Facial Feedback Hypothesis

The hypothesis that facial expressions provide feedback to the responder that is necessary or sufficient to affect significantly his or her emotional experience and behavior. See basic emotions, and Facial Action Coding Scheme (FACS).

Reference:

Buck, R. (1980). Nonverbal behavior and the theory of emotion: the facial feedback hypothesis. Journal of Personality and Social Psychology, 38(5), 811-824. https://psycnet.apa.org/doi/10.1037/0022-3514.38.5.811