The process by which the facial muscles send messages to the brain about the basic emotion being expressed. Somewhat counter-intuitively, some parts of the brain seem to read the state of of the face to decide which emotion to feel, rather than feeling an emotion and then telling the face how to express it outwardly. One can actually make themselves feel happy, angry, or sad by moving their facial muscles in a position associated with smiling, a frowning, or a crying.