Revisiting the Stanford Prison Experiment 50 years later (2024)

In 1971, Stanford University psychologist Philip Zimbardo conducted a notorious experiment in which he randomly divided college students into two groups, guards and prisoners, and set them loose in a simulated prison environment for six days, documenting the guards' descent into brutality. His findings caused a media sensation and a lot of subsequent criticism about the ethics and methodology employed in the study. Zimbardo died last month at 91, but his controversial legacy continues to resonate some 50 years later with The Stanford Prison Experiment: Unlocking the Truth, a new documentary from National Geographic.

Director Juliette Eisner started working on the documentary during the pandemic when, like most people, she had a lot of extra time on her hands. She started looking at old psychological studies exploring human nature and became fascinated by the Stanford Prison Experiment, especially in light of the summer protests in 2020 concerning police brutality. She soon realized that the prevailing narrative was Zimbardo's and that very few of the original subjects in the experiment had ever been interviewed about their experiences.

"I wanted to hear from those people," Eisner told Ars. "They were very hard to find. Most of them were still only known by alias or by prisoner number." Eisner persevered and tracked most of them down. "Every single time they picked up the phone, they were like, 'Oh, I'm so glad you called. Nobody has called me in 50 years. And by the way, everything you think you know about this study is wrong,' or 'The story is not what it seems.'"

Her original intention was to debunk the experiment, but over the course of making the documentary, her focus shifted to the power of storytelling. "Even when stories are riddled with lies or manipulations, they can still capture our imaginations in ways that we should maybe be wary of sometimes," Eisner said, particularly when those stories "come out of the mouth of somebody who is such a showman, such an entertainer."

The documentary's structure reflects Eisner's research journey. The first episode ("The Hallway") focuses on the standard account of the experiment that has dominated for the last 50 years. The second ("The Unraveling") focuses on subsequent criticisms and debunkings and the accounts of original participants, many of whom have rather different takes. The third episode ("A Beautiful Lie") brings the original participants to Los Angeles for a re-enactment with professional actors and includes an interview with Zimbardo himself.

"We grappled with the structure and how to let the story unfold and decided, let's tell the audience what they think they know, and then let's take it apart," said Eisner. "And then a surprise twist, let's give you a different look at it and let the man at the center of it all defend the experiment against these claims. It was really important to me to have all these perspectives be heard, and not just one person's story as it had been for the past 50 years. Everybody had a different take on this experiment, even though they all lived it together."

For the re-enactment, NatGeo commissioned a set based on the floor plans of the Stanford basement where the original experiment was conducted. "We really needed visuals to help bring a lot of these stories to life," said Eisner. "Despite the fact that Zimbardo says he filmed the whole thing, he really only filmed six hours over the course of six days. So we needed that visual toolbox, but then it also allowed us to play with these different perspectives."

A controversial experiment

Zimbardo's research involved de-individuation and dehumanization in the context of what drives people to engage in antisocial and/or brutal acts that they would normally find morally repugnant. He designed the Stanford Prison Experiment specifically to investigate the power of roles, rules, group identity, and "situational validation of behavior." He recruited the participants via help wanted ads in the local newspapers and selected 24 young men from the 75 who applied. All were screened for criminal backgrounds, psychological problems, and physical health.

The experiment was conducted in the basement of Jordan Hall. A small corridor served as the prison yard; a janitor's closet was used for solitary confinement ("the Hole"); there were several mock prison cells designed to hold three prisoners each with cots, mattresses, and sheets; and a bigger room housed the guards and the prison warden (Zimbardo's undergraduate research assistant David Jaffe). The guards worked eight-hour shifts and were allowed to leave the site; prisoners had to remain 24/7.

The experiment officially kicked off when the Palo Alto police conducted mock arrests of those participants designated as prisoners—something the latter was not told would happen and a breach of ethics. After being booked, fingerprinted, and sitting for mugshots, they were strip-searched and made to wear smocks with no underwear and stocking caps on their heads. Over the next six days, the guards psychologically tormented their charges with sleep disruption, spraying rebellious prisoners with a fire extinguisher, removing mattresses as punishment, forcing prisoners to drop for pushups, restricting bathroom access so that prisoners had to relieve themselves in a bucket in their cells, and so on—all accompanied by constant verbal abuse.

After 36 hours, it became too much for a prisoner named Doug Korpi ("Prisoner 8612"), who had been tossed into the Hole for insubordination. He underwent what seemed to be a mental breakdown, causing him to be released early from the experiment. On Day 5, friends and family were allowed to visit for 10 minutes; those visits were sufficiently upsetting that several parents intended to contact lawyers to get their children released from the experiment. Zimbardo's fellow psychologist and then-girlfriend, Christina Maslach, also visited the setup and was so appalled she sharply chided Zimbardo for his lack of oversight and called the experiment immoral. Zimbardo decided to end the experiment on Day 6.

One positive outcome was that the Stanford Prison Experiment led US universities to overhaul their ethical requirements for any experiments involving human subjects. But many researchers were troubled both by the methodology and the simplicity of Zimbardo's interpretations. French researcher Thibault Le Texier has been among the strongest critics, pointing out that many of Zimbardo's conclusions were written out in advance, and the experiment was carefully manipulated to produce the results Zimbardo wanted. Zimbardo dismissed Le Texier's work as an ad hominem attack that ignores any contradictory data, but the original participants interviewed for the NatGeo documentary largely confirmed many of Le Texier's claims.

Playing to the camera?

Former prisoner Clay Ramsay, for instance, replaced Korpi in the experiment and quickly became disillusioned with the situation. "It had no intellectual integrity at all," he told Ars, noting that this was particularly obvious during the staged parole board hearings the prisoners were forced to participate in. "They clearly didn't have any kind of common script," he said. "So I came up with the idea of a hunger strike, and then most of my behavior was doing nothing. It turned out to be more dramatic than it had to be."

He ended up tossed in "the Hole" for his insubordination, but rather than being traumatized, he took advantage of the isolation to grab some shut-eye to make up for all the sleep deprivation. "It's supposed to be this major penalty, then it's the only place where you can get a night's sleep in the whole joint," he said.

While Zimbardo has repeatedly insisted over five decades that he simply put college kids into a situation with little guidance and just let things evolve, that's not entirely true. The guards, most notably, participated in a lengthy training session that lasted several hours, in which they were given a daily schedule for the prisoners and tips for inflicting psychological pain, starting by referring to prisoners by number rather than name as a means of dehumanizing them.

Zimbardo also occasionally allowed members of his research team to go into the experimental environment; there is even audio of research assistant David Jaffe coaching a reluctant guard and urging him to be tougher in his treatment of the prisoners. This led many of the guards to assume they were not part of the actual experiment but were in league with the researchers.

"It was made very clear to us that we not part of the experiment," former guard Dave Eshleman told Ars. "We were there to help the researchers get the results from the prisoners that they wanted to see. So our job was to make them uncomfortable, give them a sense of fear, but not to use physical violence. We could do everything else within our power to create that fear, and I took that very seriously, because I was on board with what they were trying to do: expose the prison system as evil. Given the zeitgeist at the time, we were all on board with that. Those were the days when anybody with the establishment was automatically evil, and what more evil part of the establishment could there be but the prison system?"

There are also valid questions about whether or not the prisoners' behavior was truly authentic. Doug Korpi later claimed he faked his mental breakdown in the Hole, having become disillusioned with the study. He had thought it would give him some downtime to study for the Graduate Record Exam, but the guards wouldn't allow it. So he staged a breakdown to secure his release.

Korpi was not alone in this. Despite being the poster boy for the guards' collective brutality, "I was absolutely playing for the camera," said Eshleman. "I knew where the camera was, I knew that it was on most of the time, I could hear the researchers talking behind the wall. I was also an acting student and did a lot of improv exercises. So I treated this is an improv, and I created my character based on what my understanding was of what the researchers wanted from us." He based his character on Strother Martin, the fictional evil prison warden from Cool Hand Luke (1967); Eshleman even occasionally spoke actual lines from the film, and his antics earned him the moniker "John Wayne."

Ramsay's experience as a prisoner was a bit different. "I don't think any of the prisoners were conscious of the camera, honestly," he told Ars. "We were not entirely sure where it was, we thought we saw it sometimes. But we were not getting regular instructions, we were being fed badly, clothed badly, et cetera. In a situation like that, what the camera angle is, it's the least of your worries."

In retrospect, the Stanford Prison Experiment may have more in common with reality TV; the industry term has evolved into "unscripted" TV because of the countless ways the final product is manipulated and shaped over the course of filming. Zimbardo even admits as much in the documentary, calling his experiment "the first ever reality TV show."

Controlling the narrative

Zimbardo's version of events has long dominated the prevailing understanding of the Stanford Prison Experiment, even though some of the original participants have frequently tried to counter that narrative; their voices just never held as much sway. While Eshleman has participated in many media interviews over the ensuing decades, he said that much of his commentary was often edited out in favor of Zimbardo's preferred narrative.

For his part, Zimbardo has said repeatedly that Korpi, for instance, was lying about faking his breakdown, pointing to the fact that Korpi became a prison psychologist because of how deeply the experiment affected him. Zimbardo also denies in the NatGeo documentary that Eshleman was acting for the duration of the experiment; his interpretation is that this is how Eshleman rationalized his behavior and dealt with the guilt.

"I think I knew if I was acting or not," Eshleman countered. "How could he not even consider the possibility that not just I, but everybody in his little demonstration was acting, that we simply fell into roles that were expected of us, to be paid $15 a day? That's what galls me. He kind of decided to throw us [the guards] under the bus after directing us to do what he wanted. Maybe he never took an acting class. Those of those in the theater department are always acting in some way." In fact, the basic scenario of the Stanford Prison Experiment has found its way into many improv classes as an exercise prompt.

"I was very fortunate that Zimbardo never really got into characterizing me," said Ramsay. "But for Dave and two or three of the others, he did. He put labels on them, ascribed motivations, and went, 'I'm a professor of psychology at Stanford University. Are you going to listen to me or to them who are driven by unconscious needs?' A lifetime of that is really insulting."

Eisner admitted that her experiences making the documentary produced some complicated feelings about the Stanford Prison Experiment. "I think that it's absolutely clear there was no scientific methodology," she said. "The data was all over the place, if you can even call it data. I think it's wrong to frame it as such. But do I think the big picture questions it asks are not true, that power does not corrupt? No, I don't think so. I've spent far too many years working on documentaries about fraud and felonies not to know that power can corrupt. But I do think it's dangerous to call to a faulty experiment in order to try to prove those things."

"I really do think there was nothing genuinely malicious in what Zimbardo was doing," said Eisner. "I wish he had been more forthcoming about certain things that he definitely glossed over. But is the experiment important? Absolutely. I love that it has this life 50 years later where now we're looking at it and re-contextualizing it in a way that is totally different from back when he actually did the study."

Ramsay and Eshleman are less charitable in their assessments. "This was the chosen vessel of Zimbardo's ambition and his extraordinary PR skills," said Ramsay. "Because that was his real gift, much more than academic research. He could drive a story, and this was the one that made his career. It gave him fame and notoriety at the same time. It's a package that he drove over the needs, requirements, and values of everybody else involved throughout his life."

"He was not somebody we felt we could question at the time," said Eshleman. "It was only later that I looked back and said, 'It was good theater, but it was not good science.' There were no controls. The conclusions that supposedly came out of this, I thought were completely faulty. The whole concept that 'Oh, we just take these innocent young kids and put them in this evil environment and suddenly they do these evil things.' That's been the narrative for 50 years, and it's BS."

Perhaps the most valuable thing to come out of the documentary project was the re-enactment, which reunited the original participants for the first time in 50 years. They were able to rehash their experiences, mend some fences, and interact with the actors playing them. Eshleman even apologized to Ramsay during the reunion for his actions during the experiment. "I sincerely meant that," he said. "I would feel terrible if anybody actually suffered any damage as a result of this big play acting that we did. I wasn't aware of it at the time."

"All of us were manipulated to an extreme but in really different ways; that's why it was all so dramatic," said Ramsay. "So the things that we ascribed to each other in the experience, it's all entangled. You can't say that any one person did this. I do think that Zimbardo was wrong. There's always an underlying moral possibility that you could always choose to do something different the next day. You can act better tomorrow."

The Stanford Prison Experiment: Unlocking the Truth is now streaming on Disney+.