Abstract
BackgroundIndividuals with Autism Spectrum Disorders (ASD) typically show impaired eye contact during social interactions. From a young age, they look less at faces than typically developing (TD) children and tend to avoid direct gaze. However, the reason for this behavior remains controversial; ASD children might avoid eye contact because they perceive the eyes as aversive or because they do not find social engagement through mutual gaze rewarding.MethodsWe monitored pupillary diameter as a measure of autonomic response in children with ASD (n = 20, mean age = 12.4) and TD controls (n = 18, mean age = 13.7) while they looked at faces displaying different emotions. Each face displayed happy, fearful, angry or neutral emotions with the gaze either directed to or averted from the subjects.ResultsOverall, children with ASD and TD controls showed similar pupillary responses; however, they differed significantly in their sensitivity to gaze direction for happy faces. Specifically, pupillary diameter increased among TD children when viewing happy faces with direct gaze as compared to those with averted gaze, whereas children with ASD did not show such sensitivity to gaze direction. We found no group differences in fixation that could explain the differential pupillary responses. There was no effect of gaze direction on pupil diameter for negative affect or neutral faces among either the TD or ASD group.ConclusionsWe interpret the increased pupillary diameter to happy faces with direct gaze in TD children to reflect the intrinsic reward value of a smiling face looking directly at an individual. The lack of this effect in children with ASD is consistent with the hypothesis that individuals with ASD may have reduced sensitivity to the reward value of social stimuli.
Highlights
Individuals with Autism Spectrum Disorders (ASD) typically show impaired eye contact during social interactions
To examine the social motivation hypothesis, we examined pupillary response to faces displaying positive affect in the ASD and typically developing (TD) groups, with the underlying assumption that a happy face with direct eye gaze would be most rewarding for neurotypical individuals [14,15]
Pupil dilation analyses Analyses to examine the ‘aversion hypothesis’ To examine if individuals with ASD avoid looking at faces, and the eye region in particular, we performed a repeated measure ANOVA with gaze condition and emotion as withinsubject factors and diagnosis as a between-group factor (ASD and TD) for pupillary response magnitude, measured as the mean pupillary response from 0.6 to 1.6 s
Summary
Individuals with Autism Spectrum Disorders (ASD) typically show impaired eye contact during social interactions. Kampe et al (2001) showed that fMRI activation in the ventral striatum is modulated both by reward magnitude (degree of facial attractiveness) and direction of the gaze (direct vs averted), indicating that reward circuits are engaged when looking at people’s faces and that this network is sensitive to eye contact. These findings suggest that, for neurotypical individuals, direct eye contact during social interactions may be intrinsically rewarding
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