The Stanford Prison Experiment is a famous psych experiment performed by Philip Zimbardo where volunteers were split into groups of "guards" and "prisoners". While both sides knew it was fake, they quickly began treating it as though it was real, with both groups spontaneously falling into their "roles". The "guards" (and researchers) quickly became abusive and sadistic, while the "prisoners" attempted to riot and showed symptoms associated with long-term incarceration.
Eventually, when Christina Maslach, a graduate student asked to conduct interviews with the test subjects, objected to the appalling conditions of the experiment (Zimbardo would later notice that out of the 50 people who had observed the experiment, Maslach had been the only one who initially questioned the morality of it), Zimbardo realized that not only had the situation begun to spin rapidly out of control, he himself had also unintentionally assumed a role of his own and was starting to act more as a warden than a researcher, leading him to decide that the experiment had to be stopped. And so the entire experiment was shut down after six days (it was originally planned to last two weeks), and is often used as an example of psychological research that cannot be repeated due to ethical concerns.
While many people know of the experiment, few realize how little it proves. The experiment was tainted by a combination of selection bias, insufficient controls, a small sample population, various methodological flaws, and not noting the personalities of guards before the experiment began (there was no attempt to discern if an evil guard was always sadistic, or only became sadistic during the experiment). Zimbardo dedicated much of his career to the promotion of the idea that bad environments drive bad behavior, and it's no coincidence that this study proved exactly that.
This scenario plays out on many reality TV shows. People in a staged environment start acting as though it were real, usually with dramatic changes in personality.
It is also an easily recognized plot premise for any kind of storytelling.
- German movie Das Experiment, which recreates the original Stanford experiment - but goes further. Things don't end well.
- The American remake of Das Experiment, The Experiment, pretty much says Humans Are Bastards.
- The 2015 film The Stanford Prison Experiment, dramatic reenactment of the original event.
- When I Was Ming the Merciless by Gene Wolfe invokes this trope, apparently being set in the aftermath of a particularly brutal large scale version of the experiment in a school. While the Stanford experiment is never mentioned, it is Wolfe's style to expect his readers to be familiar with it.
- The Overstory: Douglas Pavlicek participated in the original experiment during his youth, helping to shape him as a person throughout the rest of his life as he's haunted by how much of a useless bystander he was.
- The Colony: This show has a psychology expert who frequently describes how the fake postapocalyptic scenario is being treated as real by the contestants. For the credit of the show, it was very immersive in nature, up to the point where malnourishment and severe exhaustion became a norm for people in it, further reinforcing the scenario as "real".
- Veronica Mars: One episode had a psychology class running the Stanford Prison Experiment in Veronica's university, though it doesn't turn out quite the same way. While the "Guards" quickly assume their roles, the "Prisoners" manage to use their brains to mess with the "Guards".
- Episode "Debate" had Jeff referencing this very trope to argue that "man is evil".
- Episode "Beginner Pottery" involved several of the cast members taking a week-long sailing course. The sailboat was in the parking lot, but that didn't stop them from abandoning someone who fell overboard because that's what the teacher wanted.
- Life: In an episode, the Victim of the Week was a "guard" in one of these. The professor who was running it did it every semester for 5 days using college students.
- Sabrina the Teenage Witch: One episode had her class simulate the Salem Witch Trials and of course Sabrina ends up getting persecuted by her classmates, led by the Alpha Bitch. In the final twist, while the "witch" role was supposedly non-existent (the whole point of the simulation, the teacher said, was to prove the paranoia of the Salem trials), Sabrina finds her assigned role's paper in the final seconds of the episode (losing it is what allowed Libby to exploit the paranoia to pester her)... and sure enough, it says "witch".
- Star Trek: Voyager: In a possibly related example, The Doctor attempts to learn about family relationships by creating a home life in the holodeck with a holographic wife and kids. He ends up getting really emotionally invested in it, to the point where when his holo-daughter dies, he's absolutely heartbroken.
- One season 8 episode of Castle played this completely straight - a local psychology professor, with the help of the US military, was running an unauthorized dungeon/torture chamber with students playing both parts. It's discovered when one of the students is murdered trying to escape.
- Fallout: The Vaults were meant to provoke a Stanford Prison type of environment. Each with their own means of starting an experiment.
- Half-Life 2:
- It's revealed that the lower levels of the Combine forces, "Civil Protection" are completely unmodified humans, who initially join for the added rations and other benefits. The position of power, anonymity and access to stun-sticks does the rest of work turning them into a bunch of sociopathic thugs.
- The beta took this one step further: there would have been an arcade, wherein the NPC players controlled manhack drones hunting down refugees. The citizens are just too apathetic to care.