My favorite psychologist, Peter Gray, explains why some psychological studies are flawed. He uses the famous Zimbardo prison experiment as a prime example. For those who are unfamiliar, this experiment assigned random students to roles as guards and prisoners and then observed increasing hostilities. This experiment is used to suggest that when there is power differentials, hostilities naturally occur. This study is also used to claim that people are impressionable and naturally adhere to a group norm.

Peter Gray claims that this study is not evidence of the sort. He points out a major flaw is that participants in studies naturally act out the role they think the researchers are wishing to see:

In a nutshell, here’s the criticism, somewhat simplified. Twenty-one boys (OK, young men) are asked to play a game of prisoners and guards. It’s 1971. There have recently been many news reports about prison riots and the brutality of guards. So, in this game, what are these young men supposed to do? Are they supposed to sit around talking pleasantly with one another about sports, girlfriends, movies, and such? No, of course not. This is a study of prisoners and guards, so their job clearly is to act like prisoners and guards—or, more accurately, to act out their stereotyped views of what prisoners and guards do. Surely, Professor Zimbardo, who is right there watching them (as the Prison Superintendent) would be disappointed if, instead, they had just sat around chatting pleasantly and having tea. Much research has shown that participants in psychological experiments are highly motivated to do what they believe the researchers want them to do. Any characteristics of an experiment that let research participants guess how the experimenters expect or want them to behave are referred to as demand characteristics. In any valid experiment it is essential to eliminate or at least minimize demand characteristics. In this experiment, the demands were everywhere.

This is called “demand characteristics”. Furthermore, another huge problem with the study is it used an actual inmate who directed the guards in their activities:

In the article, Prescott expressed great regret for his involvement in the study and said that it was he, not the guards in the mock prison, who came up with the ways of psychologically humiliating and harassing the prisoners.

This is not to say that power does not corrupt, but just that this particular study is a bad study to use as evidence. When we see studies purporting to prove some sort of human characteristic, we need to keep in mind how studies are conducted have a major influence in what results are achieved. When those performing the studies come to the same conclusion as their hypothesis, we should be leery of accepting the study without examination.