Philip Zimbardo reflects on ‘The Stanford Prison Experiment’ movie

July 17, 2015, 12:49 a.m.
(Courtesy of Philip Zimbardo)
(Courtesy of Philip Zimbardo)

Today, Philip Zimbardo, professor emeritus of psychology at Stanford, will see the story of his famously controversial Stanford Prison Experiment unfold on the big screen.

Conducted in 1971, the experiment simulated a prison environment with a group of 22 male college students. The young men, hand-picked for their physical and mental maturity, among other factors, were randomly assigned the role of “prisoner” or “guard.” While the students were specifically instructed against the use of physical punishment, they were given no further instructions. Throughout the six-day study, half of the prisoners suffered from “extreme emotional depression, crying, rage, and acute anxiety” and had to be excused from the experiment.

Since the study was conducted, Zimbardo has written “The Lucifer Effect,” a book in which he discusses the gradual changes experienced within the subjects and himself throughout the experiment. The research has been widely studied by psychology students and beyond, serving as a controversial but poignant example of the effect of a prison environment.

With “The Stanford Prison Experiment” set to premiere today, Zimbardo spoke with The Daily about the original study, as well as his thoughts about the motion picture.


The Stanford Daily (TSD): What were your initial expectations for the original experiment?

Philip Zimbardo (PZ): [We wanted to expand on] Milgram’s experiment on obedience through authority, in which he showed that situational factors can get good people to do bad things… Our study was a follow-up of that, in which we focus less on powerful authority and obedience…

In the earlier research – in most psychological research – it [the study] only goes for a single hour. We wanted to observe the gradual transformation of people into their character, into their role… What’s dramatic about the research – and now what’s dramatic about the movie – is that you see for the first time character transformations – people becoming their role, becoming guards, becoming prisoners – in a relatively short time.

TSD: Why did you decide to conduct the study with college-age males?

PZ: I wanted to have bright, intelligent college students. And unlike Milgram’s study, we gave them personality tests. We only picked the most normal and healthy. The bottom line is, I want to say, here we have normal, intelligent, bright, college students who should understand things about [themselves]. Even more than ordinary, uneducated people. And the point is, it works for them as well as for the ordinary men in Milgram’s study.

TSD: In some of the interviews after the experiment, students explained that the prison became more than just an experiment, that they really grew into their roles as prisoners and guards. Did you also grow into your role as prison superintendent? How did this it affect your research?

PZ: Oh, absolutely. I made the mistake of playing two roles simultaneously. One role was principal investigator of the research project, and in that role I am objective; I am distant; I am emotionally neutral. But then I made the mistake of also being the prison superintendent, and my undergraduate assistant David Chassey played the role of the warden, and my two graduate students…played the two attendants. But we all had a prison-life role to play.

Over time, hour-by-hour, day-by-day, I fell into that role, and in that role I observed guards brutalizing prisoners – in some cases sadistically… And I did not stop it. The only thing I stopped was physical force, but I didn’t stop psychological force, which, in the long run is much worse. I had become, without my awareness, the indifferent superintendent of the Stanford Prison Experiment. And in my book “The Lucifer Effect,” I write about it in great detail – that this was a mistake I made. I should have had someone else play that role.

PZ: When I finished this study, I wrote a few articles about it, because it was really, to me, not a big deal… And then what happened was Abu Ghraib in 2004 – there were obvious parallels with the prison study. Military guards put bags over prisoners’ heads, stripped them naked, humiliated them, just as our guards had done. And so I became an excellent witness to one of those military guards and got to know everything about that horrendous military situation in Iraq. And then I decided I should really go back and review what happened in the Stanford Prison Study, which was 30 years earlier.

And so what I did is I looked at 12 hours of our videotape along with two students who didn’t know anything about this study… And what I decided to do is write a book in which we basically detail what happened in the study. We basically have a chapter of each day, and of course a chapter of setting it [the experiment] up, and other chapters on other things and other kinds of evil situations. My book, “The Lucifer Effect,” [has] been a great success. It’s been in 20 different languages around the world; it’s being used not only by college students and psychologists but in military situations and even in mental hospitals.

TSD: Was there a particular time when your role started to shift from principal investigator to prison superintendent, or was it gradual?

PZ: It’s totally gradual. The point is that we all – I mean I lived there, I slept in my office – hadn’t noticed [the changes] at all. That is, we lived the experiment.

The other problem was we – we meaning my research team – were really not prepared for the intensity an experiment that goes 24/7. Because there are endless logistical things to do – prisoners have to be fed morning, lunch, evening. In order to make it realistic we had parole board hearings two times, with an ex-convict heading it. The secretaries had visiting days two times, with parents, boyfriends, girlfriends. We had a visiting by a prison chaplain…

But the changes are gradual. The changes occur, as I said, a little bit more each day. It’s not a single dramatic thing.

TSD: You mentioned that your two-week study was terminated after just six days; why did you make the decision to conclude the study at the point that you did?

PZ: It’s a critical dramatic instance of heroic action by a young woman, who brought me to my senses…On Thursday night, one of those former graduate students [coming to help with the study], a young woman named Christina Maslach [Ph.D. ’71] – she had been my graduate student at Stanford and also my teaching assistant, and she had just graduated in June – had gotten a job at Berkeley as an assistant professor in psychology and was on her way [to Stanford]…

We had just decided in addition in the beginning of August that we would move in together. We were having a romantic relationship…  So she happened to be at Stanford on Thursday working in the library, and contacted me and said, “Hey, can we get together for dinner at the end of the night shift?” And I said, “Sure, why don’t you come down and just check out what’s happening.”

And she comes down and observes guards brutalizing prisoners with bags over their head, yelling, screaming, chaining their legs together, and when I looked at what was happening on the monitor it was nothing more than the 10 o’clock toilet shift – because 10 o’clock was the last time prisoners could go to a real toilet… She begins to tear up, and runs out and says “I can’t look at this”…

I’m arguing about why this is such an important study, and then she [asks], how could I not see the suffering that was so obvious to her? And if this was the real me, because what she had known me before – the professor, who was a caring, loving teacher… I’m not sure I want to continue my romantic relationship with you. And at that point it was really stunning because it was exactly what I needed to shake me loose from my fantasy, from my craziness… At this point it’s like 11 o’clock at night, and I say, “All right, I’m going to end the study tomorrow… ” We ended the study on Friday, the next day.

TSD: Shifting focus from the actual study to the film that’s coming out, how accurately do you think the film portrays your experiment?

PZ: It’s a remarkably accurate portrayal. Now, the only issue of course is they’re compressing six days into two hours – it is a two hour film. So in fact, they had to leave out many traumatic scenes. There are no scenes that were put in that didn’t happen in the real study. There were no scenes that had to be put in for the drama. If anything, they left out a lot of what I consider powerful scenes, which they actually had in and it just went too long so they had to cut it out. I’d say it’s roughly 90 percent accurate.

Now in addition, when I was writing “The Lucifer Effect,” I was sending to the scriptwriter Tim Talbott all of the dialogue between prisoners and guards. So in the movie almost all of what the guards say to prisoners, prisoners say to guards, came exactly from “The Lucifer Effect” (and I got a screen citation).

TSD: What was your involvement with the making of the movie?

PZ: From the beginning, I was the consultant. I reviewed the script; I made significant changes in the script; I contributed to the script. And I was on the set a couple of days. Unfortunately, I couldn’t be there all the time because I was in Europe. And even when the film was shown at Sundance, there were several parts of the movie which were just wrong psychologically, and then also we added the screen credits. Several things which are now in the movie.

TSD: There have been several documentaries and informational videos made about the experiment, but this is more of a motion picture than a documentary. How do you think the dramatization of the experiment affects the events and conclusions that are presented? Are they easier to relate to for the audience?

PZ: Our movie sticks essentially to the facts… So the movie, then, is a dramatic recreation. It’s dramatic in that it’s highlighting some things and not getting into details about something else. But it has the visiting days. It has the parole board hearing. It has at least one scene of the police arrest. It has the interaction of me and my staff making group decisions about what we should do with certain prisoners. At least more than half of the movie is just prisoner and guard interaction with no one else present.

What’s dramatic is, the audience, in looking at the movie – it’s as if they’re looking through a one-way screen, as we were doing. They are taking the place of the observers looking at the drama unfolding. But they are also observing the observers. Observing the changes in me and my graduate students as these things unfold.

I think it’s a unique movie; it’s the only movie I know where the whole movie is about a psychological experiment.

TSD: If you could change something about the movie, what would you change?

PZ: The confrontation I had with Christina is the reason we ended the study – and it makes her a hero. Because in doing what she was doing, she was willing to say two things. She doesn’t know these boys, doesn’t know anything about them. But she’s just saying “I see human suffering, and you are responsible. I don’t want to have a relationship with somebody who could do that… ” That’s heroic. Heroes defend their moral cause aware of the risk.

But they didn’t use that to end the movie. They had a confrontation, and then I go down to the dungeon, and I’m looking at the video, and the video is the worst thing that happens… They wanted a traumatic scene, wanted to have the biggest traumatic impact – which it does… And then I go down, I enter the yard and say, “Okay, this study is over.” So the way the movie does, it doesn’t give her the heroic status that she deserves.

TSD: You mentioned that the audience will be encased in the basement as well. What do you hope viewers will take away from that experience?

PZ: It’s: What kind of guard would I have been if I was in that study? Would I have been a cruel guard; would I have been a good guard; would I have stopped what the bad guards did? What kind of prisoner would I have been? Would I have been defiant? Would I have stood up for my rights? Would I have helped other prisoners who were breaking down? If I would have been the prison superintendent, what would I have done to make the situation not erupt so horribly?

Essentially, we would like them to identify with the prisoners, the guards and me and my staff. And then also the question is: Would you have allowed it to go the second week, or would you end it earlier?… The point is to reflect. We’ve got all this stuff happening, prison riots in New York and Rikers Island – it’s really about abuse of power. Abuse of police power we see everywhere.


This interview has been condensed and edited.

Contact Lea Sparkman at 16lsparkman ‘at’

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