Comprehension of conventional gestures in typical children, children with autism spectrum disorders and children with language disorders

Background: Conventional gestures (CG) contribute to communication and are a precursor of verbal language. The aim of our study was: (a) to analyse the developmental course of CG comprehension in typical children; (b) from a clinical perspective, to document how children with autism spectrum disorders (ASD) and language disorder (LD) can understand CG. Methods: Comprehension of CG was evaluated through a video-based testing. The protocol consisted of 15 arbitrary gestures and 15 iconic gestures. We recruited 262 typical children aged from 3 to 10 years old and 55 children with communication impairments aged from 4 to 8 years old: 36 children with ASD and 19 with LD. Results: CG comprehension increased during the early development of typical children and the improvement of iconic gestures comprehension occurred earlier than that of arbitrary ones. Children with ASD received lower CG scores than typical children and LD children. For each gesture taken separately, children with LD performed better than not only ASD children but typical children as well. Furthermore, when we performed the analysis with both arbitrary and iconic gesture, children with LD outperformed both children with ASD and TD children. Conclusions: Our results suggest a dissociation between oral language comprehension and language gesture comprehension in children with LD and a deficit in both oral language and language gesture comprehension in children with ASD.