Those who smile frequently are considered more friendly and sociable; even more attractive sometimes. There is a lot of evidence that shows how important body language is in the impressions we make on others and we will surely agree that a good smile raises a few points of charisma. However, like everything, even smiles in excess produces the opposite effect. Fake laughter, which actually sometimes acts as social glue, has traditionally tended to be detected by frequency. It seems logical to think that if someone lives 24 hours smiling, they must be faking it.

There is also this Duchenne smile; in honor of Guillaume Benjamin Amand Duchenne, a 19th century French physician and clinical researcher who is considered a pioneer in neurology and medical photography.

This smile was the first attempt to categorize smiles. Duchenne, while conducting research on the physiology of facial expressions in the 19th century, described this type as “a smile in which there is a contraction of the zygomaticus major and minor muscles near the mouth, which raise the commissure of the lips, and the orbicularis oculi near the eyes, whose contraction raises the cheeks and produces wrinkles around the eyes ”. Many researchers have suggested that the Duchenne smile indicates a spontaneous and genuine emotion since most people cannot contract the orbicularis muscle at will. But there are other small contractions, and even harder to fake.

Body language can reveal as much or more information than words.

Only 7% of communication comes from the words we use; the rest comes from how we say it. Scientists have identified different specific patterns of the muscles of the face to differentiate the smiles that reflect true happiness from all the others. The analysis of the patterns of the more than 100 muscles, changes with expression and is almost impossible to control, functioning as a little lie detector for smiles.

All smiles are not the same,” according to Paul Ekman, a psychologist and director of the Human Interaction Laboratory at the University of California, San Francisco School of Medicine. “A polite forced smile produces a different muscle pattern than a spontaneous smile.”

In fact, of the 19 types of smiles, only 6 occur when we are having a good time. The rest occurs when we feel pain, shame, discomfort, horror, or when we are sad.

Research can be of particular importance to those who, like doctors or therapists, sometimes have to rely on subtle cues to tell when a person is trying to hide physical pain or emotional distress. It is not easy to smile and say “I’m fine” and sound convincing, but there are those who do it, and if others believe you, they will not be able to help you. Of course, it is also of interest to all those who want to know if a smile, in general, can be a lie.

In spontaneous smiles, the cheeks are subtly raised and the muscles around the eyes contract, creating “crow’s feet”, as Duchenne said, is what usually happens. However, we now know that it is not accurate; quite a few people can contract a part of the eye voluntarily, and can still get crow’s feet. What it cannot do is, when the smile is big enough, lower the skin around the eyebrow. This is what happens with sincere smiles: the bulge that we have just under the eyebrow slopes a little towards the eye, subtly covering it – the height differs with age – and we cannot lower that muscle at will.

You can go a long way with a smile. You can go a lot farther with a smile and a gun. – Al Capone.

In fake smiles, however, the face shows feelings of unhappiness hidden behind the smile: for example, a slight furrow between the eyebrows. The eyes will not always develop crow’s feet, although as we say there are those who can, at least when the smile is big enough to force them; but even so, the loss of the skin around the eyebrow, as we said, does not occur.

In addition, according to the study, it is advisable to take into account other factors. For example, if it occurs abruptly or remains on the face too long or occurs too quickly after the phrase it is supposed to accompany. It should also be borne in mind that the smile can start sincerely and turn false because you want to keep it longer than it is felt for the other person – for education or to be convincing. And, for the same reason, there is also doubt when it is too symmetrical. It may sound counterintuitive, but real smiles are not quite as symmetrical: we are more of a quick “grin”. When we make a fake smile and want to show that it is real, we ironically make it “too perfect”, which betrays the lack of spontaneity.