Within the first week of life, typical human newborns give preferential attention to the eyes of others. Similar findings in other species suggest that attention to the eyes is a highly conserved phylogenetic mechanism of social development. For children with autism, however, diminished and aberrant eye contact is a lifelong hallmark of disability.
To quantify preferential attention to the eyes of others at what is presently the earliest point of diagnosis in autism.
We presented the children with 10 videos. Each video showed an actress looking directly into the camera, playing the role of caregiver, and engaging the viewer (playing pat-a-cake, peek-a-boo, etc). Children's visual fixation patterns were measured by eye tracking.
Fifteen 2-year-old children with autism were compared with 36 typically developing children and with 15 developmentally delayed but nonautistic children.
Main Outcome Measure
Preferential attention was measured as percentage of visual fixation time to 4 regions of interest: eyes, mouth, body, and object. Level of social disability was assessed by the Autism Diagnostic Observation Schedule.
Looking at the eyes of others was significantly decreased in 2-year-old children with autism (P < .001), while looking at mouths was increased (P < .01) in comparison with both control groups. The 2 control groups were not distinguishable on the basis of fixation patterns. In addition, fixation on eyes by the children with autism correlated with their level of social disability; less fixation on eyes predicted greater social disability (r = − 0.669, P < .01).
Looking at the eyes of others is important in early social development and in social adaptation throughout one's life span. Our results indicate that in 2-year-old children with autism, this behavior is already derailed, suggesting critical consequences for development but also offering a potential biomarker for quantifying syndrome manifestation at this early age.