Spontaneous Facial Emotion Discrimination in Individuals with Autism Spectrum Disorders and Fragile X Syndrome

Background: Previous studies of emotion recognition have found that individuals with autism spectrum disorder (ASD) and fragile X syndrome (FXS) perform similarly to carefully matched typically developing individuals on explicit measures of emotion recognition. However, previous studies using eye tracking measures have highlighted atypical looking patterns in individuals with ASD and FXS during emotion processing. Although it appears that this does not affect explicit emotion recognition, it has not yet been investigated as to whether atypical looking patterns during emotion processing impacts spontaneous emotion discrimination.

Objectives: To examine and compare the spontaneous discrimination of faces posed in happy and disgusted expressions from neutral faces, using eye-tracking in a passive habituation/dishabituation paradigm.

Methods: Participants were fourteen individuals with ASD, nine individuals with FXS, and twelve typically developing individuals.  We measured eye gaze patterns during the passive viewing of pairs of human faces.  Participants were presented with either two neutral faces, side by side, or one neutral face alongside a disgusted or happy face.  Neutral-neutral pairs were presented on 80% of trials, whereas neutral-disgust and neutral-happy pairings were presented on 10% of trials each.  Looking patterns during neutral-disgust and neutral-happy trials were examined for preferential looking times to the novel (disgust, happy) emotional expressions. We also measured eye gaze patterns to the eyes and mouth region of the facial stimuli.

Results: Both typically developing participants and participants with ASD looked at both the disgusted and happy faces more than the neutral faces during the critical trials.  This suggests that both of these groups spontaneously recognised the difference between neutral and disgusted and neutral and happy faces.  Participants with FXS discriminated disgusted from neutral faces, but not happy from neutral faces. Individuals with ASD looked significantly more at the mouth region than both the TD and FXS individuals. In addition, participants with ASD and FXS exhibited a non-significant tendency to look less at the eye region than TD individuals.

Conclusions: These results suggest that individuals with ASD, like TD individuals, can spontaneously distinguish between different emotions. However, individuals with FXS do not spontaneously distinguish happy from neutral faces. These results highlight a possible discrepancy between explicit emotion recognition, which previous research has suggested is largely intact in FXS, and spontaneous emotion discrimination. These results also suggest that the underlying mechanisms subserving spontaneous emotion discrimination in ASD and FXS may differ. Individuals with ASD looked more at the mouth than both those with FXS and TD individuals. Therefore, it is possible that emotion discrimination in ASD is more heavily affected by information obtained from the mouth area. However, individuals with FXS may not have obtained the information required for emotion discrimination from either the eye or the mouth area, at least for happy faces, as they exhibited less looking at the eye region and no increase in looking at the mouth area.