Does symmetry play a role in aesthetics?
The head, limbs, and most organs of humans and vertebrates are laterally equal (symmetrical) along the longitudinal axis of the body (median sagittal plane).
Symmetrical faces and symmetrical breasts are perceived more attractive than asymmetrical ones. Each facial feature has a unique perceptual threshold for asymmetry. The asymmetry of the eyelid at rest is the most sensitive facial feature (perception threshold: two millimeters).
This is followed by deviations of the corners of the mouth (three millimeters), the position of the eyebrows (3.5 millimeters), deviations of the tip of the nose (four millimeters) and the shape of the chin (six millimeters). (Source: Wang TT, et al. Discriminative Thresholds in Facial Asymmetry: A Review of the Literature. Aesthet Surg J. 2017 Apr 1;37(4):375-385.). The supposedly perfect symmetry of a photomontage seems disconcerting or unnatural.