Zimbardo and his team aimed to test the hypothesis that the inherent personality traits of prisoners and guards are the chief cause of abusive behavior in prison.
Our study of prison life began, then, with an average group of healthy, intelligent, middle-class males.
These boys were arbitrarily divided into two groups by a flip of the coin.
In contrast, the guards lived in a very different environment, separated from the prisoners.
They were given rest and relaxation areas, and other comforts.
Many of the prisoners passively accepted psychological abuse and, by the officers' request, actively harassed other prisoners who tried to stop it.