Mirror neurons help explain an essential characteristic of humans: we have an instinct to imitate one another—to synchronize our bodies, our actions, even the way we speak to each other. This synchrony we enjoy with others often has an emotional component. For example, a study of how an interviewer’s warmth impacts an interviewee’s reaction showed that warm interviewers—those that leaned forward, smiled, and nodded—elicited similar movements, smiles, and nods from interviewees.
Such motor mimicry seems to play not only a communicative role, but also a perceptual one. Psychologist Ulf Dimberg of Uppsala University in Sweden demonstrated exactly that by studying the activity of facial muscles of subjects looking at pictures of happy or angry faces. When subjects were observing happy faces, activity increased in the cheek muscles that contract to smile; when they were observing angry faces, activity spiked in brow muscles that contract in anger.
Why all the mimicry? The answer comes from a study led by Paula M. Niedenthal, an American social psychologist who is director of research at Université Blaise Pascal in France. In her experiment, two groups of participants were asked to detect changes in the facial expressions of other people. The key was that one group was prevented from freely moving their own faces by holding a pencil between their teeth. The pencil severely restricts the ability to smile, frown, and make most other facial expressions—just try it. Therefore, the pencil hinders mimicry. Surprisingly, the participants holding the pencils between their teeth were much less successful in detecting changes in others’ emotional facial expressions than were participants who were free to mimic the expressions they observed. Mimicking others is not just a way of communicating nonverbally; it helps us to perceive others’ expressions (and therefore their emotions) in the first place.
I believe that mirror neurons provide an automatic simulation (or “inner imitation”) of the facial expressions of other people, and that the process of simulation does not require explicit, deliberate recognition of the expression mimicked. Mirror neurons send signals to the emotional centers located in the limbic system of the brain, and thus trigger emotions appropriate to the observed facial expressions—the happiness associated with a smile, the sadness associated with a frown. Only after we feel the emotions internally are we able to explicitly recognize them. When a participant is asked to hold a pencil between his teeth, the motor activity required by that action interferes with the motor activity triggered by mirror neurons to mimic the observed facial expressions. The subsequent cascade of neural activations that would lead to explicit recognition of emotions is also disrupted.
If mimicry indeed supports recognition of emotions, then it follows that good imitators should also be good at recognizing emotions, and so endowed with a greater empathy for others. The tendency to imitate others and the ability to empathize with them ought to be correlated. That is exactly the hypothesis tested by the social psychologists Tanya L. Chartrand and John A. Bargh, then of New York University. In one experiment of theirs, the subjects were asked to choose the most stimulating pictures from a set of photographs. They were videotaped, and their motor behavior was measured. An experimenter pretending to be another subject sat in the same room with every real subject. (In experimental jargon, the posing subject was the “confederate.”) While the real subject was choosing a picture, the confederate was engaged in a very deliberate action, either rubbing his face or shaking his foot. Analyzing the videotapes, Chartrand and Bargh discovered that subjects unconsciously mimicked the action of the confederate. Subjects sharing the room with the face-rubbing confederate rubbed their own faces more than subjects who shared the room with shaking confederates, and vice versa.
In a second experiment, Chartrand and Bargh tested the hypothesis that one of the functions of the “chameleon effect,” or mimicry, is to increase the likelihood that two individuals will readily get along. Again, participants were asked to choose pictures in the company of a confederate pretending to be another participant. This time the participant and confederate took turns describing what they saw in various photos. All the while, the confederate either imitated the spontaneous postures, movements, and mannerisms of the subject or kept a neutral posture. At the end of the interactions, participants were asked to complete a questionnaire to report how much they liked the other participant (that is, the confederate) and how smoothly they thought the interaction had gone. You can predict the results by now: the participants who were mimicked by the confederates liked those confederates much more than the participants who were not imitated. Furthermore, the mimicked subjects rated the smoothness of the interaction higher than the participants who were not imitated. Clearly, imitation and “liking” tend to go together.