Electrocortical responses to NIMSTIM facial expressions of emotion

Emotional faces are motivationally salient stimuli that automatically capture attention and rapidly potentiate neural processing. Because of their superior temporal resolution, scalp-recorded event-related potentials (ERPs) are ideal for examining rapid changes in neural activity. Some reports have found larger ERPs for fearful and angry faces compared with both neutral and other emotional faces, and a key aim of the present study was to assess neural response to multiple emotional expressions using the NIMSTIM. Importantly, no study has yet systematically evaluated neural activity and self-report ratings for multiple NIMSTIM expressions. Study 1 examined the time-course of electrocortical activity in response to fearful, angry, sad, happy, and neutral NIMSTIM faces. In Study 2, valence and arousal ratings were collected for the same faces in a separate sample. In line with previous findings, the early P1 was larger for fearful compared with neutral faces. The vertex positivity (VPP) was enhanced for fearful, angry, and happy expressions compared to neutral. There was no effect of expression on the N170. Marginally significant enhancements were observed for all expressions during the early posterior negativity (EPN). The late positive potential (LPP) was enhanced only for fearful and angry faces. All emotional expressions were rated as more arousing and more pleasant/unpleasant than neutral expressions. Overall, findings suggest that angry and fearful faces might be especially potent in terms of eliciting ERP responses and ideal for emotion research when more evocative images cannot be used.