Why is a smile so powerful?

We start the new year by sending our best wishes to the people around us for their health, their success, their resolutions to come true and in particular, for them to smile more. Smiling is the most distinctive and powerful clue for happiness and joy. We smile when we are happy and we feel good when we see smiling faces. Especially if the smile is a genuine one.

But how do we know whether a smile is a genuine or a fake one?

In the mid-19th century, French neuroanatomist Guillaume Duchenne studied the muscles in the face and how their activity was related to emotional expression. Based on his research, he described two types of smiles: (1) Smiles that involve both the muscle that pulls the lip corners up to produce a smiling mouth and the muscle around the eyes that narrows the eyes and gathers the skin around the eye; and (2) Smiles that involve only the lip muscle.

The first one is called the Duchenne-smile and is like how you would smile when you watch your child performing on stage. The second non-Duchenne smile is more like how you would smile to strangers at an office party.

Duchenne-smiles are believed to be the genuine signs of happiness because they are rather hard to fake by the majority. Researchers asked children and adults to compare videos of people who smiled in a Duchenne or non-Duchenne style1. Participants associated Duchenne-smiles more with enjoyment. So even from an early age, we pay attention to the eyes to decide whether someone is genuinely happy and smiling, or if they are just pretending.

How does our brain process such different facial expressions?

In another study2, researchers asked adult participants to look at photos of faces that were either neutral, or angry, or fearful or Duchenne-type happy. While they looked at the photographs, the researchers recorded the electrical activity between the nerve cells of their brains (with a non-invasive method, no harm to anyone!). The brain regions they looked at are involved in developing emotional states. Researchers wanted to see how fast these regions responded to seeing a particular facial expression. The results showed our brains are quicker in distinguishing negative expressions from the positive ones, in comparison to distinguishing positive expressions from the neutral ones.

This is perhaps linked to some form of self-defense mechanism. Instinctively, we notice angry and fearful faces first in order to protect ourselves from a potential danger.

Then, there is the other side of the story. The story of the smiling person and how their own act of smiling affects their emotional state.

When we are happy, we tend to approach more positively to the world around us. Our brains are wired in a way that the nerve cells involved in our facial movements are also linked to our emotional states. So scientists wondered if our facial movements upon smiling could alone influence our perception of others.

In a 2015 study3, researchers asked adult participants to smile and to adopt a neutral face. Then in each state, they showed them somebody else’s happy face and neutral face. During these tasks, they measured the electrical activity in their brain. Remarkably, when the participants themselves smiled, their brains processed the other person’s neutral and happy faces in a similar way. When they had a neutral expression themselves, their brain processed the other faces differently. This meant our own facial movements alone are powerful enough to affect our interpretation of other people’s faces. When we smile, it is as if the world is also smiling at us.

Smiling is the universally accepted sign of enjoyment and happiness, and science shows smiling alone can make us feel better about ourselves and about others. Perhaps if everyone put more effort to genuinely smile at each other, the world would be a better place.

Wishing everyone a year full of smiles!



For more:

Here is a TED talk by Ron Gutman about the “The hidden power of smiling”


1 Pierre Gosselin et al., 2002. Children’s and Adults’ knowledge of the distinction between enjoyment and nonenjoyment smiles. Journal of Nonverbal Behaviour, 26.

2 Manuel G. Calvo et al., 2013. When does the brain distinguish between genuine and ambiguous smiles? An ERP study. Brain and Cognition, 81.               Pubmed ID: 23262178

3 Alejandra Sel et al., 2015. When you smile, the world smiles at you: ERP evidence for self-expression effects on face processing. SCAN, 10.  Pubmed ID: 25717074


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