Abstract
In his original description of autism, Kanner [1] noted that the parents of autistic children often exhibited unusual social behavior themselves, consistent with what we now know about the high heritability of autism [2]. We investigated this so-called Broad Autism Phenotype in the parents of children with autism, who themselves did not receive a diagnosis of any psychiatric illness. Building on recent quantifications of social cognition in autism [3], we investigated face processing by using the "bubbles" method [4] to measure how viewers make use of information from specific facial features in order to judge emotions. Parents of autistic children who were assessed as socially aloof (N = 15), a key component of the phenotype [5], showed a remarkable reduction in processing the eye region in faces, together with enhanced processing of the mouth, compared to a control group of parents of neurotypical children (N = 20), as well as to nonaloof parents of autistic children (N = 27, whose pattern of face processing was intermediate). The pattern of face processing seen in the Broad Autism Phenotype showed striking similarities to that previously reported to occur in autism [3] and for the first time provides a window into the endophenotype that may result from a subset of the genes that contribute to social cognition.