Facial symmetry

Facial symmetry is one specific measure of bodily asymmetry. Along with traits such as averageness and youthfulness it influences judgments of aesthetic traits of physical attractiveness and beauty. For instance, in mate selection, people have been shown to have a preference of symmetry. This is due to the fact that it is seen an indicator of health and genetic fitness, but also as holding adaptation qualities; reflecting the ability to withstand the changes in their environments.

Facial symmetry has been suggested as a possible physical manifestation of the 'big-five' personality traits. For example, it is found that extraversion and openness are strongly associated with the symmetry of the face. Hormones such as testosterone and estrogen are believed to be associated with developmental processes and growth of facial features during puberty and as a result are hypothesized to be the cause for individual differences in the implications associated with facial symmetry.

Facial bilateral symmetry is measured via fluctuating asymmetry of the face comparing random differences in facial features of the two sides of the face that develop and accumulate throughout one's lifetime as a result of stressors.

Facial symmetry has been shown to have an effect of ratings of attractiveness in human faces. More symmetrical faces are perceived as more attractive in both males and females, although facial symmetry plays a larger role in judgments of attractiveness concerning female faces. A wide variety of methods has been used to examine the claim that facial symmetry plays a role in judgments of beauty.

Blending of multiple faces to create a composite and face-half mirroring have been among the techniques used. While studies employing the first method produced results that indicate that more symmetrical faces are perceived as more attractive, studies applying the later method have indicated that humans prefer slight asymmetry. Also studies show that nearly symmetrical faces are considered highly attractive compared to unsymmetrical ones, yet more specifically, people tend to find a face unattractive if a person has an unsymmetrical nose, and effect of unsymmetrical lips do not really affect people on judging attractiveness.

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