Similarity #2. Both Milgram and Zimbardo stated reported the effects of personality differences were very limited. For Zimbardo, the only personality characteristic that seemed to have any effect was authoritarianism; and this characteristic was important only for prisoner behavior. Those prisoners who were high in authoritarianism were best able to handle the oppressive conditions in the prison and, thus, remained there the longest. At least four (and maybe five) of the initial group of nine prisoners, on the other hand, had to be released even before the study was ended because of severe stress caused by the conditions.
Difference #1. A major difference between Zimbardo’s and Milgram’s studies is that, in the prison study, only one experimental manipulation was performed — being assigned to the role of prisoner or guard. This is a major limitation because we cannot know, as we did in the Milgram study, which factors in the situation were most important for the behaviors observed. There is no doubt that each participant’s self-definition as prisoner or guard was important, but it might have helped us to develop a deeper understanding of how such a self-definition can be maintained if Zimbardo and his colleagues had varied other factors in the situation. For example, would wearing normal clothes, which might have caused increased feelings of individuality, have resulted in decreased role-playing? Would a decrease in the reality of the simulation (perhaps by removing the bars on the doors, or having campus security “arrest” the prisoners) have done the same? It would have been very interesting, for example, if we had found that none of these factors were important — that, instead, it was simply the assigning of an arbitrary social role by an authority figure and the