ABSTRACT
While diagnostic assessments for autism routinely screen for reduced frequency of gestures, evidence supporting reduced gesture production in autism is inconsistent. This systematic review and meta-analysis aimed to clarify differences in frequency of gestures between autistic and neurotypical individuals. Included studies compared frequency of gestures between autistic and neurotypical individuals. Database searches (APA PsycInfo, ERIC, MEDLINE, ProQuest Dissertations and Theses Global) and a call for unpublished data on the International Society for Gesture Studies listserv identified research from January 1994 to March 2023. Study quality was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Designs. Quantitative synthesis involved a narrative review of all findings and meta-analysis of articles allowing effect size calculations, stratified by the type of gesture. Thirty-one articles comparing frequency of gestures between 701 autistic and 860 neurotypical individuals were included in the narrative review, 25 of which were also included in the meta-analysis. Compared to neurotypical individuals, meta-analyses found that autistic individuals produced significantly less total, deictic, and emblematic gestures. While the number of iconic gestures appeared comparable between groups, studies investigating iconic gestures exhibited an almost equal trend of both positive and negative effect sizes, which were mostly nonsignificant. The way gesture production was measured, age, observer familiarity, and task structure (but not overall study quality) moderated the effect size, albeit inconsistently across the types of gestures. Findings have implications relating to profiling gesture use in diagnostic assessments for autism and highlight gaps in our understanding of differences in gesture production in autism. (PsycInfo Database Record (c) 2023 APA, all rights reserved).
ABSTRACT
Compelling evidence suggests observing iconic gestures benefits learning. While emerging evidence suggests typical iconic gestures benefit comprehension to a greater extent than atypical iconic gestures, it is unclear precisely when and for whom these gestures will be most helpful. The current study investigated factors that may moderate when and for whom gesture benefits narrative comprehension most, including the type of gesture, task difficulty, and individual differences in cognitive ability. Participants were shown a video narrative in which they observed either typical gestures (commonly produced gestures, highly semantically related to accompanying speech), atypical gestures (gestures that are seldom produced), or no gestures. The video narrative was either viewed with interference (background noise to increase task difficulty) or no interference (no background noise). To determine whether the effects of gesture observation and externally imposed task difficulty on narrative comprehension further depend on an individual's cognitive abilities, participants completed four measures of cognitive abilities (immediate and delayed non-verbal memory, attention, and intellectual ability). Observing typical gestures significantly benefitted narrative comprehension compared with atypical and no gestures combined, which did not differ significantly. Participants with below average and average levels of delayed non-verbal memory benefitted more from typical gestures than atypical or no gestures compared with those with an above average level of delayed non-verbal memory. However, this interaction was only significant when the task was difficult (i.e., with interference) but not when the task was simple (i.e., no interference). This finding suggests that the type of iconic gesture observed may affect gesture's beneficial effect on narrative comprehension, and that such gestures may be more beneficial in difficult tasks, but only for certain individuals.
