Our social nature: the surprising science of smiles

Flickr.com / Gwen

All hail the powerful smile. The right smile, at the right time, wins friends and calms enemies. The smile held for too long, not long enough, flashed too intensively or too dimly, arouses suspicion, fear or anger. Far from being a straightforward show of joy, the language of smiles is filled with subtlety: a meld of our inner state, surroundings, social training, conscious and unconscious.

The new book Lip Service: Smiles in Life, Death, Trust, Lies, Work, Memory, Sex, and Politics, published on 8 August, explores the nuances and effects of an expression we use often, but rarely think about. Wired spoke with author, Marianne LaFrance, an experimental psychologist at Yale University, about why we smile, how we do it, and the rise of the emoticon.

Wired: Are we able to intuitively tell when someone is faking a smile?

Marianne LaFrance: Yes, often, but not always. When experimental studies are done in which fake and apparently spontaneous smiles are shown in pictures or brief videos, to both adults and kids, and the only thing they have to do is mark a smile as genuine or not, people are pretty good at telling the difference. On the other hand, in more complicated real-world settings most people are not very good.

Wired: Why the difference?

LaFrance: In many interactions we're not paying very close attention. Details that we might catch as not exactly right if we paid attention, we miss because we're not looking. Also there are a lot of theories about what a real smile looks like. Some of those are patently wrong. People think they can tell by looking at what the overall face looks like, but in fact there is one muscle [that shows sincerity]. It's a muscle, called the obicularis occuli, that encircles the eye socket. Most people don't pay very close attention to and it's very hard to deliberately adopt. So when people genuinely smile, in a true burst of positive emotion, not only to the corners of the mouth, controlled by the zygomaticus major, but this muscle around the eye also contracts. This causes the crows feet wrinkles that fan out from the outer corners of the eyes and its also responsible for folds in the upper eyelid. Most people can't do that deliberately.

Wired: What about actors and con men?

LaFrance: The muscle doesn't seem to be under voluntary control normally, but with training and practice, people can learn to use it, some better than others. And of course your garden variety psychopath or Machiavellian personality tends to be better at it. A characteristic of con men is that they somehow manage to exude a positive, good feeling to get themselves into your good graces, only to exploit it.

Wired: Are many muscles involved in smiling?

LaFrance: Two, the obicularis occuli and zygomaticus major, are the primary muscles involved in the so-called genuine smile. But the so-called mouth smile can co-occur with a number of other muscles on the face at the same time. So the mouth may be smiling but the brows could be showing anger, the eyes could be showing surprise or fear, the upper lip could be showing contempt, the nose could be showing some disgust. So the smile is interesting to those of us who study it because it's not just one thing. It's multiple and complicated.

Even the temporal pattern is important. Genuine smiles tend to come on the face relatively languidly and go off the face in the same kind of way. Fake smiles often seem to snap on the face and snap off.

Wired: Humans have always been captivated by smiles. When did smile science get its real start?

LaFrance: In the late 1800s Charles Darwin published his famous book The Expression of Emotions in Man and Animals. He devoted some time to smiling, but was more interested in other facial expressions. His colleague across the channel, Guillaume-Benjamin Duchenne, was doing experiments where he would zap single muscles on the face with electricity and then look at the changes. His primary distinction was between smiles that came from the soul, non-deliberate smiles, and the ones put there consciously. That's why people who study smiles call the spontaneous smile the Duchenne smile.

Wired: What does a person's tendency to smile tell us about them?

LaFrance: Some people are inclined to smile more, and that tends to indicate they are a more upbeat personality. But it's not a perfect correlation. Some people don't smile often and are quite content. Others smile a lot of the time, but it is out of anxiety.

Most smiling is social. There are a kazillion situations that, as we become socialised, we learn that many situations call for a smile. Kids learn early on -- girls learn much faster than boys -- that it is good to fake a smile in some circumstances. Imagine you are given a tacky or disappointing gift; it is a mature behavior to smile and thank the person, because that is the socially appropriate thing to do.

When people are by themselves, believing they are not being observed, there isn't a lot of smiling. We might think that if we're reading a book by ourselves and we come across a funny passage we'd break into a smile, but it's actually pretty rare. But if that same passage is being read to us, or other people are in the room, we're more likely to smile.

Wired: Are there differences in the way males and females smile?

LaFrance: On average girls and women smile more. This appears to be a function of two things. Boys are encouraged not to smile very much. Expressivity is taken by some as sign of emotionality, of femininity, something many men, wouldn't be caught dead being associated with.

Now women, even when they are not feeling much, are strongly encouraged to look and sound as though they are. Spend some time around young teenage girls and you hear a lot of, "Ooh! Oh, that's wonderful! Love it! That's fabulous! Fabulous!" Women who are not very expressive are regarded with some suspicion. They seem cold, withholding, depressed. Acquiring the rules of how expressive one should be with their face is a very socialised process.

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