Cognitive Flexibility in Autism Spectrum Disorders: Deficits On a Pure and Sensitive Card Sorting Task

Background: The rigid and repetitive pattern of interests and activities seen in individuals with an autism spectrum disorder (ASD) has been related to deficits in cognitive flexibility. However, studies examining this cognitive flexibility deficit in ASD have yielded inconsistent findings, mainly due to differences is tasks used. There are two problems with these tasks. Firstly, some tasks are impure measures of cognitive flexibility, since task performance requires a broad range of cognitive processes. As a consequence it is questionable whether failure on these tasks is indeed due to cognitive flexibility deficits. Secondly, some tasks might not be sensitive enough to detect cognitive flexibility deficits.

Objectives: The aim of this research is to test whether or not children with an ASD have difficulties with cognitive flexibility on a more pure and sensitive task.

Methods: We modified a card sorting task previously used to investigate brain correlates of cognitive flexibility in healthy subjects (Watson, Azizan, & Squires, 2006). In this modified task subjects had to sort a target card according to colour or shape. After each response, feedback was given, indication which of the two possible sorting rules was correct. The sorting rule changed randomly after 7, 8 or 9 successive correct answers. Task performance was compare between 21 children with ASD (IQ > 80; aged between 8 and 14 years old) and 21 healthy controle subjects, matched for age, verbal IQ, performal IQ, full-scale IQ and gender.

Results: Compared to healthy control subjects, children with an ASD made significantly more perseveration errors and they anticipated a switch less frequently. Concerning the reaction times, both groups showed significant switch costs. In addition, these costs were higher for children with an ASD compared to healthy controls.

Conclusions: These results indicate that children with an ASD do have problems with cognitive flexibility, even when measured with a controlled experimental task. However, it remains to be investigated whether performance on this task correlates with day-to-day behavioural flexibility, and whether it can explain the pattern of rigid and repetitive interests and activities seen in children with an ASD.