Development of Oculomotor Function in the First Two Years of Life in Children At High- and Low-Risk for Developing Autism Spectrum Disorders

Background:  Previous research has investigated properties of visual saccades and fixations in school-aged children and toddlers with autism spectrum disorders (ASD) using a natural viewing paradigm. The results confirm findings from two separate bodies of literature, indicating that basic mechanisms of oculomotor function are intact in children with ASD, but that children with ASD differ from their typically-developing (TD) peers in terms of the social content on which they preferentially focus. Other research using longitudinal methods to study viewing patterns of naturalistic scenes has also found that children with ASD exhibit a preference for different aspects of a social scene than TD children. However, the developmental trajectory of oculomotor function during a natural viewing task has not yet been explored between these groups. The current study intends to address that topic.

Objectives:  To characterize developmental changes of oculomotor properties of visual fixations and saccades during natural viewing of social scenes and to compare oculomotor function in infants with ASD and TD infants.

Methods:  Fixation and saccades were identified from data in a longitudinal study using eye-tracking equipment to examine the viewing patterns of naturalistic scenes in infants at high- and low-risk for developing ASD. Eye-tracking data were collected at months 2, 3, 4, 5, 6, 9, 12, 15, 18, and 24 months while infants viewed videos of actresses engaging in child-directed caregiving behaviors and of toddlers interacting in playground settings. Diagnoses were given at 36 months, assigning infants into ASD (n = 15) and TD (n=48) groups. The following properties and content of eye movements were analyzed cross-sectionally and longitudinally, and then compared between groups: fixation duration; frequencies of saccade and fixations; relationship between saccade amplitude and duration; and relationship between saccade velocity and amplitude.

Results:  Preliminary analyses suggest that while basic properties of saccades and fixations undergo developmental change, they do not differ between infants with ASD and typically-developing controls.

Conclusions:  Physiological properties of eye movements appear to develop normally in young children with ASD. This suggests that differences in visual scanning of social content, observed previously in infants with ASD relative to typically-developing peers, are not the result of oculomotor impairment, but rather reflect differences in what aspects of a social scene are most salient.