"Smiling Eyes" and true happiness

Carnegie Mellon study questions influential Duchenne smile hypothesis

March 14, 2021
The Scitech

A smile that lifts the cheeks and crinkles the eyes is thought by many to be truly genuine. But new research at Carnegie Mellon University casts doubt on whether this joyful facial expression necessarily tells others how a person really feels inside. In fact, these "smiling eye" smiles, called Duchenne smiles, seem to be related to smile intensity, rather than acting as an indicator of whether a person is happy or not, said Jeffrey Girard, a former post-doctoral researcher at CMU's Language Technologies Institute.

Duchenne smiles might not be as popularly known as Mona Lisa smiles or Bette Davis eyes, but there is a camp within psychology that believes they are a useful rule of thumb for gauging happiness. But another camp is skeptical. Girard, who studies facial behavior and worked with CMU's Louis-Phillippe Morency to develop a multimodal approach for monitoring behavior, said that some research seems to support the Duchenne smile hypothesis, while other studies demonstrate how it fails. So Girard and Morency, along with Jeffrey Cohn of the University of Pittsburgh and Lijun Yin of Binghamton University, set out to better understand the phenomenon. They enlisted 136 volunteers who agreed to have their facial expressions recorded as they completed lab tasks designed to make them feel amusement, embarrassment, fear or physical pain. After each task, the volunteers rated how strongly they felt various emotions. Finally, the team made videos of the smiles occurring during these tasks and showed them to new participants (i.e., judges), who tried to guess how much positive emotion the volunteers felt while smiling. A report on their findings has been published online by the journal Affective Science.

Unlike most previous studies of Duchenne smiles, this work sought spontaneous expressions, rather than posed smiles, and the researchers recorded videos of the facial expressions from beginning to end rather than taking still photos. They also took painstaking measurements of smile intensity and other facial behaviors. Although Duchenne smiles made up 90% of those that occurred when positive emotion was reported, they also made up 80% of the smiles that occurred when no positive emotion was reported. Concluding that a Duchenne smile must mean positive emotion would thus often be a mistake. On the other hand, the human judges found smiling eyes compelling and tended to guess that volunteers showing Duchenne smiles felt more positive emotion. Multimodal systems such as the ones being developed in Morency's lab hold the promise of giving physicians a new tool for assessing mental disorders, and for monitoring and quantifying the results of psychological therapy over time.

(Source: Carnegie Mellon University news release written by Byron Spice)