Knock, knock. It’s late, but you open the door anyway and find police officers standing outside. They inform you that you’re under arrest for armed robbery. You try to insist that they’ve got the wrong person, that you were at home studying for your psychology exam. It’s useless. They drive you down to the station, get your fingerprints, and snap a mugshot. You’re taken to prison. That night, you hear an inmate hysterically screaming until guards drag him away – you don’t see him in the morning. Guards punish you for the slightest misstep and take pleasure in humiliating you. How do you react to this new environment?


The infamous Stanford Prison “Experiment” was allegedly designed to find the answers to these questions. Lead researcher Philip Zimbardo reported that he wanted to see how people reacted to drastically different assigned roles: would participants rebel against them or seamlessly slip into them?

Stanford Prison Experiment 

In the middle of August 1971, Philip G. Zimbardo held what would be later called the Stanford Prison Experiment. Twenty four participants were split into two groups: prisoners and guards. Originally planned to last two weeks, the study was stopped after six days once an outside observer expressed concerns over the ethicalness of the work as well as over the wellbeing of the participants. The study has historically pointed to how ordinary people in the right environment will inevitably become broken victims or violent aggressors. It’s raised a plethora of ethical questions and recent evidence questions if not outright invalidates Zimbardo’s findings.

The Experiment

Day one at Stanford University was rather uneventful. On day two, prisoners rebelled, blocking cell doors with their cots and refusing to listen to guards. In response, guards used fire extinguishers to subdue them. From there, things only got worse. One prisoner suffered such a terrifying mental breakdown that he was released. Guards denied prisoners cots, made them use a bucket as a bathroom, insisted that prisoners’ numbers were their new identities, and performed other acts of cruelty. One third of the guards were reported to display sadistic tendencies. Zimbardo insisted prisoners had also thoroughly internalized their roles, citing that some had said they’d accept “parole” and when told that a fellow prisoner would be released from solitary only if all prisoners returned their blankets, only one actually did so. Zimbardo used his findings to insist that it was a person’s environment, not their personality, that caused their behavior.

Issues Raised

This study was hugely unethical. Prisoners were kept in unsafe, unsanitary, and dehumanizing facilities. Several of them told guards they wanted to leave, but they were refused. The three men who were removed from the study were only allowed to when researchers thought they were too traumatized to safely continue. One prisoner later lamented that he never sued the researchers over their ill treatment. Zimbardo’s study wasn’t just unethical – it was illegal.  

In recent years, the legitimacy of Zimbardo’s work has come under attack. Guards were briefed beforehand and told that their role was to instill a feeling of fear and helplessness in prisoners. They didn’t “naturally” come up with their acts of cruelty on their “own” – many were suggested ideas by Zimbardo and his undergraduate student David Jaffe. In fact, Zimbardo and Jaffe even served as superintendent and ward of the makeshift prison. It begs the question of whether participants were merely acting how they thought experimenters wanted them to.

Considering the testimonies of the star guard and prisoner, the answer is most likely a firm yes. Both stated that they treated it as an improv experiment. The prisoner, Douglas Korpi, reported that keeping up the roll was often exhausting and that his alleged breakdown was completely staged. Considering he also requested to leave several times, it’s not hard to imagine he faked his torment in order to get out early or garner favor with the researchers. The guard, Dave Eshleman, said he purposefully adopted an over-the-top persona to help the experimenters get the results they wanted. It’s also worth noting that when guards did small favors for prisoners and treated them kindly, they were told to be more “tough” by researchers.  

Finally, there are also confounding variables. For example, it’s been found that more aggressive and less empathetic individuals will respond to an ad asking for participants in a “prison life” study. There was no control group or independent variable either. It’s also questionable whether participants were truly randomly assigned to their groups, and Zimbardo himself was not a neutral observer. He’s stated multiple times that he “lost himself” in his role. The Stanford Prison Experiment is not an experiment.

Why Care?/Using It

If the Stanford Prison Experiment was highly manipulated, why should we still care about it? For one, it serves as a reminder that we need to be more rigorous and responsible when conducting an experiment. Participants place a lot of trust in researchers – thus, researchers must strive to be worthy of that trust. Also, when we meddle to get particular results, we’ll miss equally interesting findings. The Stanford Prison Study certainly doesn’t prove that any individual, if assigned a role, will independently conform to it. It does however show that certain institutions and environments demand sadism and tyranny, and some individuals are willing to work for them. Also, people are far too willing to commit cruelty in the name of “greater good.”

    Learn More

    Learn More

    1. Blum, Ben. “The Lifespan of a Lie.” Gen, 7 Jun 2018.
    2. Carnahan, Thomas and Sam McFarland. “Revisiting the Stanford Prison Experiment: Could Participant Self-Selection Have Led to the Cruelty?” Personality and Social Psychology Bulletin, vol 33, issue 5, May 2007, pp 603-624. Doi: 10.1177/0146167206292689.
    3. Le Texier, T. “Debunking the Stanford Prison Experiment.” American Psychologist, vol 74, issue 7, 2019, pp 823–839. Doi: 10.1037/amp0000401
    4. Onishi, So L. and Randy S. Herbert. “The Stanford Prison Experiment: Implications for the Care of the “Difficult” Patient.” American Journal of Hospice and Palliative Medicine, vol 33, issue 1, Sept 2014, pp 64-68. Doi: 10.1177/1049909114552126.
    5. Zimbardo, Philip. The Lucifer Effect: Understanding How Good People Turn Evil. Random House, New York, 2013.

    Think Further

    Think Further

    1. What parts of the study can’t be replicated because of today’s ethical standards?
    2. The study was later ethically recreated without the coaching of the guards. Do you think that those results would be significantly different? How so?
    3. What are some other lessons we can take away from the Stanford Prison Experiment?

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