Quiet Rage: The Stanford Prison Experiment (2 min) Stanford Prison Experiment (5.5 min) BBC - The Stanford Prison Experiment - 1/3 BBC - The Stanford Prison Experiment - 2/3 The Stanford prison experiment was a study of the psychological effects of becoming a prisoner or prison guard. The experiment was conducted in 1971 by a team of researchers led by Psychology Professor Dr. Philip Zimbardo, Ph.D., at Stanford University. Twenty-four undergraduates were selected out of over 75 to play the roles of both guards and prisoners and live in a mock prison in the basement of the Stanford psychology building. Roles were assigned at random. The participants adapted to their roles well beyond what even Zimbardo himself expected, leading the guards to display authoritarian measures. The experiment even affected Zimbardo himself. Five of the prisoners were upset enough by the process to quit the experiment early, and the entire experiment was abruptly stopped after only six days. The experimenta...