The Eyes as Window to the Mind.

In this issue,Moriuchi et al. report on a fascinating study (1) on a long-standing question: Why do children with autism look less at other people’s eyes, relative to typically developing children? The authors pit two theories against each other: gaze aversion and gaze indifference. Their results point to the latter, not the former, although the question of why remains. One now quite old idea is that children with autism don’t see other people’s eyes as a window to the mind (2). Their well-established difficulties in attributing mental states to other people may mean that they see other people’s eyes as parts within the face that move, but they struggle to interpret what thesemoving partsmean.Whereas the typical child pays a lot of attention to where others are looking because they understand that what someone looks at indicates their mental state (what that person is interested in), children with autism maynot appreciate the mentalistic significance of a person’s eyes. Nor might people with autism understand that a person’s eyes are a reflection of a range of mental states—cognitive, volitional, or affective. Considerhowwhenwe try to interpret a person’s basic emotions, such as happy, sad, angry, afraid, disgust, or surprise (Figure 1A), people with or without autism score equallywell if they are presentedwith the eyes or the mouth, although seeing the whole face leads to better performance. But when the task is to judge a complex emotion, such as arrogant, guilt, thoughtful, or revenge (Figure 1B), seeing the eyes alone results in as good performance as seeing the whole face, and both eyes and whole face are better than the mouth alone. Moreover, on such challenging tests, adults with Asperger’s syndrome show impaired performance when shown just the eyes. Using the Reading the Mind in the Eyes test, collecting data online, our group found that the impairment in autism is very clear, as is the sex difference (female superiority) in typical participants and the absence of any sex difference in autism (4), confirming earlier studies (5, 6) (Figure 2). Performance on the Eyes test is associated with activity in the amygdala and in the left inferior frontal gyrus (7, 8); the female advantage on the test is associated with greater activity in the left inferior frontal gyrus, and the autistic deficit is associated with reduced activity in this same area. This deficit is also seen in parents of such children, suggesting that it arises for genetic reasons (9, 10). Lesion studies confirm the importance of these brain regions in mentalizing the eyes (11). Candidate gene studies suggest that sex steroid pathway genes play a role in performance on the Eyes test (12), and a FIGURE 1. Examples of Basic and Complex Emotional Stimuli