In his book, , Zimbardo explained that he told the participants how they were supposed to behave:We can create boredom. We can create a sense of frustration. We can create fear in them, to some degree. We can create a notion of the arbitrariness that governs their lives, which are totally controlled by us, by the system, by you, me.…They’ll have no privacy at all, there will be constant surveillance—nothing they do will go unobserved. They will have no freedom of action. They will be able to do nothing and say nothing that we don’t permit. We’re going to take away their individuality in various ways.…In general, what all this should create in them is a sense of powerlessness. We have total power in the situation. They have none. (pp. 55)The fact that Zimbardo was both the head researcher and the prison superintendent added to the demand characteristics because the 'guards' wanted to please the 'superintendent', and the overlap between the superintendent and the head psychologist means the participants would have have followed demand characteristics more strongly.