Research Digest

Harris, L. T. & Fiske, S. T. . Dehumanising the lowest of the low: Neuroimaging responses to extreme out-groups. Psychological Science, 17: 847-853.

Trying to understand the origins of cruelty to other human beings has always been difficult, perhaps because the examples are so diverse, ranging as they do from lone murderers to the cooperative actions of organized genocide. However, accounts of inhumanity tend to share a common theme: the victims are viewed as radically “different” and somehow less human. Indeed, atrocities on a scale that requires group coordination may be impossible unless the victims can be regarded as an out-group of one description or another. It also seems likely that all humans experience some of these feelings toward those we are prejudiced against, even though we tend not to act on these opinions. To investigate this phenomenon, Harris and Fiske devised functional-imaging studies of different social groups, using a sample of U.S. undergraduate students. Known empathy-related brain regions in medial prefrontal cortex (reviewed in previous editions of this Digest) were activated when viewing positively regarded empathy-inducing groups, such as those inducing pride (U.S. Olympic athletes), or pity (the elderly and disabled), or even envy (rich people). A key difference occurred when viewing less well regarded groups, which included drug addicts and the homeless. Remarkably, activation of this medial prefrontal cortex region was entirely absent when viewing these images. Instead, there was activation of a brain region (the insula) that is often associated with feelings of disgust. Naturally, the study might be interpreted as showing something rather negative about the nature of Princeton University students in the United States—namely, that they have a poorly developed social conscience. However, the central outcome is a clear set of brain findings related to an important social marker. The study clearly of