Face perception in autism spectrum disorder: Modulation of holistic processing by facial emotion

Individuals with Autism Spectrum Disorder (ASD; autistic individuals) may exhibit atypical face perception because they fail to process faces holistically. In the context of this hypothesis, it is critical to determine whether autistic individuals exhibit diminished susceptibility to the composite face illusion, widely regarded as a key marker of holistic face processing. To date, however, previous studies have yielded inconsistent findings. In light of recent evidence suggesting that facial emotion cues increase the strength of the composite face illusion in typical individuals, the present study sought to determine whether the presence of facial emotion also modulates the strength of the composite face illusion in autistic individuals, many of whom experience difficulties recognizing facial expressions. We therefore measured composite face effects in a sample of autistic individuals (N = 20) and matched typical controls (N = 29) using an incidental emotion procedure in which distractor regions varied systematically in their emotion strength. As expected, the presence of facial emotion in the distractor regions of composite face arrangements increased the strength of the illusory distortion induced. The extent of the modulation by facial emotion was similar in the two groups. The composite effects seen in the ASD group were qualitatively and quantitatively similar to those seen in the typical group, suggestive of intact holistic processing in this population.