The Stanford prison experiment was argued about for forty-seven years before anyone read its record. This piece follows the argument in order: the account its authors gave, the people who doubted it from the account alone, and the exchange that followed when the archive was read.

The account

The first report was a press release, typed on August 16, 1971, the second day, which said that “The guards themselves formulated a set of operating rules along with the warden, and were free to devise new rules, procedures, punishments and privileges as they deemed necessary”, and that the study would make the public “aware of the prison reforms needed at a psychological level”. A second release on August 20, the day the prison closed, told the San Francisco papers, as Thibault Le Texier quotes it from the Examiner, that “this has a message for prison reform. It shows the need for a change in psychological conditions, which won’t cost the taxpayer any money.” On October 12 the Stanford Daily put the experiment on its front page; on October 25 Zimbardo told a House subcommittee that the guards “made up their own rules for maintaining law, order, and respect”; on November 26 NBC’s Chronolog broadcast the videotapes.

The scientific paper came in 1973, first in the September Naval Research Reviews, because, as Zimbardo explained in 2018, the Office of Naval Research “insisted that I document my research in its journal”, and then in the International Journal of Criminology and Penology “at the invitation of the editor”. Its abstract said: “Neither group received any specific training in these roles.” Its method said the guards “were intentionally given only minimal guidelines for what it meant to be a guard”, and that “The guards generally believed that we were primarily interested in studying the behavior of the prisoners.” Its results said that guard aggression rose daily and “was emitted simply as a ‘natural’ consequence of being in the uniform of a ‘guard’ and asserting the power inherent in that role”. A version for the New York Times Magazine on April 8, 1973, “A Pirandellian Prison”, carried the names of Zimbardo, Haney, Banks and Jaffe.

Then the account was packaged. A slide show with a taped narration, made in 1972 by Zimbardo and his assistant Greg White, toured for twenty years and ended, in Le Texier’s quotation: “As a consequence of the time we spent in our simulated prison, we could understand how prison, indeed how any total institution, could dehumanize people, could turn them into objects and make them feel helpless and hopeless, and we realized how people could do this to each other.” Ken Musen’s documentary Quiet Rage, made with Zimbardo and released by Stanford in 1992, replaced it. Its narration says of Prisoner 8612 that “8612 decided that the only way to get out was to show everyone he had gone crazy—then they would have to release him. He began to play the role of the crazy person, but soon the role became too real as he went into an uncontrollable rage.” Zimbardo wrote the experiment into Psychology and Life and later Psychology: Core Concepts, and presented it in the PBS series Discovering Psychology in 1990. In 2004, when the photographs from Abu Ghraib appeared, he was called on television to explain them and testified for Staff Sergeant Ivan Frederick; in 2007 he published The Lucifer Effect, in which, as Le Texier quotes it, the guards “had no formal training in becoming guards, were told primarily to maintain law and order, not to allow prisoners to escape, and never to use physical force against the prisoners, and were given a general orientation about the negative aspects of the psychology of imprisonment.” Richard Griggs surveyed introductory textbooks in 2014 and found the experiment in nearly all of them, most without criticism; Jared Bartels found the same in 2015.

The doubters

The criticism began with the report and stayed there. Erich Fromm, in The Anatomy of Human Destructiveness in 1973, argued that since “two thirds of the guards did not commit sadistic acts for personal ‘kicks,’ the experiment seems rather to show that one can not transform people so easily into sadists by providing them with the proper situation”. Ali Banuazizi and Siamak Movahedi, in American Psychologist in 1975, gave 150 students the advertisement, the description of the procedure, the rights the subjects had waived and the arrest, and asked them what the experimenter expected: 81 per cent named the hypothesis, and 90 per cent predicted the guards would be “oppressive, hostile, aggressive, humiliating”. The demand, they argued, was in the design. Leon Festinger, looking back in 1980, called the study a “happening”. In 1979 Lovibond, Mithiran and Adams in Australia ran three regimes with sixty volunteers and found that only the standard custodial one produced hostility; Zimbardo cites their conclusion that “hostile, confrontive relations in prisons result primarily from the nature of the prison regime”, and Haslam and his colleagues cite the same paper for the opposite point, that it was the instructions that made the difference.

In December 2001 Alex Haslam and Stephen Reicher ran a prison study of their own for the BBC, with fifteen men, no guidance to the guards beyond a ban on violence, and no experimenter as superintendent. The guards did not become cruel; the prisoners organised, and the guards, in Zimbardo’s 2018 summary of it, “became ‘increasingly paranoid, depressed and stressed and complained most of being bullied.’” Zimbardo wrote to the British Journal of Social Psychology in 2006 that “I believe this alleged ‘social psychology field study’ is fraudulent”, as Ben Blum quotes him; in 2018 he called it a “reality-show” that did not meet “the scientific criteria for a replication”. On April 28, 2005, the Stanford Daily printed an op-ed, “The lie of the Stanford Prison Experiment”, under Carlo Prescott’s name, which said that “ideas such as bags being placed over the heads of prisoners, inmates being bound together with chains and buckets being used in place of toilets in their cells were all experiences of mine at the old ‘Spanish Jail’ section of San Quentin and which I dutifully shared with the Stanford Prison Experiment braintrust months before the experiment started”, and that the guards “were merely doing what Zimbardo and others, myself included, encouraged them to do at the outset or frankly established as ground rules”. In July 2018, in a telephone call recorded by Zimbardo’s assistant, Prescott said he had never written a word of it; Zimbardo named a Los Angeles screenwriter, who had wanted the film rights, as its author. Le Texier adds that Prescott, in other recorded interviews, acknowledged that the buckets had been his idea.

The exchange of 2018

Le Texier read the Stanford boxes in 2017. His Histoire d’un mensonge appeared in Paris in April 2018; he had sent Zimbardo a draft of his English paper on April 10 and heard nothing, and on May 3 he sent Blum the transcript of the warden’s talk with the reluctant guard. Blum’s “The Lifespan of a Lie” was published on Medium on June 7, 2018. It opened with Korpi in the Hole on the evening of August 16, 1971, and then: “Korpi’s breakdown was a sham.” It printed Korpi’s “Anybody who is a clinician would know that I was faking”, Eshleman’s “I took it as a kind of an improv exercise”, the orientation tape, the Jaffe talk, and Zimbardo’s successive answers on the telephone to the prisoners’ claim that they could not leave: “It’s a lie”; then that they had forgotten to say “I quit the experiment”; then, when Blum read him the staff tape, “Now, okay,” and “You don’t quit a prison. That’s the whole point of the Pirandellian prison.”

Zimbardo’s response, posted on June 23, 2018, said that “none of these criticisms present any substantial evidence that alters the SPE’s main conclusion concerning the importance of understanding how systemic and situational forces can operate to influence individual behavior”. He answered six points. The op-ed was not Prescott’s. The guards’ instructions “as documented by recordings of the guard orientation, were that they could not hit the prisoners but could create feelings of boredom, frustration, fear, and ‘a sense of powerlessness—that is, we have total power of the situation, and they have none.’ We did not give any formal or detailed instructions about how to be an effective guard.” The warden’s talk with one guard was “mild compared to the pressure exerted by actual wardens and superior officers in real-life prison and military settings”; “Although the research team asked all guards to be actively involved and firmly in control of the prisoners, it never instructed guards to employ brutality, and it explicitly banned the use of physical force.” Eshleman’s cruelty “went beyond being a tough guard”. Of Korpi: “any researcher who believes a research participant is having a breakdown is ethically obliged to treat the breakdown as real, even if the breakdown later turns out to be feigned”, and “Korpi’s story has changed several times over the past 47 years”. The BBC study was not a replication. The early publications were not an attempt to avoid peer review. He added that “I have gone to great lengths to make every bit of documentary information from the SPE publicly available”, “more than 40 boxes of observational data” and “12 hours of videos”, so that “the SPE has been a model of open science long before practices such as public archiving and data sharing were common”. And he wrote of himself: “I was transformed into the full-time role of Prison Superintendent. In my view, that is the major flaw of the SPE; it had no independent scientific observer of the unfolding events.”

Craig Haney wrote on June 25 that he had been the one to release Korpi, “just 36 hours into the study”, that “Prisoner 8612 was in genuine emotional distress when I saw him on the second night of the study—at times he was shaking, screaming, and crying”, and that “I did not believe then and I do not believe now that he was ‘faking.’” He added that the guards “certainly were not following any orders to be harsh and tough; some of them actually pushed back against me when I instructed them to treat the prisoners more humanely”. Musen wrote the same day that he had listened to all the recordings before making his film and that “The audio tapes fully document Korpi’s collapse. It was genuine.” On August 27, 2018, Haney, Haslam, Reicher and Zimbardo signed a consensus statement: both studies were “valid studies and valuable resources”, with “methodological limitations”, “best viewed as one-trial demonstration studies rather than traditional experiments”; their behaviours “were a function of many factors, including roles, norms, leadership, social identification, group pressure, and individual differences”; and “we have no definitive evidence that any signatory of this statement committed scientific fraud or deliberately misled others about their research findings.”

The journal

American Psychologist, the journal of the American Psychological Association, of which Zimbardo had been president in 2002, printed the two archive papers in its October 2019 issue. Le Texier’s “Debunking the Stanford Prison Experiment”, received on February 24, 2018, and accepted on September 16, set out seven findings and asked why no one had looked before: “Is it a lack of curiosity? Is it an excessive respect for the tenured professor of a prestigious university? Is it due to possible access restrictions imposed by Zimbardo? Is it because archival analyses are a time-consuming and work-intensive activity? Is it due to the belief that no archives had been kept? The answer remains unknown.” It ended by calling the study “an incredibly flawed study that should have died an early death.” Haslam, Reicher and Van Bavel’s “Rethinking the Nature of Cruelty” argued from the warden’s taped meeting that the guards had not conformed to a role on their own but had been led, by a warden who used “we”, “our” and “us” fifty-seven times in one conversation and presented toughness as the price of “some very serious recommendations for reform”; they thanked Le Texier for alerting them to the tape and put its full transcript in their supplement so that “students and researchers” could “review the transcript themselves”.

Zimbardo and Haney replied in the April 2020 issue, “Continuing to Acknowledge the Power of Dehumanizing Environments”. Le Texier’s answer, posted as a preprint in January 2020, quotes two of its sentences: that “[t]he SPE may be among the most carefully documented and heavily scrutinized studies in the history of our discipline”, and that “to our discredit, we quickly lost experimental control, failing to anticipate or manage the power of the environment that we created.” He wrote that the comment had not addressed three of his findings and had rebutted none of the other four, and that “in a demonstration, the conclusions are written in advance.” Reicher, Van Bavel and Haslam’s reply in the same issue ended: “don’t take our word for it. Our key point is that you no longer have to. Look at the online evidence for yourself and draw your own conclusions about whose argument is most convincing in light of the data.”

Le Texier’s English edition, Investigating the Stanford Prison Experiment: History of a Lie, was published in 2024. Philip Zimbardo died on October 14, 2024; a month later National Geographic’s three-part series The Stanford Prison Experiment: Unlocking the Truth put Korpi, Eshleman and other participants on screen beside him in one of his last interviews. The entry sets the account against the record. This piece has set out who said what, and when, so that the reader can see that until 2018 everyone in the argument was holding the same document.

Sources

• News release, Stanford Prison Experiment, August 16, 1971, Philip G. Zimbardo papers (SC0750), digitised in the Stanford Digital Repository object Stanford Prison Experiment as SC0750_s5_b11_f50.pdf; Quiet Rage: The Stanford Prison Study, transcript, 1992, in the same object as Quiet_Rage_transcript.pdf. purl.stanford.edu/vx097ry2810
• Craig Haney, Curtis Banks and Philip Zimbardo, “Interpersonal Dynamics in a Simulated Prison,” International Journal of Criminology and Penology 1 (1973), 69–97. prisonexp.org/pdf/ijcp1973.pdf
• Thibault Le Texier, “Debunking the Stanford Prison Experiment,” American Psychologist 74, no. 7 (2019), 823–839: the August 20 release and the slide show’s ending, quoted here at second hand; Fromm, Banuazizi and Movahedi, Festinger, Lovibond, Bartels and Griggs as he summarises them; The Lucifer Effect, p. 56, at second hand; the four questions and the last sentence. “The SPE Remains Debunked: A Reply to Zimbardo and Haney (2020),” PsyArXiv, January 24, 2020. doi:10.1037/amp0000401, osf.io/9a2er
• Ben Blum, “The Lifespan of a Lie,” Medium, June 7, 2018; in copyright, quoted briefly, including Zimbardo’s 2006 letter to the British Journal of Social Psychology at second hand. medium.com
• Philip Zimbardo, “Philip Zimbardo’s Response to Recent Criticisms of the Stanford Prison Experiment,” June 23, 2018; Craig Haney, statement, June 25, 2018; Ken Musen, statement, June 25, 2018; “Interview with Carlo Prescott,” July 11, 2018; “Consensus Statement on the Stanford Prison Experiment and BBC Prison Study,” August 27, 2018. In copyright, quoted briefly. prisonexp.org/response, prisonexp.org/links
• “The lie of the Stanford Prison Experiment,” op-ed under Carlo Prescott’s name, The Stanford Daily, April 28, 2005, p. 4. archives.stanforddaily.com
• S. Alexander Haslam, Stephen D. Reicher and Jay J. Van Bavel, “Rethinking the Nature of Cruelty: The Role of Identity Leadership in the Stanford Prison Experiment,” American Psychologist 74, no. 7 (2019), 809–822, read in the preprint; Stephen Reicher, Jay J. Van Bavel and S. Alexander Haslam, “Debate Around Leadership in the Stanford Prison Experiment: Reply to Zimbardo and Haney (2020) and Chan et al. (2020),” American Psychologist 75, no. 3 (2020), 406–407, read in the authors’ manuscript “Breaking Open the Jail Gates”; Philip G. Zimbardo and Craig Haney, “Continuing to Acknowledge the Power of Dehumanizing Environments,” American Psychologist 75, no. 3 (2020), 400–402, not read in full. osf.io/b7crx, osf.io/ktsrq, doi:10.1037/amp0000593
• Tribeca Festival listing of The Stanford Prison Experiment: Unlocking the Truth, National Geographic, 2024. tribecafilm.com