Duchenne Smile

Smiling is a ubiquitous facial expression that begins in infancy and is widely understood to be a display of favorable emotions, such as pleasure. People who smile are viewed as trustworthy, friendly, and cooperative. The smile is a powerful social gesture that puts others at ease and convinces them that they are safe in the smiling person's presence. Those who take advantage of others through manipulation and deceit exploit this power by using a nongenuine smile to fool victims about their true intentions.

A genuine smile, known as the Duchenne smile, involves muscles around the eyes and mouth, whereas the fake smile, known as the non-Duchenne smile, only involves muscles around the mouth. People can differentiate between the two types of smiles; the cues that distinguish between the genuine and fake smile have also been quantified in a measurement tool and computer program.

A smile is a universal facial expression that is widely perceived as a conveyance of positive affect (emotion). People of all races, ethnicities, cultures, and religious affiliations interpret a smile as a gesture of friendliness, enjoyment, happiness, and amusement. A smile is displayed in the same manner across the globe. Even those born blind can spontaneously smile during pleasurable experiences. A precursor and successor to laughter, a smile can also reflect embarrassment, frustration, anxiety, and submissiveness, as well as a variety of other emotions ranging from sexual attraction and love to haughtiness, contempt, hostility, and vengefulness. Biologists conjecture that the smile has evolved in primates and humans as a primitive gesture of submissiveness, designed to placate potential enemies or predators. Known as the “fear grin,” this protosmile involves neither a full baring nor clenching of teeth, which are signs of threat and aggression.

A wealth of research demonstrates the highly social nature of the smile. People who smile are regarded as friendly, likeable, confident, trustworthy, and approachable. In addition, in various social situations, these people are more likely than nonsmiling people to receive positive responses to requests for assistance and cooperation. Hence, the smile has powerful and inherent communal currency. The act of smiling—even in the absence of other people—is associated with changes in the brain that can elevate mood and energy and reduce the body's responses to stress.

A genuine smile, known as the Duchenne smile, involves muscles around the eyes and mouth (as with Arizona Cardinals wide receiver Larry Fitzgerald, top), whereas the fake smile, known as the non-Duchenne smile, only involves muscles around the mouth (as with American singer and model Katrina Darrell, bottom).

[Page 318]The smile might also be essential to human survival. Infants' brains are wired to fixate their eyes on human faces and to mimic the expressions of others, including smiling. Appearing between 6 and 8 months of age, the smile is a powerful tool of communication for infants and their caretakers, helping to solidify bonds and prepare the infant for more sophisticated social interactions. The failure or inability to a produce a smile or understand its meaning can signal the presence of developmental disabilities, sensory deficits, or autism.

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