A Smile Is the Chosen Vehicle for All Ambiguities

In 1852 Herman Melville, who had recently published Moby Dick to indifference, wrote a strange novel called Pierre in which a narrator observes that a smile is the chosen vehicle of all ambiguities. The line has been quoted ever since because anyone who has ever tried to read a face knows its truth. A smile may greet a friend or hide a grudge, accompany a compliment or an insult, express delight or fear. It is the most common expression in the world, and perhaps the one we are least able to interpret with confidence.

The first reason for the ambiguity is that smiles have different physical origins. In 1862 the French neurologist Duchenne de Boulogne, applying electrodes to the faces of his patients, found that a genuine smile involves not just the muscle that lifts the corners of the mouth but also a muscle around the eyes that crinkles the corners. Paul Ekman later named the genuine kind the Duchenne smile. The distinction suggests a way of telling true from false. Yet later studies have found that many people can produce the eye movement voluntarily, so that even this test is imperfect. The face has become good at imitating itself.

The second reason is culture. Ekman and Wallace Friesen showed in the 1970s that people follow display rules, learnt conventions about which emotions to show to whom. In one famous experiment, Japanese and American students watched a distressing film while their faces were recorded. When alone they showed similar expressions, but when an authority figure was present the Japanese students masked their distress with smiles. In Japan, a smile can be a form of politeness that keeps relations smooth, whatever one feels. The same face that signals pleasure in New York may signal reserve in Tokyo.

Norms differ even on whether smiling is good. In 2016 a study by Kuba Krys and colleagues across dozens of countries found that in some societies, particularly those with high levels of corruption, smiling faces were rated as less intelligent and less honest than neutral ones. Russian proverbs speak of laughing for no reason as a sign of foolishness. In the United States, a broad smile is expected of a salesman, a politician and a stranger who greets one, and its absence is taken as coldness. The meaning of a smile depends on what a place expects of one.

The meaning of a smile depends on what a place expects of one.

The workplace exposes the ambiguity. The sociologist Arlie Hochschild studied flight attendants for her book The Managed Heart in 1983 and described how airlines required them to smile as part of the product they sold. The employees had to produce the feelings of warmth on demand, which she called emotional labour, and many reported that after a time they no longer knew what they felt. When a smile is a uniform, it cannot be read as evidence of anything. A customer who receives a smile from a shop assistant is told something about the company's policy and very little about the person.

A smile also communicates things other than happiness. It can be appeasement, offered by a subordinate to show that he means no threat. Primatologists have observed that a grin in monkeys is a signal of submission and fear, and some think the human smile has the same origin. It can be a mask for pain, as when a patient smiles to spare the doctor or a mourner smiles at a funeral. It can be contempt, as in the smirk of a man who thinks he is better, and menace, as in the smile on the face of a predator. Anyone who has known a bully knows that smiling is not incompatible with cruelty.

Art has long exploited the ambiguity. The Mona Lisa, painted by Leonardo around 1503, has fascinated viewers for centuries because her expression seems to change with the angle and the light. Researchers have shown that the smile appears stronger when one looks away from the mouth and fades when one looks directly at it, due to the way the eye processes fine and coarse detail. The Buddha's faint smile in Gandhara sculpture and the grin of Lewis Carroll's Cheshire Cat, which remains after the cat has vanished, play with the same unsettling openness. A smile that cannot be pinned down invites us to supply its meaning.

The ambiguity also has social uses. Diplomats, negotiators and judges depend on the face that conveys courtesy without commitment. A smile keeps a conversation going when a frown would end it, and it allows people who dislike each other to work together. Civilisation in this view depends on the capacity to disguise feeling. If every face were an open book, the friction of daily life would be unbearable. A world of readable smiles would be more honest, but it might also be crueller.

There is a further twist, which is that smiling may affect the person who does it. In 1988 Fritz Strack and colleagues reported that people holding a pen in their teeth, which forces a smile, found cartoons funnier than those holding it in their lips. A large replication effort in 2016 failed to reproduce the result, and later analyses have found only a small effect of expression on feeling. The question remains disputed. If a smile can create a little of the happiness it pretends to show, the line between the real and the false smile is thinner than we thought, and the pretender becomes the person he pretends to be.

This leaves the topic with a final difficulty. We are certain that smiles are ambiguous, but we cannot say for sure how ambiguous they are, because we read them with the help of everything else we know. Context, voice, history and relationship resolve most of the doubt, and this means that the smile alone was never the vehicle. The one who smiles is often not sure himself what he is saying, and the person who receives the smile is left to decide, which may be what makes it such a convenient thing to send.