Infant Siblings At Risk for ASD: Directed and Non-Directed Gesture Use in Infants and Related Maternal Communication Behaviours

Background: Infants at risk for ASD show impairments in gesture use by 12 months of age. Conventionally defined, a gesture is an action produced with the hands, arms, fingers, body or face; that is directed to a person; and serves a communicative function. However, our previous work examining infant gesture use during a communication assessment with a clinician (i.e., clinical context) showed that infants at risk for ASD produced gestures but did not always direct these gestures to a communication partner.  

Objectives: In this study, we examined directed and non-directed gesture use in 15-month-old infant siblings at risk for autism (AR-ASD) and low risk control (LRC) infant siblings during a naturalistic, play interaction with their mothers (i.e. home context). In addition, we also examined three maternal behaviours that we hypothesized would be related to gesture use. 

Methods: Seventeen, infant -mother dyads were recruited from a longitudinal study of the emergence of autism symptoms in infants with an older sibling with ASD (AR-ASD, n = 8; LRC, n = 9). Infant-mother dyads were videotaped in their homes. Infant gestures were coded as directed or non-directed. Evidence that a gesture was directed (d+) included: (a) giving an object to a person, (b) touching a person, (c) coordinating a gesture with eye gaze or vocalization, (d) producing a gesture in response to a statement. Gestures without evidence of directness were coded as non-directed (d-). Gesture rates (per minute) were calculated for each infant. Three maternal behaviours were coded: (a) rate of gestures, (b) rate of prompts to encourage infant gesturing (e.g., model, verbal or physical prompt), and (c) responsiveness to infants’ gestures. 

Results: Two one-way ANOVA’s were conducted to evaluate the hypothesis that AR-ASD infants have a lower rate of d+ gestures and a higher rate of d- gestures than LRC infants in a home context. AR-ASD infants had a lower rate of d+ gestures, F( 2, 15) = 14.83, p = .002, partial h² = .32, and a higher rate of d- gestures, F( 2, 15) = 7.17, p = .014, partial h² = .44. To examine maternal behaviours that may be related to infants’ gestures, two one-way ANOVA’s compared the mean rates of gesture use and use of prompts. No significant differences were found between groups in the mean rate of maternal gesture use, F( 2, 15) = .416, p = .529, or the mean rate of maternal use of prompts F( 2, 15) = .481, p = .498.

Conclusions: Fifteen-month old AR-ASD infants have a lower rate of d+ gestures and a higher rate of d- gestures than LRC infants in a home context. Mothers of infants at risk for ASD and those with no risk appear to gesture and prompt infant gestures at similar rates. Because mothers may be more likely to respond to their infants’ directed gestures, maternal responsiveness to directed and non-directed infant gestures will be explored separately. Targeting directedness (e.g., adding eye gaze or vocalization) to make non-directed gestures communicative may be important in intervention.