Enhanced visual search in infancy predicts emerging autism symptoms

In addition to core symptoms, i.e., social interaction and communication difficulties and restricted and repetitive behaviours, autism is also characterized by aspects of superior perception [1]. One well-replicated finding is that of superior performance in visual search tasks, in which participants have to indicate the presence of an odd-one-out element amongst a number of foils [2,3,4,5]. Whether these aspects of superior perception contribute to the emergence of core autism symptoms remains debated [6,4]. Perceptual and social interaction skills could reflect co-expressed but biologically independent pathologies, as suggested by a “fractionable” phenotype model of autism [7]. A developmental test of this hypothesis is now made possible by longitudinal cohorts of infants at high risk, such as of younger siblings of children with ASD. Around 20% of younger siblings are diagnosed with autism themselves [8], and up to another 30% manifest elevated levels of autism symptoms [9]. We used eye-tracking to measure spontaneous orienting to letter targets (O, S, V and +) presented amongst distractors (the letter X, Figure 1). At 9 and 15 months, emerging autism symptoms were assessed using the Autism Observation Scale for Infants (AOSI; 10) and at 2 years of age using the Autism Diagnostic Observation Schedule (ADOS; 11). Enhanced visual search performance at 9-month predicted a higher level of autism symptoms at 15 months and at 2 years. Infant perceptual atypicalities are thus intrinsically linked to the emerging autism phenotype