Children with autism do not show sequence effects with auditory stimuli.

Categorization decisions that reflect constantly changing memory representations might be an important adaptive response to dynamic environments. We assessed One such influence from memory (i.e., sequence effects) on categorization decisions made by individuals with autism. A model of categorization (i.e., memory and contrast model, Stewart, Brown, & Chater, 2002) assumes that contextual influences in the form of sequence effects drive categorization performance in individuals with typical development. Difficulties with contextual processing in autism, described by the weak central coherence account (Frith, 1989; Frith & Happé, 1994) imply reduced sequence effects for this participant group. The experiment reported in this article tested this implication. High-functioning children and adolescents with autism (ages 10 to 15 years), matched on age and IQ with typically developing children, completed a test that measures sequence effects (i.e., category contrast effect task, Stewart et al., 2002) using auditory tones. Participants also completed a pitch discrimination task to measure any potential confound arising from possible enhanced discrimination sensitivity within the autism spectrum disorder group. The typically developing group alone demonstrated a category contrast effect. The data suggest that this finding cannot be attributed readily to participant group differences in discrimination sensitivity, perseveration, difficulties on the associated binary categorization task, or greater reliance on long-term memory. We discuss the broad methodological implication that comparison between autism spectrum disorder group and control group responses to sequential perceptual stimuli might be confounded by the influence of preceding trials. We also discuss implications for the weak central coherence account and models of typical cognition.