A group of researchers were curious to understand the behaviour of guards in prisons and wanted to know whether it was due to dispositional (personality) or environment-dependent (situational) factors. To study the roles of guards and prisoners they created a mock prison. 23 men unfamiliar with each other volunteered to participate in the study and were assigned the roles of prisoners and guards. Both adapted to their new roles. A rebellion on the second day led to harsh retaliation by the guards. Ruthless retributive action was taken to punish the prisoners. The researchers intended to run the experiment for 2 weeks. It was, however, terminated on the sixth day due to the emotional breakdown of prisoners and excessive aggression by the guards. The experiment revealed how people conform to the social roles they are expected to play.