Gesture as a Methodological Tool? Adolescents with ASD Use Their Hands to Explain Balance

Background: Deficits in gesture, an expression of non-verbal communication, are included in the diagnostic criteria for autism spectrum disorders (ASD).  Although all forms of gesture are thought to be reduced in ASD, gesture has received scant empirical attention in this population.  As studied in typically developing (TD) individuals, information expressed through gesture often complements speech and adds complexity to interpersonal exchanges.  In addition to its communicative function, gesture has also been shown to benefit speakers during problem solving by allowing them to entertain multiple representations simultaneously (i.e., one in speech and one in gesture).  Given the clinical assumption that gesture use is impaired in ASD, it might be expected that individuals with ASD benefit less from gestures in cognitive problem solving; this hypothesis has not been tested.

Objectives: This study explores the role of gesture as a conceptual aid for speakers with ASD during problem solving.  We compared strategies encoded in both speech and gesture by adolescents with TD and ASD on a task that requires participants to balance wooden beams and verbalize their strategies for doing so.  Explanations of balance are naturally conducive to gesture, and allowed an assessment of whether adolescents with ASD also use gesture to facilitate conceptual representations.  If they do, clinical formulations of gesture impairments in ASD may benefit from more detailed or precisely defined descriptions.

Methods: Participants included 15 high-functioning adolescents with ASD and 13 TD adolescents matched for age, gender, IQ, and receptive vocabulary (all F’s < 2, p’s > .18).  Participants were asked to balance eight wooden beams on a fulcrum, and to explain this process.  Videos of task performance were analyzed separately for strategies expressed in speech and gesture.  Strategies involving concepts of weight, centeredness, and distance were coded separately (as in Pine, Lufkin, and Messer, 2004). 

Results: All participants performed at ceiling, demonstrating that they were successfully able to balance all beams.  Although adolescents with ASD used significantly fewer speech strategies (p = .01), there was no group difference in the number of gesture strategies expressed (p = .75).   Overall, the ASD and TD groups represented each balance strategy within the same modality (main effect: speech or gesture, p < .001; group X modality interaction: ns); for example, most participants tended to express weight through speech and distance through gesture. 

Conclusions: When asked to provide a verbal explanation for balancing, adolescents with ASD spontaneously produced gestures at the same rate as adolescents with TD, despite reduced reliance on speech to express the same strategies.  Moreover, adolescents with ASD appear to choose the same communicative modality in which to express specific concepts as TD adolescents do.  These findings suggest that adolescents with ASD may use gesture during problem solving similarly to TD adolescents.  Gesture may in fact be an important methodological tool for the study of implicit cognition in ASD, and cited gesture impairments in ASD may reflect a quality other than rate (e.g., timing, integration with speech, etc.).  Research pursuing this possibility is currently being conducted in our laboratory.