THE HUMAN AMYGDALA IN SOCIAL JUDGMENT

Studies in animals have implicated the amygdala in emotional(1-3) and social(4-6) behaviours, especially those related to fear and aggressio n. Although lesion(7-10) and functional imaging(11-13) studies in huma ns have demonstrated the amygdala's participation in recognizing emoti onal facial expressions, its role in human social behaviour has remain ed unclear. We report here our investigation into the hypothesis that the human amygdala is required for accurate social judgments of other individuals on the basis of their facial appearance. We asked three su bjects with complete bilateral amygdala damage to judge faces of unfam iliar people with respect to two attributes important in real-life soc ial encounters: approachability and trustworthiness. All three subject s judged unfamiliar individuals to be more approachable and more trust worthy than did control subjects. The impairment was most striking for faces to which normal subjects assign the most negative ratings: unap proachable and untrustworthy looking individuals. Additional investiga tions revealed that the impairment does not extend to judging verbal d escriptions of people. The amygdala appears to be an important compone nt of the neural systems that help retrieve socially relevant knowledg e on the basis of facial appearance.