Xenophobic exclusion has been ubiquitous throughout history. However, the explanation of such a phenomenon has been little understood. Interesting research conducted by Stapel and Lindenberg published in the latest Science has brought us closer to some answers. They found that people who are in a disordered environment (e.g. unclean subway station) exhibit greater discriminatory behavior (e.g. decision to sit further away from a black person compared to a white person). The authors suggest that when the brain faces disorder there is a natural drive for order. One way to reach order is through stereotyping. It's the brain's way of making sense of the world. Too bad it doesn't work all the time.
Editorial Expression of Concern
Stapel DA, & Lindenberg S (2011). Coping with chaos: how disordered contexts promote stereotyping and discrimination. Science (New York, N.Y.), 332 (6026), 251-3 PMID: 21474762