Abstract
In recent years there has been considerable interest in the perceptual mechanisms engaged when observers view social interactions from third-person perspectives. According to one influential account, pairs of interacting individuals engage specialized neurocognitive processing, analogous to that recruited by upright faces. If dyadic social interactions recruit face-like processing, one might expect people who experience lifelong face recognition problems – developmental prosopagnosics (DPs) – to exhibit atypical visual processing of social interactions. To test this possibility, we explored whether DPs demonstrate reduced ability to detect changes in interpersonal distance. Interpersonal distance is a key perceptual feature of social interactions that can be used to infer interaction valence and the nature of the relationship between interactants. A sample of DPs (N = 36) and matched typical controls (N = 48) completed three signal detection tasks in a counterbalanced order. In two of the tasks, participants viewed two images of interacting dyads presented sequentially, and were asked whether the distance between the people depicted changed or remained constant. One of the tasks employed images of dancers. The other task employed images of boxers. Each stimulus image was presented for 750 ms with an inter-stimulus-interval of 1000 ms. Participants also completed a third, non-social version of the task, in which the sequentially presented images depicted pairs of clocks. At the group level, we found no evidence that DPs are less sensitive to changes in interpersonal distance relative to typical participants. The DPs were also unimpaired when detecting changes in inter-object distances in the clocks task. Our findings suggest that visual processing of social interactions may be typical in DP. In light of these results, it seems unlikely that social interactions engage face-like visual processing. Our findings speak against an account of DP based on a domain-general deficit that impairs the encoding of spatial relationships.