FACIAL EXPRESSION

Emotion's Face Value

Sign. The act of communicating a mood, attitude, opinion, feeling, or other message by contracting the muscles of the face.

Usage: The combined expressive force of our mobile chin, lip, cheek, eye, and brow muscles is without peer in the animal kingdom. Better than any body parts, our faces reveal emotions, opinions, and moods. While we learn to manipulate some expressions (see, e.g., SMILE), many unconscious facial expressions (see, e.g., LIP-POUT, TENSE-MOUTH, and TONGUE-SHOW) reflect our true feelings and hidden attitudes. Many facial expressions are universal, though most may be shaped by cultural usages and rules.

Summary of facial expressions. 1. Nose: nostril flare (arousal). 2. Lips: grin (happiness, affiliation, contentment); grimace (fear); lip-compression (anger, emotion, frustration); canine snarl (disgust); lip-pout (sadness, submission, uncertainty); lip-purse (disagree). 3. Brows: frown (anger, sadness, concentration); brow-raise (intensity). 4. Tongue: tongue-show (dislike, disagree). 5. Eyelids: flashbulb eyes (surprise); widened (excitement, surprise); narrowed (threat, disagreement); fast-blink (arousal); normal-blink (relaxed). 6. Eyes: big pupils (arousal, fight-or-flight); small pupils (rest-and-digest); direct-gaze (affiliate, threaten); gaze cut-off (dislike, disagree); gaze-down (submission, deception); CLEMS (thought processing). (NOTE: See individual entries elsewhere in The Dictionary.)

RESEARCH REPORTS: So closely is emotion tied to facial expression that it is hard to imagine one without the other. 1. The first major scientific study of facial communication was published by Charles Darwin in 1872. Darwin concluded that many expressions and their meanings (e.g., for astonishment, shame, fear, horror, pride, hatred, wrath, love, joy, guilt, anxiety, shyness, and modesty) are universal: "I have endeavoured to show in considerable detail that all the chief expressions exhibited by man are the same throughout the world" (Darwin 1872:355). 2. Sylvan S. Tomkins found eight "basic" facial emotions: surprise, interest, joy, rage, fear, disgust, shame and anguish (Tomkins 1962; Carroll Izard proposed a similar set of eight [Izard 1977]). 3. Studies indicate that facial expressions of happiness, sadness, anger, fear, surprise, disgust, and interest are universal across cultures (Ekman and Friesen 1971).

Evolution I. During the Jurassic period mammalian faces gradually became more mobile (and more expressive) than the rigid faces of reptiles. Muscles that earlier controlled pharyngeal arches (i.e., primitive "gill" openings) came to move mammalian lips, muzzles, scalps, and external ear flaps. Nerve links from the limbic system to the facial muscles--routed through the brain stem's facial and trigeminal nerves (cranial VII and X)--enable us to express joy, fear, sadness, surprise, interest, anger, and disgust today.

Evolution II. That a nose-stinging whiff of ammonium carbonate can cause our face to close up in disgust shows how facial expression and smell and taste are linked. The connection traces back to the ancient muscles and nerves of the pharyngeal arches of our remote Silurian ancestors. Pharyngeal arches were part of the feeding and breathing apparatus of the jawless fishes; sea water was pumped in and out of the early pharynx through a series of gill slits at the animal's head end. Each arch contained a visceral nerve and a somatic muscle to close the gill opening in case dangerous chemicals were sensed. Very early in Nonverbal World, pharyngeal arches were programmed to constrict in response to noxious tastes and smells.

Anatomy. The ancient pattern is reflected in our faces today. In infants, e.g., a bitter taste shows in lowered brows, narrowed eyes, and a protruded tongue--the "yuck-face" expression pictured on poison-warning labels. A bad flavor causes baby to seal off its throat and oral cavity as cranial nerves IX and X activate the pharyngeal gag reflex. Cranial V depresses the lower jaw to expel the unpleasant mouthful (then closes it to keep food out), as cranial XII protrudes the tongue.

Embryology. The nerves and muscles that open and close our mouth derive from the 1st pharyngeal arch, while those that constrict our throat derive from the 3rd and 4th arches. In the disgusted yuck-face, cranial VII contracts orbital muscles to narrow our eyes, as well as corrugator and associated muscle groups to lower our brows. (Each of these muscles and nerves derives from the 2nd pharyngeal arch.) We may express positive, friendly, and confident moods by dilating our eye, nose, throat, and mouth openings--or we may show negative and anxious feelings (and inferiority) by constricting them. Thus, the underlying principle of movement established in the jawless fishes long ago remains much the same today: Unpleasant emotions cause cranial nerves to constrict our eye, nose, mouth, and throat openings, while more pleasant sensations widen our facial orifices to incoming cues.

Neuro-notes. "The homologue of Broca's area in nonhuman primates is the part of the lower precentral cortex that is the primary motor area for facial musculature. . . . electrical stimulation of this area in squirrel monkeys . . . yields isolated movements of the monkey's lips and tongue and some laryngeal actvity but no complete vocalizations" (Lieberman 1991:106; see SPEECH).

See also BODY MOVEMENT.

Copyright 1999 (David B. Givens/CNS)