The Stanford Prison Experiment Was Coached, According to the Tapes

Phil Zimbardo's 1971 prison simulation in the basement of Stanford's psychology building has been one of the most cited results in social psychology. Twenty-four students, randomly sorted into "guards" and "prisoners," were said to have spontaneously generated a brutal dynamic in days. The standard reading: ordinary people, given roles, will behave abominably.

That reading has not held up under recent scrutiny. In 2018 the French researcher Thibault Le Texier published Histoire d'un Mensonge, a book-length reanalysis based on materials Zimbardo had deposited in the Stanford University Archives. Le Texier listened to the original audiotapes and read the staff briefings.

What he found contradicts the spontaneous-cruelty story. Guards were not left to invent their behaviour. In a recorded briefing, the warden — Zimbardo's research assistant David Jaffe — explicitly told them to be tough and to make prisoners feel powerless. Several guards on tape resisted; one was pressured to play the role more harshly. The famous breakdown of "Prisoner 8612," presented for decades as a stress reaction, was later acknowledged by the prisoner himself, Douglas Korpi, as partly performance to get released early.

A 2019 article in American Psychologist by Texas State's Stephen Reicher and St Andrews' Alex Haslam, drawing on Le Texier's archive work, called the study "unsalvageable" as evidence for situational evil. The British Psychological Society and several major textbooks have since either dropped the study or rewritten how it is presented.

Zimbardo, who died in 2024, defended the study to the end. The reinterpretation does not vindicate cruelty; it just relocates it from the participants to the experimenters.