Valence-Arousal Asymmetry: Rethinking Facial Emotion Recognition in Preschool Autism Through Eye-Tracking.

Facial emotion recognition is a fundamental socioemotional skill often impaired in autism spectrum disorder (ASD). Yet findings remain inconsistent, partly due to reliance on discrete emotion categories that neglect affective dimensions. Guided by a valence-arousal framework, this study re-examined facial emotion recognition in preschool children with ASD using eye-tracking and pupilometry. Eighty-two Chinese preschoolers (40 ASD, 42 typically developing [TD]) completed an emotion recognition task with facial stimuli systematically varied in valence (positive vs. negative) and arousal (high vs. low). Eye movements and pupil size were analyzed within a 2 (group) × 2 (valence) × 2 (arousal) × 4 (AOI: eyes, nose, mouth, other) design. Results showed robust effects of valence: TD children allocated more fixations and longer gaze to positive faces, especially the eye region, whereas ASD children showed attenuated patterns. Arousal effects were weaker but interacted with valence, with high-arousal negative faces eliciting avoidance and high-arousal positive faces enhancing pupil responses. These findings highlight valence-arousal asymmetry as a key mechanism underlying atypical emotion processing in preschool ASD and underscore the value of dimensional approaches for early socioemotional assessment and intervention.