Pupillary response during social emotion tasks in autism spectrum disorder.

Autistic individuals encounter challenges in recognizing emotional expressions of others. Pupillary response has been proposed as an indicator of arousal dysregulation or cognitive load. The pupillary response of autistic individuals during socio-affective tasks remains unclear. This study investigated pupillary response in autistic adults when viewing emotional faces/eyes and recognizing emotions during the Reading the Mind in the Eyes Test (RMET) and watching interpersonal touch scenes in the social touch task. The study included 98 participants diagnosed with autism spectrum disorder and 37 typically developing controls (TD). Pupil size was measured using the Tobii X2-30 Eye Tracker. The results showed that autistic adults had larger maximal pupil sizes, smaller minimal pupil sizes, and greater change rates of pupil size, particularly during the RMET Eyes task. Clinical correlations revealed that attention switching difficulty positively correlated with mean pupil size in TD participants, while social communication deficits positively correlated with mean pupil size in autistic participants. In conclusion, our findings suggest atypical pupillary responses in autistic adults during socio-affective tasks, indicating heightened cognitive demand. Further investigation is necessary to understand the underlying mechanisms and their association with autistic traits.