Processing of facial expressions in peripheral vision: Neurophysiological evidence

•Facial expressions in peripheral vision modulate N1, N2pc, and SPW ERPs.•N1 develops following the initial outburst of smile visual saliency (∼95 ms).•Enhanced N1 and N2pc reflect capture and allocation of attention to happy faces.•SPW deflection reveals facilitated response decision in happy face categorization.•Expression recognition is perceptually driven, without affective discrimination.

We investigated the time course and processes in the recognition of facial expressions in peripheral vision (10.5°). Happy faces were categorized more accurately and faster than angry, fearful, sad, and neutral faces. Consistently, the N1 (90 to 130 ms post-stimulus) and N2pc (200–300 ms) ERP (event-related-potentials) components were more negative, and the SPWs (slow positive waves; 700–800 ms) were smaller, for happy than for non-happy faces. Computational modeling revealed that the smiling mouth became visually salient earlier (95 ms) than any other region, in temporal correspondence with the N1, thus showing an attentional capture by the smile. The N2pc presumably reflected the subsequent selective allocation of processing resources to happy faces. As a result, the reduced SPWs suggest that the decision process in expression categorization became less demanding for happy faces. We propose that facial expression recognition in peripheral vision is mainly driven by perceptual processing, without affective discrimination.

Graphical abstractTime course and ERP components and processes differentiating happy from non-happy expressions in peripheral vision.Figure optionsDownload full-size imageDownload as PowerPoint slide