Do you cover Zimbardo's prison study? Read this.

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In 2013, Thibault Le Texier, a French academic, accidentally tripped over Philip Zimbardo’s 2008 “The Psychology of Evil” TED Talk. Le Texier became so fascinated by Zimbardo’s prison study, he devoured everything he could find about it. Like others, he thought it would make an excellent documentary. A couple film producers received a grant to send Le Texier to Stanford to take a deep dive into the prison study’s archives.(Le Texier, 2018). About what he learned, Le Texier wrote:

C'est là, en juillet 2014, que mon enthousiasme a fait place au scepticisme, puis mon scepticisme à l'indignation, à mesure que je découvrais les dessous de l'expérience et l'évidence de sa manipulation.

It was there, in July 2014, that my enthusiasm gave way to skepticism, then my skepticism to indignation, as I discovered the underside of the experiment and the evidence of its manipulation. [Google translation, with the translation stamp of approval from this blog post author based on her limited French]

Le Texier published what he learned in his well-researched 2018 book, Histoire d’un mensonge: Enquête sur l’expérience de Stanford (available from Amazon). While the book has not yet been published in English, a not-too-bad Google translation is freely available.

In 2019, Le Texier provided us with a summary of his findings in an American Psychologist article (Le Texier, 2019). If your library does not carry this journal, you can download a copy of the article from Le Texier’s website.

I remember when the 2019 American Psychologist article came out. It was the July/August edition. I made a mental note to read the article, but never made the time to actually read it. I’m currently working on a writing project that gave me the impetus to finally read it.

If you cover the prison study in any of your courses, the American Psychologist article is a must-read.

The biggest surprise to me was the amount of guidance and direction the guards were given. The popular narrative is that the power of the prison situation created guards who enthusiastically took on the role of who they believed a guard is. Instead, the guards were instructed to engage in particular behaviors, such as the middle-of-the-night counts. In fact, the guards thought of themselves as fellow experimenters who were tasked with creating a stressful psychological environment for the prisoners. During the guards’ orientation, Zimbardo told them that he had

a grant to study the conditions which lead to mob behavior, violence, loss of identity, feelings of anonymity. [. . .] [E]ssentially we’re setting up a physical prison here to study what that does and those are some of the variables that we’ve discovered are current in prisons, those are some of the psychological barriers. And we want to recreate in our prison that psychological environment (Le Texier, 2019, p. 827).

This was indeed the original purpose of the study—to see how a stressful prison-like situation could impact mock prisoners. Zimbardo wrote in The Lucifer Effect,

I should mention again that my initial interest was more in the prisoners and their adjustment to this prisonlike situation than it was in the guards. The guards were merely ensemble players who would help create a mind-set in the prisoners of the feeling of being imprisoned. […] Over time, it became evident to us that the behavior of the guards was as interesting as, or sometimes even more interesting than, that of the prisoners (Zimbardo, 2007, p. 55).

What has been lost to time, however, is that the guards did not decide for themselves how to behave.

Another big factor that affected what happened during the study is how much the guards and prisoners were paid: $15 per day. In 2022 dollars, that is $110/day (Webster, 2022). Both guards and prisoners said that it was in their best interest to act as Zimbardo expected in order to stretch the experience out as long as they could. The longer they stayed, the more money they would all make.

As for my own writing project, I knew I could not delete the prison study wholesale. Too many people know something about it, and it is well past time for us to discuss what the historical record tells us. In the end, I framed my coverage of the study in the context of the study’s demand characteristics.

Perhaps in a strange twist of fate, Zimbardo’s point about the prison study holds, but not in the way he describes it. The power of the situation can, indeed, greatly affect our behavior. The power of the situation in the prison study, however, does not come from taking on the role of guard or prisoner in a prison situation, but comes from taking on the role of experimenter (or, at least, experimenter assistant as the guards believed themselves to be) and the role of research participant (as the prisoners knew themselves to be) in a research situation.

In the end, the prison study appears to be an excellent object lesson in the power of demand characteristics in a psychological research situation.



Le Texier, T. (2018). Histoire d’un mensonge: Enquête sur l’expérience de Stanford. Éditions La Découverte.

Le Texier, T. (2019). Debunking the Stanford Prison Experiment. American Psychologist, 74(7), 823–839.

Webster, I. (2022, September 4). $15 in 1971 is worth $109.73 today. CPI Inflation Calculator.



About the Author
Sue Frantz has taught psychology since 1992. She has served on several APA boards and committees, and was proud to serve the members of the Society for the Teaching of Psychology as their 2018 president. In 2013, she was the inaugural recipient of the APA award for Excellence in the Scholarship of Teaching and Learning at a Two-Year College or Campus. She received in 2016 the highest award for the teaching of psychology--the Charles L. Brewer Distinguished Teaching of Psychology Award. She presents nationally and internationally on the topics of educational technology and the pedagogy of psychology. She is co-author with Doug Bernstein and Steve Chew of Teaching Psychology: A Step-by-Step Guide, 3rd ed. and is co-author with Charles Stangor on Introduction to Psychology, 4.0.