Internal model deficits impair joint action in children and adolescents with autism spectrum disorders

Qualitative differences in social interaction and communication are diagnostic hallmarks in autism spectrum disorders (ASD). The present study investigated the hypothesis that impaired social interaction in ASD reflects a deficit to internally model the behavior of a co-actor. Children and adolescents with ASD and matched controls performed a computerized bar-balancing task in a solo condition (S), and together with another individual in two joint action conditions (J2 and J4) in which they used either two or four hands to control the bar lift. Consistent with predictions derived from the 'internal modelling hypothesis', results from the J2 task indicated that ASD dyads were impaired in predicting the occurrence of their partner's response and failed to coordinate their actions in time. Furthermore, results from the J4 task showed that ASD participants used an adaptive strategy to disambiguate their responses from their partner's by regulating opposite sides of the bar during lifting. These findings provide empirical support of theories positing the existence of an internal modelling deficit in ASD. In addition, our findings suggest that impaired social reciprocal behavior and joint cooperative play exhibited by individuals with ASD may reflect behavioral adaptations to evade conflicting or ambiguous information in social settings. (C) 2011 Elsevier Ltd. All rights reserved.