The recent shooting of American soldiers by a Muslim American military psychiatrist at Fort Hood made many Muslim Americans fear that this single attack in Texas will undermine the progress that has been made in relations between Muslim and non-Muslim Americans. They are worried that the outgroup homogeneity would lead people to make the false assumption that a Muslim man committing a crime is representative of other Muslims. Their worries may have a good reason.
Humans are a tribal species. The social psychological literature on intergroup relations is rich and diverse. For example, studies demonstrated that people make spontaneous ingroup-outgroup categorization and favor ingroup over outgroup members in a wide variety of situations. Furthermore, people have a specific stance with respect to outgroups and intergroup situations. When intergroup relations are salient, people readily show prejudice against members of outgroups and find it easy to morally justify intergroup aggression and violence. The traditional explanation of these phenomena focuses on people’s ingroup psychology. That is, being a highly social and cooperative species, humans likely possess tendencies to exalt the ingroup. As a byproduct of favoring ingroups, people will show indifference toward, or worse, a dislike for outgroups. Recently, Mark Van Vugt and Justin H. Park offered another explanation that treated negativity toward outgroups as psychological tendencies –warfare and disease avoidance. More specifically, people are more likely to infrahumanize (e.g. denying outgroup member’s typical human qualities such as politeness and civility) members of outgroups, particularly when these outgroups constitute a coalitional treat. Moreover, for people within any given culture, certain outgroups may appear especially foreign with respect to disease-relevant domains, such as food preparation and hygiene practices. Because each culture has developed (via cultural evolution) its own set of practices for preventing infection, cultures with different practices – especially in the domains of food preparation and hygiene – may be perceived as posing disease threats. Thus, the perception of outgroups, particularly those that are subjectively foreign, may activate disease avoidance responses.
The evolutionary framework also makes various suggestions for interactions to improve intergroup relations, such as altering the perceptual cues that elicit threat responses toward particular outgroups, or changing the specific cognitive and affective responses toward outgroups.