It's a far cry from the almond eyes and radiant smiles of poetry, but according to psychology research, beauty lies, with some sterility, in the averageness and symmetry of a face. That much we know.
The trouble is, studies on this topic have tended to create highly average faces by morphing lots of real faces altogether, and in the process they've created faces that are also highly symmetrical. It's a similar tale for investigations of symmetry, where the creation of artificially symmetrical faces has tended to also lead to highly average faces.
In other words, it's been difficult to tease apart these two factors. Research that asks people to rate the attractiveness of real faces can get around this problem, but these studies are also prone to error because they've tended to only use a few anchoring points when measuring symmetry.
Now Masashi Komori and colleagues think they've found the answer. They've borrowed an innovative mathematical technique from the world of paleontology called "geometric morphometrics" and used it to measure the averageness and symmetry of 96 undergrad faces based on 72 facial feature points.
Comparing their facial measurements with the attractiveness ratings given to these faces by 114 participants, the researchers concluded that for women, it is only averageness that predicts perceived attractiveness - that is, the closer a woman's face to the average female face, the more highly attractive she was rated by participants. For male faces, by contrast, attractiveness was linked to both averageness and greater symmetry.
Why should symmetry be linked with perceived attractiveness for male faces, but not for female faces? Kormori's team aren't sure, but one clue could come from the fact that symmetry correlated with the perceived masculinity of a face (whereas its inverse correlation with the femininity of female faces was only weak). This suggests that a symmetric male face is perhaps seen as highly masculine, and a good prospect as a reproductive partner.
"In the future it is necessary to investigate which facial areas contribute to facial averageness and symmetry, and which facial areas have a greater impact on facial attractiveness," the researchers said.
Komori, M., Kawamura, S., & Ishihara, S. (2009). Averageness or symmetry: Which is more important for facial attractiveness? Acta Psychologica, 131 (2), 136-142 DOI: 10.1016/j.actpsy.2009.03.008
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.