Gesture and Autism: Functional Relationships to Both Motor Skills and Autistic Symptomotology

Background: Researchers have taken several different behavioral approaches to examine deficits in imitation and gesture. For example, some suggest that impairments in motor skills underlie imitative and gestural deficits in autism spectrum disorders (ASD) and have examined motor abilities related to coordination, speed, balance, and abnormal gait.  Complimentary neurological data is also available that supports motor skills deficits in ASD. Dewey and colleagues (2007) and Dziuk and colleagues (2007), however, provide evidence that gestural deficits in children with ASD are not solely attributable to these isolated deficits in motor coordination skills.  Instead, they suggest that such gestural deficits may be better explained through their functional relationship with associated social, communicative, and behavioral impairments (Dziuk et al., 2007).

Objectives: The purpose of the current study is to examine the relationship between motor skills and autism symptom severity on the gesture use of children with ASD.

Methods: The current sample consists of 1191 children diagnosed with ASD (M CA = 8 years, 10 months; SD = 40.90, range 4 years, 0 months-17 years, 11 months; 1031 M, 160F) who participated in the Simons Simplex Collection (data release 10; SFARI.org).  Participants met ASD criteria on the ADI-R and ADOS-WPS as well as strict DSM-IV criteria by an experienced clinician. Parent report and observational measures of gesture use (ADI-R and ADOS), parent report of symptom severity (Social Responsiveness Scale (SRS)), and an observational measure of motor skills (Purdue Pegboard Test) were collected. To test the competing hypotheses that gesture use in ASD is driven by motor impairment or social impairment a median split was created for both variables: the overall SRS T score and the dominant hand score of the Purdue Pegboard test. Current gesture use was represented by averaging the gesture item from the ADOS-WPS (#A8 on Modules 1 and 2; #A9 on Modules 3 and 4) and the ADI-R “current” gesture item (#45).   

Results: In the sample of children, the main effect of social impairment was significant F(1,15.74)=40.70, p<.001.  This indicates that participants with greater social impairment had significantly lower gesture use (M=70.79, SD=8.28) than participants with less social impairment (M=87.93, SD=2.75), a medium effect size (partial η²=.033).  The main effect of dominant hand performance on the Purdue Pegboard Test was not significant, F(1,0.29) = 0.74, p=0.39, thus the overall gesture use of high and low motor skills performers were similar.

Conclusions: The preliminary findings in the current sample support the theory that gesture deficits in autism may be part of more global impairments related to ASD (e.g. social, communicative, and behavioral) than to specific deficits in motor skills coordination. This information may be useful when developing comprehensive intervention programs that target social communication in children with ASD.  For example, treatment programs addressing symptom severity in ASD may be more effective than motor skills training to promote the integration of gesture use with spoken language.