Effects of eye and face shape on perception of masculinity, attractiveness, and age

The effect of masculinity on male facial attractiveness has been studied with controversial results. Eye and eyebrows are sexually dimorphic and change when faces are warped along the male - female axis, but are also fundamental in decoding emotion. The effects of masculinity on attractiveness may be secondary to changes in the perceived emotional tone of the target stimulus faces. To dissect these two effects, we have created two sets of stimuli using conventional morphing techniques. In one set, the shape of eyes and eyebrows of an average male face was changed in a continuum along a morphometric male - female axis without warping the rest of the face. A second and complementary set of stimuli was created by warping face shape while blocking eyes and eyebrows. We asked twenty-five female observers to rate the four extremes of the two face continua for masculinity. It was found that either manipulation changed the perceived masculinity of the target face (p < 0.01). We then asked forty female observers to select the most attractive face along these continua as well as along a third continuum generated by warping eyes and face together. In accordance with previous reports (Perret et al, 1998 Nature 394 884 - 887), female subjects showed a preference for slightly feminised male faces (-8% along the warp axis), when the whole face configuration was manipulated. When eyes and face outline were manipulated separately, a significantly larger degree of feminisation was preferred (-18% and -21%, respectively). We conclude that eyes and face outline contribute additively to the perception of masculinity, and that masculinity is a primary cue for attractiveness. On the other hand, masculinisation of the eyes, but not of the face outline, changes the perceived age of the target face.