The idea that certain situations can turn good people evil has spread like wildfire ever since Philip Zimbardo's (in)famous Stanford Prison Experiment. The study ended prematurely when the "ordinary" participants acting as "guards" turned sadistic. Zimbardo has said this showed "the evil that good people can be readily induced into doing to other good people", and recently he has explained the Iraqi prisoner abuse at Abu Ghraib in similar terms.
But what if the participants in the Stanford Prison Experiment weren't "good people"? What if the idea of participating in a prison experiment, or working at an interrogation facility, appeals to a certain type of character?
Thomas Carnahan and Sam McFarland posted two adverts, just like the ones used in Zimbardo's study, in several campus newspapers. One advert invited male participants for “a psychological study of prison life”; the other invited participants for “a psychological study”.
Just as in Zimbardo's study, all participants with mental health problems or a criminal or anti-social background were omitted. Crucially, the remaining 30 applicants to the "study of prison life" scored significantly higher on measures of aggression, authoritarianism, Machiavellianism, social dominance, and lower on measures of altruism and empathy, than did the 61 volunteers for the "psychological study".
Contrary to Zimbardo's situationist perspective, the finding is compatible with a more interactionist view of human behaviour – one that acknowledges that people's personalities affect the situations they find themselves in. “We spend our lives selecting to be in some situations while avoiding others”, the researchers said. Moreover, like-minded individuals are likely to seek out similar situations. So, whether in Zimbardo's study, or in Abu Ghraib, similar characters may have “mutually weakened each other’s constraints against abuse and reinforced in each other their willingness to engage in it”.
Carnahan, T. & McFarland S. (2007). Revisiting the Stanford Prison Experiment: Could Participant Self-Selection Have Led to the Cruelty? Personality and Social Psychology Bulletin, 2007, 33, 603-614.