Most prisoners believed that the subjects selected to be guards were chosen because they were bigger than those who were made prisoners, but actually, there was no difference in the average height of the two groups. What do you think caused this misperception?

This question is incomplete, here´s the complete question.  

In 1971, Phillip Zimbardo set up the Stanford Prison Experiment in which 18 young, middle-class white men were randomly allocated to the role of guards and prisioners for the next six days. The experiment was prepared as if it were a play or a film, but te dramatization quickly became believable: the perceived roles were played out as if for real. When the prisoners rebelled, the guards´ perception of the prisoners changed, so that it was no longer only an experiment. The guards saw the prisoners as troublemakers and ´out to get them´. The guards imposed severe penalties on the prisoners. One prisoner broke down after 36 hours and another after 48 hours, despite being ratified as psycologically healthy beforehand; this meant that the experiment had to be cut short. The experiment demonstrated how people were liable to both vivious aggression and self-confirming victimhood.

Most prisoners believed that the subjects selected to be guards were chosen because they were bigger than those who were made prisoners, but actually, there was no difference in the average height of the two groups.

What do you think caused this misperception?

I think the misperception about the guars is part of the process of self-confirming victimhood and the effect of the poor treatment the perceived prisoners got during the experiment.

Explanation:

Having people dressing as guards may have already provided them with an aura of power, related to the image we have collectively of policemen and guards being strong and big. Furthermore, considering the psychological consequences of the violent manner those guards behaved, it´s no surprise that the prisoners begun to see them as powerful, and accordingly "bigger".

as university of miami psychologists debra lieberman and adam smith pointed out in a recent article in the journal current directions in psychological science, humans have social and psychological mechanisms to deter incest. with very few exceptions, marriages between brothers and sisters and between parents and their children are verboten in every human culture. the primary psychological anti-incest mechanism is the yuck response. even the idea of sex with their mom or dad, bro or sis is upsetting to most people. the psychologist jonathan haidt has found that nearly everyone is repelled by the prospect of brother-sister sex, even in hypothetical situations in which there is no chance of pregnancy).

the biological cost of incest

this raises an interesting question: just what’s so bad about incest? sure, having sex with your dad or your sister seems gross — but why? some anthropologists have argued that incest taboos are learned social conventions. this explanation, however, doesn’t make sense to me as it does not explain the widespread existence of anti-incest mechanisms in creatures ranging from cockroaches to chimpanzees. second, the incest taboo is about as close to a universal law as human moral rules get.

why should mechanisms to avoid incest be so widespread both in nature and across human societies? the answer is simple. the problem with having sex close with relatives is that there is an astonishingly high chance that your offspring will be born with a serious birth defect.