Evidence That the Local Processing Bias in Autism Is Modulated by the Social Deficits

Background: In their novel theoretical account in which they posit autism and positive schizophrenia to be diametrically opposed disorders, Crespi and Badcock (2008) claim that autistic and positive schizophrenia traits contrastingly affect preference for local (i.e., piecemeal) versus global (i.e., integrative) processing. Specifically, these authors argue that while individuals with positive schizophrenia tend to process information at a more global level, individuals with autism process information at a more local level. While our previous study provided initial support for these claims, this work also highlighted that there is limited understanding of the precise basis of the local processing bias in autism. A specific question raised was whether this processing bias is a general characteristic of individuals with autism, or whether this bias is modulated by specific autistic traits.

Objectives: The current study aimed to further investigate the basis of the local processing bias in autism by exploring how particular subsets of autism symptoms relate to performance on the Embedded Figures Test (EFT). This task requires one to resist experiencing an integrated visual stimulus or gestalt in favour of seeing a composition of single elements, and thus has been used commonly in the autism literature to assess processing style preference.

Methods: Since a diagnosis of autism requires the presence of social deficits, impairments in communication, and restricted interests and repetitive behaviours, separating the relationship between a local processing bias and different facets of the disorder in autism samples is difficult. Therefore, the current study used the Autism Spectrum Quotient (AQ) to identify students with high levels of specific autistic-like features. In accord with the notion that the autism spectrum consists of independent behavioural domains, investigations of the factor structure of this measure have found it to comprise largely independent factors. Since the most consistently replicated AQ factors reported by ourselves and other authors have been “Social Skills” and “Details/Patterns” factors, which neatly divide the social and non-social aspects of autism, these factors were of most interest to the current investigation. Accordingly, using a group based design (N=80), the current study compared the EFT performance of high and low scorers on these two factors. The study was then replicated with a second independent sample. 

Results: Surprisingly, in the two samples tested, superior EFT performance was found to significantly relate to higher “Social Skills” scores (i.e., greater social difficulty), but not to higher scores on “Details/Patterns”. Therefore, the results suggest that the local processing bias in autism may link specifically to the social deficits.

Conclusions: The finding that it was only the social dimension of the AQ that relates to superior performance on the EFT is interesting, especially in the context of other recent studies that have concluded that the local processing bias in autism is not linked to autistic traits per se, but is instead linked to correlates of autism such as systemizing. The current results have potential implications for our understanding of the basis of the social deficits in autism, as well as the diagnostic specificity and treatment of the disorder.