A study by Golle, Mast & Lobmaier (2013) shows how emotional expressions of happiness influence the judgment of attractiveness. The researchers manipulated faces with computer graphics software to systematically change shape-related attractiveness and happiness, while they kept other facial attributes constant.
In this way, the participants saw identical faces that only differed in attractiveness and expressed happiness. Participants preferred the more smiling faces although the task was to choose the more attractive face of a pair.
More specifically, less attractive but happy faces were judged as equally or even more attractive than attractive but less smiling faces for both male and female faces. Both men and women increased their attractiveness by smiling, however, men benefited more from a happy smile than women, which contradicts earlier findings.
Participants were also more accurate in choosing a happy face when the face was more attractive. This is probably due to the fact that facial attributes (e.g., gender, eye gaze, identity) influence the way we perceive emotions.
The authors further argue that people pay more attention to attractive than less attractive people, which in turn makes them more sensitive towards them (and their emotions).
Unfortunately, the results of this study do not show the difference in attractiveness of a genuine smile (Dunchenne smile) relative to a fake smile. Theoretically speaking, genuine smiles should influence the ratings of attractiveness more positively because a genuine smile is more pleasing to the observer.
However, Dunchenne smiles may not always be the result of “true” positive emotions because some people have the ability to produce Duchenne smiles deliberately (Gunnery et al., 2013).
Here are several explanations that could account for the findings of this study. A brain study by O’Dohert and colleagues found that happy faces are more rewarding, at a neural level, than neutral faces:
“The activity in the brain’s reward system when viewing attractive faces was modulated by expressed happiness of the face.” (p.9)
On the basis of these findings, attractiveness and happiness may share some common processing mechanisms. Another theory is that happy faces influence the emotional well-being of the observer, which in turn makes it more attractive.
A smile may also signal better health, and indeed, positive emotions have been found to improve health (e.g., cardiovascular function).
Therefore, the facial expression of positive emotions may either consciously or unconsciously lead to a better perceived health status, and the expression of good health has been associated with attractiveness in a number of studies.