Sarah McCrackin¹, Florence Mayrand¹, Jelena Ristic¹; ¹McGill University

Human attention is spontaneously oriented in the direction of eye gaze. Such gaze following behavior is more pronounced if the person shifts their gaze and reacts emotionally with a facial expression, which is thought to be adaptive for facilitating orienting towards environmentally important events. It remains unknown, however, how the emotional expression on the face is processed along with eye-gaze information to produce the gaze following enhancement. Here we investigated this question by presenting participants with faces that averted their gaze and then either reacted emotionally or remained neutral. They responded to peripheral targets appearing in gaze-congruent or gaze-incongruent locations. Critically, half of the faces were unoccluded, while the other half had their lower part occluded by a surgical mask. Experiment 1 (N=74) presented fear, happy, and neutral expressions. Experiment 2 (N=77) presented disgust, surprise, and neutral expressions (pre-registered: https://osf.io/8uzgf). Thus, facial expressions varied both in eye size (i.e., smaller for disgust, larger for surprise) and in whether their most emotionally diagnostic facial features were visible (e.g. wide eyes for fear remaining unoccluded, wrinkled nose for disgust occluded). In both experiments, participants were overall significantly faster to locate gaze-congruent compared to gaze-incongruent targets, demonstrating classic gaze following behavior. This effect was larger when the faces displayed emotional expressions (fearful and happy vs. neutral in Experiment 1; disgusted and surprised vs. neutral in Experiment 2), but critically did not significantly vary with face occlusion condition. This shows that the information from the eye-region alone appears to contain enough emotional information within the face to drive the emotional enhancement of gaze following, highlighting the powerful nature of the eyes in emotional perception.

Acknowledgements: This research was supported by the Natural Sciences and Engineering Council of Canada (NSERC; JR & SM), and the G.W. Stairs Grant (SM & JR)