Divergence of Object Play Trajectories Between High-Risk Infant Siblings and Low-Risk Controls Occurs Between 15 and 18 Months of Age

Background: Assessment of object play behaviors in early childhood can have important implications for screening of autism spectrum disorder (ASD) and for predicting social and communicative competence of children with ASD in later life (Stone et al., 2008; Ozonoff et al., 2008; Bruckner and Yoder, 2007; Lewis, 2003). While unusual characteristics of object play in children with autism before the age of two have been reported via parent reports and analysis of family home videos, confirmation of diagnosis typically does not occur until age 3 or older. Currently, it has been estimated that almost 20% of the infant siblings of children on the spectrum (High-Risk sibs) develop an ASD (Ozonoff et al., 2011). Thus, studying this population could provide profound insights on the developmental trajectory of ASD during the first two years of life.

Objectives: This study compares object play behaviors in High-Risk sibs and the infant siblings of typically developing children (COMP-sibs) from 9 months through 18 months of age.

Methods: Object play was examined longitudinally in high-risk sibs (n= 9) and COMP-sibs (n= 9) at 9, 12, 15, and 18 months of age. Infants and their caregivers participated in the Play-based Assessment of Referential Communication (PARC) task in which the infant is seated across from his/her caregiver and is surrounded by 9 different types of toys. During the 6 minutes of the PARC, infants and their caregivers engage in a play session in which caregivers are instructed not to initiate or prompt interaction/play with their child (i.e. vocalizing or smiling) unless the child initiates first. Using an adapted version of the Developmental Play Assessment (DPA; Yoder, 2007), differentiated and undifferentiated play behaviors were coded. Differentiated play refers to object-specific actions that were identified for each toy a priori.  Undifferentiated play refers to actions that are indiscriminant and can be used with any toy regardless of its physical properties (e.g., mouthing, banging, or visual inspection). Four variables were coded during play: rate per minute of differentiated and undifferentiated play actions; number of different actions of toys; and number of different toys used.

Results: From 9 months through 15 months, there were no group differences in number of differentiated play actions or number of toys used. At 18 months of age, High-Risk sibs (M= 1.23, SD=1.08) showed a lower rate of differentiated play actions than COMP-sibs (M= 3.28, SD=1.55), p =.03. High-Risk sibs (M= 2.60, SD=1.52) engaged in fewer distinct differentiated play actions than COMP-sibs (M=5.86, SD=2.48), p=.03. High-Risk sibs (M= 2.00, SD=1.00) tended to play with fewer toys than COMP-sibs (M= 3.43, SD=1.40), p = .08. There were no group differences on undifferentiated play.

Conclusions: Differences in differentiated object play between High-Risk sibs and COMP-sibs emerge by 18 months, as reflected by High-Risk sibs demonstrating fewer overall differentiated play actions, fewer distinct actions, and engaging with fewer toys than COMP-sibs. The implications of this group difference in developmental trajectory will be examined in a larger sample with reference to development of social communicative competencies and diagnostic outcomes.