Self-Categorisation and Autism: Exploring the Relationship Between Autistic Traits and Group Homogeneity

Skorich, D. P. (University of Queensland), Cassidy, L. M. (University of Queensland), Karimi, K. S. (University of Queensland), Haslam, S. A. (University of Queensland)

The Integrated Self-Categorization model of Autism (ISCA) argues that the theory of mind differences seen in autism arise from weak central coherence/enhanced perceptual functioning, via a dysfunctional self-categorization mechanism. The ISCA model also makes the novel prediction that all those phenomena that arise from self-categorisation should also be affected in autistic people. In this paper, we report three studies exploring this prediction in the context of one such phenomenon: group homogeneity. We first measure participants’ autistic traits, then ask them to make homogeneity judgments of their ingroup alone or their outgroup alone (in Study 1, and in the Alone conditions of Studies 2 and 3); or of their ingroup in comparison to their outgroup or their outgroup in comparison to their ingroup (in the Compare conditions of Studies 2 and 3). As predicted, we found that: the degree of autistic traits negatively predicts overall group homogeneity; that this relationship is mediated by social identification as a proxy for self-categorisation; and that typical comparison-related group homogeneity effects are strengthened at higher, relative to lower, levels of autistic traits. Together, these studies provide convergent evidence for the ISCA model, and for the important role played by self-categorisation in autism.

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Social Identity and Intergroup Processes