Symmetry is not the only factor that affects , of course. For example, Marilyn Monroe had a prominent mole on only one side of her face. This mole may have helped to draw people’s to her face, which then increased her perceived beauty.

One demonstration that symmetry is important to judgments of facial attractiveness comes from morphing studies. In these experiments, people rate the attractiveness of a series of faces along with one face that is the morphed average of the set of faces. This morphed average is generally seen as more attractive than the mean rating of all of the faces from which it was generated. A big reason for this advantage for the average face is that it is much more symmetric than the individual faces from which it was generated. The morphing process eliminates the asymmetries in the individual faces.

An interesting paper by Jamin Halberstadt, Diane Pecher, Rene Zeelenberg, Laurent Ip Wai, and Piotr Winkielman in the November, 2013 issue of Psychological Science demonstrates that the familiarity of a face may play an even bigger role in the attractiveness of the faces than symmetry.

The authors started with 28 pictures of celebrities from the Netherlands and 28 pictures of celebrities from New Zealand. They created morphs of pairs of faces to create 14 morphs. Then, participants from the Netherlands and New Zealand rated the attractiveness of the morphs as well as the attractiveness of the individual faces. All of the morphs were rated first. Participants were also asked whether they recognized the morphs and the individual faces.

When participants rated faces of celebrities from another country, the typical averaging effect was observed. The New Zealand participants found the morphs of two Dutch celebrities to be more attractive than the individual photos. The Dutch participants found the morphs of two celebrities from New Zealand to be more attractive than the individual photos.

When people judged celebrities from their own country, though, familiarity took over. On average, the ratings of the individual faces of celebrities from that culture were seen as more attractive than the morphs. The more strongly that a person recognized the celebrity, the more strongly they preferred the individual faces to the morphs.

This study is a nice demonstration of the influence of familiarity on judgments. We are wired to prefer familiar things to unfamiliar ones. For example, the mere exposure effect demonstrates that seeing something even once makes it more desirable than something that has never been seen before. So, even though there may be general factors that can make something attractive or desirable, there is no substitute for making it familiar.

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