Motor demands impact speed of information processing in autism spectrum disorders.

The apparent contradiction between preserved or even enhanced perceptual processing speed on inspection time tasks in autism spectrum disorders (ASD) and impaired performance on complex processing speed tasks that require motor output (e.g., Wechsler Processing Speed Index) has not yet been systematically investigated. This study investigates whether adding motor output demands to an inspection time task impairs ASD performance compared to that of typically developing control (TDC) children. The performance of children with ASD (n = 28; mean Full Scale IQ (FSIQ) = 115) and TDC (n = 25; mean FSIQ = 122) children was compared on processing speed tasks with increasing motor demand. Correlations were run between ASD task performance and Autism Diagnostic Observation Schedule (ADOS) Communication scores. Performance by the ASD and TDC groups on a simple perceptual processing speed task with minimal motor demand was equivalent, though it diverged (ASD worse than TDC) on 2 tasks with the same stimuli but increased motor output demands. ASD performance on the moderate but not the high speeded motor output demand task was negatively correlated with ADOS communication symptoms. These data address the apparent contradiction between preserved inspection time in the context of slowed "processing speed" in ASD. They show that processing speed is preserved when motor demands are minimized, but that increased motor output demands interfere with the ability to act on perceptual processing of simple stimuli. Reducing motor demands (e.g., through the use of computers) may increase the capacity of people with ASD to demonstrate good perceptual processing in a variety of educational, vocational, and social settings.