Dozens of scientific studies speak to the importance of parsing the heterogeneous category of smiles according to the activity of the orbicularis oculi muscle. Duchenne smiles differ morphologically in many ways from the many other smiles that do not involve the action of the orbicularis oculi muscle. They tend to last between one and five seconds, and the lip corners tend to be raised to equal degrees on both sides of the face. Smiles missing the action of the orbicularis oculi and likely masking negative states can be on the face for very brief periods (250 milliseconds) or very long periods (a lifetime of polite smiling by oppressed airline stewardesses and fast-food servers). Non-D smiles are more likely to be asymmetrical in the intensity of muscle firing on the two sides of the face.
D smiles tend to be associated with activity in the left anterior portion of the frontal lobes, a region of the brain preferentially activated during positive emotional experiences. Non-D smiles, in contrast, are associated with activity in the right anterior portion of the brain—a region associated with the activation of negative emotion. When a ten-month-old is approached by his or her mother, the face lights up with the D smile; when a stranger approaches, the same infant greets the approaching adult with a wary non-D smile.
And importantly, several studies have found that Duchenne and non-Duchenne smiles, brief two-to three-second displays differing only in the activation of the orbicularis oculi muscle, map onto entirely different emotional experiences. For example, in a longstanding collaboration with my friend George Bonanno, a pioneer in the study of trauma (see chapter 7), we interviewed middle-aged adults six months after their deceased spouse had passed away. These individuals were asked to describe their relationship with their deceased spouse for six minutes. I spent a summer coding the occurrence of Duchenne and non-Duchenne smiles from videotapes of these narratives. We then related measures of bereaved participants’ D and non-D smiles to their reports of how much enjoyment, anger, distress, and fear they felt during the interview, which we gathered immediately after the participants had finished talking about their deceased spouse.
Portrayed in the table below are the correlations between how much participants showed these brief Duchenne and non-Duchenne smiles and their ensuing self-reports of emotion gathered moments later. Positive scores indicate that the more they showed the particular smile during the six-minute interview, the more they subsequently felt the particular emotion listed on the left. Negative correlation values reveal the opposite, that the more the participant smiled in Duchenne or non-Duchenne fashion, the less of the emotion they felt. Asterisks indicate that the observed correlation was statistically significant, and not likely produced by chance.
DUCHENNE SMILES
NON-DUCHENNE SMILES
ENJOYMENT
.35*
–.25*
ANGER
–.28*
.09
DISTRESS
–.49*
–.16
FEAR
–.31*
.04
What is impressive about these data is that very brief Duchenne smiles involving the activity of the orbicularis oculi were associated with increased feelings of enjoyment during the conversation, and reduced feelings of anger, distress, and fear. Non-Duchenne smiles were associated with the opposite pattern of experience—reduced feelings of enjoyment and none of the negative emotions.
The Duchenne/non-Duchenne distinction is the first big distinction in a taxonomy of different smiles. One kind of smile involves the orbicularis oculi muscle, and accompanies high spirits and goodwill. As we shall see, when other movements are added to the D smile, people can communicate different positive states like love, awe, and desire. A second kind of smile is the non-D smile, which reflects the attempt to mask some underlying negative state. In Emotions Revealed, Ekman deconstructed the non-D smile into a dizzying array of smiles, including pained smiles, fearful smiles, contemptuous smiles, and submissive smiles.
Twenty-five summers ago, as I served that reliable customer his four burgers and coffee, I am absolutely confident that not a trace of orbicularis oculi activity was to be seen on my late-pubescent face. I would have been an easy case study for Ekman; it would have been simple for him to reveal which negative states—despair, frustration, contempt—I was attempting to hide with my halfhearted McD smile. Off work, and at last with friends jumping off rocks into alpine rivers, I am sure the D smiles would have washed over my face. Studies inspired by Ekman’s analysis would reveal that these D smiles are a glue of social life, and a provenance of the camaraderie that make me nostalgic for those carefree times.
THE SMILE AS SOCIAL CHOCOLATE
In the 1980s developmental psychologists Ed Tronick, Jeff Cohn, and Tiffany Field became interested in what postpartum depression does to mother-child interactions. Their studies, and those of other investigators, revealed that postpartum depression mutes the positive emotionality of the mother—she smiles less, she vocalizes with less warm intonation, and her positive emotional repertoire is less contingent upon the actions of her child. Children of mothers experiencing postpartum depression tend to show complementary behavior—they are more agitated, distressed, and anxious.
Answers to the smile quiz on chapter 6: For the first gentleman, the D smile is on the right; for the second, it’s on the left.
This kind of result is compellingly intuitive. Any parent or friend who has been up close to this phenomenon, who has been in the living room of a depressed mother whose positive emotion is dampened and disengaged from that of her child, readily knows how essential the exchanges of smiles, coos, touch, play faces, and interested and encouraging eyebrow flashes are to the parent-child dynamic. Yet from a scientific standpoint, the finding—the mother’s impoverished positive emotional repertoire brings about anxiety and agitation in the child—is plagued by alternative explanations. Perhaps agitated, fussy infants produce muted positive emotionality and depression in the mother. Perhaps they both share some genetically based tendency that predisposes their parent-child interactions to lack mutual smiles, coos, touches, and play. Perhaps their shared emotional condition is the product of deeper structural causes—underpaid work, poverty, alienated or abusive husbands, and the like.
So to study the role of smiling and muted positive emotionality in parent-child interactions, Tronick, Cohn, and Field developed what has come to be known as the still-face paradigm. This experimental technique is profoundly simple but powerfuclass="underline" The mother is requested to simply be in the presence of her young infant, say nine months old, but to show no facial expressions whatsoever, and none of the most common of facial expressions for young mothers—smiles. As the young child navigates around the laboratory environment, approaching toy robots and stuffed elephants and brightly colored objects that make farm animal noises, the child looks to the mother’s face for signals about the environment. The child seeks information in facial muscle movements about what is safe, fun, and worthy of curious exploration, and what is not, and the mother sits there impassionate, stone-faced, and unresponsive.