Early Object Manipulation In Infants at Risk for Autism Spectrum Disorder

Background: Relative to typical infants, infants later diagnosed with autism spectrum disorder (ASD) show more atypical object exploration at 12 months (Christensen et al., 2010) and deficits in functional play at 18 months (Ozonoff et al., 2008). Little is known about the developmental course of these atypicalities, as infants were assessed only at 12 or 18 months.

Objectives: Our goal is to understand differences in the development of early object manipulation between high-risk infant siblings (infants with an older sibling with ASD) and low-risk controls (infants with no family history of ASD). 

Methods: We observed solo, interactive, and atypical object manipulation in high-risk infant siblings and low-risk controls at 6, 12, and 18 months. We coded behaviours from video-recordings of infants engaged in play in the context of the Autism Observation Scale for Infants, a semi-structured assessment of early signs of autism. Each infant sat on his parent’s lap, facing an examiner across a small table. The infant was allowed to play freely with a set of toys (e.g., a rattle, ball, small toy animals, and blocks) for 3 - 5 minutes. The duration of the behaviours of interest was coded using Noldus Observer software. Object manipulation was categorized for analyses as: (1) lower-level solo (e.g., banging, mouthing); (2) higher-level solo (e.g., throwing a ball, building a tower of blocks); (3) interactive (e.g., reaching, showing); and (4) atypical (e.g., atypical grasp, sensory stimulation).

Results: We compared the percentage of time infants spent engaged in object manipulation across age (6, 12, & 18 months) and between groups using four 3 x 3-way ANOVAs. Infants were grouped according to 36-month outcome as: (1) siblings with ASD (ASD siblings); (2) siblings without ASD (non-ASD siblings); and (3) low-risk controls. Preliminary results indicate that, overall, infants showed similar patterns of development of solo object manipulation. Specifically, across ages the percentage of time infants engaged in solo object manipulation decreased for lower-level behaviours, and increased for higher-level behaviours. However, at 6 months, ASD siblings spent more time than controls engaged in lower-level solo object manipulation, while at 18 months, ASD siblings spent more time than controls engaged in higher-level solo object manipulation. As expected, ASD siblings spent more time engaged in atypical behaviours than controls; although, this was true only at 12 months and occurred only ~ 5% of the time. The percentage of time infants engaged in interactive object manipulation increased between 6 and 18 months for controls but not for ASD siblings. Non-ASD siblings showed a mixed pattern, with some behaviours more similar to controls and others more similar to ASD siblings.

Conclusions: These preliminary results suggest that, until 18 months, ASD siblings spend more time engaged in solitary play than controls, much of which appears qualitatively similar to that of controls. By 18 months, ASD siblings spend less time than controls engaged in behaviours that involve others in their play. Given the role of play on cognitive and social development, these findings may point to critical targets for early intervention for ASD.