Atypical facial mimicry for basic emotions in children with autism spectrum disorder

During social encounters, people tend to reproduce the facial expressions of others, termed "facial mimicry," which is believed to underlie many important social cognitive functions. Clinically, atypical mimicry is closely associated with serious social dysfunction. However, findings regarding the facial mimicry ability of children with autism spectrum disorder (ASD) are inconsistent; it is necessary to test whether deficits in facial mimicry are core defects of autism and explore the potential mechanism underlying this process. Using quantitative analysis, this study investigated voluntary and automatic facial mimicry performance of six basic expressions in children with and without ASD. There was no significant group difference in mimicry accuracy, but children with ASD showed less intensity in voluntary and automatic mimicry than typically developing children; they also presented less voluntary mimicry intensity for happy, sad, and fearful expressions. Performance on voluntary and automatic mimicry was significantly correlated with the level of autistic symptoms (r >-.43) and theory of mind (r >.34). Furthermore, theory of mind mediated the relationship between autistic symptoms and the intensity of facial mimicry. These results suggest that individuals with ASD show atypical facial mimicry (i.e., less intensity for both voluntary and automatic mimicry, mainly for voluntary mimicry of happiness, sadness, and fear), which might offer a potential cognitive marker for quantifying syndrome manifestations in children with ASD. These findings suggest that theory of mind plays a mediating role in facial mimicry, which may provide insight into the theoretical mechanism of social dysfunction in children with autism.