Autism and Developmental Prosopagnosia: A Cross-Disorder Study

It has been suggested that developmental prosopagnosia (DP) and autism spectrum disorder (ASD) are co-occurring conditions; i.e., that the incidence of DP is greater in ASD than in the general population, and vice versa. Consistent with this suggestion, several case studies have described individuals with ASD who also exhibit severe face recognition difficulties. These reports document a number of anecdotes widely regarded as classic hallmarks of DP, including the use of hairstyle, voice and clothing cues for identity recognition. Despite the hypothesized relationship between the two conditions, virtually nothing is known about the effects of co-occurring DP on the perceptual abilities of individuals with ASD, or the effects of co-occurring ASD in DP. The present study sought a better understanding of this co-occurrence, and the respective influence of ASD and DP on face and object recognition. A novel three group design was employed, allowing direct comparison of 18 observers with ASD, 18 with DP and 18 typically developing controls. All participants completed measures of prosopagnosic and autistic traits, and completed objective measures of face and object recognition ability. Consistent with the co-occurrence hypothesis, we found that i) individuals with ASD reported more prosopagnosic traits, and ii) individuals with DP reported more autistic traits, than controls. A subset of the ASD group reached the threshold for prosopagnosia and a subset of the DP group reached cut-off for clinically significant levels of autistic traits. As expected, prosopagnosic traits correlated closely with face recognition ability. Interestingly however, autistic traits were not predictive of face recognition ability once prosopagnosic traits were accounted for, but were associated with wider object recognition ability. These results have important implications for future research addressing visual perception in ASD and DP. A better appreciation of this co-occurrence may help to understand the heterogeneity seen in these conditions.