Abstract
Poor motor skills have been recognized as a possible feature of Autistic Spectrum Disorders (ASD). Recent studies have established that children with ASD are particularly bad at ball skill tasks as indexed by standardized movement batteries. Nevertheless, it has yet to be established if an intrinsic motor difficulty exists or if established difficulties with social interaction lead to poor performance. We decided to explore an interceptive timing task in an attempt to determine if motor deficits, per se, exist in children with ASD. We employed a recent experimental paradigm (tested in adults) that allows an objective exploration of the skills inherent in a catching task. We adapted this task to allow an exploration of timing ability in children with ASD and a normal population of children (5 groups of 10 children in age bands between 5 and 12 years). The design of the task reduced the effects of practice and social interaction thereby allowing us to explore objectively this component of catching. The task consisted of hitting a target with a 1 degree-of-freedom manipulandum that moved along a straight track, perpendicular to the (straight) path of the target. The 3 targets (differing in size) moved at a constant velocity and remained within the “strike” zone for a limited time. Sophisticated optoelectronic tracking equipment (Optotrak) was used to allow precise measurement of performance (10 randomised trials per condition). The data quantified the behaviour and allowed us to examine the lawful relationship that exists between the movement time and time window found in adults. Performance in our task was compared with a conventional measure of skilled timing (i.e. the ball skill component of the Movement Assessment Battery for Children). The findings highlight the developmental course of interceptive timing skills and suggest that the ‘social’ component of motor tasks needs careful consideration in ASD.