Dyadic Synchrony and Responsiveness Within the Context of Elevated Autism Likelihood: Applying Time-Varying Effect Models.

The ability to engage in synchronous interactions develops in the first year, as infants learn to sequentially regulate prosocial behaviors. Difficulty developing competence in these early social building blocks is linked to later developmental concerns, including autism spectrum disorder (ASD). Currently, metrics for quantifying social competence rely primarily on mean-level indices; however, interactions are dynamic. The present study modeled change in the odds of dyadic synchrony (DS), maternal responsiveness (MR), and infant responsiveness (IR) over time to explore if temporal patterns can inform developmental monitoring. Dyads were recruited from families with at least one older child with ASD (elevated ASD likelihood, n = 95) or families with no history of ASD (typical ASD likelihood, n = 72). Theory-driven indices of dyadic synchrony and responsiveness were derived from micro-analytically coded gaze, positive affect, and vocalizations. A series of logistic time-varying effect models (TVEMs) were conducted to compare temporal changes in synchrony and responsiveness across the infant/toddler groupings of (1) elevated- vs typical-ASD likelihood and (2) typical (TYP), ASD, or other developmental concerns (Non-ASD DC). DS, IR, and MR patterns were temporally stable but lower for the elevated ASD likelihood group. Temporal patterns of DS, IR, and MR were more variable for the ASD and Non-ASD DC groups. TVEMs captured meaningful dyadic information and could be used in future studies to inform prospective monitoring and parent-mediated intervention approaches.