Children with Autism Spectrum Disorders (ASD), and their infant siblings (ASD-siblings), exhibit deficits in their ability to shift visual attention, and to initiate and respond to joint attention. The current study examined early associations between visual attention and joint attention, and between these types of attention and later language ability and ASD severity in ASD-siblings (n = 31). This study investigated the possibility that ASD-siblings, who are at-risk for atypical development, differed from infants who have an older sibling(s) with no evidence of an ASD (Comparison-siblings; n = 23) on the following: 1) means of visual and joint attention, 2) the associations between these constructs, and 3) developmental trajectories of joint attention. Early visual attention was measured using infants' gazes at and away their parents' faces during the Face-to-Face Still-Face Protocol at 6 months. Initiating joint attention (IJA) and responding to joint attention (RJA) were measured during the Early Social Communication Scales at 8, 10, 12, 15, and 18 months. Language ability was measured with the Mullen Scales of Early Learning language at 24 and 36 months. ASD severity was measured on the Autism Diagnostic Observation Schedule at 30 months. Results indicated that ASD-siblings and Comparison-siblings were comparable in their gaze shifting and mean durations of gazes away from their parents' faces. These two components of visual attention were associated with parent behaviors, and the type of chair infants sat in. There were group differences in IJA at 10 months and RJA at 8, 15, 18 months, with ASD-siblings performing fewer behaviors than Comparison-siblings. There were developmental associations between visual and joint attention, and joint attention and later language and ASD severity. ASD-siblings differed from Comparison-siblings in their RJA development. ASD-siblings also had lower language ability and greater ASD severity than Comparison-siblings. The current study's limitations included low statistical power, and a difficulty inherent to prospective studies, which are at a disadvantage because a high proportion ASD-siblings may not develop an ASD. Nevertheless, the findings have clinical implications for the development of interventions targeting RJA behaviors within the first year of life.

Compared to other children, children with Autism Spectrum Disorder (ASD) are known to engage less in joint attention - the sharing of attention between two individuals toward a common object or event. Joint attention behaviors - for example gaze following, alternating gaze, and pointing - play an important role in early development, as they provide a foundation for learning and social interaction. Study I and Study II focused on infant siblings of children with ASD. These infants, often termed high risk (HR) infants, have an increased probability of receiving a later ASD diagnosis. Studying them therefore allows for the detection of early signs of ASD. Live eye tracking was used to investigate different joint attention behaviors at 10 months of age. Study I showed that omitting the head movement that usually accompany experimenters’ eye gaze shifts in similar designs reduced gaze following performance in the HR group, but not in a group of infants at low risk (LR) for ASD. HR infants may thus be less sensitive to eye information, or may need more salient cues in order to follow gaze optimally. Study II focused on the infants’ tendency to initiate joint attention by alternating their gaze between a person and an event. LR infants engaged more in alternating gaze than HR infants, and less alternating gaze in infancy was associated with more ASD symptoms at 18 months. This relation remained when controlling for visual disengagement and general social interest in infancy. Study III explored the role of joint attention later in development, by investigating the microstructure of the looking behaviors of autistic and typically developing children (~6 years old). The results indicated that seeing somebody look at an object influenced the processing of that object less in autistic children than in the typically developing controls. Both groups followed gaze effectively, suggesting that differences in joint attention at this age may be subtle, but detectable with eye tracking technology. Together, the studies contribute to our understanding of the role that joint attention atypicalities play both in the early development of infants at risk for ASD, and later in the development of children with a confirmed diagnosis.