Orientation and affect directed towards social and nonsocial targets in infant siblings of children with Autistic Spectrum Disorder (ASD)
This study contributes to a growing body of work aimed at documenting and defining behavioral markers associated with early autism spectrum disorder (ASD) and its broader phenotype. A total of 19 infants (sib-ASD), who have a sibling diagnosed with ASD were seen at 6.5 months, and 23 infants were seen at 9 months. Sib-ASD infants were matched in age and gender with low-risk infants (sib-TD), who have a typically developing sibling. Infants were simultaneously presented two stimuli, a person’s face (the social stimulus) and a brightly colored toy (the nonsocial stimulus). We found there were no significant differences between at-risk infants and low-risk infants in their responsiveness to and disengagement from the stimuli. However, a significant group difference did appear in the 9 month infants’ time smiling. Sib-TD infants spent more time smiling at the nonsocial as compared to the social stimulus relative to the sib-ASD infants, who showed no preference in time smiling for one stimulus over the other. This unexpected finding contradicted our initial predictions that sib-TD infants would prefer the social stimulus and thus spend more time smiling at the experimenter’s face, while sib-ASD infants would prefer the nonsocial stimulus, and thus spend more time smiling at the toy.