“Research in facial attractiveness is difficult because of the inherent subjectivity of rating,” lead author Natalie Popenko, MS, a third-year medical student at Chicago Medical School, tells Cosmetic Surgery Times. 

“Most people can look at a face and instinctively tell you whether that face is attractive or not, by subconsciously picking up on biologic cues like fertility, coloration and proportions,” she says.

The researchers used synthetic morph frontal digital images of the faces of 20 white women, ages 18 to 25 years, to generate five varied lip surfaces for each face. These 100 faces were cardinally ranked by attractiveness.

Later, four variants for each of the 15 highest-ranked faces were created, for a total of 60 faces. The upper to lower lip ratio for each of these 60 faces were then rated by attractiveness by internet focus groups (428 participants).
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