The role of task relevance in saccadic responses to facial expressions

Recent research on healthy individuals suggests that the valence of emotional stimuli influences behavioral reactions only when relevant to ongoing tasks, as they impact reaching arm movements and gait only when the emotional content cued the responses. However, it has been suggested that emotional expressions elicit automatic gaze shifting, indicating that oculomotor behavior might differ from that of the upper and lower limbs. To investigate, 40 participants underwent two Go/No-go tasks, an emotion discrimination task (EDT) and a gender discrimination task (GDT). In the EDT, participants had to perform a saccade to a peripheral target upon the presentation of angry or happy faces and refrain from moving with neutral ones. In the GDT, the same images were shown, but participants responded based on the posers' gender. Participants displayed two behavioral strategies: a single saccade to the target (92.7%) or two saccades (7.3%), with the first directed at a task-salient feature, that is, the mouth in the EDT and the nose-eyes regions in the GDT. In both cases, the valence of facial expression impacted the saccades only when relevant to the response. Such evidence indicates the same principles govern the interplay between emotional stimuli and motor reactions despite the effectors employed.