Why do we use facial expressions to convey emotions?
Mark A. W. Andrews, director and professor of physiology at Lake Erie College of Osteopathic Medicine at Seton Hill University in Greensburg, Pa., replies:
Just as a picture is worth a thousand words, our faces can express a wealth of information. The ability to communicate subtle emotions with a simple raised eyebrow or curl of the lip may be innate. Charles Darwin was one of the first to propose this theory in his book The Expression of the Emotions in Man and Animals, published in 1871, in which he wrote: “The young and the old of widely different races, both with man and animals, express the same state of mind by the same movements.”
Recent work supports Darwin’s theory that smiles, grimaces and more nuanced expressions are hardwired—an artifact of living in social groups. For example, studies show that infants, including those who are blind or have underdeveloped brains, use facial cues to tell their parents how they feel. Infants communicate with their faces even before they are old enough to understand the meaning of their own expressions. Because humans depend on one another for survival, we must communicate; facial expressions may have evolved as efficient ways to telegraph feelings and intentions.
Although using facial expressions to convey emotions may be largely instinctive, there is also a learned component. Japanese women and men, for instance, are taught to mask overt displays of emotion in favor of a socially acceptable smile.
By studying faces, researchers have matched subtle changes in the positioning of the mouth, eyes and eyebrows to variations in six basic human emotions—happiness, surprise, disgust, sadness, anger and fear. Scientists are using this information to develop computer technology that analyzes facial movements and tics to help assess the veracity of suspects’ testimony.
Facial expressions do not just give us away; they may also allow us to experience our own emotions more fully. This process is still not well understood, but it is possible that forcing your face to express happiness, sadness or anger may help you feel those emotions. In addition, new research using MRI reveals that facial expressions not only reflect what people are feeling, they influence it, too. Studies have shown, for example, that when people make an angry face, they exhibit less activity in regions of the cerebral cortex associated with empathy and decision making.