Over-imitation in autism spectrum disorder: causally opaque and transparent actions

Over-imitation refers to the human tendency to imitate actions with such high fidelity, that even irrelevant action steps are reproduced to the expenses of task efficiency. A couple of studies have evaluated the pattern of over-imitation in autism spectrum disorder (ASD) but contradictory results were reported. In the present study we employed a two-method approach paradigm and directly tested whether the availability of causal information could explain the disparate findings reported. We also evaluate whether participants with ASD copied the exact methods used to perform both relevant and irrelevant action steps. Results showed that individuals with ASD and matched control participants displayed comparable over-imitative behaviour. However, we further observed that when presented with the irrelevant action steps, participants with ASD emulated them more often than the control group. Moreover, the reproduction’s fidelity of the sequence of action steps differed between groups. No differences were found in either group when causal information was available. We interpreted these preliminary findings as being due to a malfunctioning imitation mechanism that repercusses in the tendency of individuals with ASD to excessively emulate novel actions, even when their causality cannot be perceived.