US scientists studying the facial expressions of blind and sighted Olympic athletes from more than 20 countries concluded that the way our faces show emotion is determined by our genes: it is hardwired and not learned.

The study was the work of San Francisco State University Psychology Professor David Matsumoto and colleague Bob Willingham and is due to be published later today, 29 December, in the Journal of Personality and Social Psychology.

The study is thought to be the first to show that sighted and blind people use the same facial expressions, where face muscles move in the same way, in response to specific emotional states. It also gives new information on how humans control their emotional expressions depending on social contexts.

For the study, Matsumoto and Willingham studied sighted and blind judo athletes competing at the 2004 Summer Olympics and Paralympic Games. They examined more than 4,800 photographs of competitors from 23 countries.

Matsumoto said that:

“The statistical correlation between the facial expressions of sighted and blind individuals was almost perfect.”

“This suggests something genetically resident within us is the source of facial expressions of emotion,” he added.

The researchers found that sighted and blind people managed their facial expressions of emotion in the same way for the same social context. For instance, 85 per cent of the silver medallists who lost their medal showed the same “social smile”, where only the mouth smiles. This is not the same as a “real” or Duchenne smile, where the eyes narrow and “twinkle” and the cheeks go up.

Matsumoto said that losers pushed out their lower lip “as if to control the emotion on their face and many produced social smiles”.

“Individuals blind from birth could not have learned to control their emotions in this way through visual learning so there must be another mechanism,” he suggested.

Perhaps our emotions and the systems that control them have passed down to us from our evolutionary ancestors, said Matsumoto. “It’s possible that in response to negative emotions, humans have developed a system that closes the mouth so that they are prevented from yelling, biting or throwing insults,” he explained.

In evolutionary terms, such a behaviour would have conferred survival advantage to individuals that carried this trait in their genes.

Duchenne was a 19th century French neurologist who discovered that a smile that results from true happiness involved the eyes as well as the mouth, hence the expression “Duchenne smile”. He used electrical stimulation on live subjects to demonstrate his theories.

“Spontaneous Facial Expressions of Emotion in Congenitally and Non-Congenitally Blind Individuals”.
David Matsumoto and Bob Willingham.
Journal of Personality and Social Psychology, Vol. 96, No.1, January 2009.

Click here for Journal of Personality and Social Psychology.

Sources:San Francisco State University, wikipedia.

Written by: Catharine Paddock, PhD