What do people really do all day, every day? We “read” the world. And much of the world consists of other people. When a tennis player raises his racquet, for example, you know instantly whether he’s going to take a practice swing or throw his racket across the court in anger. We all make dozens—hundreds—of such distinctions every day. It is, quite literally, what we do, usually without a second thought. It all seems so ordinary.
In fact, it’s extraordinary—and even more extraordinary that it feels ordinary! We achieve our very subtle understanding of other people thanks to certain collections of special cells in the brain called mirror neurons. They are at the core of how we navigate through our lives. They bind us with each other, mentally and emotionally.
[ad:51 1121]Mirror neurons are incredibly powerful; “vicarious” would not be a strong enough word to describe their effects. When we watch movie stars kiss onscreen, some of the cells firing in our brains are the same ones that fire when we kiss our lovers. And when we see someone else suffering or experiencing pain, mirror neurons help us to read her or his facial expression and make us viscerally feel the suffering or the pain of the other person. Those moments, I will argue, are the foundation of empathy (and possibly of morality). Research on mirror neurons gives anyone interested in how we understand one another some remarkable food for thought.
Consider the teacup experiment I published an account of in 2005 [see illustration below]. Test subjects are shown three video clips involving the same simple action: a hand grasping a teacup. In one clip, there is no context for the action, just the hand and the cup. In another, the subjects see a messy table, complete with cookie crumbs and dirty napkins—the aftermath of a tea party, clearly. The third video shows a neatly set table, in apparent readiness for the tea party. In all three video clips, a hand reaches in to pick up the cup. Nothing else happens, and the grasping action observed by the subjects in all three versions of the experiment never changes. Besides the difference in context, there is only one other variation: in the “neat” scenario the cup is full, whereas in the messy one the viewer cannot tell if the cup contains liquid.
Do mirror neurons in the brains of the subjects notice the differences in context and in the contents of the cup? Most definitely. When a subject observes the grasping scene with no context at all, mirror neurons are the least active. The neurons are more active when the subject watches the after-tea-party scene, but they are most active during the neat, full-cup scene. Why? Because drinking is a much more fundamental intention for us than cleaning up. The teacup experiment—now well known in the field of neuroscience—belongs to a wealth of recent empirical evidence suggesting that our brains are capable of mirroring the deepest aspects of the minds of others at the fine-grained level of a single brain cell. Reading the intention of others is only one example of the kinds of distinctions that can be made with a remarkable lack of effort. We do not have to draw complex inferences or run complicated algorithms. Instead, we use mirror neurons.
Mirror neurons were first discovered in the brains of monkeys, where they are concentrated in two linked areas, called the ventral premotor cortex and the inferior parietal lobule, that are important for selecting appropriate motor behavior. Mirror neurons make up approximately 20 percent of the neurons in those regions, which lie close to the primary motor cortex, the area of the brain that sends electric signals to the muscles. In humans, however, mirror neurons may be located in many more regions of the brain, in varying amounts. (I hope to publish new findings about their location soon.)
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Mirror neurons seem to have nothing in common with deliberate, effortful, and cognitive attempts to imagine being in somebody else’s shoes. So how do they actually predict the action that will follow an observed scene? How do they let us understand the intention associated with such an action?My hypothesis is this: we activate a chain of mirror neurons when we watch an action. This chain of neurons can anticipate a whole sequence—say, reaching for the cup, grasping it, bringing it to the mouth—and so can simulate the intention of the human we are watching.
Mirror neurons in such a chain may be of different types. One kind—so-called strictly congruent mirror neurons—respond to identical actions, either performed or observed. For instance, a strictly congruent mirror neuron fires both when a monkey grasps an object with two fingers, in a “precision” grip, and when that same monkey sees another primate grasping with a precision grip. A different mirror neuron, also strictly congruent, fires when the monkey grasps with its whole hand as well as when the monkey sees somebody else grasping in the same fashion.
Other mirror neurons, however, show a less strict correspondence between performed and observed actions. Those are known as broadly congruent mirror neurons. They fire at the sight of actions that may not be identical, but that achieve similar goals. For instance, a broadly congruent mirror neuron may fire when the monkey is grasping food with its hand, and also when the monkey sees somebody else bringing food to the mouth.
An important subset of the broadly congruent type of mirror neurons fire in anticipation of logically related actions. These logically related mirror neurons, as they are logically called, are probably the neuronal elements needed to understand intentions associated with observed actions. I see you grasping a cup with a certain kind of grip, and my grip mirror neurons fire, the strictly congruent ones. So far I am only simulating a grasping action. However, given that the context suggests drinking, my logically related mirror neurons, the ones that code for the action of bringing the cup to the mouth, fire even before the cup is brought to the mouth. By activating this chain of mirror neurons, my brain is able to simulate the intentions of others.
Why do some cells fire for actions that are logically related? No one knows for sure, but it’s likely that mirror neurons “learn” from experience—such as when babies watch or interact with their caregiver. Suppose a baby sees a caregiver’s hand put food on the table, and then the baby grasps the food to eat. Grasping food and seeing food placed become associated in the baby’s brain. It’s not that the mirror neurons know there is a logical connection between the two actions; rather, the baby-caregiver interaction links the two as part of a sequence.
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.
In their final, most critical experiment, Chartrand and Bargh tested the hypothesis that the more you mimic others, the more you are concerned about other people’s feelings—that is, the more empathy you have. The setting was the same as in the first experiment, with the confederates either rubbing their faces or shaking their feet. The novel aspect, though, was that the participants also responded to a questionnaire that measured their empathic tendencies. Chartrand and Bargh found a strong correlation between the degree of imitative behavior displayed by a participant and his or her tendency to empathize. The more the subject imitated the face rubbing or the foot shaking, the more empathic an individual that subject was. These results suggest that it is in large part through mimicry that we are able to feel what other people feel, and so to respond compassionately to their emotional states.
The well-designed studies of Chartrand and Bargh are compelling, and join a host of others. For example, couples tend to have a “higher facial similarity” (they look more alike) after a quarter century of married life than at the time of their marriage. Moreover, the happier the marriage, the higher the couple’s facial similarity. That’s no surprise, really. Loving, sharing, and living together makes a spouse somewhat like a second self. Such examples point to the vital role of mirror neurons in our interactions with others.
Because "mirroring" is essential for empathy and social connection, impairment of the capacity to mirror can have profoundly negative consequences. In the late 1980s, psychiatrist and developmental psychologist R. Peter Hobson at University College, London, made a series of observations about children with autism that are very suggestive in the light of the later discovery of mirror neurons. Hobson was convinced that the main deficit in autism was emotional, not cognitive, and that it lay in the children’s inability to “identify” with the emotions of others. To explore this hunch, Hobson devised a series of experiments that tested the ability of children with and without autism to notice facial expressions and to imitate behaviors associated with emotions—two skills vital to social communication and bonding that we now think may depend on normally functioning mirror neurons.
With his colleague S. Jane Weeks, a psychologist then at the Institute of Psychiatry in London, Hobson showed children with and without autism pictures of women or men, wearing either woolen caps or floppy hats, and making either happy or gloomy faces. The children were asked to sort the pictures based on how they differed. Obviously, the children could have chosen to sort by gender, hat, or facial expression. The first time, both the non-autistic children and those with autism used gender to sort the pictures. Weeks and Hobson then asked them to sort the pictures again, this time without regard to gender. Here came the difference: non-autistic children picked facial emotion as the sorting factor, whereas children with autism picked the hat. Such results encouraged Hobson in his conviction that the problem for children with autism is the missing emotional connection.
To test whether imitation deficits in children with autism are linked to their inability to resonate emotionally with other people, Hobson and his colleague Anthony Lee of the Tavistock Clinic, London, came up with an experiment in which children could imitate both what people did to accomplish a goal and the “style” with which they conducted themselves. Initially the children—divided into one group with autism and another without—were not even told to imitate Lee, who simply said, “Watch this.” Then he performed simple actions with a number of objects. For example, he strummed a stick along a pipe rack, making a graceful and gentle strumming action for half of each group, and a harsh strumming for the other half of each group. After a break, the children were allowed to use the stick and pipe. What did they do? All the children strummed the stick along the pipe rack, but only the non-autistic children imitated the harsh or gentle style that Lee had adopted in front of them.
It should come as no great surprise, then, but serves as important proof, that at least six different laboratories using a variety of techniques for studying the human brain have recently confirmed deficits in mirror neuron areas and their interactions with the limbic system in individuals with autism.
Our growing knowledge of the powerful neurobiological mechanisms underlying human sociality provides an invaluable resource not only for understanding and helping children with social deficits, but also for helping all of us learn how to increase empathy in our lives and in the world. My hope is that a more explicit understanding of our empathic nature will become a factor in the deliberate, reflective discourse that shapes society. For instance, our knowledge of the basis of human sociality can help us open ourselves to other cultures without losing touch with our own.
People often say that they are moved to sadness when they watch a tearjerker film; they are moved to joy when their child hits a home run or performs in a recital. In a literal sense, they are indeed “moved.” Their mirror neurons are subtly activating the matching muscles in their faces and bodies. There is something like physical contact, like a beautifully synchronized partner dance, when we orchestrate motions and emotions in our minds while watching someone else.
People seem to have the intuition that “being moved” is the basis of empathy, and thus of morality. We have evolved to connect deeply with other human beings. Our new awareness of how literally this is true can and should bring us even closer to one another.
[media:node/1543 vertical small right]This article was adapted from Mirroring People: The New Science of How We Connect with Others, by Marco Iacoboni, © 2008. Click here for ordering information.