Masking emotions

Depending on the number of facial muscles involved in the facial expression and the complexity of their movements, it may take a second or more for the facial expression to be fully formed. This means that other signals could interrupt or "short-circuit" the facial expression, allowing some individuals to compose themselves and show a "poker face" even in the midst of powerful emotional experiences.

Older children and adults have also learned how to "put on" false facial expressions in social settings, such as an insincere smile when the individual doesn't genuinely feel happy. However, the true emotion is often displayed on the face for an instant before the masking expression is composed.