There are some different scenarios when one may display a smile without feeling any happiness at all. For example, this may be out of politeness, or more ironically, used to mask an unpleasant emotion. How then, can we trust a smile? And is there a way to distinguish a sincere smile from a one that has been posed?
I’ll give you a hint….It’s all in the eyes.
Using an unusual (and questionable) technique over 150 years ago, researcher Duchenne de Boulogne used some electrical probes to stimulate the facial muscles of one of his patients. Duchenne discovered that when he engaged muscles around the mouth of his patient, the patient would produce the smile lips, but did not appear to look happy. Intrigued, Duchenne told his patient a joke to trigger a genuine joy response. Duchenne noticed that when his patient experienced true happiness, it wasn’t only the muscles of his mouth that were utilised, but also those of the eyes.
As you will see from the photos, it’s almost impossible to tell which photo is displaying genuine happiness while the eyes are covered. It’s only by seeing the muscles around the eyes (the Orbicularis Oculi) contract and create the crows feet that we can distinguish the two smiles.
Such “genuine” smiles are now known as Duchenne smiles in his honour.