Expressive behavior is multi-modal from early in life (Yale et al., 2003). Gestures and vocal production become more coordinated over time, but little is known about the developmental origins of the speech-geture link (Iverson, 2010). Gestures provide a means for children to communicate meaning beyond their lexical abilities (Ozcaliskan et al., 2005). However, many children with ASD demonstrate motor difficulties which may impede gesture development and are associated with language delays (Stone & Yoder, 2001).
Objectives:
- Determine gesture inventory produced by children with and without autism.
- Examine patterns of gesture use and associations with language development using parent report and clinical measures.
Methods:
Participants were 231 sibs-A (57.1% male) assessed at 14, 18, 24, and 36 months. Outcome diagnoses were assigned at 36 months. Children were classified as ASD (n = 68), non-ASD delay (n = 63), or non-ASD (n = 106).
Parents completed the MacArthur-Bates Communicative Development Inventories: Words & Gestures version at 14 months and Words & Sentences version at 18, and 24 months. The trajectory of vocabulary development was assessed using the total number of words produced at each assessment.
Clinicians administered the Mullen Scales of Early Learning at 14, 18, and 24 months. The Receptive (RL) and Expressive language (EL) age equivalents were used.
Results:
Gesture Use at 14 Months. Across all types of gestures, the non-ASD group produced more gestures than the ASD or Non-ASD Delay groups (all p < .01). The ASD and Non-ASD Delay groups did not differ from each other. The number of gestures produced was also associated with Mullen RL and EL, and CDI words produced at 14, 18, and 24 months (all p < .01).
Trajectory of Language Development. Hierarchical linear modeling demonstrated quadratic growth in parent-reported vocabulary development, expressive and receptive language within each of the groups. Further, on all language measures, the ASD group showed a divergent pattern from both the non-ASD Delay and non-ASD groups. The non-ASD Delay group became more similar to the non-ASD group over time.
Total number of gestures at 14 months was associated with greater gains from 14-24 months in words produced on the CDI for the non-ASD group only (t(215) = 2.20, p < .05). On the Mullen, total gesture use at 14 months was associated with gains in receptive and expressive language trajectories from 14-24 months for both the non-ASD (RL: t(215) = 2.08, p < .01; EL: t(215) = 2.94, p < .01) and non-ASD delay groups (RL: t(215) = 2.68, p < .01; EL: t(215) = 3.18 p < .01).
Conclusions:
These data corroborate previous reports that children with ASD demonstrate fewer gestures early in life (Landa et al., 2007). Early gesture use was not related to language trajectories for children ASD. The speech-gesture link requires integration of multiple systems, particularly motor and vocal. Children with ASD may have more difficulty integrating these systems, which may limit the communicative quality of early gestures and diminish the potential for early gesture use to promote language development.
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