A systematic review of action imitation in autistic spectrum disorder.

Imitative deficits have been associated with autistic spectrum disorder (ASD) for many years, most recently through more robust methodologies. A fresh, systematic review of the significance, characteristics, and underlying mechanism of the association is therefore warranted. From 121 candidates, we focused on 21 well-controlled studies involving 281 cases of ASD. Overall, children with ASD performed worse on imitative tasks (Combined Logit p value < .00005). The emerging picture is of delayed development in imitation, implicating a deficit in mapping neural codings for actions between sensory and motor modalities, rather than in motivation or executive function. We hypothesise that ASD is characterised by abnormal development of these mappings. such that they are biased towards object-oriented tasks at the expense of those required for action imitation per se.