It's probably the most famous psychological experiment ever to come out of Stanford University. Now, 50 years later, critics are saying the entire thing was "a fraud."

If you took a psychology class in college, I guarantee you studied this one. If not, you've heard of it. And, its findings have been trumpeted before members of Congress and other policymakers for years.

But what if the entire thing was a sham?  

Below, we'll describe the experiment, its impact, and why it's suddenly become highly controversial to the point that critics are throwing around a word they rarely have the courage to use: "lie."

The Stanford Prison Experiment

The year was 1971, and a Stanford professor named Philip Zimbardo recruited graduate students to play the roles of inmates and guards in a mock jail. The experiment was supposed to run 14 days, but it was reportedly shut down early when both jailers and the jailed began to take their roles too seriously.

Ultimately, the Stanford Prison Experiment became very widely known, and it was used to demonstrate that people who are given power will often naturally abuse it, and that people who have all power stripped from them will often fall into despair, regardless of circumstances.

Now, it's facing withering criticism. As Vox put it in a summary recently, the Stanford Prison Experiment's "findings were wrong. Very wrong. And not just due to its questionable ethics or lack of concrete data -- but because of deceit."

'The Lifespan of a Lie'

The study has been controversial over the years, but the recent focus is the result of the work of a Ph.D and journalist named Ben Blum. Among his findings, based on recently found footage and audio recordings, along with a French filmmaker's work on the subject, Blum says:

  • A "prisoner" who famously had a breakdown after hours in fact was just fine--but acting--as he admitted in an interview with Blum last summer.
  • "Guards" who supposedly began acting sadistically of their own accord (basically the entire main takeaway of the experiment) had in fact been coached and told to be mean.
  • "Guards" who  supposedly came up with their own strict rules for the prisoners, in fact copied them from an earlier, much shorter "fake jail" experiment--or learned them from a former San Quentin inmate who served as a consultant on the project.

"The most famous psychology study of all time was a sham," Blum wrote in his more than 7,000-word expose, published on Medium, entitled, The Lifespan of a Lie. "Why can't we escape the Stanford Prison Experiment?"

Okay ... But why lie?

Before we go further, we need to disclose a weird circumstance that explains how Blum came to look at Zimbardo's work. It turns out that Blum is the cousin of a former U.S. Army Ranger named Alex Blum, who was arrested and convicted of bank robbery in 2009.

Alex Blum received an extraordinarily lenient sentence, partly based on the expert testimony of an expert witness psychologist. That expert witness's name? You guessed it--Philip Zimbardo.

You might call this a conflict of interest--except for the fact that the target of Ben Blum's investigation is same person who helped his cousin, and Blum's report is anything but helpful to Zimbardo. 

It truly is a damning takedown. Blum says he uncovered video and audio evidence that completely many of undermines Zimbardo's claims--even his testimony before Congress.

All of which leaves an obvious question: Why lie?

Why would Zimbardo embellish his study's findings; why would participants go along with it?

Blum's explanation for this largely comes down to the most pedestrian reasons.

Students playing the roles of guards and prisoners were worried about things like getting into graduate school, he says, and simply played along. 

And Zimbardo himself wasn't prepared for the impact his experiment would have--in part because a national dialogue about prison conditions that was sparked at exactly the same time as his experiment, Blum claims.

In short, nobody involved thought it would be remembered or cited for as long as it has. After interviewing Zimbardo, Blum seems to conclude that the experiment became the psychologist's life's work, did so almost in spite of him--and that defending it is exhausting for him.

"After my talk with you, I'm not going to do any interviews about it. It's just a waste of time," Blum quotes Zimbardo as saying. "It's the most famous study in the history of psychology at this point. ... I'm not going to defend it anymore. The defense is its longevity."