You don't need a psychology degree to have heard about the Stanford Prison Experiment.

The famed research-endeavor-turned-nightmare earned ample publicity after it concluded in August 1971. By design, Stanford psychology professor Philip Zimbardo left 24 college-age males locked in the university's basement for six days, posing as prisoners and guards. In evoking apparent emotional trauma, he claimed to have demonstrated a new psychological truth: That evil-doing stems from situation and authority, not one's morality or personal characteristics.

That principle has been an immovable fixture of psychology textbooks and legal defenses— not to mention the pop culture canon — ever since.

Turns out it could be wrong.

In his sharply reported article, "The Lifespan of a Lie," Ben Blum lays out why the Stanford Prison Experiment and its supposed conclusion could be bogus.

In reporting based on recent interviews and newly-released documents, Blum explains that Zimbardo and his assistants essentially choreographed much of the behavior, therefore "fostering exactly the pathological behavior that Zimbardo would later claim had arisen organically." In an interview with Blum, one of the inmate participants revealed that his much-cited breakdown was merely acting on his part. Another revealed that Zimbardo had encouraged the guards to act aggressively.

According to Blum, Zimbardo knowingly hid these aspects of the experiment for years, maintaining tight control over the narrative, and ultimately allowing the project to become thoroughly and incorrectly enmeshed with our perception of human nature.

We talked to Blum about what he found, why it matters and what we should think about the experiment going forward.

What motivated you to start looking into this?

I'd always been aware of the Stanford Prison Experiment in the kind of vague way that I think a lot of people are aware of it. But my first personal contact with Zimbardo came as he became involved in the legal defense of my cousin, Alex Blum, who participated in an armed bank robbery carried out by a team of army rangers in 2006. He was a 19-year-old teenager at the time, and he explained to my family that he thought the whole thing was a training exercise carried out by his superiors. [Blum wrote about the experience in his 2016 book, Ranger Games.

I read Zimbardo's book The Lucifer Effect then. I found it immensely helpful with trying to understand someone who I knew to be of good character — an idealistic, patriotic guy who always wanted to be an army ranger and then was involved in behavior beyond the pale of what our family considered him capable of. I was completely onboard with Zimbardo's research.

And then things started to get a little weird. Alex confessed to me that he had known more about the crime then he had let on before. It was indeed pitched to him as a training exercise, but by the time the bank robbery happened, he knew that it was the real deal. He lacked the courage to back out.

That was the moment my kernel of doubt appeared. I wondered how much explanatory power the Stanford Prison Experiment really had. It began to seem simplistic to give situational factors so much primacy in explaining why we do what we do, in explaining evil actions.

I stared reading a little more. The big turning point came when I watched the feature film in 2015 and noticed a few key departures from the factual event as I understood it.

To be clear, that film was a fictionalized telling, right?

It was — that's important to note. For me, it raised some interesting questions about what extent departures from a historical record are justifiable in a retelling of a scientific experiment versus a historical drama or biopic. There seems to be a different standard of truth than the standard that we apply to history.

I was curious to what narrative end these factual departures served. So I went back to Zimbardo's book and began mapping it out. I was shocked to discover a whole other story of the experiment lying just under the surface of the rhetorical devices that Zimbardo has been using for a long time to obscure it.

And then I gradually began reaching out to former subjects, finding that their accounts supported this alternate narrative. Many of them were quite upset with the use that Zimbardo had made of their story. They felt their experiences had been misrepresented over the years.

It all kind of snowballed from there for me.

Your article references the work of Thibault Le Texier. (A french filmmaker and academic, Le Texier's Histoire d'un Mensonge, "History of a Lie," was published this April. It includes newly released archival material with revealing details about the experiment.) How did his work inform yours?

Le Texier deserves a ton of credit. But I'd actually reached my conclusion independently of him. I was first starting to pitch a piece about this about a year ago, and as I started interviewing more and more people, I started hearing, "Hey, I just spoke to this French guy." He and I have been in communication ever since.

The final moment that really clicked it in for me was when I talked to Zimbardo. I was able to interview him about Le Texier's findings, which Le Texier himself was not able to do.

As Zimbardo changed his story over the course of the conversation, I realized these were more than just slips of the tongue.

I'm curious why the prisoners and participants didn't come forward sooner.

I think we're seeing these dynamics play out in a number of different arenas right now. Powerful figures are able to control a narrative for years because the people that have been adversely affected don't know each other and aren't able to synthesize their experiences in order to change the narrative. There were a lot of individual voices out there, but they weren't uniting.

There also wasn't yet a strong alternative scientific explanation for the truly awful things that happened in the Stanford Prison Experiment. I think new research by Alex Haslam and Stephen Reicher (who performed a similar experiment in Great Britain in 2001) is very important in this regard, giving us a scientific way forward.

The experiment has been used to give us some comprehension of tragically cruel phenomena — everything from the Holocaust to ISIS. Do we know less about the psychological factors at play than we thought?

I do think we need to rethink our understanding of almost everything the experiment has been used to explain.

The findings offered a very simplistic view of the nature of human wrongdoing. The experiment implied that evil is lurking in all of us, just waiting for us to put on the right clothes and be given power to express itself — waiting for a situation. And 'situation' is defined in this very limited psychological way as the kind of thing you can create in a lab from scratch.

I think the implications of Haslam's and Reicher's research do a better job of accounting for some of the things that the Stanford Prison Experiment used to be offered to explain. The basic theory is that we are more prone to follow orders when we identify with the leader who seems to share our values and frames those orders in the language of our shared values.

Do you blame Zimbardo for our false understanding?

I think certainly there was a hunger in the culture for the story Zimbardo was telling, but, yeah, Zimbardo is a master storyteller. He's devoted an enormous amount of resources over the years to promoting this narrative.

There was the documentary, Quiet Rage, in the mid-80s. There was the PBS documentary series, Discovering Psychology. There was the book, The Lucifer Effect. He spent something like 20 years trying to get a feature film made about it.

And he's also been involved in several legal cases over the years, invariably defending someone who's done terrible things within an institutional setting. The most prominent of those being Ivan "Chip" Frederick, the non-commissioned officer in charge of the guys who committed the Abu Ghraib abuses.

You mention the public sort of hungered for this story — what was it about the takeaways from the experiment that we so wanted to believe?

I think the most seductive feature of the Stanford Prison Experiment is its ability to diffuse away all moral accountability.

The people who commit abuses aren't accountable because they were just slipping into a role. The people who are giving the orders aren't accountable because they too were just slipping into a role. And then the people who are being abused have no agency to better their situations because they are equally a victim of circumstance.

And that message is very convenient. If you feel powerless in the face of institutional forces larger than yourself — as everyone does at one time or another — there's a personally seductive explanation and politically seductive explanation.

Also, it's just a cracking good tale. A mock prison was built in the basement of the Stanford psychology department. I mean, how crazy is that? What we've realized now is that these prisoners were really led to believe that they couldn't escape this nightmare experiment that they were trapped in. It was even worse than the story made it out to be for so many years.

What kind of reaction have you gotten from the public?

I've been a little overwhelmed by the response. Quite a lot of psychology professors and sociology professors have been discussing the article on twitter, calling for the experiment to be removed from textbooks. There's discussion about the new research by Haslam and Riecher.

It's been very encouraging. I had my doubts that anything could topple this narrative at this point.

Is your article a cautionary tale about our willingness to accept scientific research?

Psychology is in the midst of a replication crisis, and I think these new revelations about the Stanford Prison Experiment can't help but lend to the argument that we need to be more careful. We need to be more scrupulous in trumpeting the data from psychological experiments.

But I really do not want this to be seen as some kind of referendum on the field of psychology. I think we're learning important new things about human nature, and I don't think the Stanford Prison Experiment was conducted in fully bad faith. I think Zimbardo was genuinely interested in how institutional forces shape human behavior.

And there still is really interesting stuff in that data. Part of what's so exciting about the narrative cracking open is that it's giving us a fresh look at what really happened in an experimental setting that can't ever be repeated for ethical reasons.

So people should not lose faith in science. Forces can prevent us from being as questioning as we should about canonical experiments. But the progress toward truth keeps marching along.

This interview has been edited for length and clarity.

In response to Blum's piece, Zimbardo published a 26-page defense of the experiment. Among his detailed criticisms of Blum's article, Zimbardo alleges:

• There's evidence to show the prisoners and guards weren't faking it.

• The British experiment by Alex Haslam and Stephen Reicher is not scientifically valid.

• He worked to make archival material public over the years and kept nothing hidden.

• The underlying takeaway of the SPE is not that perpetrators should be absolved of their sins, but that "preventing undesirable behavior of individuals or groups requires an understanding of what strengths, virtues, and vulnerabilities that they bring into any given situation.

• Read Zimbardo's 26-page response written to recent criticisms of the Stanford Prison Experiment here.

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