Developmental Trajectories of the Attunement of Visual Salience in Infants at High-Risk for ASD with Varying Levels of Affectedness at Outcome

Background: Infants actively shape their environment by directing their attention towards content that they perceive to be most salient. From birth, typically developing (TD) infants are already remarkably attuned to the social world, displaying preferential attention to people. By selectively attending to socially adaptive signals, TD infants create opportunities for social learning that further refine their attention towards those stimuli with greatest relevance to their developmental goals. In contrast, reduced interest in the social world—a hallmark of Autism Spectrum Disorders (ASD), observed already by the second month of life—may lead to increasingly atypical development and schemas of salience. By dynamically assessing group agreement in allocation of visual resources within particular contexts over the first two years of life, this study examines how deviation from typical norms may yield increasingly divergent schemas of salience during infancy. Analyses were performed in infants at high-risk for ASD to examine the impact of deviations from typical norms dimensionally across the full spectrum of social ability to disability.

Objectives: To map developmental trajectories of attunement of visual salience in infants with varying levels of social disability.

Methods: Longitudinal eye-tracking data were collected from children at high-risk for ASD at 10 time points between 2 and 24 months of age. Participants watched naturalistic videos of caregivers and toddler interactions. Diagnostic evaluations at 24 and 36 months identified high-risk infants who: were clinically unaffected (HR-UA; N=33), exhibited subthreshold symptoms of ASD (BAP; N=19), or received a diagnosis of ASD (N=24). Allocation of visual resources was quantified by kernel density analysis at each movie frame in a sample of 24-month-old TD toddlers (N=79) to create a moment-by-moment map of normative salience in relation to movie content. This process was then repeated for HR-UA, BAP, and ASD infants at each longitudinal time point. The salience maps of TD 24-month-olds were used as a baseline for comparison of salience maps generated in HR-UA, BAP, and ASD infants.

Results: Results showed graded effects by outcome, with HR-UA infants displaying the greatest attunement to features perceived as salient by TD 24-month-olds and infants with ASD showing the least attunement to such features. Preliminary results indicate that HR-UA infants’ moment-by-moment deployment of dyadic attention to eyes and mouths is synchronized with that of TD 24-month-olds by as early as 7 and 9 months of age, respectively. By contrast, BAP infants showed delays in reaching these milestones for dyadic eyes and mouth (and never reached baseline levels for attention to peer faces), while ASD infants failed to reach all milestones except for dyadic attention to mouths (delayed by 3 months).

Conclusions: This research demonstrates that deviations from typical trajectories of visual attention are associated with greater social disability at outcome in infants at high-risk for ASD. By failing to deploy attention in a manner that provides experiences that are important for social learning, BAP and ASD infants are learning about the world in very different ways, leading to increasingly atypical trajectories of learning and development.