The Stanford prison experiment was a study of the psychological effects of becoming a prisoner or prison guard. The experiment was conducted at Stanford University from August 14 to August 20 of 1971 by a team of researchers led by psychology professor Philip Zimbardo. It was funded by the US Office of Naval Research and was of interest to both the US Navy and Marine Corps as an investigation into the causes of conflict between military guards and prisoners.
24 male students out of 75 were selected to take on randomly assigned roles of prisoners and guards in a mock prison situated in the basement of the Stanford psychology building. The participants adapted to their roles well beyond Zimbardo’s expectations, as the guards enforced authoritarian measures and ultimately subjected some of the prisoners to psychological torture.
Many of the prisoners passively accepted psychological abuse and, at the request of the guards, readily harassed other prisoners who attempted to prevent it. The experiment even affected Zimbardo himself, who, in his role as the superintendent, permitted the abuse to continue. Two of the prisoners quit the experiment early and the entire experiment was abruptly stopped after only six days. – Wikipedia