Differences in Object Sharing and Locomotor Development Between Infants at Risk for Autism and Typically Developing Infants in the First 15 Months of Life

Background: Older infants engage in triadic joint attention to share object play with their caregivers (Bakeman & Adamson, 1984). Infants move in different ways to express their intent to share by turning to look, pointing to, showing objects, giving objects, vocalizing, or approaching the caregivers with objects. Advancements in locomotor skills could facilitate a child’s object sharing or joint attention bids (Karasik et al., 2011). Young children who later develop Autism Spectrum Disorders (ASDs) show social as well as motor impairments. Moreover, early motor impairments may facilitate social impairments in young infants at risk for ASDs (i.e. infant siblings of children with ASDs or AU sibs).  

Objectives: In the present study, we compared object sharing behaviors between AU sibs and typically developing (TD) infants at 9, 12, and 15 months. In addition, we examined the influence of locomotor development on the object sharing abilities of both groups of infants. 

Methods:  16 AU sibs and 16 TD infants were observed during an object sharing task at 9, 12, and 15 months with developmental follow-up and autism screening at 18 and 24 months. During each visit we collected video data for 14 minutes wherein infants were seated facing their caregivers near multiple small toys. In the spontaneous condition (7 minutes), the caregiver was asked to be quiet and wait for the child to initiate a social interaction. In the social condition (7 minutes), the caregiver initiated a clean up activity wherein they pointed to the toy and asked the child for a particular toy. Dependent variables included total rates and types of object sharing bids including throws, reaches, approaches towards CG without objects, and approaches with objects. In addition, we grouped infants by locomotor status at each visit (i.e.; crawlers or walkers).

Results: Rates of object sharing bids were greater in the social condition than the spontaneous condition. In addition, object sharing interacted with motor skill level in both groups of infants. Specifically, infants with advanced locomotor skills i.e.; walkers showed greater rates and variety of object sharing behaviors than crawlers. AU sibs had lower rates of object sharing bids, specifically in the social condition compared to TD infants. Differences between TD infants and AU sibs were significant among walkers but not in crawlers. Moreover, AU sibs with poor social communication and motor delays had lower rates of sharing than AU sibs without social communication and motor delays. 

Conclusions: Our results suggest that object sharing behaviors may provide an early marker for future risk of ASDs within the first year of life. Moreover, early fine motor and gross motor delays may contribute to the social communication delays in infants at risk for ASDs. Therefore, it would be important to facilitate these social actions as well as motor development during treatment sessions of infants at risk for ASDs.