The Discovery of the Duchenne (Genuine) Smile

The story begins with one of the worlds great Neurologists – Duchenne de Boulogne.

In 1852 the great French neurologist Duchenne de Boulogne was able to catalog the muscles and muscle groups involved in a variety of different facial expressions.

He was able to do this by using electrical probes to stimulate the muscles in the faces of his subjects.
Duchenne believed that understanding facial expressions could reveal an “accurate rendering of the soul’s emotions”.

While conducting his research Duchenne discovered that when he stimulated the muscles used to smile (Zygomatic Major), his subject produced a large smile, yet did not look truly happy. See left image.

It’s worth noting that this particular subject had an anesthetic condition of the face and could feel no pain.

Intrigued by this un-genuine smile, Duchenne told the man a joke, capturing his reaction immediately after. See right image.

Can you see the difference?

What Duchenne had discovered was that when we feel true enjoyment we engage the muscle surrounding our eyes as well as the muscles that produce a smile.

The contraction of the muscles surrounding our eye (Orbicularis Oculi) is extremely difficult to do voluntarily and therefore is a good indicator of true enjoyment.
An easy way to spot the difference is to look for wrinkling around the outside of the eye, often referred to as crows feet. If these wrinkles appear or become deeper, it is likely the Orbicularis Oculi is engaged and you are witnessing a ‘genuine smile’.

Such ‘genuine smiles’ are now known as Duchenne smiles.

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