The facial feedback effect is the tendency of facial muscle states to trigger corresponding emotional feelings. Smiling can make a person feel happier; frowning can lower mood.

The idea traces to the James-Lange theory of emotion, which held that bodily changes contribute to the experience of emotion. Modern experiments have tested the claim by manipulating facial expressions without the participant’s full awareness—holding a pen in the teeth to produce a smile-like posture, or in the lips to prevent one. People in the smile-like condition often rate cartoons as funnier or report more positive affect. Similar effects have been found for other expressions and for posture.

The effect is typically modest and can be overridden by strong situational information. It does not mean that emotions are nothing but facial feedback; rather, the face is one of several bodily channels that can color and intensify feeling. The findings have practical implications for emotion regulation and for understanding how expressive behavior and experience interact.

The face does not merely display emotion. Under some conditions it helps create it.