The letter is on the letterhead of the Committee on the Judiciary of the House of Representatives, dated October 18, 1971, and signed by its chairman, Emanuel Celler of New York. “Subcommittee No. 3 of this Committee has scheduled a public hearing on prisoners, prison reform, and prisoners’ rights in San Francisco on October 25, 1971. This will confirm the invitation to testify at the Subcommittee’s hearing which you have received and, I understand, accepted. The hearing is scheduled to begin at 9:30 a.m., in the Ceremonial Courtroom, Federal Building Courthouse, 450 Golden Gate Avenue, San Francisco, California.” It went to Philip Zimbardo at Stanford, nine weeks after his prison closed, and it is in the archive of the experiment, in Box 11, Folder 45.

The subcommittee was chaired by Robert Kastenmeier of Wisconsin, and its members that day included John Conyers of Michigan, Edward Biester of Pennsylvania and Hamilton Fish of New York. It had spent the previous days inside San Quentin and Soledad, where George Jackson had been killed on August 21, and it heard, in order, the director of the California Department of Corrections, the associate warden of San Quentin, the chairman of the California Adult Authority, a sheriff, the president of the correctional officers’ association, lawyers for prisoners, two congressmen, a sociologist, and former prisoners including Popeye Jackson of the United Prisoners Union. Zimbardo came last. The printed record, Serial No. 15 of the committee’s hearings on corrections, carries his spoken testimony at pages 110 to 121 and the statement he had submitted, “The Psychological Power and Pathology of Imprisonment”, at pages 152 to 157.

What he said

“Although I am a psychologist at Stanford University, I really come here just as a researcher and a concerned citizen,” he began. “I would like to use the microphone so that the hardy band of people who stayed here can hear some of my comments. It should be noted most of the correctional officers and people from the California correctional institutions did not feel it worthwhile to stay to hear anything but their own comments.” Then he read a letter he had received that week from a prisoner in an Ohio penitentiary who had spent thirty-seven months in solitary confinement and now, he wrote, thought only of killing the men who had beaten him. The prisoner had written because he had read about the Stanford experiment.

The experiment itself took a few minutes. “We put an advertisement in the newspaper asking for volunteers for a study on prison life. We got over 70 volunteers and screened each one individually. My students, Craig Haney and Curt Banks, did psychological interviews of each one. We selected two dozen of the most mature, emotionally stable, normal, intelligent young men that we could find. These were what I would call the cream of the crop of this generation.” Then: “Half were arbitrarily designated as prisoners by a flip of a coin, the other half as guards. So we began with a group of boys that were identical in every way, no difference at all except we said, ‘you half are prisoners, you half are guards.’ 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. They served 8-hour, three-man shifts.” The prisoners were picked up by the police. “Now, they were getting $15 a day for this work—which was very good pay. Being an experiment, they figured it would be fun and games. They needed the money. It was summer and most of them were without work.” The written statement says the same more briefly: “The guards were made aware of the potential seriousness and danger of the situation, and their own vulnerability. They made up their own formal rules for maintaining law, order, and respect, and were generally free to improvise new ones during their 8-hour, 3-man shifts.” And: “The pay was good ($15 a day) and their motivation was to make money.”

“At the end of only 6 days, we had to close down the mock prison. It was no longer apparent to us or most of the subjects where they ended and their roles began.” Three prisoners had been released in the first four days “because they had such acute situational traumatic reactions as hysterical crying, confusion in thinking, and severe depression.” Offered parole in exchange for forfeiting their pay, “all but three said ‘yes, if you parole me, I will forfeit all the money.’ We said, ‘OK, go back to your cell and we’ll consider it.’ Each one got up and went back to his cell.” They should, he said, have quit the experiment instead. “They did not have the right to quit. They no longer felt they had any rights.” The rebellion of the second day had been put down first by force and then by the privilege cell: “Once the guards did this, then they set the men against each other.” About a third of the guards “became tyrannical in their arbitrary use of power”. Some were good guards, “but the really important message, and a subtle one, is that no good guard ever interfered.” One guard had kept a prisoner in the Hole for three hours against the rule of one; “My assistant, Curt Banks, was there and said, ‘You cannot do this, it is not permissible.’” Carlo Prescott, “an ex-con friend of mine, who served 16 years in almost all of California’s jails, would get so depressed when he came down that he had to leave because it was so realistic.”

“By the end of the week, the experiment became a reality, as if it were a Pirandello play directed by Kafka that just keeps going after the audience walks out.” He had stopped it, he said, “not because of the horror I saw, not because of what I saw boys doing to other boys, but really because of the horror of realizing that I could easily have traded places with the most brutal guard or become the weakest prisoner full of hate at being so powerless that I could not eat, sleep, or go to the toilet unless I got somebody’s permission. It became clear to me I could have been Calley at Mylai, George Jackson at San Quentin, or I could have been one of the men at Attica. One of the important messages from this study, I think, is that every one of you could, too.”

What he concluded

Two implications, he said. The first: “individual behavior is largely under the control of social forces and environmental contingencies, things that occur, rather than some vague notions of personality traits, character, will power, or other empirically unvalidated constructs. Thus, we create an illusion of freedom by attributing more internal control to ourselves, to the individual, than actually exists.” The second: “the mere act of assigning labels to people, calling some people prisoners and other guards, is sufficient to elicit pathological behavior. This pathology is not predictable from any available diagnostic indicators we have in the social sciences. We could not tell which guards would become sadistic.” And so: “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.” The written statement set the experiment beside the real one in a phrase: he would relate its results “to the ‘experiment’ which our society is conducting using involuntary subjects”.

“For me,” he went on, “a prison is any situation in which one person’s freedom and liberty are denied by virtue of the arbitrary power exercised by another person or group. Thus our prisons of concrete and steel are really only metaphors for the social prisons we create and maintain through enforced poverty, racism, sexism, and other forms of social injustice.” Prison riots came from within, “from within every man and woman who refuses to let the system turn them into an object, a number, a thing, or worse, a no-thing”; “If we do not listen to the pleas of the prisoners of Attica—what was their plea: their plea was to be treated like a human being—then we have all become brutalized by our priorities for property rights over human rights.”

The written statement ends with thirteen recommendations. Do not demand simple solutions. Keep searching for them, and fund the research. Put prison reform “in the broader context of societal reforms and social injustice”. Investigate the public’s attitudes to punishment and re-educate it. Insist that judges keep an interest in the people they sentence. Make the public aware “that they own the prisons, and that their business is failing”, with “the seventy percent recidivism rate” as evidence. “Remove the cloak of secrecy from the prisons”: he had been refused permission to join the subcommittee’s tour of San Quentin and Soledad, and so had the press. An ombudsman in every prison, “not under the pay or control of the prison authority”. Better training for guards, who “are also prisoners of the system who can be sacrificed to the demands of the public to be punitive and the needs of politicians to preserve an image”. Rename them: guards would be “teachers” or “counselors”, prisoners “trainees”, with bonuses for teachers whose trainees left early and did not return. Keep the prisoner tied to his community. Attach no stigma to a trainee who has finished the course: “no need to be labeled an ‘ex-con.’” And last: “the main ingredient necessary to effect any change at all in prison reform, in the rehabilitation of a single prisoner, or even in the optimal development of your own child, is caring.”

What the subcommittee said

Kastenmeier thanked him for “an excellent statement” and took exception to one part of it: the subcommittee had not been given a tour of show rooms, he said; it had visited “any and all inmates” and the maximum security areas, and had spent “an undue amount of time in the Adjustment Center”. Zimbardo apologised: his comments had been based on what former prisoners told him. Conyers took “specific and on-the-record exception” to the idea that the subcommittee had had full cooperation: “We could not bring in tape recorders. We were specifically forbidden from taking certain prisoners—’political prisoners’—into private quarters to be interviewed.” Zimbardo said he had met the same wall years before, when he had studied the manuals detectives used to get confessions and asked to watch an interrogation through a one-way screen: “No one—judges, lawyers, Congressmen—no one is allowed to observe it.” Biester asked about the swastikas he had seen scratched into the walls of four cells in O wing at Soledad, and Zimbardo answered that the appeal of Nazism in a prison was the appeal of power: “Total power is to confront someone whom you have nothing against and kill them only because you want to.” Fish spoke last. “I just want to thank you, Dr. Zimbardo. I wish you had been at the start as well as the end, because in your discussion of your experiment, in view of other observations, you certainly helped me a great deal in clarifying some of the things we have seen the past few days and understanding them.”

“I would like to mention in no way am I a criminologist,” Zimbardo said in reply. “I never even was interested in prisons until late spring when I happened to meet this man Carlo Prescott, so it is not that I have a history of training in prisons. It just became obvious that here is a psychological situation where horrible things were happening.” The hearing adjourned at 6:30 in the evening.

Zimbardo testified again in September 1973, before the Senate Subcommittee to Investigate Juvenile Delinquency under Birch Bayh, on the jailing of juveniles; Prescott testified beside him. In 2018, answering his critics, he wrote that in 1971 “the Subcommittee of the United States Congress House of Representatives wanted not only my analyses, but also recommendations for reform”, and that his advocacy had “largely taken the form of consciousness-raising about the necessity for ending the ‘social experiment’ of prisons”. The entry sets what he told the subcommittee about the guards’ rules and training beside what the tapes of the week record.

Sources

• 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, pp. 110–121, and his statement, pp. 152–157, with the exchanges with Kastenmeier, Conyers, Biester and Fish. A congressional document, public domain; read in full in the copy on the experiment’s site. prisonexp.org/pdf/congress.pdf
• Emanuel Celler to Philip Zimbardo, October 18, 1971, Philip G. Zimbardo papers (SC0750), Box 11, Folder 45, digitised in the Stanford Digital Repository object Stanford Prison Experiment as SC0750_s5_b11_f45.pdf; Zimbardo’s typed statement, SC0750_s5_b10_f04.pdf. purl.stanford.edu/vx097ry2810
• Philip Zimbardo, “Philip Zimbardo’s Response to Recent Criticisms of the Stanford Prison Experiment,” June 23, 2018, for the 1973 Senate testimony and the words quoted in the last paragraph; KGO Radio news release, September 14, 1973, in the digital object as SC0750_b17_f10_Press_SPE.pdf, for Prescott’s testimony beside him. prisonexp.org/response