Adolescents with ASD and TD Show Equivalent Patterns of Gesture Use During Lexical Retrieval

Background: Researchers have studied co-speech gestures to gain insight into cognitive and communicative processes including problem solving, language acquisition, and speech production.  Gesture plays an important facilitating role in these processes for typically-developing individuals.  In contrast, gesture is thought to be reduced across the lifespan in individuals with autism spectrum disorder (ASD), though this assumption has received limited empirical attention.  It remains unknown whether gesture can be used to study these important processes in ASD, and if so, how specifically gesture is used in this population.  If individuals with ASD gesture similarly to individuals with typical development (TD), then we may be able to apply paradigms employed in the typical literature to use gesture to explore cognitive and communicative functions in ASD.

Objectives: Gesture is thought to play an important role in lexical retrieval.  Using two confrontation naming tasks that have been shown to elicit gesture in TD, we examine the role of gesture in lexical retrieval by adolescents with ASD.  If individuals with ASD gesture during lexical retrieval in the same way as individuals with TD do, then this suggests that gesture may be an important tool for studying speech production in ASD.

Methods: Participants were 15 high-functioning adolescents with ASD and 14 TD adolescents matched for age, gender, IQ, and receptive vocabulary (all p’s > .18).  Participants completed two lexical retrieval tasks.  In Task 1, the Boston Naming Test, participants were shown line drawings of natural kinds and artifacts (e.g., octopus, abacus) and were asked to produce their names.  In Task 2, administered only to participants who made fewer than five errors on Task 1 (n = 18), participants were given definitions of obscure words and asked to name the word that was being defined.  Videos were coded for accuracy, gesture frequency, and gesture type.

Results: Accuracy on both tasks was equivalent for the ASD and TD groups.  Across tasks, adolescents in both groups were equally likely to gesture (Task 1, p = .61; Task 2, p = .47).  In addition to similar rates of gesture, the two groups also produced the same types of gestures; although some gesture types were used with greater frequency than others (main effect of gesture type: Task 1, p = .01; Task 2, p = .003), this pattern was followed by both groups equivalently (group X type interaction: Task 1, p = .54; Task 2,  p = .81).   

Conclusions: When asked to retrieve lexical items based on target pictures or word definitions, adolescents with high-functioning autism gestured as often, and produced the same gesture types, as TD adolescents.  Although the group-level comparisons in this study represent null results, this finding is uniquely informative, given that gesture deficits have been so widely assumed by both clinicians and researchers.  These results suggest that adolescents with ASD use gesture in the same way as TD adolescents when retrieving words from the lexicon, and that gesture may in fact prove useful in the study of speech production in ASD.