Just look at that angry forehead.

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Facial Expressions: The Seven Faces of Adam and Eve

You know that when you speak to your parent or child, a frown indicates sadness or dissatisfaction. But is it because a frown is a learned behavior? One researcher, Paul Ekman, wondered this same thing. He decided to travel the world to study people from different cultures to determine if our expressions are learned behaviors. After studying people from foreign cities, faraway lands and isolated jungles, Ekman learned that all humans share at least seven primary facial expressions with identical meanings:

  • Happiness. The expression for happiness involves raising the lip corners, raising and wrinkling cheeks, and narrowing eyelids, producing "crow's feet" (wrinkles in the corners of the eyes).
  • Sadness. This expression features narrowed eyes, eyebrows brought together, a down-turned mouth, and a pulling up or bunching of the chin.
  • Fear. In fear, the mouth and eyes are open, eyebrows are raised and nostrils are sometimes flared.
  • Anger. Anger involves lowered eyebrows, a wrinkled forehead, tensed eyelids and tensed lips.
  • Disgust. A look of disgust includes nose scrunching, raising of the upper lip, downcast eyebrows and narrowed eyes.
  • Surprise. Surprise appears with a dropped jaw, relaxed lips and mouth, widened eyes and slightly raised eyelids and eyebrows.
  • Contempt. Contempt is notable for its raising of one side of the mouth into a sneer or smirk.

Ekman went even further and, with fellow researcher W.V. Friesen, mapped out (through observation and biofeedback) which facial muscles were responsible for which expressions. He codified them into a system called the Facial Action Coding System (FACS).

The anatomy of a face

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Measuring expressions isn't so easy. For one thing, the FACS doesn't identify the emotion, only the muscles involved in making an expression. The measurements used are Action Units (AUs), with each Action Unit representing a specific motion (for instance, bunching the eyebrows together is AU 4, raising the eyebrows is AU 1). The measurements don't include "sneer" or "half-smirk," because using such descriptive terms might influence the interpretation of a specific expression. It's also noted whether the expression is voluntary or involuntary, spontaneous or intentional.

­The intensity of an expression is also important. Smile strength (identified as AU 12) can be classified one of six different ways, depending on the degree the corners of the mouth are turned up. Eye constriction (AU 6) is likewise measured. Measuring duration takes into account the time it takes your mouth to reach the apex of its smile, how long the apex is held, and the time it takes to return to a nonsmiling state. Are other expressions simultaneously occurring? Are they connected or separate from the smile? Is the smile symmetrical? If not, what are the measurements for each side of the face?

And to think of all those bumper stickers demanding that you "Smile!" without once taking into consideration how complicated an order that is to fulfill.

Next, we'll learn about the frowns between the smiles: microexpressions.