A neuropsychological investigation of the 'weak central coherence' anomaly in autism

Abstract

Autistic Spectrum Disorders (ASD), including Asperger's Syndrome and Pervasive Developmental Disorder, are believed to be caused by abnormalities of brain development and function. One theory to account for the unusual processing style of children with ASD is called Weak Central Coherence (WCC; Frith,1989), a notion which purports that the ability to integrate visual stimuli is deficient, resulting in an unusually local, detail-oriented approach to perceptual tasks. Prior studies of autistic adults have supported WCC on the basis of superior performance on embedded figures, block design, visual illusions, homograph performance, and even savant skills. The purpose of the present study was (1) to contrast patterns of perceptual asymmetry (PA) in healthy control children and children with ASD. It was predicted that the groups would show different patterns on a chimeric task of happy facial affect. Specifically, a rightward bias of face chimeras was predicted for autistic children; (2) to examine the relationship between PA and performance on CC measures (Children's Embedded Figure, CEFT, and Block Design, BD). For autistics, children with a stronger rightward bias (greater degree of left PA) were expected to show better performance on the tests of CC; and (3) to examine the relationship between PA and clinical indices of autism severity (Childhood Autism Rating Scale, CARS) and social emotional behavior (Aberrant Behavior Checklist, ABC). It was predicted that autism symptoms would be significantly associated with degree of reversed PA. Twenty children with ASD were compared to 20 age-matched controls on Raven's Coloured Progressive Matrices, BD and LEFT, and a chimeric face paradigm. As predicted, the ASD group showed a preference for the right side of faces, implicating a reversed PA, or left hemisphere bias, which differed significantly from controls. Within groups, Asperger's children performed most like typical children on the chimeric task, demonstrating a right hemisphere bias. In contrast to study predictions, neither severity of autism (CARS, ABC) nor performance on the CC measures correlated significantly with PA. Chronological age showed a trend with PA for ASD children only. Results are described in terms of neurodevelopment and reorganization, face processing, functional neuroanatomy, CC, and associated difficulties in the social realm in ASD. Also discussed is the unexpected Asperger's group difference, and potential implication for heterogeneity within ASD. (PsycINFO Database Record (c) 2002 APA, all rights reserved)