Prototype formation in autism: can individuals with autism abstract facial prototypes?

Prototype formation is a critical skill for category learning. Research suggests that individuals with autism may have a deficit in prototype formation of some objects; however, results are mixed. This study used a natural category, faces, to further examine prototype formation in high-functioning individuals with autism. High-functioning children (age 8-13 years) and adults with autism (age 17-53 years) and matched controls were tested in a facial prototype formation task that has been used to test prototype formation abilities in typically developing infants and adults [Strauss, 1979]. Participants were familiarized to a series of faces depicting subtle variations in the spatial distance of facial features, and were then given a forced choice familiarity test between the mean prototype and the mode prototype. Overall, individuals in the autism group were significantly less likely to select the mean prototype face. Even though the children with autism showed this difference in prototype formation, this pattern was driven primarily by the adults, because the adults with autism were approximately four times less likely to select the mean prototype than were the control adults. These results provide further evidence that individuals with autism have difficulty abstracting subtle spatial information that is necessary not only for the formation of a mean prototype, but also for categorizing faces and objects.