The Brain Behind the Hollywood Smile

Take a random picture of a group of people, like a family picture on Christmas-eve. Is everyone smiling? Apart maybe from a grumpy granny and newborn nephew, the answer is probably yes. But are they really smiling, or are the corners of their mouths pointing upwards? Now cover the mouths of those in the photo and ask yourself again who is smiling. In fact, were you smiling on that picture?

Faking a smile is notoriously difficult. Models, actors and politicians, who smile for a living, know that curling up the corners of their mouth is not enough for a convincing transfer of emotion. But why? The answer can be found in the way our brain is wired. The brain areas controlling the voluntary movements of your face (used for fake smile(s)) are different from those generating facial expressions resulting from emotions. Real and fake smiles respectively activate different parts of the motor cortex (part of the outer layer of the brain, controlling our muscles). Christian Keysers, neuroscientist at the Netherlands Institute for Neuroscience, defines the two distinct systems as the ‘cold’ and the ‘hot’ facial expression system.

In this distinction, the ‘hot’ motor system is the part of your brain that transforms the ‘heat’ of true emotions into observable facial expressions and body language. The cold motor system, on the other hand, is active in voluntary movements of the face, including chewing, arguably attractive duck-faces and forced smiles on never-flattering group-photos.

When faking a smile, we activate our cold motor system in order to deliberately mimic the sequence of facial muscles used when smiling. However, this only leads to a poor imitation of a real smile: it will never capture the countless subtle movements of the entire face form an expression of true joy.

The difference between the hot and the cold motor system used for facial expressions becomes even more evident when one of the two is damaged after a brain lesion. Patients with a defective ‘hot’ system are only able to deliberately produce facial expressions; their faces will not move when they experience emotions. Conversely, people with a defective ‘cold’ system are unable to deliberately move their facial muscles, meaning they cannot produce fake-smiles (maybe this would be a suitable lesion for all fake-smiling politicians).

According to neuroscience, the solution for a convincing smile during your next job-interview or Christmas-eve family reunion is simple. Remember the last time you laughed until you had tears of joy in your eyes. Forget about the Hollywood-smile. A beautiful smile is not in your whitening toothpaste, it’s in your head!

For further reading:

C. Keysers, The empathic brain . How the discovery of mirror neurons changes our understanding of human nature (2011). Smashwords Edition

Morecraft, R.J., Stilwell-Morecraft, K.S., and Rossing, W.R. (2004). The motor cortex and facial expression: new insights from neuroscience. Neurologist 10, 235-249.

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