Stimulus exposure duration alters implicit processing of neutral and emotional faces

Abstract

Stimulus exposure duration in emotion perception research is often chosen pragmatically; however, little work exists on the consequences of stimulus duration for the processing of emotional faces. We utilized the spatiotemporal resolution capabilities of magnetoencephalography (MEG) to characterize early implicit processing of emotional and neutral faces in response to stimuli presented for 80 and 150ms. We found that the insula was recruited to a greater degree within the short (80ms) condition for all face categories, and this effect was more pronounced for emotional compared to neutral faces. The orbitofrontal cortex was more active in the 80-ms condition for neutral faces only, suggesting a modulation of task difficulty by both the duration and the emotional category of the stimuli. No effects on reaction time or accuracy were observed. Our findings caution that differences in stimulus duration may result in differential neural processing of emotional faces and challenge the idea that neutral faces constitute a neutral baseline.