On Saturday, August 14, 1971, at eleven in the morning, a tape recorder was running in a room in Jordan Hall, the psychology building of Stanford University, and a professor of thirty-eight was explaining to a dozen young men what he wanted from them. “My name is Phil Zimbardo, I’m a professor of psychology here.” He said what could not be done to the men who would arrive the next day: “in real prisons you know, there are gang raids, and guys get beaten up and get electric shocks and sometimes they even get killed.” Then he said what could. “Nevertheless we can create boredom; we can create a sense of frustration; we can create a sense of fear in them, to some degree; we can create a notion of arbitrariness that their life is totally controlled by us, by the system, you, me, Jaffe and so they’ll have no privacy at all.” The cells would have bars. “There’ll be constant surveillance—nothing they do will go unobserved. They have no freedom of action, they can do nothing, or say nothing that we don’t permit. We’re going to take away their individuality in various ways.” Nobody would use their names. “In general what all of this leads to is a sense of powerlessness, that is, we have total power in the situation and they have none.”

The young men in the room were the guards. The prisoners had not yet been arrested; that was arranged for the morning, and the professor had to leave to see the police about it. Before he went he answered a question about money. Two weeks of this would cost “somewhere between 5 to 8 thousand dollars”, from a government grant he had “to study the conditions which lead to mob behavior, violence, loss of identity, feelings of anonymity”. The guards would get $15 a day, by cheque, “whenever it ends”. And from the moment the prisoners came through the door, “at no point will we mention study or experiment—they are in a prison”.

The transcript of that morning is seven typed pages headed “Orientation of Guards, Sat. Aug 14, 1971”. The archive calls the recording Tape 2. For most of the next fifty years the published account of what followed said that the guards “received no specific training” in their roles and “were intentionally given only minimal guidelines for what it meant to be a guard”. The tape said otherwise, and it was in a box the whole time: first in the professor’s files, then, from 2011, in the Stanford University Archives, which digitised it and put it online. In 2017 a French researcher sat down and listened. This is the story of the experiment, of what was said about it, and of the forty-seven years between the recording and the hearing.

Who ran it

Philip George Zimbardo was born in New York City on March 23, 1933, grew up in the South Bronx, took his degree at Brooklyn College in 1954 and his doctorate at Yale in 1959, taught at New York University until 1967 and at Columbia for a year, and came to Stanford as a full professor in 1968. By the summer of 1971 he was the author of a leading introductory textbook, Psychology and Life, and a researcher on persuasion, vandalism and deindividuation. He had, he told a congressional subcommittee that autumn, “never even was interested in prisons until late spring”.

The spring had brought two people into his classroom. One was David Jaffe, an undergraduate in his social psychology course, who in May 1971 had run a prison of his own for a weekend in the basement of Toyon Hall, a dormitory, with classmates and friends, and had written it up. The other was Carlo Prescott, recently paroled after about sixteen years in San Quentin, Soledad, Folsom and other California prisons, whom Jaffe had brought to the class. Zimbardo and Prescott taught a summer course together, “The Psychology of Imprisonment”; Prescott became the experiment’s consultant and chaired its parole board; Jaffe became its warden. The graduate students were Craig Haney, who interviewed the applicants, and W. Curtis Banks. The money came from the Office of Naval Research, under a contract for a project the forms called “Individual and Group Variables Influencing Social Action”.

The subjects answered an advertisement. In the Stanford Daily of August 3, 6 and 10, 1971, among the classifieds, it read: “MALE students needed to participate in psychological study of prison life. $15 per day for 1-2 weeks, beginning Aug. 14. Further information and applications may be obtained in rm-248 Jordan Hall.” Seventy-five men applied, by the published paper’s count; “over 70”, Zimbardo told Congress. Twenty-four “judged to be most stable (physically and mentally), most mature, and least involved in anti-social behaviors” were chosen: college students, mostly middle class, all but one white, strangers to each other. A coin decided who would be a guard and who a prisoner. Two reserve prisoners were never called and one reserve guard withdrew before the start, so the published data rest on ten prisoners and eleven guards. The press release Zimbardo issued on the second day counted nine students in the cells and twelve on the shifts.

The people who read the record afterwards were not of the experiment’s own generation. Thibault Le Texier, a researcher at the University of Nice, went through the boxes at Stanford and at Akron, Ohio, in 2017, interviewed fifteen of the participants by telephone, and published a book in Paris in April 2018 and a paper in American Psychologist in 2019. Ben Blum, a writer, interviewed Douglas Korpi, who had been Prisoner 8612, and Dave Eshleman, the guard the prisoners called John Wayne, and published in June 2018. Alex Haslam, Stephen Reicher and Jay Van Bavel, two of whom had run a prison study for the BBC in 2001, read the same tapes and published beside Le Texier. And the participants, by then in their late sixties, turned out to have said most of it already, into the experimenters’ own microphones, in 1971.

What they were trying to find out

The hypothesis is stated most plainly in the first report, which Haney, Banks and Zimbardo published in 1973 as “Interpersonal Dynamics in a Simulated Prison”. Prisons were brutal, they wrote, and the usual explanation was dispositional: the people in them, guards or prisoners or both, were bad. The alternative was that the place made them so. The two could not be told apart in a real prison, where the people and the place came together, so the authors proposed “a research strategy in which a ‘new’ prison is constructed, comparable in its fundamental social-psychological milieu to existing prison systems, but entirely populated by individuals who are undifferentiated in all essential dimensions from the rest of society”. “No specific hypotheses were advanced other than the general one that assignment to the treatment of ‘guard’ or ‘prisoner’ would result in significantly different reactions.” If normal men, sorted by a coin, became guards and prisoners anyway, the situation had done it. The role makes the man.

That was one claim. The sheet given to applicants in August 1971 put it as a question: “how powerful are labels (such as ‘prisoner,’ ‘guard’) in exercising a controlling influence on behavior? Will our simulating ‘prisoners’ and ‘guards’ come to behave in a relatively short time in a manner similar to prisoners and guards in real life prisons?” The application to the human subjects committee called the study “an observational one of the development of norms, rules and expectations as a consequence of assignment of a label to the individual”, with “no other experimental variations”.

There was a second claim, which was about real prisons, and it was in writing before the second count. The press release of August 16, the second day, ended by saying the study expected “to uncover not only some of the consequences of the psychological state of being imprisoned, but to discover something about the kinds of people who most readily assume their assigned roles, as well as making us aware of the prison reforms needed at a psychological level in order that men who commit crimes are not made into dehumanized objects by their prison experience”. Zimbardo put it to the Stanford Daily that autumn in one sentence: “when the American people are exposed to the results of this experiment it could well prove to be the most significant agent toward prison reform yet in this country.” The first claim could be tested by watching the basement. The second could not be tested in a basement at all, and it is the one the basement was built to serve.

What they built

The prison was a 35-foot stretch of corridor in the basement of Jordan Hall, closed at both ends with fabricated walls, one holding the only door and the other a small observation screen with video equipment behind it. Three laboratory rooms, six feet by nine, became cells, with barred doors and three cots each. A closet opposite, two feet by two and seven high, unlit, was the Hole. The guards’ uniforms were khaki, with a whistle, a wooden police baton and reflecting sunglasses “which made eye contact impossible”. The prisoners’ were loose muslin smocks with a number front and back, no underwear, rubber sandals, a cap made from a nylon stocking, and a light chain locked round one ankle. The cells had no windows. The protocol filed on July 31 said that prisoners “will however be led to believe that they cannot leave, except for emergency reasons”, and, under the heading on humiliation and harassment, that “Prison subjects will be discouraged from quitting.”

The rules were seventeen, read twice to the prisoners on the first evening and later posted in the cells. The 1973 paper said they were “developed by the guards and the warden”. The archive holds the rules of Jaffe’s Toyon Hall weekend, and when Le Texier laid the two lists side by side, eleven of the seventeen were the same, with small changes of wording, among them numbers only, never names; guards to be addressed as “Mr. Correctional Officer”; and Rule 9, “Prisoners must never refer to their condition as an ‘experiment’ or a ‘simulation.’ They are in prison until paroled.” The “Suggested Daily Schedule” handed to the guards that Saturday was the Toyon Hall schedule adapted, with a count at 2:30 in the morning and five more through the day. Jaffe wrote in his log for the following Tuesday, Wednesday and Thursday: “Schedule followed pretty carefully”; “Daily schedule followed pretty closely”; “Again, basic schedule followed pretty closely.” The weekend in May is told in Toyon Hall.

The rest of the orientation, after Zimbardo left for the police station, was Jaffe’s, and ran, by his log, from eleven until half past three. Only part of it was taped. Banks told the guards they were the “primary source of data, source of observation”, since the staff would not be in the corridor: “we have to rely upon you to notice and keep aware of and record as much as possible, everything that goes on.” Jaffe told them what had worked in May: a count in which the prisoners were lined up against the wall and made to call off their numbers for forty minutes, and then to repeat “Yes we all enjoyed the count, Mr. Correctional Officer”; “a certain sarcasm sometimes that the guards used, ‘Ah, that’s too bad!’”; a blanket filled with straw and burrs that took hours to pick clean, “or maybe we can use one of the prisoners’ blankets”; push-ups; “a cell for honor prisoners”. And, to the men in the room: “A lot of this, of what happens, does depend on you. You were selected. It was a pretty selective thing.”

Jaffe’s own account of his part, written for Zimbardo after the week, is in the same box. “Even before I arrived, Dr. Zimbardo suggested that the most difficult problem would be to get the guards to behave like guards. I was asked to suggest tactics based on my previous experience as master sadist, and, when I arrived at Stanford, I was given the responsibility of trying to elicit ‘tough-guard’ behavior.” He believed, he wrote, “and still do, that without rules, without gruff and mildly realistic guard behavior, the simulation would have appeared more like a summer camp than a prison.”

On Sunday, August 15, from ten in the morning, Palo Alto police officers called at the prisoners’ homes, charged each man with suspicion of burglary or armed robbery, handcuffed him, booked and fingerprinted him at the station, blindfolded him, and handed him to the staff, who drove him to Jordan Hall. In the basement each man was stripped, sprayed with a deodorant as a delousing powder, and left standing naked and blindfolded against the wall; then came the smock, the cap, the chain, a photograph and a cell. Jaffe’s log lists nine numbers in three cells by the afternoon. “Prisoner 8612 smiling when came in,” Jaffe noted, “but stopped smiling when standing and waiting.” A guard’s remark went into the log beside it: “He didn’t think it was such a joke anymore.”

The second day

Monday, August 16, is the day the published story turns on, and the day the archive has most to say about.

In the morning the prisoners rebelled. Four tore the numbers off their smocks. Cell 1 pushed its cots against the door so that it could not be opened; Cell 2 got the lock off its door and tried to get out. The other shifts were called in. The guards took the beds out of two cells, stripped prisoners, put the leader of the rebellion in the Hole, and made the third cell, which had been quiet and had spent the morning picking burrs out of a blanket, a privilege cell with water, lunch and beds. Zimbardo told Congress in October that “the really effective thing was psychological pressure”: “Once the guards did this, then they set the men against each other.” One guard did not come back. “One of the guards refused to continue,” the press release of that day said, “because he said ‘it was too heavy,’ the other guards got too much into it.”

That morning, by Jaffe’s own account, Zimbardo told him to take another guard aside, one who had sat on the sidelines during the rebellion, and get him “off the sidelines and into the fray”. The conversation was recorded. “We noticed this morning that you weren’t really, you know, lending a hand,” Jaffe begins. “I was wondering if there was anything wrong?” “But generally you’ve been kind of in the background,” Jaffe goes on, “and we really want to get you active and involved. Because the guards have to know that every guard is going to be what we call a tough guard.” The guard: “I don’t know about that.” Jaffe: “whether or not we can make this thing seem like a prison which is the aim of the thing” depends “largely on the guard’s behavior.” The guard answers that if it were up to him, “I wouldn’t do anything. And I’d just let it cool off.” Jaffe keeps going. The point is “so that we can learn what happens in a total institution which is set up and what a prison is and a mental hospital is”, and “so that we can get on the media and in the press with it. And say now look at what this is really about.” And at the end: “for the time being, you know, we need you to play the part of, you know, tough guard. And to forget some of the more sophisticated psychology that you might know. And try and react as you picture the pigs reacting.” The guard: “You can’t just do it by movies and something.”

Le Texier dates the talk to the third day; Zimbardo’s statement of 2018 places it before the rebellion and says that even after it “none of the guards behaved in a dominant way during the first two shifts”; Jaffe’s log puts it on the Monday, “rebellion day”. Zimbardo’s account of what the guards had been told, in his 2007 book The Lucifer Effect, as Le Texier quotes it, was that they “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.”

The same Monday, Prisoner 8612 asked to leave. He was Douglas Korpi, a Berkeley graduate of twenty-two by Blum’s account and twenty-one by Musen’s, who had taken the job, he told Blum in 2017, to study for his graduate entrance examinations. At about noon, Jaffe’s log records, he “requested interview—claimed to be ill. Granted at 3:30 p.m.—’rebellion cures his ills.’ Wants out.” He was not let out. Prisoner 1037 asked the same day with the same result. The next day Zimbardo told his team about it, on a tape the archive calls Tape 8: “the guys who came in yesterday—the two guys came in and said they wanted to leave. And I said no—you know—there are only two conditions under which you can leave—in other words—medical health or psychiatric and that’s the condition under which this other guy left.” He added: “I think they really believed they can’t leave.”

At 7:30 that evening Korpi tore the cover off a camera hole in the wall and was put in the Hole for fifty minutes, then brought, blindfolded and handcuffed, to Jaffe. That interview is Tape E. “I’m so fucked up inside,” he says. “I want to get out! I WANT TO GET OUT NOW!” Jaffe tells him he will have to spend the night. Korpi: “I mean JESUS CHRIST, I’m burning up inside, DON’T YOU KNOW?” Then, calmer: “I’m sorry. It’s not personal, and I know it’s the experiment.” Then, his voice breaking: “This is an experiment. You’re messing with my head, man, my head. No reason. You’ve no right to fuck with my head.” Jaffe takes off the blindfold and softens his voice. Korpi stops crying. “Man, I’m not crying you know. Maybe I’m inducing myself to cry so I can get out. I don’t know why it is.” He had been in the prison about thirty-six hours. Haney saw him afterwards, could not reach Zimbardo, asked him whether he wanted to stay, and when he said he wanted to go home, let him go, at nine or ten o’clock. The press release typed that day had already said: “One prisoner is already begging to be released. He will see a psychiatrist and be given a medical parole if he is not malingering.”

What it looked like from inside

The week went on for four more days. On Tuesday the prisoners were, Jaffe wrote, “very cooperative—sharp contrast to Monday”. A rumour that Korpi would come back with friends to break the others out “spread thru staff like wildfire all day”, and the prisoners were moved for three hours to a janitor’s closet on the fifth floor. No data were collected that day. On Wednesday a priest who had been a prison chaplain interviewed the prisoners, who gave him their numbers; Prisoner 819 was released that evening after the guards had the others chant that “819 did a bad thing” while he sat in the next room, and Prisoner 3401 went to the health centre with a rash and did not come back. On Thursday a replacement prisoner, 416, refused to eat, and a guard offered the others a choice: give up their blankets and he would come out of the Hole, or keep them and he would stay the night. They kept their blankets. That evening Christina Maslach, a new professor at Berkeley whom Zimbardo was seeing, came to take him to dinner, and watched the ten o’clock toilet run with the prisoners hooded and chained. He decided at midnight to stop. On Friday, August 20, a public defender interviewed the five who were left, and the prisoners were debriefed at one, the guards at two, and everyone together at three.

What the participants said about it, that week and in the months after, fills the folders. Korpi came back on Thursday, August 19, to answer the final questionnaire into a microphone, and the archive has it as Tape 7. “The big thing, I couldn’t decide whether the prison experience had really freaked me out, or whether I induced that freaked out thing.” Of the Monday: “I decided I ‘want out’ and then I went to talk to you guys and everything, and you said ‘no’ and you bullshitted me and everything, and I came back and I realized that you were bullshitting me, and that made me mad, so I decided I’m getting out and I was going to do anything, and I made up several schemes whereby I could get out. The easiest one, the one that wouldn’t hurt anybody or hurt any equipment, was to just act mad, or upset, so I chose that one. When I was in the Hole, I purposely kind of built it up”, and then: “even while I was being upset, I was manipulating and I was being upset—I was still upset, you know—how could you act upset unless you were upset”. What had been worst? “Knowing that I couldn’t get out if I wanted. That must be the most oppressive thing.” A year later, on a tape dated September 16, 1972, he told Zimbardo the same, and in the late 1980s he said it again on camera for Musen’s documentary Quiet Rage, in a passage that was cut. In 2017 he told Blum: “Anybody who is a clinician would know that I was faking.”

Eshleman, Guard 4, a theatre major on the night shift, was interviewed on the last day. “Well, throughout the entire experiment I was an actor, and I was hamming it up,” he said. “So, I purposely put on this attitude of being the mean impersonal—you drill sergeant type of thing, when you’re really hounding the guy.” Why? “I thought it would be better for the study if I presented what I thought to be a realistic relationship between guard and prisoner.” Another guard on the same tape: “I think in a lot of cases it’s almost the job makes the man, or that some people are better actors than others. I don’t think that I’m a very good actor.” A third wrote to Zimbardo two months later, as Le Texier quotes him, that the warden “gave us very good sado-creative ideas”, and that “I felt that any niceness on my part would eliminate me from the experiment.” Guard 6, one of the quiet ones, told Zimbardo in 1972 that the guards had thought they were the study’s staff: “It was our job to make sure this was a simulated prison, not that we were being experimentees too.” The 1973 paper confirms the half of this the guards could not see: “The guards generally believed that we were primarily interested in studying the behavior of the prisoners. Of course, we were as interested in the effects which enacting the role of guard in this environment would have on their behavior and subjective states.”

The prisoners, too, kept saying where they were. Prisoner 5704 wrote that after the rebellion “we were going to try to break out but then we decided that it would put the money we were going to earn in jeopardy so we decided against it. The one thing that kept me there was the money.” Prisoner 416, who would not eat, told NBC: “I was terrified to discover that I had a part of me that would say ‘ok $15.00/day, sure, drop your freedom’.” A guard’s diary from the last day: “After I talked to the other prisoners, they told me I was a good guard and thanks for being that way. I knew inside I was a shit.” And Jaffe, in the self-perception he wrote for the file: “While I believe that it was necessary for staff to enact the Warden role, at least some of the time, I am startled by the ease with which I could turn off my sensitivity and concern for others for ‘a good cause.’” He could not think back on the week, he wrote, without “dredging up instances of my own behavior that demonstrate what a classic subject I was in a study on institutional brutality that was originally my own creation.”

What happened

The report went out before the data were analysed, and it went out fast. On August 20 a release told the San Francisco papers, in Le Texier’s quotation of it, that “this has a message for prison reform.” On August 21 George Jackson was killed in an escape attempt at San Quentin, forty miles to the north; on September 9 the prisoners of Attica, New York, took their prison, and on September 13 the state took it back. Life ran the experiment on October 15. The Stanford Daily ran it on the front page on October 12, under the headline “Prison Experiment Too Realistic”.

On October 18 Emanuel Celler, chairman of the House Committee on the Judiciary, wrote to confirm Zimbardo’s invitation to testify at Subcommittee No. 3’s hearing on prisons in the Ceremonial Courtroom of the Federal Building in San Francisco on October 25, at 9:30 in the morning. Zimbardo was the last witness of a day that ended at 6:30 in the evening. “Half were arbitrarily designated as prisoners by a flip of a coin, the other half as guards,” he told the subcommittee. “The guards were simply told that they were going to go into a situation that could be serious and have perhaps some danger, although they knew it was an experiment, of course. They made up their own rules for maintaining law, order, and respect. They were free to improvise any new rules.” And then: “The prison situation in our country is guaranteed to generate severe enough pathological reactions in both guards and prisoners as to debase their humanity, lower their feelings of self-worth, and make it difficult for them to be part of a society outside of their prison.” Representative Hamilton Fish of New York thanked him: “you certainly helped me a great deal in clarifying some of the things we have seen the past few days and understanding them.” The day is told in The hearing. NBC broadcast the videotapes on Chronolog on November 26.

The scientific report came in 1973, in the September Naval Research Reviews, because the Office of Naval Research wanted its research in its own journal, and in the first volume of the International Journal of Criminology and Penology, at the editor’s invitation; a version for the public appeared in the New York Times Magazine on April 8, 1973. The journal abstract said: “Neither group received any specific training in these roles.” The text said the guards “were intentionally given only minimal guidelines for what it meant to be a guard”, with one explicit prohibition, on physical punishment; that the rules were “developed by the guards and the warden”; and that guard aggression “was emitted simply as a ‘natural’ consequence of being in the uniform of a ‘guard’ and asserting the power inherent in that role”. It said half the prisoners had developed “acute emotional disturbance—severe enough to warrant their early release”. It also said, in a paragraph on method, that “some of the data was subject to possible errors due to selective sampling”, and in its acknowledgments it thanked David Jaffe, “who served as ‘warden’ and pre-tested some of the variables in the mock prison situation”. It ended: “guards are also society’s prisoners.”

From there the story travelled without its instrument. A slide show that Zimbardo made in 1972 toured colleges and prisons for twenty years; Ken Musen’s film Quiet Rage, made with Zimbardo and released in 1992, introduced Korpi’s screaming by saying that “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 presented the PBS series Discovering Psychology and wrote the textbooks, testified for one of the Abu Ghraib guards in 2004, and published The Lucifer Effect in 2007. Criticism had existed from the start, and all of it was made from the report: Erich Fromm in 1973, who noted that two thirds of the guards had not been sadistic; Ali Banuazizi and Siamak Movahedi in 1975, who found that 90 per cent of students who merely read the procedure predicted that the guards would be “oppressive, hostile, aggressive, humiliating”; Reicher and Haslam’s BBC study of 2002, in which guards given no guidance produced no cruelty; and an op-ed in the Stanford Daily in 2005 under Prescott’s name, which Prescott disowned in 2018. The whole of it, from the first release to the last reply, is in The argument. None of the critics had read the boxes, because the boxes were Zimbardo’s.

After

He gave them to Stanford in accessions from 2011 to 2017: 182 boxes, 256 linear feet, the Philip G. Zimbardo papers, call number SC0750, with two boxes of participants’ files closed to protect their privacy. The library reformatted the tapes and film in 2015 and 2016 and put the transcripts, logs, forms and recordings online as a single digital object, open to anyone; what it holds is set out in The boxes. Le Texier counted what was there: six hours of film and forty-eight hours of audio, of which about fifteen hours of audio and the six of film were made during the 150 hours of the experiment, less than 15 per cent, and none of it on the third day. Haney had said as much in a report he wrote at the time, which is in Box 10: “our video sample was seriously biased at the outset. For the most part, our concerns in filming were cinematic: we recorded primarily the dramatic (e.g., counts) or the unusual (e.g., the priest’s visit).” Greg White, who analysed the tapes that winter, warned Zimbardo, as Le Texier quotes him, that “the degree to which the guards were prompted in their roles by the experimenters, while not certain, appears to be considerable. Thus, the strength of the ‘guard’ label is actually unknown.”

Le Texier’s Histoire d’un mensonge came out in Paris in April 2018, and he sent Blum the Jaffe transcript on May 3. Blum’s “The Lifespan of a Lie” appeared on June 7 and put Korpi’s and Eshleman’s interviews, the Jaffe talk and the orientation tape in front of a general readership. Zimbardo, reached on the telephone, had first called the prisoners’ claim that they could not leave “a lie”, then said they had forgotten a safe phrase, “I quit the experiment”, which is not in the consent form, and then, when Blum read him the Tape 8 transcript, said “Now, okay,” and explained: “You don’t quit a prison. That’s the whole point of the Pirandellian prison.” On June 23 Zimbardo posted a response. The guards had been told, he wrote, “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.” 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 one concession, unasked: “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.” Haney wrote two days later that he had released Korpi himself and had not believed then, and did not believe now, that he was faking. On August 27, 2018, Zimbardo, Haney, Haslam and Reicher signed a joint statement calling both prison studies “best viewed as one-trial demonstration studies rather than traditional experiments”.

American Psychologist printed Le Texier’s “Debunking the Stanford Prison Experiment” and Haslam, Reicher and Van Bavel’s “Rethinking the Nature of Cruelty” together in October 2019. Le Texier’s seven findings were that the design was borrowed from Toyon Hall; that the guards knew what results were wanted and how to produce them; that they were given a part to play and not told they were subjects; that the prisoners could not leave; that the participants almost never lost sight of the experiment; that the data were incomplete and biased; and that the conclusions “had been written in advance according to nonacademic aims”. The paper also recorded what he called “one of the most puzzling facts that I discovered during my investigation”: that in nearly fifty years, with the critics it had had, “no psychologist seems to have wanted to know what exactly the archives contained.” Haslam and his colleagues read the Jaffe tape as leadership: the warden used “we”, “our” and “us” fifty-seven times in one meeting, once every thirty words, to make the guard one of the team and the team’s cause a noble one. Zimbardo and Haney replied in 2020 that “to our discredit, we quickly lost experimental control, failing to anticipate or manage the power of the environment that we created”. Philip Zimbardo died at his home in San Francisco on October 14, 2024, aged ninety-one. A month later National Geographic broadcast three hours of the participants, now in their seventies, saying it again.

What it taught

Start with what the basement recorded, because some of it is beyond dispute. Twenty-one young men chosen for their ordinariness lived or worked for six days in a corridor with bars on the doors, and by the end some of the ones in khaki were making the ones in smocks do push-ups with other men on their backs, some of the ones in smocks were weeping, and two who had asked to go home had been told there were only two ways out. The question the archive raises is not whether that happened but what made it happen, and the report answered in a way its own recordings do not support.

An experiment has two records, and the one that travels is the report. The paper of 1973 said the guards received no specific training, were given minimal guidelines, and made the rules with the warden. The tape of August 14 has the professor listing boredom, frustration, fear, arbitrariness and powerlessness, the warden recommending sarcasm and a blanket full of burrs, and a research assistant telling the guards they were the instrument. The two records were made by the same people in the same week. One was published, cited, filmed and taught; the other sat in a box. Whoever reads an experiment reads its report, and should know that the report is the experimenters’ account of the instrument, not the instrument.

“No specific training” was a claim about the instrument, and it was checkable. Every doubter between 1973 and 2006 argued from the report. Le Texier’s puzzle is the real finding of 2018: the boxes had been at Stanford since 2011, catalogued and open, and nobody in the discipline had asked to see them. A criticism that stays inside the published account can be answered from the published account for fifty years. The one that ended the argument was the one that went to the shelf.

When the subjects know what you want, you measure the briefing. The guards were told the aims, told they were selected, told they were the source of data, told that whether “this thing” seemed like a prison depended on them, and paid at the end. The prisoners were told they could not leave. Banuazizi and Movahedi showed in 1975 that students who had merely read the procedure could say what was wanted; the tapes show that the people in the corridor had been told. What the experiment then recorded was a group of paid men doing a job they had been briefed for, as several of them said at the time, in writing, to the man who had briefed them.

The role did make the man; the archive shows who wrote the role. This is the complication, and it cuts both ways. The published story had no villains: good men, a bad situation, the role as the only agent. The archive does not restore the villains. It shows that the role had authors, and that the authors were in roles themselves: a professor who wrote the list on the blackboard and then, by his own account, became a prison superintendent; an undergraduate who had run the thing once before, was handed the job of eliciting tough-guard behaviour, and wrote afterwards of “what a classic subject I was in a study on institutional brutality that was originally my own creation”; a consultant who gave them San Quentin; a team that filmed the counts because they were dramatic. Nobody in the basement was free of the situation, and the situation was an experiment that needed to come out a certain way. The lesson the experiment is taught for is true of the experiment. It is not what the experiment showed about prisons, because the only prison in Jordan Hall was the one its designers made.

Check the story before you learn from it. The study began on Sunday, August 15, 1971, by every log in the archive, and on Sunday, August 14, by Zimbardo’s letter to Stanford Magazine in 2011 and his statement of 2018; the library’s catalogue says August 15 to 21. There were twenty-four men selected and twenty-one in the data, nine prisoners and twelve guards in the first press release, ten and eleven in the paper, seventy-five applicants in the paper and “over 70” in the hearing. Three prisoners left in four days by the testimony, five before the end by the paper, two with anything Le Texier would call a breakdown. There were twelve hours of videotape by Zimbardo’s count and six by Le Texier’s. Jaffe talked to the reluctant guard on the Monday by his own log, on the third day by Le Texier, before the rebellion by Zimbardo. None of these moves the finding, and all of them are the normal condition of a record made by hand, in a hurry, by people inside the thing they were recording. What the record supports without argument is a tape made on a Saturday morning, before a single prisoner arrived, on which the people who ran the experiment said what they wanted to happen. It happened.

Sources

• Audio transcript, tape 2, Orientation of Guards, Saturday, August 14, 1971; Philip G. Zimbardo papers (SC0750), Stanford University Libraries, Department of Special Collections and University Archives, digitised in the Stanford Digital Repository object Stanford Prison Experiment (druid vx097ry2810) as Tape2.pdf and, with Jaffe’s and Banks’s parts, Orientation_of_guards.pdf; the recording is SC0750_s5_b2_02. Every quotation from the orientation, including “we can create boredom”, the cost, the pay and “at no point will we mention study or experiment”, and Jaffe’s count, sarcasm, blanket and “You were selected”. Read in full. purl.stanford.edu/vx097ry2810, purl.stanford.edu/dx583pt8943
• Dave Jaffe, log, August 14 to 20, 1971, and “Self Perception” and “Additional Anecdotes and Perceptions”, undated; SC0750, Box 9, Folder 40, digitised as SC0750_s5_b09_f40.pdf. The hours of the orientation, the nine numbers in three cells, “He didn’t think it was such a joke anymore,” the rebellion, the privilege cell, the rumour and the fifth floor, “Schedule followed pretty carefully,” “master sadist,” “tough-guard,” “summer camp,” “a good cause,” and “a classic subject.” Read in full. purl.stanford.edu/gg576zj2664
• Tape A, interview with 8612 and the warden’s meeting with a guard, August 1971; SC0750, Box 1, Folder 4, digitised as TapeA_8612.pdf, recording SC0750_s5_b2_21. The whole of the “tough guard” exchange quoted above. Read in full. purl.stanford.edu/wn708sg0050
• Tape E, the warden’s two interviews with Prisoner 8612 on August 16, 1971, digitised as TapeE.pdf; Tape 7, “Final Reactions to Experiment”, Prisoner 8612, August 19, 1971, digitised as Tape7.pdf, recording SC0750_s5_b2_07; Tape 8, staff discussion, digitised as Tape8.pdf. Korpi’s words on the Monday evening and the Thursday, and Zimbardo’s “only two conditions under which you can leave.” Read in full. purl.stanford.edu/fb554xz1315
• Tape 3, guard final evaluations, August 20, 1971, digitised as Tape3.pdf. “throughout the entire experiment I was an actor,” “it was all role playing,” and “it’s almost the job makes the man.” Read in full. purl.stanford.edu/bz479qj7845
• News release, Stanford Prison Experiment, August 16, 1971 (SC0750_s5_b11_f50.pdf); Prison Life Study: General Information, August 1971; Consent form; Prisoner Rules Prepared by the Warden and Guards; Suggested Daily Schedule (Box 11, Folder 21); Application for Institutional Approval of Research Involving Human Subjects, July 31, 1971 (Box 11, Folder 51); Jaffe’s speech to the prisoners; Log, day 6, August 20, 1971, with the prisoners’ and guards’ later words and the public defender’s letter of August 29. All in the same digital object; the information sheet, consent form, rules and application are also on Zimbardo’s site. purl.stanford.edu/kn089qv2813, purl.stanford.edu/jw499xv3383, pdf.prisonexp.org/geninfo.pdf, pdf.prisonexp.org/consent.pdf, pdf.prisonexp.org/humansubjects.pdf
• Craig Haney, “Video Tape Analysis”, undated, SC0750, Box 10, Folder 8: “our concerns in filming were cinematic.” Read in full. purl.stanford.edu/gc938ns7497
• David Jaffe, “A Simulated Prison”, Social Psychology, Spring 1971, 82 pages, SC0750, Box 9, Folder 60: the Toyon Hall weekend of May 15 and 16, 1971, its schedule and rules. Read in the digitised copy. purl.stanford.edu/cj735mr4214
• Philip G. Zimbardo papers (SC0750), finding aid, Online Archive of California: the extent, the series, the restrictions on Boxes 9 and 9A, the accessions of 2011 to 2017 and the biographical note. oac.cdlib.org
• Craig Haney, Curtis Banks and Philip Zimbardo, “Interpersonal Dynamics in a Simulated Prison”, International Journal of Criminology and Penology 1 (1973), 69–97, and the same text as “A Study of Prisoners and Guards in a Simulated Prison”, Naval Research Reviews, September 1973, Office of Naval Research. The hypothesis, the 75 and the 24, the ten and eleven, the corridor and the cells, “Neither group received any specific training,” “intentionally given only minimal guidelines,” “The guards generally believed,” the selective sampling, the acknowledgment of Jaffe, and “guards are also society’s prisoners.” Read in full. prisonexp.org/pdf/ijcp1973.pdf, archive.org
• Corrections, Part II: Prisons, Prison Reform, and Prisoners’ Rights: California, hearings before Subcommittee No. 3 of the Committee on the Judiciary, House of Representatives, 92nd Congress, first session, October 25, 1971, Serial No. 15, Government Printing Office, 1971; Zimbardo’s testimony at pp. 110–121 and his statement “The Psychological Power and Pathology of Imprisonment” at pp. 152–157, with the letter of invitation from Emanuel Celler, October 18, 1971 (SC0750, Box 11, Folder 45). A congressional document, public domain. Read in full. prisonexp.org/pdf/congress.pdf
• The Stanford Daily, August 3, 6 and 10, 1971, the classified advertisement; October 12, 1971, Andy Israel, “Prison Experiment Too Realistic,” with Zimbardo’s “most significant agent toward prison reform,” Banks’s “The hypothesis is generally,” and the Office of Naval Research contract “under attack”; October 21, 1971, Philip Zimbardo, “Modest Reply”; April 28, 2005, “The lie of the Stanford Prison Experiment,” published under Carlo Prescott’s name. Stanford Daily Archives. archives.stanforddaily.com/1971/08/03, archives.stanforddaily.com/1971/10/12, archives.stanforddaily.com/2005/04/28
• Thibault Le Texier, “Debunking the Stanford Prison Experiment,” American Psychologist 74, no. 7 (2019), 823–839, open access; the seven findings, the method (16 boxes, one box, 6 hours of film, 48 of audio, 15 interviews), the comparison of the rules, the quotations from Guard 1, Guard 3, Guard 6, Guard 11, Prisoner 5704, Prisoner 819, Greg White’s remarks, the August 20 release, The Lucifer Effect, Fromm and Banuazizi and Movahedi, all of which are quoted here at second hand from this paper where the entry says so; and “no psychologist seems to have wanted to know.” Read in full, with its supplemental material. doi:10.1037/amp0000401, osf.io/mjhnp
• Thibault Le Texier, Histoire d’un mensonge: Enquête sur l’expérience de Stanford, La Découverte, Paris, 2018, and Investigating the Stanford Prison Experiment: History of a Lie, Palgrave Macmillan, 2024; both in copyright and not read in full; the 2018 book is cited for its date and the 2024 edition for its existence. Thibault Le Texier, “The SPE Remains Debunked: A Reply to Zimbardo and Haney (2020),” PsyArXiv, January 24, 2020, from which the two sentences of Zimbardo and Haney (2020) are quoted at second hand. osf.io/9a2er
• Ben Blum, “The Lifespan of a Lie,” Medium, June 7, 2018. In copyright; quoted briefly: Korpi’s “Anybody who is a clinician,” his age and his examinations, Eshleman’s Cool Hand Luke, and Zimbardo’s “It’s a lie,” “I quit the experiment,” “Now, okay,” and “You don’t quit a prison.” 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; Craig Haney, Alex Haslam, Stephen Reicher and Philip Zimbardo, “Consensus Statement on the Stanford Prison Experiment and BBC Prison Study,” August 27, 2018. All on the experiment’s official site; in copyright, quoted briefly. prisonexp.org/response, prisonexp.org/links
• 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 authors’ preprint; the fifty-seven collective pronouns and the leadership reading of the Jaffe tape. Philip G. Zimbardo and Craig Haney, “Continuing to Acknowledge the Power of Dehumanizing Environments: Comment on Haslam et al. (2019) and Le Texier (2019),” American Psychologist 75, no. 3 (2020), 400–402, not read in full. doi:10.1037/amp0000443, osf.io/b7crx, doi:10.1037/amp0000593
• Quiet Rage: The Stanford Prison Study, transcript, 1992, in the digital object as Quiet_Rage_transcript.pdf: “He began to play the role of the crazy person.” Philip Zimbardo, letter to the editor, Stanford Magazine, August 2011, in the digital object as SC0750_s5_b09_f62.pdf: the dates August 14 to 19 and the account of John Mark. purl.stanford.edu/vx097ry2810
• Philip Zimbardo, The Lucifer Effect: Understanding How Good People Turn Evil, Random House, 2007, p. 56, quoted at second hand from Le Texier (2019); Haney, Banks and Zimbardo’s New York Times Magazine article of April 8, 1973, “The Mind Is a Formidable Jailer: A Pirandellian Prison,” cited for its date and authors.
• “Stanford psychologist behind the controversial ‘Stanford Prison Experiment’ dies at 91,” Associated Press, October 19, 2024, for the date and place of Zimbardo’s death; Tribeca Festival listing of The Stanford Prison Experiment: Unlocking the Truth, National Geographic, 2024, for the series and its participants. wypr.org, tribecafilm.com