-hearing-day-2.jpg|thumb|Parole hearing{{Clarify|reason=The article doesn't mention the parole hearing|date=January 2022}}|alt=B/w photo of several white and one black person who are sitting at a table with a whiteboard on the wall behind. They are all looking to one white male person sitting at the table wearing a white t-shirt with a number on the chest.]]
In response, guards sprayed fire extinguishers at the prisoners to reassert control. The three back-up guards were called in to help regain control of the prison. Guards removed all of the prisoners' clothes, removed mattresses and sentenced the main instigators to time in the special detention unit. They attempted to dissuade any further rebellion using psychological warfare. One of the guards said to the other that, "these are dangerous prisoners".<ref name=":4"/>{{rp|5–8}}

=== Tuesday, August 17: Day 3 ===
In order to restrict further acts of disobedience, the guards separated and rewarded prisoners who had minor roles in the rebellion. The three spent time in the "good" cell where they received clothing, beds, and food denied to the rest of the jail population. After an estimated 12 hours, the three returned to their old cells that lacked beds.

Guards were allowed to abuse their power to humiliate the inmates. They had the prisoners count off and do pushups arbitrarily, restricted access to the bathrooms, and forced them to relieve themselves in a bucket in their cells.

==== Prisoner 8612 ====
The first prisoner to leave the experiment was Douglas Korpi, prisoner 8612. After 36 hours, he had an apparent mental breakdown in which he yelled, "Jesus Christ, I'm burning up inside" and "I can't stand another night! I just can't take it anymore!" Upon seeing his suffering, research assistant Craig Haney released Korpi.<ref name=":4" />{{rp|8–11}}

In 1992, in a documentary movie about the study, ''Quiet Rage'', Korpi asserted that the prison experiment had deeply affected him, and that experience caused him to later become a prison psychologist.<ref name="auto" /> However, in a 2017 interview, Korpi stated that his breakdown had been fake, and that he did it only so that he could leave and return to studying for his Graduate Record Exam; he had originally thought that he could study while "imprisoned", but the "prison staff" would not allow him. Korpi expressed regret that he had not filed a false imprisonment charge at the time.

Zimbardo responded to this criticism in 2018. First, while this experiment has been criticized overall for its ethics, Zimbardo stated that he needed to treat the breakdown as real and release the prisoner. Further, Zimbardo believes Korpi's 2017 interview was a lie.<ref name="auto" />

[[File:SPE1971-prisoner-breaks-down.jpg|thumb|Prisoner breaks down.|alt=Photo of a white male person sitting in a seminar chair, bending over and hiding his face in his elbow. He is wearing a long white cotton smock and no pants.]]

===Wednesday, August 18: Day 4===
Witnessing that guards were dividing prisoners based on their good or rebellious behavior, the inmates started to distance themselves from one another. Rioters believed that other prisoners were snitches and vice versa. Other prisoners considered the rebels as a threat to the status quo since they wanted to have their sleeping cots and clothes again.

==== Prisoner 819 ====

"Prisoner 819" began showing symptoms of distress and began crying in his cell. A priest was brought in to speak with him, but the young man refused to talk with him and instead asked for a medical doctor. After hearing him cry, Zimbardo reassured him of his actual identity and removed the prisoner. When "Prisoner 819" was speaking with Zimbardo, the guards cajoled the remaining inmates to loudly and repeatedly decry that "819 did a bad thing". "Prisoner 819" broke down immensely as he heard them calling him "bad". Zimbardo released 819 and gave him his pay.<ref name=":4"/>{{rp|11–12}}

===Thursday, August 19: Day 5===
The day was scheduled for visitations by friends and family of the inmates in order to simulate the prison experience.

[[File:SPE1971-guards_walking_in_SPE_yard.jpg|thumb|Guards walking in SPE yard|alt=Black and white photo of a white hallway with a plaque reading "Stanford County Prison". Two white male guards in uniforms wearing sunglasses walk along the hallway. One white male guard is sitting on top of a table in a corner in the background.|left]]

Zimbardo and the guards made visitors wait for long periods of time to see their loved ones. Only two visitors could see any one prisoner and only for just ten minutes while a guard watched. Parents grew concerned about their sons' well-being and whether they had enough to eat. Some parents left with plans to contact lawyers to gain early release of their children.

On the same day, Zimbardo's colleague [[Gordon H. Bower]] arrived to check on the experiment and questioned Zimbardo about what the [[independent variable]] of the research was. [[Christina Maslach]] also visited the prison that night and was distressed after observing the guards abusing the prisoners, forcing them to wear bags over their heads. She challenged Zimbardo about his lack of caring oversight and the immorality of the study. Finally, she made evident that Zimbardo had been changed by his role as Superintendent into someone she did not recognize and did not like. Her direct challenge, as well as the shared opinion from others, such as Curtis Banks (researcher), prompted Zimbardo to end the SPE the next day.<ref name=":4"/>{{rp|13–16}}

=== Friday, August 20: Day 6 ===
[[File:SPE1971 Jaffe, Hanley and Zimbardo.jpg|thumb|David Jaffe, [[Craig Haney]] and Zimbardo|alt=Photo of three white male people wearing shirts and ties talking to each other in front of a white wall. They are standíng beside a tape recording machine.]]
[[File:SPE1971-debriefing-session-with-participants.jpg|thumb|Debriefing|alt=B/w photograph of a group of male people dressed in casual shirts, sitting in a circle in a room looking in the same direction. The room is furnished with desks and a TV-set.]]
Due to Maslach's objections, the parents' concerns, and the increasing brutality exhibited by guards in the experiment, Zimbardo ended the study on day 6. Zimbardo gathered the participants (guards, prisoners, and researchers) to let them know that the experiment was over, and he arranged to pay them for the six days the experiment lasted. Zimbardo then met for several hours of informed debriefing first with all of the prisoners, then the guards, and finally everyone came together to share their experiences. Next, all participants were asked to complete a personal retrospective to be mailed to him subsequently. Finally, all participants were invited to return a week later to share their opinions and emotions. 

Joel E. Dimsdale quotes Philip Zimbardo in a little known interview from 1997: "more than 50 people had observed the study in progress and none had objected". ("Anatomy of Malice: The Enigma of the Nazi War Criminals", chapter 12, ''Malice as categorically different: encounters with "The Other".''

Later, the physical components of the Stanford County Jail were taken down and out of the basement of Jordan Hall as the cells returned to their usual function as graduate student offices.&nbsp;Zimbardo and his graduate student research team, Craig Haney and Curtis Banks, began compiling the multiple sources of data that would be the basis for several articles they soon wrote, both about their experiment and for Zimbardo's later expanded and detailed review of the SPE in ''The Lucifer Effect'' (2007).<ref name=":4"/>{{rp|16–17}}

== Interpretation and reproducibility of results ==

According to Zimbardo's interpretation of the SPE, it demonstrated that the simulated-prison situation, rather than individual [[personality psychology|personality traits]], caused the participants' behavior. Using this [[situational attribution]], the results are compatible with those of the [[Milgram experiment]], where participants complied with orders to administer seemingly dangerous and potentially lethal [[electric shock]]s to a [[shill]].<ref name="NewYorker">{{Cite magazine |url=https://www.newyorker.com/science/maria-konnikova/the-real-lesson-of-the-stanford-prison-experiment |title=The Real Lesson of the Stanford Prison Experiment |last= Konnikova |first=Maria |magazine=The New Yorker |quote=Occasionally, disputes between prisoner and guards got out of hand, violating an explicit injunction against physical force that both prisoners and guards had read prior to enrolling in the study. When the "superintendent" and "warden" overlooked these incidents, the message to the guards was clear: all is well; keep going as you are. The participants knew that an audience was watching, and so a lack of feedback could be read as tacit approval. And the sense of being watched may also have encouraged them to perform. |date=June 12, 2015 |access-date=July 12, 2018}}</ref> Others have posited that the guards assumed aggressive roles due to encouragement from researchers rather than conforming to the situation.<ref>{{Cite journal |last1=Haslam |first1=S. Alexander |last2=Reicher |first2=Stephen D. |last3=Van Bavel |first3=Jay J. |date=October 2019 |title=Rethinking the nature of cruelty: The role of identity leadership in the Stanford Prison Experiment. |url=http://doi.apa.org/getdoi.cfm?doi=10.1037/amp0000443 |journal=American Psychologist |language=en |volume=74 |issue=7 |pages=809–822 |doi=10.1037/amp0000443 |pmid=31380665 |hdl=10023/18565 |s2cid=199436917 |issn=1935-990X|hdl-access=free }}</ref>

Conclusions and observations drawn by the experimenters were largely [[Subjectivity|subjective]] and [[anecdotal evidence|anecdotal]], and the experiment is practically impossible for other researchers to [[reproducibility|reproduce]] accurately. In 1973, [[Erich Fromm]] argued, as only a third of the guards displayed sadistic behaviors, SPE is more accurately an example of how a situation cannot influence a person's behavior.<ref name="auto2" /> He states that there were generalizations in the experiment's results and argued that the personality of an individual does affect behavior when imprisoned. This ran counter to the study's conclusion that the prison situation itself controls the individual's behavior. Fromm also argued that the methods employed to screen participants could not determine the amount of sadism in the subjects.<ref>{{Cite news |date=December 28, 2014 |title=1971: Philip Zimbardo, Stanford Prison Experiment – precursor for Abu Ghraib torture |language=en-US |work=AHRP |url=http://ahrp.org/1971-stanford-prison-experiment-conducted-by-philip-zimbardo-was-an-exercise-that-unleashed-unprovoked-violence-and-a-predilection-for-abuse-bordering-on-torture/ |access-date=March 31, 2018}}</ref>

The experiment has also been used{{By whom|date=January 2022}} to illustrate [[cognitive dissonance]] theory and the power of [[authority]].<ref>{{Cite web |title=What Is The Cognitive Dissonance Theory Of The Stanford... |url=https://www.ipl.org/essay/What-Is-The-Cognitive-Dissonance-Theory-Of-F3UJTR74AJP6#:~:text=The%20Stanford%20Prison%20Experiment%20conducted,to%20shape%20an%20individual%27s%20behavior.&text=This%20experiment%20has%20been%20used,and%20the%20power%20of%20authority.|access-date=August 19, 2021 |website=www.ipl.org}}</ref>

=== BBC prison study ===
Psychologists [[Alex Haslam]] and [[Steve Reicher]] conducted the BBC Prison Study in 2002 to examine Zimbardo's themes of tyranny and resistance, and they published the results in 2006.<ref>{{cite web |title=Welcome to the official site for the BBC Prison Study |url=http://www.bbcprisonstudy.org |website=bbcprisonstudy.org}}</ref> It was a partial replication of the SPE performed with the assistance of the [[BBC]], which broadcast a documentary series about the SPE called ''[[The Experiment]]''.

As in the SPE, there was a makeshift prison, and all participants were male. Unlike the SPE's invitation to participate, Haslam and Reicher advertised their study as a university-backed social science experiment to be shown by television. Guards were not instructed on how to behave, only to figure out how to manage a prison.<ref name="auto" /> Those selected as prisoners were instructed to daily complete a questionnaire. Both prisoners and guards in this study wore microphones on their shirts, and cameras followed all participants' actions.<ref name="auto" />

Their results and conclusions differed from Zimbardo's and resulted in a number of publications concerning tyranny, [[stress (biology)|stress]], and leadership. The results were published in major academic journals such as ''[[British Journal of Social Psychology]]'', ''[[Journal of Applied Psychology]]'', ''[[Social Psychology Quarterly]]'', and ''[[Personality and Social Psychology Review]]''. The BBC Prison Study has now been taught as a core study on the UK [[A-level]] [[Psychology]] OCR syllabus.<ref>{{Cite web |last=Glavin |first=Chris |date=2019-04-13 |title=Similar Studies to the Stanford Prison Experiment {{!}} K12 Academics |url=https://www.k12academics.com/Education%20Scandals%20and%20Controversies/Academic%20Scandals/Stanford%20Prison%20Experiment/similar-studies-st |access-date=2022-11-16 |website=www.k12academics.com |language=en}}</ref>

While Haslam and Reicher's procedure was not a direct replication of Zimbardo's, their study casts further doubt on the generality of his conclusions. Specifically, it questions the notion that people slip mindlessly into roles. Their research also indicates the importance of leadership in the emergence of tyranny, such as the type displayed by Zimbardo when briefing guards in the Stanford experiment.<ref name=":3" /><ref name=":5" />

Zimbardo initially regarded Haslam and Reicher's study as a reality show as both prisoner and guard knew they were being televised and probably over-acted in their role for the purpose of entertaining watchers of the documentary. He felt that there were definite similarities to reality shows; prisoners had a confessional to describe their feelings, and there were contests for the prisoners. Despite its dissimilarities, Zimbardo believes the results of the BBC study replicated his own in that the participants were affected by the situation.<ref name="auto" /> In 2018, Zimbardo, Reicher, and Haslam issued a joint statement<ref>{{cite web |last1=Haney |first1=C. |last2=Haslam |first2=A. |last3=Reicher |last4=Zimbardo |first4=P. |date=2018 |title=Consensus statement on the Stanford Prison Experiment and BBC Prison Study |url=https://static1.squarespace.com/static/557a07d5e4b05fe7bf112c19/t/5b84796f352f53d4e6a1ee86/1535408496256/ConsensusStatement.pdf |access-date=November 9, 2021}}</ref> asserting that both experiments were valid. They also agreed that behaviors observed in all participants could have been caused by more than the situation. They urged people to continue research into toxic behaviors, arguing that their studies were unique and need replications to demonstrate reliability and significance.

== Legacy ==
One positive result of the study is that it has altered the way US prisons are managed. For example, juveniles accused of federal crimes are no longer housed before trial with adult prisoners, due to the risk of violence against them.<ref name=":0" />{{Better source needed|reason=Source does not provide any elaboration on this claim.|date=April 2024}}

Zimbardo submitted a statement to the 1971 [[US House Committee on the Judiciary]] about the experiment's findings.<ref>{{Cite book|last=No. 3|first=United States Congress House Committee on the Judiciary Subcommittee|url=https://books.google.com/books?id=Y18jUYWXQ9wC&q=Zimbardo+reported+his+findings+on+the+experiment+to+the+U.S.+House+Committee+on+the+Judiciary&pg=RA1-PA110|title=Corrections: Hearings Before Subcommittee No. 3 of the Committee on the Judiciary, House of Representatives, Ninety-second Congress, First [and Second] Session on Corrections|date=1971|publisher=U.S. Government Printing Office|language=en}}</ref>

=== Comparisons to Abu Ghraib ===
When [[Abu Ghraib torture and prisoner abuse|acts of prisoner torture and abuse at the Abu Ghraib prison in Iraq]] were publicized in March 2004, Zimbardo was struck by the similarity with his own experiment. He was dismayed by official military and government representatives shifting the blame for the torture and abuses in the [[Abu Ghraib prison|Abu Ghraib]] American military prison onto "a few [[bad apples]]", rather than acknowledging the possibly systemic problems of a formally established military incarceration system.<ref>{{Cite web |last=Dittmann |first=Melissa |date=2004 |title=What makes good people do bad things? |url=https://www.apa.org/monitor/oct04/goodbad |access-date=2022-09-30 |website=apa.org}}</ref> Zimbardo was then quoted saying "I argue that we all have the capacity for love and evil—to be Mother Theresa, to be Hitler or Saddam Hussein. It's the situation that brings that out".<ref>{{Cite web |last=Dittman |first=Melissa |date=2004 |title=What makes good people do bad things? |url=https://www.apa.org/monitor/oct04/goodbad |access-date=2022-09-30 |website=www.apa.org}}</ref>

Eventually, Zimbardo became involved with the defense team of lawyers representing one of the Abu Ghraib prison guards, Staff Sergeant [[Ivan Frederick|Ivan "Chip" Frederick]]. Zimbardo was granted full access to all investigation and background reports, and he testified as an [[expert witness]] in Frederick's [[court martial]]. The trial resulted in an eight-year prison sentence for Frederick in 2004.<ref>{{Cite web|last=|last2=|last3=|first3=|last4=|last5=|last6=|last7=|last8=|first8=|last9=|date=October 21, 2004|title=Top-Ranked Abu Ghraib Soldier Gets 8 Years in Prison|url=https://www.latimes.com/world/middleeast/la-102104abughraib_lat-story.html|access-date=August 19, 2021|website=Los Angeles Times|language=en-US}}</ref>

Zimbardo drew from his participation in the Frederick case to write the book ''[[The Lucifer Effect|The Lucifer Effect: Understanding How Good People Turn Evil]]'', which deals with the similarities between his own Stanford prison experiment and the Abu Ghraib abuses.

=== In popular culture ===
Italian moviemaker [[Carlo Tuzii]] was the first director to film a story based on the experiment when, in 1977, he directed the [[TV film|television movie]] {{lang|it|La gabbia}} ('The cage'), for [[Rai 1]]. Tuzii's original story called for a group of twenty young people from various social backgrounds, who were divided randomly into "guards" and "prisoners" and instructed to spend one month on opposite sides of an enormously high gate, with [[barbed wire]] on top, built in the middle of a large park. Before principal photography started, however, some concerns from [[RAI]] executives forced Tuzii and the screenwriters to alter the script into a very similar story to the actual Stanford experiment, including the outcome. [[Miguel Bosé]] featured as prisoner Carlo; [[progressive pop]] music band [[Pooh (band)|Pooh]] scored the movie and had a hit in Italy with a 7-inch edit of the theme tune.{{citation needed|date=January 2022}}

The 2001 German-language movie ''[[Das Experiment]]'' featuring [[Moritz Bleibtreu]] is based on the experiment. It was remade in 2010 in English as ''[[The Experiment (2010 film)|The Experiment]]''<ref>{{Cite web|date=August 21, 2015|title=1971 Experiment 'hard to believe'|url=https://www.arkansasonline.com/news/2015/aug/21/1971-experiment-hard-to-believe-2015082/|access-date=August 19, 2021|website=Arkansas Online|language=en}}</ref><ref>{{Citation|title=The Experiment (2001) – IMDb|date=March 8, 2001|url=https://www.imdb.com/title/tt0250258/|language=en-US|access-date=August 19, 2021}}</ref> and was directed by Paul T. Scheuring and starred Adrien Brody, Forest Whitaker, Cam Gigandet, Clifton Collins, Jr., and Maggie Grace.

The 2015 movie ''[[The Stanford Prison Experiment (film)|The Stanford Prison Experiment]]'' is based on the experiment.<ref>{{Cite web|first=Samantha |last=Highfill |date=2015-07-17|title=Billy Crudup turns college students into prison guards in 'The Stanford Prison Experiment'|url=https://ew.com/article/2015/07/17/stanford-prison-experiment-billy-crudup/|access-date=2023-03-16|website=EW.com}}</ref>

The [[YouTube]] series ''[[Mind Field]]'', hosted by [[Michael Stevens (educator)|Michael Stevens]], features an episode discussing the experiment.<ref>{{Cite web|last=Milligan|first=Kaitlin|title=MIND FIELD Revisits The Stanford Prison Experiment in New Episode|url=https://www.broadwayworld.com/bwwtv/article/MIND-FIELD-Revisits-The-Stanford-Prison-Experiment-in-New-Episode-20181219|access-date=August 19, 2021|website=BroadwayWorld.com|language=en}}</ref>

In Season 3, Episode 2 of the television series ''[[Veronica Mars]]'', entitled "[[My Big Fat Greek Rush Week]]", a similar experiment is featured.<ref name="IGN">{{cite web|url=http://www.ign.com/articles/2006/10/11/veronica-mars-my-big-fat-greek-rush-week-review|title=Veronica Mars: "My Big Fat Greek Rush Week" Review|work=[[IGN]]|last=Goldman|first=Eric|date=October 11, 2006|access-date=June 14, 2015}}</ref>

In ''[[The Overstory]]'' by [[Richard Powers]], the fictional character Douglas Pavlicek is a prisoner in the experiment, an experience which influences later decisions.<ref>{{Cite web|last=Rich|first=Nathaniel|date=May 11, 2018|title=The Novel That Asks, 'What Went Wrong With Mankind?'|url=https://www.theatlantic.com/magazine/archive/2018/06/richard-powers-the-overstory/559106/|access-date=August 19, 2021|website=The Atlantic|language=en}}</ref>

In Season 15, Episode 10 of television show ''[[American Dad (TV series)|American Dad]]'', "American Data", Roger recruits Steve, Toshi, Snot and Barry into a similar experiment.<ref>{{Cite web|title=American Dad: Season 15 Episode 12 – TV on Google Play|url=https://play.google.com/store/tv/show/American_Dad?cdid=tvseason-M4dIVKYglBraW5d7ZeHTYw&gdid=tvepisode-JkCyEdvxhGc&id=aYF0bEQa5GY&hl=en_US&gl=US|access-date=August 19, 2021|website=play.google.com|language=en}}</ref>{{Failed verification|date=April 2022}}

In Volume 10, Chapter 92 of ''[[Prison School]]'', Kate Takenomiya makes reference to and implements a similar scheme to the school's prison.

In 2024, Disney released a [[National Geographic]] three episode documentary series ''The Stanford Prison Experiment: Unlocking the Truth'' with first hand accounts of the original participants in the study.<ref>{{Cite web |date=November 13, 2024 |title="The Stanford Prison Experiment: Unlocking the Truth" |url=https://www.nationalgeographic.com/tv/show/6b363dd7-fac5-4ec8-a530-cbc97b1a3322 |access-date=November 22, 2024 |website=National Geographic}}</ref>

== Ethical concerns ==
Some of the guards' behavior allegedly resulted in dangerous and psychologically damaging situations.<ref>{{cite web|title=Conclusion|url=http://www.prisonexp.org/slide-31.htm|website=Stanford Prison Experiment|access-date=December 29, 2008|archive-date=December 19, 2008|archive-url=https://web.archive.org/web/20081219043133/http://www.prisonexp.org/slide-31.htm}}</ref> Ethical concerns about the experiment often draw comparisons to the [[Milgram experiment]], performed ten years earlier in 1961 at [[Yale University]], where [[Stanley Milgram]] studied obedience to authority.<ref name="NewYorker" /> With the treatment that the guards were giving to the prisoners, the guards would become so absorbed into their role as a guard that they would emotionally, physically, and mentally humiliate the prisoners:

{{blockquote|Each prisoner was systematically searched and stripped naked. He was then deloused with a spray, to convey our belief that he may have germs or lice... Real male prisoners don't wear dresses, but real male prisoners do feel humiliated and do feel emasculated. Our goal was to produce similar effects quickly by putting men in a dress without any underclothes. Indeed, as soon as some of our prisoners were put in these uniforms they began to walk and to sit differently, and to hold themselves differently – more like a woman than like a man.<ref>{{Cite web|url=https://www.prisonexp.org/arrival|title=3. Arrival|website=Stanford Prison Experiment|language=en-US|access-date=April 29, 2019}}</ref>}}

The experiment was perceived by many to involve questionable ethics, the most serious concern being that it was continued even after participants expressed their desire to withdraw. Despite the fact that participants were told they had the right to leave at any time, the researchers did not allow this.<ref name=":0" /> Although there was only limited ethical oversight at the time, some aspects of the study were in contradiction of the contract that was signed with participants.<ref name=":0" />

Since the time of the SPE, [[Guidelines for human subject research|ethical guidelines for experiments involving human subjects]] have become more strict.<ref>{{citation|title=US Department of Health & Human Services Code of Federal Regulations|chapter=Title 45, Part 46, Protection of Human Subjects|publisher=US Department of Health & Human Services}}</ref><ref>The Belmont Report, Office of the Secretary, Ethical Principles and Guidelines for the Protection of Human Subjects of Research, The National Commission for the Protection of Human Subjects for Biomedical and Behavioral Research, April 18, 1979</ref><ref>{{citation|title=The Nuremberg Code|publisher=US Department of Health and Human Services}}<!-- This existed before SPE --></ref> The Stanford prison experiment resulted in the implementation of rules to preclude any harmful treatment of participants. Before they are implemented, human studies must now be reviewed by an [[institutional review board]] (US) or ethics committee (UK) and found to be in accordance with ethical guidelines set by the American Psychological Association or British Psychological Society.<ref name=":0" /> These guidelines involve the consideration of whether the potential benefit to science outweighs the possible risk for physical and psychological harm.

A post-experimental debriefing is now considered an important ethical consideration to ensure that participants are not harmed in any way by their experience in an experiment. Though the researchers did perform debriefing sessions, they were several years after the SPE.{{Clarify|reason=Is there any particular reason why they chose to debrief them at that time?|date=January 2022}} By that time, numerous details were forgotten; nonetheless, Zimbardo has concluded from his follow-up research that participants experienced no lasting negative effects.<ref name=":0" />{{Better source needed|reason=This should be sourced directly to him if possible.|date=January 2022}}{{Clarify|reason=Do others agree with his interpretation?|date=January 2022}} The American Psychological Association specifies that the debriefing process should occur as soon as possible to assess any psychological harm that may have been done and to rehabilitate participants if necessary. If there is an unavoidable delay in debriefing, the researcher is obligated to take measures to minimize harm.<ref>{{citation |title=Ethical Principles of Psychologists and Code of Conduct|publisher=American Psychological Association|at=Section 8.07|date=January 1, 2016|url=http://www.apa.org/ethics/code/}}</ref>

== Similar studies ==
In 1967, [[The Third Wave (experiment)|The Third Wave experiment]] involved the use of authoritarian dynamics similar to [[Nazi Party]] methods of mass control in a classroom setting by high school teacher [[Ron Jones (teacher)|Ron Jones]] in [[Palo Alto, California]] with the goal of demonstrating vividly to the class how the German public in [[World War II]] could have acted in the way it did.<ref name="wave">{{cite web |url=http://www.thewavehome.com/1976_The-Third-Wave_story.htm |title=The Third Wave |last1=Jones |first1=Ron |date=1976 |website=The Wave Home |archive-url=https://web.archive.org/web/20150202082041/http://www.thewavehome.com/1976_The-Third-Wave_story.htm |archive-date=February 2, 2015 |access-date=December 3, 2016 }}</ref> Although the veracity of Jones' accounts has been questioned, several participants with the study have gone on record to confirm the events.<ref>{{cite web|url=http://www.lessonplanmovie.com/|title=Lesson Plan: The Story of the Third Wave (The Wave, Die Welle)|publisher=lessonplanmovie.com}}</ref>

In both experiments, participants found it difficult to leave the study due to the roles they were assigned. Both studies examine human nature and the effects of authority. Personalities of the subjects were thought to have little influence on both experiments despite the test before the prison experiment.<ref name=":2">{{Cite web|title = Comparing Milgram's Obedience and Zimbardo's Prison Studies|url = http://sccpsy101.com/2011/11/25/comparing-milgrams-obedience-and-zimbardos-prison-studies/|website = PSY 101 – Introduction to Psychology by Jeffrey Ricker, Ph.D.|access-date = November 12, 2015|language = en-US|date = November 25, 2011}}</ref>

Both the Milgram and Zimbardo studies concluded that participants conform to [[social pressure]]s. [[Conformity]] is strengthened by allowing some participants to feel more or less powerful than others.<ref>{{Cite journal |last1=Haslam |first1=S. Alexander |last2=Reicher |first2=Stephen. D. |date=2012-11-20 |title=Contesting the "Nature" Of Conformity: What Milgram and Zimbardo's Studies Really Show |journal=PLOS Biology |volume=10 |issue=11 |article-number=e1001426 |doi=10.1371/journal.pbio.1001426 |issn=1544-9173 |pmc=3502509 |pmid=23185132 |doi-access=free }}</ref> In both experiments, the people's behaviors altered to match the group stereotypes, demonstrating a tendency to conform to others passively, even if a particular subject is malevolent.

A 2007 study on prison-life examined the potential relationship between participant self-selection and the disposition toward aggressive behaviors. They found that when responding to an advertisement, participants "were&nbsp;significantly higher on measures of aggressiveness, [[authoritarianism]], [[Machiavellianism (psychology)|Machiavellianism]],&nbsp;[[narcissism]],&nbsp;and&nbsp;social dominance than those who responded to a parallel ad that omitted the&nbsp;words 'of prison&nbsp;life,'&nbsp;and&nbsp;they&nbsp;were&nbsp;significantly lower in dispositional [[empathy]] and [[altruism]]".<ref>{{Cite journal |last1=Carnahan |first1=Thomas |last2=McFarland |first2=Sam |date=May 2007 |title=Revisiting the Stanford Prison Experiment: Could Participant Self-Selection Have Led to the Cruelty? |url=http://journals.sagepub.com/doi/10.1177/0146167206292689 |journal=Personality and Social Psychology Bulletin |language=en |volume=33 |issue=5 |pages=603–614 |doi=10.1177/0146167206292689 |pmid=17440210 |s2cid=15946975 |issn=0146-1672|url-access=subscription }}</ref>

== See also ==
{{Portal|San Francisco Bay Area}}
{{cols}}
* ''[[Eichmann in Jerusalem: A Report on the Banality of Evil]]''
* ''[[Humankind: A Hopeful History]]''
* [[Milgram experiment]], which involves situational attribution
* [[Person–situation debate]]
* [[Project MKUltra]]
* ''[[Rhythm 0]]''
* [[Trier social stress test]]
* [[Unethical human experimentation in the United States]]
{{colend}}

== Footnotes ==
{{Reflist|30em}}

== References ==
* {{cite journal | last1 = Haney | first1 = C. | last2 = Banks | first2 = W. C. | last3 = Zimbardo | first3 = P. G. | year = 1973 | title = A study of prisoners and guards in a simulated prison | journal = Naval Research Review | volume = 30 | pages = 4–17 }}
* {{cite journal | last1 = Haslam | first1 = S. A. | last2 = Reicher | first2 = S. D. | year = 2003 | title = Beyond Stanford: questioning a role-based explanation of tyranny | journal = Dialogue (Bulletin of the Society for Personality and Social Psychology) | volume = 18 | pages = 22–25 }}
* {{cite journal | last1 = Haslam | first1 = S. A. | last2 = Reicher | first2 = S. D. | year = 2006 | title = Stressing the group: social identity and the unfolding dynamics of responses to stress | journal = [[Journal of Applied Psychology]] | volume = 91 | issue = 5| pages = 1037–1052 | doi=10.1037/0021-9010.91.5.1037| pmid = 16953766 | s2cid = 14058651 }}
* {{cite journal | last1 = Haslam | first1 = S. A. | last2 = Reicher | first2 = S. D. | year = 2012 | title = When prisoners take over the prison: A social psychology of resistance | journal = [[Personality and Social Psychology Review]] | volume = 16 | issue = 2| pages = 154–179 | doi=10.1177/1088868311419864| pmid = 21885855 | s2cid = 30021002 }}
* Musen, K. & Zimbardo, P. G. (1991). ''Quiet rage: The Stanford prison study.'' Video recording. Stanford, CA: Psychology Dept., Stanford University.
* {{cite journal | last1 = Reicher | last2 = Haslam | first2 = S. A. | year = 2006 | title = Rethinking the psychology of tyranny: The BBC Prison Study | journal = [[British Journal of Social Psychology]] | volume = 45 | issue = Pt 1| pages = 1–40 | doi = 10.1348/014466605X48998 | pmid = 16573869 }}
* Zimbardo, P. G. (1971). "The power and pathology of imprisonment",  ''[[Congressional Record]]'' (Serial No. 15, 1971-10-25). Hearings before Subcommittee No. 3, of the [[United States House Committee on the Judiciary]], Ninety-Second Congress, ''First Session on Corrections, Part II, Prisons, Prison Reform and Prisoner's Rights: California.'' Washington, DC: US Government Printing Office.
* Zimbardo, P. G. (2007). "[https://www.democracynow.org/2007/3/30/understanding_how_good_people_turn_evil Understanding How Good People Turn Evil]." Interview transcript. ''[[Democracy Now!]]'', March 30, 2007. Accessed January 17, 2015.

== Further reading ==
* {{Cite web|last1=Fernandez|first1=Ismael|last2=Triola|first2=V. V.|date=2021|title=Analysis of 'A Study of prisoners and guards in a simulated prison'|url=https://medium.com/coast-to-coast-notes/analysis-of-a-study-of-prisoners-and-guards-in-a-simulated-prison-107b485b51ac|website=Medium|language=en}}
* {{Cite web|last1=Haslam|first1=A.|last2=Reicher|first2=S.|date=2008|title=Science and society: How has Zimbardo responded to our work?|url=http://www.bbcprisonstudy.org/faq.php?p=122|website=Bbcprisonstudy.org|publisher=The BBC Prison Study}}
* {{Cite journal|last=Zimbardo|first=P. G.|date=2004|title=Quiet Rage|url=http://purl.stanford.edu/jc730zt0628|website=purl.stanford.edu|publisher=Stanford Digital Repository|location=Palo Alto, Calif.|language=en}}

== External links ==
* [http://www.prisonexp.org/ The official website for Stanford Prison Experiment], with extensive information on and materials used in the study, further reading and resources, and media links
* [http://www.oac.cdlib.org/findaid/ark:/13030/kt7f59s371 Philip G. Zimbardo Papers (Stanford University Archives)]
*[https://stanfordmag.org/contents/the-menace-within Interviews with guards, prisoners, and researchers in July/August 2011 ''Stanford Magazine'']
* Zimbardo, P. (2007). [http://www.in-mind.org/special-issue/from-heavens-to-hells-to-heroes.html From Heavens to Hells to Heroes] {{Webarchive|url=https://web.archive.org/web/20081210094533/http://www.in-mind.org/special-issue/from-heavens-to-hells-to-heroes.html |date=December 10, 2008 }}. ''In-Mind Magazine''.
* [http://www.bbcprisonstudy.org The official website of the BBC Prison Study]
* "[https://stanforddailyarchive.com/cgi-bin/stanford?a=d&d=stanford20050428-01.2.24&e=-------en-20--1--txt-txIN------- The Lie of the Stanford Prison Experiment]", ''[[The Stanford Daily]]'' (April 28, 2005), p.&nbsp;4&nbsp; – Criticism by Carlo Prescott, ex-con and consultant/assistant for the experiment
* [https://www.bbc.co.uk/news/world-us-canada-14564182 BBC news article – 40 years on, with video of Philip Zimbardo]
* [https://www.cbsnews.com/pictures/shocking-prison-study-40-years-later-what-happened-at-stanford/12/ Photographs] at cbsnews.com
* [https://www.vox.com/science-and-health/2018/6/14/17464516/stanford-prison-experiment-audio#:~:text=In%20the%20experiment%2C%20Stanford%20professor%20Philip%20Zimbardo%20assigned,are%20given%20power%20and%20others%20are%20denied%20it.] – Vox article detailing how the study is a sham

'''Abu Ghraib and the experiment''':
* [https://news.bbc.co.uk/2/hi/uk_news/magazine/3683115.stm BBC News: Is it in anyone to abuse a captive?]
* [https://news.bbc.co.uk/2/hi/uk_news/magazine/3700209.stm BBC News: Why everyone's not a torturer]
* [http://wais.stanford.edu/War/war_05152004.htm Ronald Hilton: US soldiers' bad behavior and Stanford Prison Experiment]
* [http://www.slate.com/id/2100419/ Slate.com: Situationist Ethics: The Stanford Prison Experiment doesn't explain Abu Ghraib], by William Saletan

{{Incarceration}}
{{Conformity}}
{{Medical ethics cases}}

[[Category:1971 in California]]
[[Category:1971 in science]]
[[Category:Academic scandals in the United States]]
[[Category:August 1971 in the United States]]
[[Category:Conformity]]
[[Category:Fictional prisons]]
[[Category:Group processes]]
[[Category:History of psychology]]
[[Category:Human subject research in psychiatry]]
[[Category:Human subject research in the United States]]
[[Category:Imprisonment and detention]]
[[Category:Psychology experiments]]
[[Category:Research ethics]]
[[Category:Stanford University]]