Emotion processing in typically developing infants and infant siblings of children with autism

Abstract

Successfully perceiving and interpreting facial cues is crucial for the development of social competence. Individuals with autism have shown emotion processing deficits and abnormal gaze patterns while viewing faces. Few studies have investigated the early development of face processing abilities in autism. Even fewer studies have examined gaze patterns used by typically developing (TD) infants while viewing faces. Face and emotion processing strategies were investigated in a prospective study of TD infants and infant siblings of children with autism (sibs-A). We aimed to look for early signs of autism and the broader autism phenotype in sibs-A, who are at increased genetic risk for autism. Eye-tracking technology was used to perform an in-depth analysis of visual attention. In Study 1, gaze behavior of TD infants was examined at ages 4, 6, and 12 months during habituation to Upright and Inverted facial expressions of emotion. In Study 2, a group of sibs-A was followed from ages 6 to 24 months to determine whether face-processing skills at 6 months were related to 24-month outcome scores. In Study 1, infants overall showed an upright advantage for discriminating emotions. At all three ages, infants were able to discriminate upright emotions. The ability to discriminate inverted emotions emerged later and was less stable; infants were able to discriminate inverted emotions only at 6 months, not at 4 or 12 months. In regards to gaze patterns, the eye region was more salient to infants when faces were upright. When faces were inverted, visual fixations were more broadly distributed across facial features. In Study 2, infants were classified into 3 groups based on 18- and 24-month scores: "affected" infants who showed signs of autism, autism spectrum disorder, or language delay; unaffected sibs-A; and TD controls. TD infants were able to discriminate upright emotions at an earlier age (6 months) than affected infants (12 months). Affected infants displayed deviant gaze patterns at 6 months, looking less at eyes and more at noses of upright faces than TD infants. Unaffected sibs-A also displayed deviant gaze patterns, looking more at noses and mouths than the TD group. Importantly, these abnormal gaze patterns predicted 24-month outcomes, specifically poorer expressive language skills. These results provide important insights on the early development of face and emotion processing skills in infants both with and without autism-related delays.