Sex, beauty, and the relative luminance of facial features.

It has been suggested that the consistent luminance difference between the darker regions of the eyes and mouth and the lighter regions that surround them forms a pattern unique to faces. One of the more consistent uses of cosmetics to make the female face more attractive is to darken the eyes and mouth relative to the surrounding skin. The hypothesis that the size of the luminance difference between the eyes and mouth and the rest of the face affects the attractiveness of male and female faces differently was tested in four experiments in which attractiveness ratings were obtained for images of faces in which the luminance difference between the eyes and mouth and the rest of the face had been manipulated. Female faces were found to be more attractive when this luminance difference was increased than when it was decreased, and the opposite was found for male faces. An interpretation consistent with these results is that the luminance difference between the eyes and mouth and the rest of the face is naturally greater in women than men. In this case increasing or decreasing the luminance difference will make a face more feminine or masculine, respectively, and hence, more or less attractive depending on the sex of the face. Implications for the causes of cosmetics usage are discussed.