The Science of Smiling

science of smiling

Dr. Ekman explains the science of smiling and facial expressions.

Different types of smiles

What’s in a smile?

Smiles, specifically the different types of smiles, are probably the most underrated and misunderstood of the seven universal facial expressions, with the science of smiling being much more complicated than most even realize.

Not all smiles are created equally

There are dozens of different types of smiles, each different in both appearance and intended message. For example, most smiles convey positive emotions, such as enjoyment due to physical or sensory pleasure. However, there are many people find themselves smiling when they feel miserable. These smiles aren’t forced and, therefore, are not the same as false smiles which are used to convince others that they are happy while masking the true expression of a negative emotion.

Dr. Ekman’s research has revealed that most people are not better than chance at determining which of these smiles are false, and the problem, he posits, isn’t merely a failure to recognize deceptive smiles. Rather, he believes this is an issue stemming from a general lack of understanding of our own emotions and nonverbal expressions, and ignorance around cultural influences, especially cultures different from our own. Unfortunately, because of this, many false smiles can’t be distinguished from authentic ones without first knowing how each resembles and differs from all of the other principal members of the smile family. The following are descriptions of eighteen different kinds of smiles, none of which are deceptive or falsified.

The science of how we smile

The common element in most members of the smile family is the appearance change produced by the zygomatic major muscle. This muscle reaches from the cheekbones down and across the face, attaching to the corners of the lips. When contracted, the zygomatic major pulls the lip corners up at an angle toward the cheekbones. With a strong action, this muscle also stretches the lips, pulls the cheeks upward, bags the skin below the eyes, and produces crow’s feet wrinkles beyond the eye corners. (In some individuals this muscle also pulls down slightly the tip of their nose; in still others there will be a slight tug at the skin near their ears).

The simple action of the zygomatic major muscles produces the smile shown for genuine, uncontrolled, positive emotions. No other muscles in the lower part of the face enter into this felt smile. The only action that may also appear in the upper face is the tightening of the muscles that circles the eyes. The felt smile lasts longer and is more intense when positive feelings are more extreme. I believe that all of the positive emotional experiences—enjoyment of another person, the happiness of relief, pleasure form tactile, auditory, or visual stimulation, amusement, contentment—are shown by the felt smile and differ only in the timing and intensity of the action.

For an in-depth understanding of how each emotion is expressed anatomically, Dr. Ekman’s Facial Action Coding System (FACS) Manual remains the gold standard for learning how to interpret individual actions of the face.

Non-enjoyment Smiles

The contempt smile is another misnomer, for this expression too has not much to do with positive emotions, although it is often so construed. The chief difference between the contempt smile and the felt smile is the tightened lip corners, which are present in contempt and absent in the felt smile.

The miserable smile acknowledges the experience of negative emotions. It is not an attempt to conceal but a facial comment on being miserable. The miserable smile usually also means that the person who shows it is not, at least for the moment, going to protest much about his misery. He is going to grin and bear it. We have seen this miserable smile on the faces of people when they were sitting alone in our laboratory watching one of our gory films, unaware of our hidden camera. Often it appeared early when they seemed to first become aware of just how terrible our films are. We have also seen miserable smiles on the faces of depressed patients, as a comment on their unhappy plight.

Miserable smiles are often asymmetrical. They are often superimposed on a clear negative emotional expression, not masking it but adding to it, or they may quickly follow a negative emotional expression. If the miserable smile is acknowledging an attempt to control the expression of fear, anger, or distress, the miserable smile may appear much like a dampened smile. The key difference between the miserable smile and the dampened smile is the absence of any evidence of the muscle around the eyes tightening. The action of that muscle—pulling in the skin around the eye and crow’s feet wrinkles—is part of the dampened smile because enjoyment is felt and absent from the miserable smile because enjoyment is not felt. The miserable smile may also show in the eyebrows and forehead the felt negative emotions being acknowledged.

Emotional blends

In a blend, two or more emotions are experienced at once, registered within the same facial expression. Any emotion can blend with any other emotion.
When people enjoy being angry, the enjoyable-anger blend will show a narrowing of the lips and sometimes also a raising of the upper lip in addition to the felt smile (this could also be called a cruel smile, or a sadistic smile.)

In the enjoyable-contempt expression the felt smile merges with the tightening of one or both lip corners.

Sadness and fear can also be enjoyed, at those who make horror and tear-jerking films and books. In enjoyable-sadness the lip corners may be pulled down in addition to the upward pull of the felt smile, or the felt smile may just merge with the upper face.

The enjoyable-fear blend shows the upper face with the felt smile merged with the horizontal stretching of the lips. Some enjoyable experiences are calm and contented, but sometimes enjoyment is blended with excitement, in an exhilarating feeling.

In enjoyable-excitement the upper eyelid is raised in addition to the felt smile. The film actor Harpo Marx often showed this excited, gleeful smile, and at times when pulling a prank, the enjoyable-anger smile. In enjoyable-surprise the brow is raised, the jaw dropped, the upper lid raised, and the felt smile shown.

The Chaplin smile is unusual, produced by a muscle that most people can’t move deliberately. Charlie Chaplin could, for this smile, in which the lips angle upward much more sharply than they do in the felt smile, was his hallmark. It is a supercilious smile that smiles at smiling.

Smiles with a gaze

Two other smiles involve merging the felt smile with a particular gaze. In the flirtatious smile the flirter shows a felt smile while facing and gazing away from the person of interest and then, for a moment, steals a glance at the person, long enough to be just noticed as the glance shifts away again. One of the elements that makes the painting of the Mona Lisa so unusual is that Leonardo depicted her caught in the midst of such a flirtatious smile, facing one way but glancing sideways at the object of her interest. In life this is an action, with the gaze shift lasting but a moment.

In the embarrassment smile the gaze is directed down or to the side, to that the embarrassed person does not meet the other’s eyes. Sometimes there will be a momentary upward lift of the chin boss (the skin and muscle between the lower lip and the tip of the chin) during the felt smile.

Social smiles

The next four smiles all share the same appearance, but they serve quite different social functions. In each the smile is deliberately made. Often these smiles will show some asymmetry.

The qualifier smile removes some of the harshness from an otherwise unpleasant or critical message, often trapping the distressed recipient of the criticism into smiling in return. The smile is set deliberately, with a quick, abrupt onset. The qualifier smile is often marked with a head nod and a slightly down and sideways tilt to the head so that the smiler looks down a little at the person criticized.

The compliance smile acknowledges that a bitter pill will be swallowed without protest. No one thinks the person showing it is happy, but this smile shows that the person is accepting an unwanted fate. It looks like the qualifier smile, without that smile’s head position. Instead, the brows may be raised for a moment, a sight may be heard, or a shrug shown.

The coordination smile regulates the exchange between two or more people. It is a polite, cooperative smile that serves to smoothly show agreement, understanding, intention to perform, or acknowledgment of another’s proper performance. It involves a slight smile, usually asymmetrical, without the action of the muscle orbiting the eyes.

The listener response smile is a particular coordination smile used when listening to let the person speaking know that everything is understood and that there is no need to repeat or rephrase. It is equivalent to the “mm-hmm,” “good,” and head not it often accompanies. The speaker doesn’t think the listener is happy but takes this smile as encouragement to continue. Any of these four smiles—qualifier, compliance, coordination, or listener—may sometimes be replaced by a genuine felt smile. Someone who enjoys giving a qualifying message, who takes pleasure in complying, listening, or coordinating, may show the felt rather than one of the unfelt smiles I have described.

False smiles and how to identify them

Now let’s consider the false smile. It is intended to convince another person that positive emotion is felt when it isn’t. Nothing much may be felt, or negative emotions may be felt that the liar tries to conceal by using the false smile as a mask. Unlike the miserable smile that acknowledges pleasure is not felt, the false smile tries to mislead the other person to think the smiler is having positive feelings. It is the only smile that lies.

There are a number of clues for distinguishing false smiles from the felt smiles they pretend to be:

  • False smiles are typically more asymmetrical compared to authentic smiles.
  • The false smile will not be accompanied by the involvement of the muscles around the eyes, so that the slight to moderate false smile will not show raised cheeks, bagged skin below the eyes, crow’s feet wrinkles, or a slight lowering of the eyebrow that will appear in the slight to moderate felt smile.
  • The offset time of the false smile may appear noticeably inappropriate. The smile may drop off the face too abruptly, or there may be a stepped offset, in which the smile decreases, and then is held, before either disappearing or going through another stepped decrease as it leaves the face.
  • When used as a mask, the false smile will only cover the actions of the lower face and the lower eyelid. The reliable muscles that appear in the forehead to signal fear or distress may still appear. Even in the lower face, the false smile may not succeed in completely covering the signs of the emotion it is intended to conceal; instead, there may be a merging of elements so that some trace still appears, as if it is an emotion blend.


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