The Stanford Prison Experiment lasted less than a week in 1971, but its claims about human nature endured for decades. Now, a new Netflix series is bringing one of psychology’s most controversial studies, and some of the biggest concerns surrounding it, back into the spotlight.
Organized by American psychologist Philip Zimbardo, the experiment involved a mock prison set up in the basement of a Stanford University building. He selected 24 male college students out of more than 70 respondents to a newspaper ad for “a psychological study of prison life” and randomly divided them into prisoners and guards. At the heart of this work was a fundamental question about good and evil.
“Zimbardo was basically trying to figure out if regular people could be willing to both give and follow orders if they were placed in a particular environment, and see what was the role of the situation at producing people’s behavior,” said Catherine Sanderson, Poler Family Professor of Psychology at Amherst College and a former student of Zimbardo’s. She was not involved with the experiment. “What he wanted to show is that normal people can do horrible things.”
<img src="https://media.cnn.com/api/v1/images/stellar/prod/44-blindfolded-with-guards.jpg?c=original&q=w_780,c_fill” alt=”Guards handle a blindfolded prisoner in a still from the original Stanford Prison Experiment in 1971.”>
Guards handle a blindfolded prisoner in a still from the original Stanford Prison Experiment in 1971.
The study’s 24 participants were randomly split into two groups: guards and inmates.
The experiment, meant to last up to two weeks, rapidly got out of hand — at least according to the official narrative. Within 36 hours one of the prisoners had an apparent mental breakdown, and on the second day the inmates staged a rebellion. The guards vigorously repressed it, spraying the perpetrators with fire extinguishers, stripping them naked and locking them up in a dark closet named “the hole.”
All of this was unfolding against a backdrop of real-world unrest over prison conditions and the treatment of incarcerated people. Just weeks after the experiment ended, a prison uprising at Attica Correctional Facility in New York was thwarted with deadly force, resulting in 43 deaths. The event brought media attention to Zimbardo’s work, launching it beyond the academic realm and into the social discourse, where it has remained since.
But through the years, the profile of the Stanford Prison Experiment has dramatically changed, going from an unprecedented insight into the human psyche to a widely criticized study whose methods and conclusions have been called into question.
Philip Zimbardo (first from right) took on the role of prison superintendent.
“Our understanding of what happened has really evolved a lot over time,” Sanderson said. “There have been not only ethical challenges posed about the study, but also about whether the behaviors occurred spontaneously, or were rather sort of instructed by Zimbardo.”
As Netflix debuts its own reimagined version of the experiment, one key question remains: Did the study reveal something fundamental about authority — or did the way it was conducted help produce the behaviors it became famous for?
Zimbardo conceived the study partly as a follow-up to famous obedience experiments conducted by American psychologist Stanley Milgram in the early 1960s. In the first of such studies, participants were told to deliver what they believed were increasingly painful electric shocks to an unseen person, for giving incorrect answers in a memory test, and 65% of participants continued to the maximum level despite hearing the person’s apparent distress.
In reality, the distress was faked by an actor, and — if planned today — both Milgram’s and Zimbardo’s experiments would face serious obstacles under modern ethical research rules because of issues with deception, psychological harm, conflict of interest and lack of informed consent about the intensity of the experience.
Stanford professor Philip Zimbardo discusses the Stanford Prison Experiment on August 20, 1971.
For starters, the Stanford experiment prisoners had no idea the study would kick off with local police realistically arresting them at their homes. Upon entering the mock prison, the inmates underwent a strip-search and then had to put on loose-fitting smocks with no underwear. They wore nylon stockings over their heads, simulating shaved hair.
The guards wore uniforms and mirrored sunglasses to avoid eye contact. The study team gave them wooden batons and instructions to not physically harm the prisoners, but maintain law and order. Zimbardo acted as the prison’s superintendent, observing and recording the experiment.
As prisoners started to show evident signs of distress early on, some relatives who were allowed to visit expressed the intention of contacting lawyers to stop the study. Within the first four days, three inmates had been released after showing signs of distress.
On the fifth day, Christina Maslach, then a recent Stanford graduate in social psychology who would later marry Zimbardo, visited the prison and was horrified by what she saw. Zimbardo ended the experiment the next day.
Audio and video evidence from the experiment, as well as post-study interviews with the participants, later revealed that Zimbardo, who died in 2024, directly influenced the study’s outcome by interacting with the participants and coaching the guards, as well as preventing some inmates from leaving the mock prison when they first requested it.
“One of the hallmarks of good experimental design is that we don’t have the experimenter in charge of the study interacting with the participants,” Sanderson said. “The fact that Zimbardo was so heavily involved is a major problem, because he did have particular beliefs, expectations — one might even say goals — in conducting the study.”
But at the time, the results were well regarded and Zimbardo leaned into a newfound fame: “In the public eye, like lecturing to a large class, you are a performer and so must put on a good performance and learn from mistakes to be more effective next time,” he said in 2009 interview.
The psychological stress made some of the students playing the role of inmates leave the study early.
Zimbardo was a very powerful and compelling speaker “The Stanford prison study had brought him a lot of fame, and he was very charismatic,” she said. “This sort of lure meant that people weren’t paying a lot of attention to maybe some of the details about what actually happened.”
Still, the revelations about his involvement did serve to undermine the findings about authority and human nature that Zimbardo championed.
“I think there is certainly a general view that good people can do bad things under particular circumstances, such as being anonymous, or being ordered to do so,” Sanderson said. “However, the Stanford prison study is not a good example of evidence for that.”
That skepticism reflects a broader reckoning within psychology over the reliability of study results. In 2015, an attempt to replicate 100 studies published in leading psychology journals resulted in only 36% of replications achieving statistically significant results, compared with 97% in the original studies. This “replicability crisis” has exposed flaws in how psychological research is conducted and published, including small sample sizes and pressure to produce striking results rather than robust, reproducible findings.
The first major attempt to revisit the Stanford experiment did, in fact, produce a completely different outcome. But that initial redo, commissioned by the BBC, also started by shaking up the approach.
The BBC broadcast its take on Zimbardo’s work in 2002 as a television series called “The Experiment.”
The study involved 15 male volunteers — six guards and nine prisoners — in prison built on a movie studio lot. But the guards did not become tyrannical, as in the Stanford experiment. Instead, the prisoners challenged the guards and gained the upper hand. Even more surprisingly, they later built a shared community.
According to Stephen Reicher, Bishop Wardlaw Professor of Psychology at the University of St. Andrews in England, who conducted the research along with Alex Haslam, then a psychologist at the University of Exeter, the striking difference in outcome was partly due to the fact that the guards were not coached beforehand by an authoritative figure like Zimbardo.
“Normally in an experiment you are neutral,” Reicher said. “Zimbardo actually positioned himself as head guard. In broad terms, he tells them what to do. He tells them to impose power. He tells them to make people feel helpless.”
In the BBC version, there is no such leadership: “We took seriously the notion that we should just put people in the role and see what happens. Without clear leadership, we found that the guards didn’t want to impose power, didn’t want to be brutal, and therefore they became powerless. They didn’t cohere as a group. They didn’t know what to do,” Reicher noted. “Conversely, the prisoners did cohere as a group, did have a clear sense of how to act, and actually that reversed the power relations in our study.”
The revisited experiment, although made for TV, was designed as a scientific study, Reicher said.
“We took it through a scientific ethics committee,” he added. “We designed it as we would any other study. We didn’t just film what people did, we did surveys every day. We even took hormonal data.”
However, even though the prisoners came together to create a more equal system, they could not truly control what was going on: “So they felt more and more helpless, and they became more and more attracted to a strong man, to authoritarianism,” Reicher said. “What we found was that the failure of groups to be able to control their own environment makes them attracted to authoritarian regimes, which I think is actually quite an important message given what’s going on in the world today.”
Zimbardo’s construct that a bad situation can make a good person do evil things, Reicher said, is dangerous: “When you look at examples of brutality in history, afterwards those responsible nearly always try to deny accountability. The excuse is they were only following orders, they couldn’t help it,” he said. “The explanation given by Zimbardo is not only scientifically wrong; it is socially and morally dangerous because it gives perpetrators an out.”
Questions about prisoner abuse and accountability took on renewed urgency in 2004, when photographs of US soldiers and Iraqi detainees at Abu Ghraib, a prison outside of Baghdad, shocked the world. The images prompted comparisons with the Stanford experiment and Zimbardo became a prominent commentator on the Abu Ghraib scandal, arguing that the abuses could not be understood solely as the actions of a few individuals.
Zimbardo even testified for the defense of an Abu Ghraib guard, and his observations coalesced into a 2007 book titled “The Lucifer Effect: Understanding How Good People Turn Evil,” in which he wrote, “Any deed that any human being has ever committed, however horrible, is possible for any of us — under the right or wrong situational circumstances.”
The renewed popularity of the experiment led, in 2015, to a Hollywood movie starring Billy Crudup titled “The Stanford Prison Experiment,” which included Zimbardo as a consultant and largely adheres to his own version of the events.
A frame from “The Stanford Prison Experiment,” a 2015 Hollywood movie with actor Billy Crudup (first from left) playing the role of Philip Zimbardo.
The fiercest critique of Zimbardo’s work showed up shortly after, in 2018, when Thibault Le Texier, a French historian and associate researcher at the Centre for European Sociology and Political Science in Paris, first published a French-language book about the experiment, then summarized it in a 2019 study titled “Debunking the Stanford Prison Experiment.”
Le Texier reconstructed the experiment’s entire timeline after spending weeks analyzing archival material such as recordings and transcripts at Stanford University.
“From the very beginning, the Stanford Prison Experiment was organized and planned as a show,” Le Texier told CNN. “It was more theater than science.”
Le Texier also said that while Zimbardo admitted to giving the guards broad directions, in reality either Zimbardo or his associates instructed them very specifically about how to behave during the experiment — so much that the guards were given “a blueprint” on how to act.
“They’ll have no privacy at all, there will be constant surveillance—nothing they do will go unobserved,” Zimbardo said during a guard orientation session captured on video. “They will have no freedom of action. They can do nothing and say nothing that we don’t permit. We’ll take away their individuality in various ways.”
Zimbardo’s apparent influence dashes any hopes scientists might have of gleaning firm conclusions from the Stanford prison Experiment, Le Texier added. “The only scientific conclusion you can draw is a reminder that scientists can do really bad science,” he said.
A detainee at Abu Ghraib prison, later correctly identified as Abdou Hussain Saad Faleh, standing on a box with wires attached.
According to Le Texier, Zimbardo intentionally made it difficult for prisoners to leave the experiment even if they asked to do so, and created uncomfortable living conditions for them: “They couldn’t read, they couldn’t watch TV, they couldn’t go to the toilets at night, they had absolutely nothing to do during the day, the conditions were harsher than even a real prison, simply because Zimbardo was scared that if the prisoners had a good time nothing would happen, and the experiment would be a failure,” Le Texier said.
In 2018, Zimbardo published a lengthy responseto criticism of the experiment — including that of Le Texier — in which he defended the experiment’s methods, arguing that participants could leave and that the guards’ behavior was not scripted. Le Texier rejects the response as “bulls**t,” saying that, while it served to “praise the experiment,” it did not address his criticism specifically.
The frequent parallels between the experiment and theatrical productions eventually drew the attention of Stephen Scott-Bottom, a professor of contemporary theater, drama and film at the University of Manchester.
“My first interest was thinking of it as a constructed situation where people are being asked to play roles,” he said. “If you ask people to role play in a scenario, and then get a different group of people to play that scenario again, you’ll end up with completely different results, depending on the particular combination of personalities.”
Zimbardo and his colleagues, Scott-Bottoms argued, wanted to emphasize the importance of the situation, so they downplayed the importance of individual personalities.
For a study about the experiment he published in 2020, Scott-Bottoms tracked down and interviewed several of the guards and prisoners, including the inmate whose apparent breakdown, about 36 hours into the study, became one of its most famous episodes: “The first emotional breakdown that you hear about in all the documentation was faked, by a guy who was just trying to get out,” Scott-Bottoms said.
The prisoner in question, Doug Korpi, had also admitted that his agony was an act to journalist Ben Blum, who included the revelation in a broader takedown of the experiment published in 2018. Korpi wanted to leave the experiment because he wasn’t allowed to study for an upcoming graduate school admission test, and was getting worried about being unprepared.
Zimbardo’s role in the prison, Scott-Bottoms said, was focused on preventing the experiment from stagnating: “I regard him as a media artist as much as a scientist,” Scott-Bottoms said. “He was very good at finding an angle or a hook to get your attention, so that you’ll listen to the thing that he really wants to talk about, rightly or wrongly.”
Philip Zimbardo poses for a portrait in his home in San Francisco in 2015.
Just a month after Zimbardo died in October 2024, a three-part documentary titled “The Stanford Prison Experiment: Unlocking the Truth”premiered on the National Geographic channel.It included one of Zimbardo’s final interviews.
In the documentary, several of the guards and prisoners from the original study challenge Zimbardo’s account of the event, and refer to him as “a salesman,” “kind of a clown,” “a huckster,” while repeatedly using the word “fraud” in association with the experiment.
Dave Eshleman, who emerged in the mock prison as the most ill-tempered among the guards — earning himself the nickname “John Wayne” — goes as far as calling his role within the experiment “an acting job,” and speaks of “getting in character” before entering the prison. He says Zimbardo made it appear as though the guards were not considered to be subjects in the experiment: “If it was made clear to us that we were there to be studied, not to help study prisoners, we would have acted completely differently,” he said.
In his interview, Zimbardo responds to these accusations by saying that Eshleman and the others had to justify what they did, and the easiest way to do that is to say they were acting. They could also no longer distinguish “the improv from real sadistic impulses,” the psychologist added. The fact that everybody fell into their roles, Zimbardo said, speaks to “the validity of the experiment.”
He also made no secret about the experiment’s theatrical nature: “I thought about the experiment as an improvisational drama — the basement yard, it was the stage, the actors were prisoners and guards with different uniforms and the video camera was the audience.”
The 30 participants in Netflix’s show wait to be assigned a role in the prison upon their arrival.
The show was filmed in a decommissioned section of the Cherokee County Adult Detention Center in Canton, Georgia.
The new Netflix show “The New Stanford Prison Experiment” — which was filmed in a real prison and consists of six 45-minute episodes — is not structured like the original at all, and its creators aren’t trying to conduct a scientific experiment.
“If we were simply recreating the original experiment, that would be unconscionable,” said Jane Lipsitz, the show’s executive producer, statement. “But this is a different time, with different participants, different safeguards and, ultimately, a very different journey.”
“It felt like the right time to revisit that question with a new generation and ask whether power inevitably changes us — or whether we’re capable of resisting the roles, the rules and the systems we’re placed into. What we discovered during this process was something we never saw coming,” she added.
The producers of the Netflix show said they put “several guardrails” in place to protect participants, including psychological screenings and the ability to leave at any moment just by uttering a safe word. The 30 people — including three women — involved also make up a far more diverse group than either the original study or the BBC’s work.
In the Netflix show, guards perform a “drill” in riot gear, and the inmates are handcuffed while on the floor.
Netflix
The guards are split into two groups and do receive an initial training, during which they are told to “take control.” But in stark contrast with the BBC revisitation and the requirements of a scientific experiment, the Netflix show is heavily structured and introduces radical changes to its setup as it progresses — with entertaining, if unrealistic, results.
Even half a century on, there are still interesting aspects of the original Stanford experiment, despite its flaws, Reicher noted. The new show is perhaps testament to that.
“The study is still in the textbooks. There are also still people who reject it entirely. And there are others who say there are things to learn from it, specifically about the role of leadership,” Reicher said. “In the end, in any study, you don’t describe everything. You describe what you think is important.”
