Children with Autism Show Enhanced Somatosensory-Guided Motor Learning

Background: Difficulties with performance of skilled motor gestures is a commonly reported finding in autism spectrum disorder (ASD).  Given the developmental context, impairments in motor skill learning may contribute to these findings.  In previous studies, children with autism have demonstrated anomalous patterns of motor sequence learning on visually-guided motor tasks, including serial reaction time and rotary pursuit.    Whether they show similar impairments when motor sequence learning depends on somatosensory feedback has not been studied.

Objectives: To examine whether children with ASD show impaired motor sequence learning when it depends on somatosensory feedback.

Methods: Nine children with ASD (1 female) and 7 typically developing (TD) children (1 female) ages 8-12 years completed a task in which they used a stylus pen to trace a continuous closed-loop maze composed of linear segments while blindfolded.  The task consisted of 4 blocks of trails, with 4 trials in each block.  During blocks 1, 2, and 4 subjects traced a primary maze with eight decision points at which they could either make a correct turn or an error into a dead end; during block 3 subjects traced an “interference maze“ that was a mirror image of the primary maze. The number of loops completed during each 48 second trial was recorded using a digitizing tablet.  Learning was assessed using a repeated measures ANOVA (RM-ANOVA) to examine for an increase in completed loops across trials in primary maze blocks (1, 2, and 4). 

Results: RM-ANOVA across trials from blocks 1, 2 and 4 revealed no significant effect of diagnosis on the total number of loops completed (F=1.6; p = .23).  Across both groups of subjects, there was a significant effect of trial (F = 7.5; p = .03), with the number of completed loops increasing over time.   Furthermore, there was significant trial-by-diagnosis interaction effect (F = 14.6; p = .01), such that children with HFA showed a greater increase in the number of loops completed across trials than did TD children.

Conclusions: The findings, revealing that the HFA group showed significantly greater improvement in performance during blindfolded maze tracing, suggest that children with autism show superior motor learning when it is guided by somatosensory feedback.  In contrast, findings from prior studies suggest that visuomotor learning (i.e., motor learning guided by visual feedback) may be impaired in children with autism.  The combined results suggest that increased reliance on somatosensory-guided learning may contribute to impaired acquisition of skilled motor gestures (including social and communicative gestures) that are often learned through visually-guided imitation. This has important implications for guiding therapies targeted at improving social and communicative skills and understanding the neural basis of autism-associated impairments in motor, social and communicative development.