The Stanford Prison Experiment Might Be The Most Disturbing Study Ever Conducted

In August 1971, psychology professor Philip Zimbardo led an experiment in the basement of Stanford University's Jordan Hall. The Stanford Prison Experiment, as it is now known, was supposed to investigate power dynamics and relationships in a prison setting. Using mock prisoners and mock guards all played by college-aged men, Zimbardo sought to find out if power makes people brutal and sadistic or if those qualities are intrinsic to human nature. 

Explaining human behavior isn't easy and the results of the experiment revealed much more than Zimbardo or any of the 24 participants could have imagined. Over the course of six days, the experiment spiraled out of control, resulting in psychological and ethical findings that remain controversial among psychologists today. 


  • Students Were Offered $15 Per Day To Participate In A Study About Prison Life
    Photo: Teodorvasic97 / Wikimedia Commons / CC BY-SA 4.0

    Students Were Offered $15 Per Day To Participate In A Study About Prison Life

    Seventy people applied to the ad that Phillip Zimbardo placed in the Stanford classifieds:

    "Male college students needed for psychological study of prison life. $15 per day for 1-2 weeks."

    Potential hires were interviewed and given personality tests. After eliminating anyone who displayed potential psychological problems, personality disorders, physical disabilities, or any kind of criminal or drug record, 24 white, male college students were chosen as participants. 

    None of the students knew exactly what they had signed up for. Once Zimbardo and his research team randomly divided them into prisoners and guards, the experiment began on August 17, 1971. 

  • The "Prisoners" Were Arrested And Booked By Real Cops

    There were 12 prisoners and 12 guards, nine active and three alternates in each category. On August 17, 1971, the nine prisoners were arrested by police officers from the Palo Alto police department. After being taken into custody and having their mugshots taken, the prisoners were fingerprinted, blindfolded, and moved into a holding cell.

    Once all nine were accounted for, they were moved to the mock prison setup in the basement of Stanford's Jordan Hall, which would serve as the Stanford County Prison.

  • The Fake Prison Felt Very Real

    Researchers went all-out when they created the prison for the experiment, even consulting with ex-convicts and prison officials when they designed the "cells" and the "yard." Laboratory space was converted into cells designed to house three prisoners each. The doors were barred and each cell was given a number.

    The "yard" was the hallway of the basement, the area where prisoners were allowed to walk around or exercise. Prisoners were blindfolded before being taken to the bathroom and a closet was used as "solitary confinement." 

  • A Coin Toss Determined Who Would Be Prisoners And Who Would Be Guards

    A single coin toss determined which participants would serve as prison guards and which were assigned as prisoners.

    Prisoners were stripped, deloused, and given numbered uniforms––essentially ill-fitting smocks with no underwear. They were also given stocking caps and sandals, and a chain was placed on each one of their legs. The stocking caps were made of nylons and were used in lieu of shaving the prisoners' heads. Prisoners were only addressed by their identification numbers and could only refer to themselves and others in the same way. From the outset, prisoners were dehumanized, de-gendered, and oppressed.

    Guards, however, dressed in real prison guard uniforms, even donning whistles and nightsticks, and wearing "Cool Hand Luke"-style mirrored sunglasses to prevent eye contact with prisoners.