The Development of Face Processing Deficits in Autism: A Meta-Analytic Review

Abnormal visual scanning of faces in individuals with autism is a predictor and possible precursor to more prominent social communication deficits seen in autism (Klin et al., 2002; Sasson, 2006) and it is one of the earliest symptoms (Dawson et al., 2005). The aim of the present meta-analysis is to determine the degree and significance of differences in looking behaviors between infants at high and low risk of autism, and to examine if these differences are affected by the type of social stimuli used. High and low risk infants' looking behaviors were compared when viewing static and dynamic stimuli and when participating in the still-face paradigm. Studies were included if they utilized infants (birth to 12 months) both at high risk and low risk for developing autism and used an eye-tracker to measure duration of time looking at facial stimuli. Twenty-one studies met inclusion criteria. The overall effect size of differences in looking behaviors for high and low risk infants was 0.03 (95% -0.06 - 0.12). There were no significant effects of age, gender, or type of stimulus on infants' looking behaviors. While majority of studies found an effect in the difference of looking behaviors between infants at high and low risk, the inconsistency of the combined results resulted in an overall nonsignificant effect size. These findings indicate reduced eye contact may not be as reliable of a behavioral marker within the first year of life as previous research has indicated.