Weak imitative performance is not due to a functional 'mirroring' deficit in adults with Autism Spectrum Disorders

A large number of studies have demonstrated impaired performance on a range of imitation tasks among individuals with Autism Spectrum Disorders (ASD). The theory which suggests that these impairments are caused by a mirror system deficit has become increasingly prominent. Under this view, the capacity to match observed with executed actions or to 'mirror' is impaired in individuals with ASD. This study investigated the extent to which any impaired performance on imitation tasks is due to a functional mirroring deficit by comparing the performance of adults with ASD on imitative and non-imitative versions of the 'pen-and-cups' task. Participants in this task are required to observe transitive actions and to imitate them as fast as possible. Experiment 1 revealed impaired performance by high functioning adults with ASD on the imitative version of the task compared to IQ matched controls. The same participants then completed two non-imitative versions of the task in Experiment 2. The 'geometric' version of the task required participants to perform actions specified by the movement of abstract geometric shapes. The 'verbal' version of the task required participants to describe the observed actions. Adults with ASD were as impaired on each non-imitative version of the task as they were on the imitative version, suggesting that the impaired performance on the imitation task was not due to a functional mirroring deficit. Instead, more general factors contributed to the poor performance on this task. These findings add to the weight of evidence suggesting that impairments in imitation skills should not be cited as evidence consistent with a 'mirror system deficit theory' of ASD.