Abstract
This study examined whether individuals with autism spectrum disorder (ASD) produce co-speech gestures similarly to typically developing (TD) peers. Participants were 20 youth ages 10-18 years with high-functioning ASD and 21 TD controls matched on age, gender, verbal IQ, and handedness. Gestures were elicited using a classic narrative-retelling task, in which participants watched a Tweety and Sylvester cartoon and retold the cartoon to a confederate. Analyses compared gesture rate, type, and viewpoint (character, observer, dual) across groups. Communicative utility of gestures was measured via naïve coder ratings of whether a movement was a gesture, and the clarity of a gesture's meaning. The ASD group produced shorter narratives and fewer total gestures than the TD group. Accounting for narrative length, the ASD group produced fewer gestures per clause than the TD group; however, proportions of gesture types (iconic, deictic, beat, metaphoric, emblems) did not differ. Most notably, the ASD group's gestures were rated as less clearly gestures in terms of timing and well formedness, with lower certainty ratings for gesture meaning. Gesture clarity and gesture meaning scores were related to diagnostic measures of gesture competence in ASD. Findings suggest that although fluent children and adolescents with ASD use the same type of gestures as controls, their gestures are more difficult to understand, which has significant implications for their communicative abilities more broadly. Autism Res 2017, 10: 1353-1363. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.