REVIEWS and attracti hthe ch on the n the bly ion nal pr that a don and v onal gu ts per An impo tion iss en early s gardles ith rave r pro the ext On th her ha rather than the phy of th to pe dtanandco on in the ri cture parti is attract whi can be ma mpled tails of th ask and attractive the more average o OLUME 4 MARCH 2003160NATURE REVIEWS | NEUROSCIENCE VOLUME 4 | MARCH 2003 | 169 REVIEWS Judging race, trustworthiness and attractiveness Beyond its role in recognition of basic emotions, the amygdala is involved in more complex social judge￾ments. For example, it shows differential habituation of activation to faces of people of another race54, and its activation has been found to correlate with race stereo￾types of which the viewer might be unaware55. However, the role of the amygdala in processing information about race is still unclear. Other brain regions in the extrastriate visual cortex are also differentially activated as a function of race56, and lesions of the amygdala do not seem to impair race judgements57. Other kinds of social judgement also seem to involve the amygdala. In one study, patients with bilateral amygdala damage were found to be impaired in judging how much to trust another person from viewing their face. They all judged other people to look more trust￾worthy and more approachable than did normal view￾ers58, a pattern of impairment that is also consistent with the often indiscriminately friendly behaviour of such patients in real life (FIG. 4a). The role of the amyg￾dala in processing stimuli related to potential threat or danger therefore extends to the complex judgements on the basis of which we approach or trust other people. These lesion studies have been complemented by functional imaging studies on the role of the amygdala in judging trustworthiness (FIG. 4b). When normal sub￾jects view faces of people that look untrustworthy, acti￾vation is found in the superior temporal sulcus, the amygdala, the orbitofrontal cortex and the insular cortex59, perhaps outlining a sequence of processes that encompass perception, judgement and aspects of emo￾tional response. Interestingly, some activation of the amygdala by untrustworthy-looking faces is indepen￾dent of factors such as gender, gaze, race or emotional expression of the face59. Given that much of the variance in the physical dimensions of different faces can be elim￾inated yet still produce amygdala activation, it is possible to assume that this activation reflects the judgements and inferences that subjects make about the face, rather than its perceptual properties. An important future direction will be to examine the variance in viewers’ per￾sonality traits in these social judgements, as has been done in two recent studies correlating amygdala activa￾tion to emotional expressions with viewers’ extraver￾sion60 or anxious temperament due to a POLYMORPHISM in the serotonin transporter promoter61. To the extent that the amygdala activation covaries with differences in the personality of the viewer, rather than the physical com￾position of the stimulus, we can conclude that we are tapping processes more distal to perception and closer to judgement, decision making, and the interpersonal behaviours that are based on them. Another class of social judgement that we make from faces is attractiveness, which can be manipulated by specific properties of faces. For instance, faces are perceived to look more attractive the more average or symmetrical they are, or with greater exaggeration of robusticity and NEOTENY features, all of which have been proposed to signal differential fitness. Moreover, such preferences by women can vary across different phases The bulk of research on the human amygdala has used emotional facial expressions as stimuli and has pointed most consistently to this region being involved in the processing of fear and related emotions40–42, although recent evidence indicates that its role is prob￾ably much broader43,44. Functional imaging studies show processing at several stages: a rapid, automatic evaluation and tagging of stimuli for further process￾ing16, feedback modulation of attentional processing in visual cortices45, and modes of processing that are subject to self-regulation and volitional guidance46,47. The first and last of these stages show complementary roles for the amygdala, probably operating at comple￾mentary timescales. On the one hand, some amygdala activation is seen early48, regardless of the conscious perception of the stimulus (for example, in response to subliminal stimuli49,50 or in patients with BLINDSIGHT51 or hemispatial NEGLECT52), and regardless of attention allocation in some tasks16. On the other hand, effortful self-regulation of the emotions induced by stimuli47, REAPPRAISAL of their emotional importance46 and difficult attentional tasks53, all modulate amygdala activation. These findings urge caution in the rigid assignment of cognitive processes to neural structures, because it is probable that a given structure participates in several processes, depending on the time at which its activity is sampled and on the details of the task and context. It is conceivable that the amygdala participates both in the initial, rapid evaluation of the emotional signifi￾cance of stimuli, and in a later assessment within a given context and goal. BLINDSIGHT The ability of a person with a lesion in the primary visual cortex to reach towards or guess at the orientation of objects projected on the part of the visual field that corresponds to this lesion, even though they report that they can see nothing in that part of their visual field. NEGLECT A neurological syndrome (often involving damage to the right parietal cortex) in which patients show a marked difficulty in detecting or responding to information in the contralesional field. REAPPRAISAL Reinterpretation of a situation to assign it a different value. Whereas reappraisal changes emotional response by changing one’s perception of the stimulus, other strategies of self-regulation directly modulate emotional response despite one’s original perception. POLYMORPHISM The simultaneous existence in the same population of two or more genotypes in frequencies that cannot be explained by recurrent mutations. Lateral fusiform gyrus Inferior occipital gyrus Superior temporal sulcus Figure 3 | Activation in visual cortices to viewing faces. Changeable, dynamic aspects of faces, such as expression and gaze, activate the superior temporal sulcus, whereas static aspects activate the fusiform gyrus. The top panel shows these activations on a human brain smoothed to reveal both sulci (darker grey) and gyri. The bottom panel shows a flattened representation of the same data. Data were generated by contrasting the activations to viewing faces with those to viewing houses (orange, greater activation to faces; blue, greater activation to houses). Modified, with permission, from REF. 10 © (2000) Elsevier Science