IT BEGAN WITH AN AD in the classifieds.
Male college students needed for psychological study of prison life. $15 per day for 1-2 weeks. More than 70 people volunteered to take part in the study, to be conducted in a fake prison housed inside Jordan Hall, on Stanford's Main Quad. The leader of the study was 38-year-old psychology professor Philip Zimbardo. He and his fellow researchers selected 24 applicants and randomly assigned each to be a prisoner or a guard.
Zimbardo encouraged the guards to think of themselves as actual guards in a real prison. He made clear that prisoners could not be physically harmed, but said the guards should try to create an atmosphere in which the prisoners felt "powerless."
The study began on Sunday, August 17, 1971. But no one knew what, exactly, they were getting into.
Forty years later, the Stanford Prison Experiment remains among the most notable—and notorious—research projects ever carried out at the University. For six days, half the study's participants endured cruel and dehumanizing abuse at the hands of their peers. At various times, they were taunted, stripped naked, deprived of sleep and forced to use plastic buckets as toilets. Some of them rebelled violently; others became hysterical or withdrew into despair. As the situation descended into chaos, the researchers stood by and watched—until one of their colleagues finally spoke out.
The public's fascination with the SPE and its implications—the notion, as Zimbardo says, "that these ordinary college students could do such terrible things when caught in that situation"—brought Zimbardo international renown. It also provoked criticism from other researchers, who questioned the ethics of subjecting student volunteers to such extreme emotional trauma. The study had been approved by Stanford's Human Subjects Research Committee, and Zimbardo says that "neither they nor we could have imagined" that the guards would treat the prisoners so inhumanely.
In 1973, an investigation by the American Psychological Association concluded that the prison study had satisfied the profession's existing ethical standards. But in subsequent years, those guidelines were revised to prohibit human-subject simulations modeled on the SPE. "No behavioral research that puts people in that kind of setting can ever be done again in America," Zimbardo says.
The Stanford Prison Experiment became the subject of numerous books and documentaries, a feature film and the name of at least one punk band. In the last decade, after the revelations of abuses committed by U.S. military and intelligence personnel at prisons in Iraq and Afghanistan, the SPE provided lessons in how good people placed in adverse conditions can act barbarically.
The experiment is still a source of controversy and contention—even among those who took part in it. Here, in their own words, some of the key players in the drama reflect on their roles and how those six days in August changed their lives.
Zimbardo joined Stanford's psychology department in 1968 and taught there until his retirement in 2007.
The study was focused originally on how individuals adapt to being in a relatively powerless situation. I was interested in prisoners and was not really interested in the guards. It was really meant to be a single, dramatic demonstration of the power of the situation on human behavior. We expected that we would write some articles about it and move on.
After the end of the first day, I said, "There's nothing here. Nothing's happening." The guards had this antiauthority mentality. They felt awkward in their uniforms. They didn't get into the guard mentality until the prisoners started to revolt. Throughout the experiment, there was this conspiracy of denial—everyone involved was in effect denying that this was an experiment and agreeing that this is a prison run by psychologists.
There was zero time for reflection. We had to feed the prisoners three meals a day, deal with the prisoner breakdowns, deal with their parents, run a parole board. By the third day I was sleeping in my office. I had become the superintendent of the Stanford county jail. That was who I was: I'm not the researcher at all. Even my posture changes—when I walk through the prison yard, I'm walking with my hands behind my back, which I never in my life do, the way generals walk when they're inspecting troops.
We had arranged for everyone involved—the prisoners, guards and staff—to be interviewed on Friday by other faculty members and graduate students who had not been involved in the study. Christina Maslach, who had just finished her PhD, came down the night before. She's standing outside the guard quarters and watches the guards line up the prisoners for the 10 o'clock toilet run. The prisoners come out, and the guards put bags over their heads, chain their feet together and make them put their hands on each other's shoulders, like a chain gang. They're yelling and cursing at them. Christina starts tearing up. She said, "I can't look at this."
I ran after her and we had this argument outside Jordan Hall. She said, "It's terrible what you're doing to these boys. How can you see what I saw and not care about the suffering?" But I didn't see what she saw. And I suddenly began to feel ashamed. This is when I realized I had been transformed by the prison study to become the prison administrator. At that point I said, "You're right. We've got to end the study."
[As the study was underway], there was an escape attempt at San Quentin prison and [former Black Panther] George Jackson was shot and killed. Three weeks after that, there's the Attica prison riot [in New York]. Suddenly, prisons are hot. Two government investigative committees start hearings and I'm flown out to Washington to present to a congressional subcommittee on the nature of prisons. I went from knowing nothing firsthand about prisons to being an expert. But I worked hard to learn more. I visited a number of correctional facilities all over the country. I organized a program for Stanford students to teach a course at a prison. For years I had an active correspondence with at least 20 different prisoners.
It wasn't a formal experiment. My colleagues probably never thought much of it. But as a result of the prison study, I really became more aware of the central role of power in our lives. I became more aware of the power I have as a teacher. I started consciously doing things to minimize the negative use of power in the classroom. I encouraged students to challenge me.
I think I became more self-reflective. I'm more generous and more open because of that experience. I think it made me a better person.
Maslach, PhD '71, became a professor at UC-Berkeley. She and Zimbardo married in 1972. They live in San Francisco.
I had just finished my doctorate and was about to leave Stanford to start my new job. Phil and I had started dating. The prison study was never anything I was considering playing a part in. During the first few days of the experiment, I did hear from Phil, but not in great detail. What I was getting, though, was a sense that it was becoming a real prison—people were not just fooling around but actually getting caught up in the situation. But it still wasn't evident to me what that might mean.
At first Phil didn't seem different. I didn't see any change in him until I actually went down to the basement and saw the prison. I met one guard who seemed nice and sweet and charming, and then I saw him in the yard later and I thought, "Oh my God, what happened here?" I saw the prisoners being marched to go down to the men's room. I was getting sick to my stomach, physically ill. I said, "I can't watch this." But no one else was having the same problem.
Phil came after me and said, "What's the matter with you?" That's when I had this feeling like, "I don't know you. How can you not see this?" It felt like we were standing on two different cliffs across a chasm. If we had not been dating before then, if he were just another faculty member and this happened, I might have said, "I'm sorry, I'm out of here" and just left. But because this was someone I was growing to like a lot, I thought that I had to figure this out. So I kept at it. I fought back, and ended up having a huge argument with him. I don't think we've ever had an argument quite like that since then.
I feared that if the study went on, he would become someone I no longer cared for, no longer loved, no longer respected. It's an interesting question: Suppose he kept going, what would I have done? I honestly don't know.
The clearest influence the study had on me was that it raised some really serious questions about how people cope with extremely emotional, difficult situations, especially when it's part of their job—when they have to manage people or take care of them or rehabilitate them. So I started interviewing people. I started with some prison guards in a real prison, and talked to them about their jobs and how they understood what they were doing. At first I wasn't sure what I was looking for. I was just trying to listen.
I interviewed people who worked in hospitals, in the ER. After a while I realized there was a rhythm and pattern emerging, and when I described it to someone they said, "I don't know what it's called in other professions, but in our occupation we call it 'burnout.'" And so I spent a good chunk of my professional life developing and defining what burnout is—what are the things that cause it and how can we intervene and help people cope with it more effectively. All of that work on burnout had some origins in the experience I had in the prison experiment.
People will sometimes come up to me—at conferences, or maybe they're students who have taken psychology classes—and they'll say, "Oh my God, you're such a hero! What is it like to be a hero?" And it's always a little surprising to me because it sure didn't feel heroic at the time. The prison study has given me a new understanding of what "heroism" means. It's not some egocentric, I'm-going-to-rush-into-that-burning-building thing—it's about seeing something that needs to be addressed and saying, I need to help and do something to make it better.
The son of a Stanford engineering professor, Eshelman was a student at Chapman University at the time of the experiment. He was the prison's most abusive guard, patterning himself after the sadistic prison warden (portrayed by Strother Martin) in the movie Cool Hand Luke. Today he owns a mortgage business in Saratoga.
I was just looking for some summer work. I had a choice of doing this or working at a pizza parlor. I thought this would be an interesting and different way of finding summer employment.
The only person I knew going in was John Mark. He was another guard and wasn't even on my shift. That was critical. If there were prisoners in there who knew me before they encountered me, then I never would have been able to pull off anything I did. The act that I put on—they would have seen through it immediately.
What came over me was not an accident. It was planned. I set out with a definite plan in mind, to try to force the action, force something to happen, so that the researchers would have something to work with. After all, what could they possibly learn from guys sitting around like it was a country club? So I consciously created this persona. I was in all kinds of drama productions in high school and college. It was something I was very familiar with: to take on another personality before you step out on the stage. I was kind of running my own experiment in there, by saying, "How far can I push these things and how much abuse will these people take before they say, 'knock it off?'" But the other guards didn't stop me. They seemed to join in. They were taking my lead. Not a single guard said, "I don't think we should do this."
The fact that I ramped up the intimidation and the mental abuse without any real sense as to whether I was hurting anybody? I definitely regret that. But in the long run, no one suffered any lasting damage. When the Abu Ghraib scandal broke, my first reaction was, this is so familiar to me. I knew exactly what was going on. I could picture myself in the middle of that and watching it spin out of control. When you have little or no supervision as to what you're doing, and no one steps in and says, "Hey, you can't do this"—things just keep escalating. You think, how can we top what we did yesterday? How do we do something even more outrageous? I felt a deep sense of familiarity with that whole situation.
Sometimes when people know about the experiment and then meet me, it's like, My God, this guy's a psycho! But everyone who knows me would just laugh at that.
Mark was about to begin his junior year at Stanford. He graduated in 1973 with a degree in anthropology. He lives in the Bay Area and has worked for the last 18 years as a medical coder for Kaiser Permanente.
I had spent my sophomore year at Stanford in France and returned to campus that spring. It was one of the most pivotal times in my life. Over Thanksgiving of the year before, I went with a friend to Amsterdam. You have to remember this is 1970, it was basically the '60s. We went to one of those clubs where you could buy drugs. We bought hash and actually brought some back with us, and I was caught at the French border. For a few hours I was told by French border guards that I was going to prison. In the end they let me go, but I definitely had been scared out of my wits.
When I saw this thing about a prison experiment, I thought I had some life experiences to bring to it. I felt this was going to be an important experiment. I told them all about what I'd been through and why it was important to me to be a prisoner. It was very disappointing to be assigned to be a guard, but I did the best I could.
During the day shift, when I worked, no one did anything that was beyond what you'd expect in a situation like that. But Zimbardo went out of his way to create tension. Things like forced sleep deprivation—he was really pushing the envelope. I just didn't like the whole idea of constantly disturbing people and asking them to recite their prisoner numbers in a count. I certainly didn't like when they put a guy in solitary confinement.
At that time of my life, I was getting high, all day every day. I got high before I went to the experiment; I got high on my breaks and lunch. I got high afterwards. I brought joints with me, and every day I wanted to give them to the prisoners. I looked at their faces and saw how they were getting dispirited and I felt sorry for them.
I didn't think it was ever meant to go the full two weeks. I think Zimbardo wanted to create a dramatic crescendo, and then end it as quickly as possible. I felt that throughout the experiment, he knew what he wanted and then tried to shape the experiment—by how it was constructed, and how it played out—to fit the conclusion that he had already worked out. He wanted to be able to say that college students, people from middle-class backgrounds—people will turn on each other just because they're given a role and given power.
Based on my experience, and what I saw and what I felt, I think that was a real stretch. I don't think the actual events match up with the bold headline. I never did, and I haven't changed my opinion.
A graduate student of Zimbardo's, Haney, MA '71, PhD '78, JD '78, was responsible for overseeing the experiment and analyzing the data gathered from it. He went on to become a professor at UC-Santa Cruz, a leading authority on the psychological effects of incarceration and an advocate for prison reform.
What we thought we were going to find is that there would be subtle behavioral changes that would take place over time. There were moments, in the course of deciding about whether to do it, where we wavered. Not because we thought it would go too far or be too dramatic, but because we weren't sure anything was going to happen. I remember at one point asking, "What if they just sit around playing guitar for two weeks? What the hell are we going to do then?"
People have said to me, you must have known this was going to happen. We didn't—and we were not naive. We were very well read in the literature. We just did not anticipate these kinds of things happening. It really was a unique experience to watch human behavior transform in front of your eyes. And I can honestly say that I try never to forget it. I spend a lot of time with real prisoners and real guards, and having seen what I saw then, while a graduate student, gave me respect for the power of institutional environments to transform good people into something else.
I also realized how quickly we get used to things that are shocking one day and a week later become matter-of-fact. During the study, when we decided to move prisoners to different parts of the prison, we realized that they were going to see where they were and be reminded they're not in a prison—they're just in the psych building at Stanford. We didn't want that to happen.
So we put paper bags over their heads. The first time I saw that, it was shocking. By the next day we're putting bags on their heads and not thinking about it. That happens all the time in real correctional facilities. You get used to it. I do a lot of work in solitary-confinement units, on the psychological effects of supermax prisons. In places like that, when prisoners undergo the so-called therapy counseling, they are kept in actual cages. I constantly remind myself never to get used to seeing the cages.
The prisoners in this study were a downtrodden lot by the end of it. Even the guys who didn't break down were hurting. This was a really difficult experience. And for me that was a lesson, too. Real prisoners learn how to mask their pain and act like it doesn't matter. The prison study showed what it feels like for people who have not learned how to wear that implacable mask. I try to talk to prisoners about what their lives are really like, and I don't think I would have come to that kind of empathy had I not seen what I saw at Stanford. If someone had said that in six days you can take 10 healthy college kids, in good health and at the peak of resilience, and break them down by subjecting them to things that are commonplace and relatively mild by the standards of real prisons—I'm not sure I would have believed it, if I hadn't seen it happen.
A community college student at the time, Yacco helped instigate a revolt against conditions in Zimbardo's prison. He was released one day early from the study after exhibiting signs of depression. After working in radio and television production, he now teaches at a public high school in Oakland.
At the time I was debating: If I were drafted to fight in Vietnam, what would I do? Would I be willing to go to jail? Since that was one of the considerations, I thought, well, a prison experiment would give me some insight into what that would be like.
The first thing that really threw me off was the sleep deprivation. When they woke us up the first time, I had no idea it was after only four hours of sleep. It was only after they got us up and we did some exercises and then they let us go back to bed that I realized they were messing with our sleep cycles. That was kind of a surprise from the first night.
I don't recall exactly when the prisoners started rebelling. I do remember resisting what one guard was telling me to do and being willing to go into solitary confinement. As prisoners, we developed solidarity—we realized that we could join together and do passive resistance and cause some problems. It was that era. I had been willing to go on marches against the Vietnam war, I went on marches for civil rights, and was trying to figure out what I would do to resist even going into the service. So in a way I was testing some of my own ways of rebelling or standing up for what I thought was right.
My parents came on visitors' night. They were really concerned with the way I looked. I told them that they're breaking up our sleep, that we weren't having the chance to take showers. My appearance really concerned both of my parents, my mother especially.
When I asked [Zimbardo's team] what I could do if I wanted to quit, I was told, "You can't quit—you agreed to be here for the full experiment." That made me feel like a prisoner at that point. I realized I had made a commitment to something that I now could not change. I had made myself a prisoner.
I ended up being paroled by the "parole board." They released me Thursday night. That's when they told me they were going to end the experiment the next day. What I learned later is that the reason they chose me [to parole] is because they thought I'd be the next guy to break down. I was surprised, because I never thought I was going through any kind of depression or anything like that.
One thing that I thought was interesting about the experiment was whether, if you believe society has assigned you a role, do you then assume the characteristics of that role? I teach at an inner city high school in Oakland. These kids don't have to go through experiments to witness horrible things. But what frustrates my colleagues and me is that we are creating great opportunities for these kids, we offer great support for them, why are they not taking advantage of it? Why are they dropping out of school? Why are they coming to school unprepared? I think a big reason is what the prison study shows—they fall into the role their society has made for them.
Participating in the Stanford Prison Experiment is something I can use and share with students. This was one week of my life when I was a teenager and yet here it is, 40 years later, and it's still something that had enough of an impact on society that people are still interested in it. You never know what you're going to get involved in that will turn out to be a defining moment in your life.