The experiment was conducted in 1971 by a team of researchers led by psychologist Philip Zimbardo at Stanford University.
Undergraduate volunteers played the roles of both guards and prisoners living in a mock prison in the basement of the Stanford psychology building.
Prisoners and guards rapidly adapted to their roles, stepping beyond the boundaries of what had been predicted and leading to dangerous and psychologically damaging situations.
One-third of the guards were judged to have exhibited “genuine” sadistic tendencies, while many prisoners were emotionally traumatized and two had to be removed from the experiment early.
Finally, Zimbardo, alarmed at the increasingly abusive anti-social behavior from his subjects, terminated the entire experiment early.
The experiment, which began on August 15 and was supposed to take two weeks, was terminated August 21.
Now, they've made a movie about the incident that is going to hit the big screen later this year, and it promises to be as chilling.