Consider the character Spock, the half-Vulcan, half-human science officer from Star Trek who suppresses his emotions at all costs in the pursuit of pure logic. Both of the actors who have played Spock (Leonard Nimoy in the original television series and Zachary Quinto in the 2013 film) had their human eyebrows replaced with artificial “Vulcan” ones: because Spock’s eyebrows—and eye expressions in general—appear less human, his emotions seem less human too.

As humans, we are wired to use our faces to indicate emotions (Fridlund & Russell, 2006). Although the reasons behind our facial expressions might be difficult to ascertain, several specific expressions are common across all cultures (Ekman & Friesen, 1971). A smile, for example, usually indicates happiness; a frown, sadness; raised eyebrows tend to indicate surprise, and wrinkled eyebrows, concern (see Figure 4.1).

Blind children, who cannot learn to mimic facial movements through sight, exhibit sadness, anger, disgust, fear, interest, surprise, and happiness in the same way that sighted people exhibit these feelings (Eibl-Eibesfeldt, 1973). These seven primary facial expressions are thus considered inborn, whereas most other expressions are learned from our culture (Gagnon, Gosselin, Hudon-ven der Buhs, Larocque, & Milliard, 2010). There is some evidence that pride also may be a universally recognized emotion (Tracy & Robins, 2008).

Although we’re fairly adept at deciphering these common expressions of emotion, we’re not necessarily experts at decoding all facial expressions (Bavelas & Chovil, 2006). That’s because the human face can produce more than a thousand different expressions (and as many as twenty thousand if you take into account all of the combinations of the different facial areas) (Ekman, Friesen, & Ellsworth, 1972; Harrigan & Taing, 1997). Moreover, our emotions can be concealed by facial management techniques, conscious manipulation of our faces to convey a particular expression.

One common facial management technique is masking, replacing an expression that shows true feeling with an expression that shows appropriate feeling for a given interaction. Actors use masking all the time. But you also use it when you smile at customers at the restaurant where you work even though you’re in a horrible mood and wish they’d leave (Richmond, McCroskey, & Payne, 1991).