Behavioural reactions to an emotion evoking task in infants at increased likelihood for autism spectrum disorder.

Infants at increased likelihood for autism spectrum disorder (ASD) exhibit more negative affect and avoidance behaviour than typically developing infants, and children with ASD express fear differently than typically developing peers. We examined behavioural reactions to emotion-evoking stimuli in infants at increased familial likelihood for ASD. Participants included 55 increased likelihood (IL) infants (i.e., siblings of children diagnosed with ASD) and 27 typical likelihood (TL) infants (i.e., no family history of ASD). At 18 months, we showed infants two masks that commonly elicit fearful responses in older children and examined potential behavioural differences in approach, avoidance, 'freezing', crying, gaze aversion, and smiling. At 24 months, infants were assessed with the Toddler Module of the Autism Diagnostic Observation Schedule, 2nd edition (ADOS-2). Results of video-based coding showed that (1) IL infants exhibited more intense avoidance behaviour than TL infants in response to masks, and (2) intensity of avoidance and duration of freezing were positively correlated with ADOS-2 symptom severity scores. Findings suggest that differences in response to emotion-eliciting stimuli may predict later ASD symptoms. Such behavioural differences may inform early detection and intervention in ASD.