Slowing down the presentation of facial and body movements enhances imitation performance in children with severe autism.

Imitation deficits observed among individuals with autism could be partly explained by the excessive speed of biological movements to be perceived and then reproduced. Along with this assumption, slowing down the speed of presentation of these movements might improve their imitative performances. To test this hypothesis, 19 children with autism, 37 typically-developing children and 17 children with Down syndrome were asked to reproduce facial and body movements presented on a computer at a normal/ecological and two slowed down speeds. Our main result showed that a subgroup of individuals with severe autism better reproduced the movements when presented slowly than at the ecological speed. This finding opens a new window for comprehension and rehabilitation of perceptual and imitative deficits in autism.