Same but different: 9-month-old infants at average and high risk for autism look at the same facial features but process them using different brain mechanisms.

The study examined whether 9-month-old infants at average vs. high risk for autism spectrum disorder (ASD) process facial features (eyes, mouth) differently and whether such differences are related to infants' social and communicative skills. Eye tracking and visual event-related potentials (ERPs) were recorded in 35 infants (20 average-risk typical infants, 15 high-risk siblings of children with ASD) while they viewed photographs of a smiling unfamiliar female face. On 30% of the trials, the eyes or the mouth of that face was replaced with corresponding features from a different female. There were no group differences in the number, duration, or distribution of fixations, and all infants looked at the eyes and mouth regions equally. However, increased attention to the mouth was associated with weaker receptive communication skills and increased attention to the eyes correlated with better interpersonal skills. ERP results revealed that all infants detected eye and mouth changes but did so using different brain mechanisms. Changes in facial features were associated with changes in activity of the face perception mechanisms (N290) for the average-risk group but not for the high-risk infants. For all infants, correlations between ERP and eye-tracking measures indicated that larger and faster ERPs to feature changes were associated with fewer fixations on the irrelevant regions of stimuli. The size and latency of the ERP responses also correlated with parental reports of receptive and expressive communication skills, suggesting that differences in brain processing of human faces are associated with individual differences in social-communicative behaviors.