Investigated the extent to which people would conform to the roles of guard and prisoner in a role-playing simulation of prison life
Took place in the basement of Stanford University's psychology department, which he transformed into a mock prison
Involved 24 male undergraduates who volunteered
Participants were selected based on if they were emotionally stable through psychological testing
Participants were randomly assigned to either the roles of guards or prisoners
Guards were given khaki uniforms, billy clubs, and reflective glasses
Prisoners received prisoner clothing, nylon caps, and numbers
Planned 14-day experiment was cut short due to the risk of serious harm to the prisoners
