Does facial action modulate neural responses of emotion? An examination with the late positive potential (LPP)

The facial feedback hypothesis suggests that emotional facial action causally modulates the subjective experience of emotion. Notably, some proposed that facial action modulates emotional experience because it directly modulates neural responses of emotion. At present, the robustness of the facial feedback hypothesis has been debated. Moreover, little evidence exists for the direct modulation of neural responses by facial action. To fill these gaps, we tested whether facial action systematically modulates a well-validated electrocortical signature of emotional arousal, the late positive potential. Fifty-seven young adults rated the pleasantness of 180 pictures from the international affective picture system while holding chopsticks differently in their mouth to mimic either smiling or frowning expression. Their electroencephalogram was monitored. It was found that the frowning expression increased the late positive potential for negative pictures. In contrast, the smiling expression had no significant effect. Pleasantness ratings were also consistent with the facial feedback hypothesis. We concluded that the facial feedback effect is weak but robust. Critically, we presented the first evidence that facial action modulates an emotion-related neural response. (PsycInfo Database Record (c) 2021 APA, all rights reserved).