The Perfect Smile

People have a good sense of whether a smile is real or not. Researchers have now investigated what exactly makes laughing authentic and pleasant – and what should be avoided.

They smiled because, intuitively, people always do that when they ask strangers for favors. In turn, those people only need 100 to 200 milliseconds to realize that someone is smiling – and how honest the smile is. It was precisely this ability that interested the researchers.

On the iPad, they showed a series of faces to their volunteers, more than 800 of whom they got together between 18 and 82. Or rather, it was always the same face, namely a digitally animated one whose mouth twisted dynamically into a smile. The only difference was that the smile was slightly different every time: the researchers had subtly manipulated three factors.

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A smile shouldn’t look scary

On the one hand, they varied how much the corners of the mouth pulled up when smiling, i.e., the “height.” On the other hand, they also changed the “width” of the smile, i.e., the distance between the two corners of the mouth. Finally, they changed a little in each picture whether and how much the teeth flashed out when smiling.

The scientists’ evaluation showed: A perfect smile that is authentic and pleasant can be created in different ways. In the specialist journal “Plos One,” they report that the three characteristics of height, width, and teeth have to be combined harmoniously. Otherwise, the smile quickly looks fake, creepy, or malicious.

The perfect smile is a moderate one

For example, a little smile degenerates into a malicious or contemptuous grin if the teeth are visible. A high smile without a breadth even looks slightly aggressive with teeth. If, on the other hand, the smile is more comprehensive and higher, the teeth even reinforce the open and warm impression.

A tiny smile or a very tall smile without teeth is not good either, write the psychologists. One looks bored or frustrated, the other clownish and mask-like. A half-wide, half-high smile with some teeth was, therefore, best received, AsThe perfect smile is a moderate one.

With or without teeth

As long as the smile was neither extreme in width nor height, the test subjects accepted it. The researchers also noticed that asymmetrical smiles were well-received, meaning that the left and right corners of the mouth pulled upward with a tiny delay.

These findings could help those who design virtual characters for films or computer games. But they could also help those who have had a stroke or other neurological damage. Often they can no longer control their facial muscles properly. If doctors know what the right laugh looks like, plastic surgery could alleviate some of these people’s suffering.