ORIGINAL ARTICLE
Facial Attractiveness Visual Impact of Symmetry Increases Significantly Towards the Midline Ingo N. Springer, MD, DMD, PhD,* Bjorn Wannicke, DMD,† Patrick H. Warnke, MD, DMD, PhD,* Oliver Zernial, MD, DMD,* Jorg Wiltfang, MD, DMD, PhD,* Paul A. J. Russo, MD,§ Hendrik Terheyden, MD, DMD, PhD,* Andreas Reinhardt,* and Stefan Wolfart, DMD, PhD‡
Abstract: Symmetry is thought to be a major prerequisite for an attractive face. Many faces are not symmetric, yet are still regarded as beautiful. What role, then, does asymmetry play in the perception of beauty? We studied the assessment of computer-manipulated images by independent judges (n ⫽ 200 –250): part A: nevi located at different positions; part B: standardized changes of the orbital region. The results showed that slight lateral orbital and facial asymmetry does not impair attractiveness at all and that asymmetries close to the midline are significantly less attractive than those affecting the lateral aspect of the face (P ⬍ 0.001). A single nevus which is located laterally on the face is significantly more attractive than a nevus close to the midline (P ⬍ 0.001). Faces with a completely symmetric bilateral pair of nevi in the same lateral positions (perceived as attractive when alone), received the worst ratings (P ⬍ 0.001). Symmetry is a characteristic of the attractive face, but there are exceptions to the rule. Under certain conditions symmetry can be completely unattractive. The visual impact of symmetry on the perception of beauty increases significantly when approaching the midline. Key Words: face, attractiveness, symmetry, asymmetry, beauty (Ann Plast Surg 2007;59: 156 –162)
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n humans, features of an individual face deemed attractive to others are thought to be largely consistent between observers independent of age, sex, or cultural background.1,2 Symmetric patterns are generally considered more attractive than asymmetric ones, especially when it comes to mate Received September 15, 2006, and accepted for publication, after revision, October 6, 2006. From the *Department of Oral and Maxillofacial and Facial Plastic Surgery, †Department of Conservative Dentistry and Periodontology, and ‡Department of Prosthodontics, Propaedeutics and Dental Materials, University of Kiel, Kiel, Germany; and the §Royal North Shore Hospital, University of Sydney, St Leonards, NSW, Australia. Wannicke, Warnke, and Zernial contributed equally. No grant funding was received for the conduction of this study. Reprints: Ingo N. Springer, MD, DMD, PhD, University of Kiel, Department of Oral and Maxillofacial and Facial Plastic Surgery, Arnold-Heller-Str. 16, 24105 Kiel, Germany. E-mail:
[email protected]. Copyright © 2007 by Lippincott Williams & Wilkins ISSN: 0148-7043/07/5902-0156 DOI: 10.1097/01.sap.0000252041.66540.ec
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choice.3– 8 This has also been shown for species such as swallows, female zebra finches, and others.4,5 Recently, it was reported that there are strong positive associations between symmetry and dancing ability and that these parameters again play a role in sexual selection.9 Mertens and coworkers showed that when humans observe a face, the eyes, mouth, and nose regions are the preferred targets of the center of gaze, with the outlines of eye position recordings approximating a triangle with vertices located in the center of the eyes and mouth10 (Fig. 1). Conversely, when looking at an inanimate object, the contours and prominent ornaments are the preferred targets of the gaze.10 These findings suggest that, for human faces the midline area plays a crucial role in judgments of attractiveness. Symmetry is among others thought to be one of the predominating factors that correlate with facial attractiveness, health, and mate choice.3– 6,11–14 The degree of facial symmetry is thought to indicate the degree of phenotypic and perhaps even genotypic quality.5,12,15 Other authors have shown that individuals’ preference for symmetry arise as a by-product of the need to recognize objects irrespective of their position and orientation in the visual field.3,16 It is believed by some authors that both of these selection pressures may have shaped human perceptions of facial beauty.13 Although of great value in contributing to the understanding of facial beauty, the study of the attractiveness of composite faces, which are of course completely symmetric, does not allow the consideration of small asymmetries like a “beauty spot” or an asymmetrically tilted eye (or more accurately: asymmetrically tilted intercanthal axes).2,8 The intercanthal axis is defined as the line generated by connecting the medial and lateral canthi (outer and inner angle of the eye) and should demonstrate an approximate 4 degrees upward lateral tilt as compared with the true horizontal plane.17,18 Volpe and Ramirez17 suggested that this upward tilt of the intercanthal axis is one of the most distinctive qualities of the beautiful eye. Why is it that a single nevus may be regarded as a “beauty spot” and that asymmetrically tilted eyes can still look beautiful? We set out to test the following hypotheses: 1. Certain facial variations (such as nevi) are more attractive when asymmetric as opposed to symmetric. They seem more attractive when located laterally as opposed to meAnnals of Plastic Surgery • Volume 59, Number 2, August 2007
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FIGURE 1. The assessment of attractiveness of different nevi positions as assessed by a visual analogue scale (ordinate; most attractive: 100, least attractive ⫽ 0; n ⫽ 201 participants). The original image without a nevus was significantly more attractive than all other images (P ⬍ 0.001). Nevi in position 8 (most lateral and cranial) were significantly more attractive than nevi in all other positions (P ⬍ 0.001). Least attractive were images with bilateral symmetric nevi (position 6). Nevi were significantly more attractive when located outside Mertens’ triangle (M) (paramedian, chin 关position 2兴, nasolabial fold 关position 5兴, lateral lower jaw 关position 7兴, zygomatic/ cheek bone 关position 8兴) than inside Mertens’ triangle (paranasal 关position 3兴, upper lip 关position 1兴) (P ⬍ 0.001).
dially, particularly so when located outside “Mertens’ triangle”10 as compared with inside it. 2. The impact of orbital symmetry on facial attractiveness increases towards the midline and diminishes away from the midline. In other words, the more distant an irregularity is from the midline, the less its impact on facial attractiveness.
MATERIALS AND METHODS Part A Four sets of images of 4 different people (2 female, 2 male) contained 9 different images of the face, 1 original and 8 computer-manipulated images with a nevus located at different positions (Fig. 1). These locations were position 1, paramedian, upper lip; position 2, paramedian, chin; position 3, paramedian, nose; position 4, lower lid; position 5, just lateral to the nasolabial fold; position 6, 2 bilateral symmetric nevi in position 5 (Figs. 1 and 2); position 7, lateral lower jaw; position 8, zygomatic (cheek) bone (most lateral position). Judges ranked each image for attractiveness on a visual analogue scale from most unattractive (0) to most attractive (100). All 4 sets were presented to all judges. Images were shown in a randomized order. The judges (n ⫽ 201), consisted of 3 groups: Group 1: 32 medical professionals (age range, 25– 63 years; 13 females, 19 males); participants included medical doctors and surgeons, dentists, and medical/dental students ⱖ3rd year. © 2007 Lippincott Williams & Wilkins
Group 2: 15 art professionals (age range, 24 – 44 years; 6 females, 9 males); participants included artists, designers, and art students ⱖ3rd year. Group 3: 154 persons of other professions (age range, 15– 64 years; 59 females, 85 males).
Part B Four sets of images showing the orbital region of 4 different people (2 female, 2 male) contained 1 computermanipulated symmetric image and 24 other computer-manipulated images with different standardized bilateral symmetric and unilateral asymmetric changes of the tilt of the intercanthal axis (4 degrees, 6 degrees, and 9 degrees to normal), the center of motion being located medially or laterally, respectively (Fig. 3). Tilts were never performed both bilaterally and asymmetrically. The computer-manipulated symmetric image was the basis for the 24 other images and was made as follows: the right half of the original image of each face (each original face had a 5-degree upward tilt of the lateral canthus17,18) was mirrored with respect to the median plane to replace the left side of the original image (Fig. 3). Judges ranked each image for attractiveness on a visual analogue scale from most unattractive (0) to most attractive (100). Each of the judges was randomized to one of the 4 sets of images. All of the 25 images from each of the 4 sets were shown in a randomized order. The judges (n ⫽ 250), consisted of 3 groups: Group 1: 59 medical professionals (age range, 22–56 years; 36 females, 23 males); participants included medical
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FIGURE 2. A, The original image without any nevi was significantly more attractive than all other images (P ⬍ 0.001). B, Nevi in position 8 (zygomatic/cheek bone, most lateral and cranial) were significantly more attractive than nevi in all other positions (P ⬍ 0.001), including position 4 (lower lid, C), position 5 (nasolabial fold, D) position 1 (upper lip, F) and worst of all, position 6 (bilateral symmetric nevus beside the nasolabial fold, E). All asymmetric unilateral nevi were significantly more attractive when located laterally rather than medially (P ⬍ 0.001).
doctors and surgeons, dentists, and medical/dental students ⱖ3rd year. Group 2: 32 art professionals (age range, 20 –53 years; 16 females, 16 males); participants included artists, designers, and art students ⱖ3rd year. Group 3: 159 persons of other professions (age range, 22– 64 years; 96 females, 63 males). Before taking part in the investigation the participants were asked to complete the well-validated 28-item von Zerssen and Koeller19 test of well-being (Befindlichkeitsbogen, Belts Test, Germany). We found that the characteristics of participants in the study did not differ from the general population in terms of their well-being.19,20
Statistics In Parts A and B, the mean values of corresponding variations of all 4 sets were calculated for each participant to pool the data from the survey. The data were normally distributed (Kolmogorov-Smirnov test). An analysis of variances (ANOVA) was performed to determine differences between the groups of participants. Multiple pairwise comparisons of the different variations were conducted based on the paired t test adjusted with the Bonferroni-Holm procedure to identify significantly different “esthetic levels.” Two weeks after the first evaluation, 25 of the judges were asked
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to repeatedly answer the questionnaires. These judges were shown the same randomized photos as on their first visit. To determine the reliability of the results, we performed Pearson’s correlation coefficient between the main evaluation and the second survey (2-sided). For all tests, the level of significance was set to 5%.
Ethics The study was conducted in accordance with the standards of the Ethics Committee of the University of Kiel (registration number D409/06) and with the Helsinki Declaration of 1983. The photographed participants of the study were informed of the aim and design of the study, and written consent was obtained. All participants took part voluntarily and were unpaid. Participants were interviewed individually.
RESULTS Part A Faces with Nevi in position 8 (zygomatic/cheek bone, most lateral and cranial) were significantly more attractive than faces with nevi in all other positions except the original image (P ⬍ 0.001). The 3 most attractive nevi positions in order were nevi in positions 8 (zygomatic bone), 7 (lateral lower jaw) and 5 (nasolabial fold) (Figs. 1 and 2). © 2007 Lippincott Williams & Wilkins
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FIGURE 3. Statistical analysis showed 5 levels of attractiveness, ie, 5 groups of pictures that were statistically significantly different (P ⬍ 0.001). These are only representative images of the entire set of 25 images. AA, Symmetric reference image. This image indicates possible tilts of the intercanthal axis, with the center of motion being located medially (CMM) or laterally (CML). When the center of motion is located medially, the greatest effect of movement will be seen laterally and vice versa. A, Level 1 (reference image). B, Level 1 (⫹4-degree lateral symmetric bilateral canthal tilt). C, Level 1 (⫹4-degree lateral asymmetric unilateral canthal tilt). D, Level 2 (⫹4-degree medial asymmetric unilateral canthal tilt). E, Level 2 (⫹6degree lateral asymmetric unilateral canthal tilt). F, Level 2 (⫹6-degree lateral symmetric bilateral canthal tilt). G, Level 2 (⫺4-degree lateral asymmetric canthal tilt). H, Level 5 (⫺9-degree medial asymmetric canthal tilt), the least attractive picture of the sets with unilateral, medial, and caudal rotation of the greatest amount.
All asymmetric unilateral nevi were significantly more attractive when located laterally than medially (P ⬍ 0.001). All nevi located paramedially (upper lip 关position 1兴, chin 关position 2兴, nose 关position 3兴) on the face were significantly less attractive than nevi located along position 4 (lower lid), position 5 (nasolabial fold), and position 7 (lateral lower jaw) (P ⬍ 0.001). The latter were significantly less attractive than the most lateral nevus (position 8 ⫽ zygomatic bone) (P ⬍ 0.001). Although images with a nevus located just beside the nasolabial fold 关position 5兴 were among the 3 most attractive images, faces with bilateral symmetric nevi in this position received the worst ratings (P ⬍ 0.001) (Figs. 1 and 2). All asymmetric 1-sided nevi were significantly more attractive when located outside Mertens’ triangle (paramedian, chin 关position 2兴, nasolabial fold 关position 5兴, lateral lower jaw 关position 7兴, zygomatic bone 关position 8兴) as © 2007 Lippincott Williams & Wilkins
compared with inside Mertens’ triangle (paranasal 关position 3兴, upper lip 关position 1兴) (P ⬍ 0.001).
Part B Multiple pairwise comparisons (paired t test) demonstrated 5 levels (ranks) of attractiveness that were all statistically significantly different (P ⬍ 0.001). Within the most attractive level (level 1) were the symmetric reference pictures, and slight (4 degrees) asymmetric (⫽ unilateral) or symmetric (⫽ bilateral) upward tilts of the lateral canthus. The natural 5-degree upward tilt of the lateral canthus that was given in the reference pictures (see Materials and Methods), and an additional 4 degrees (total 9 degrees) of unilateral (asymmetric) or bilateral (symmetric) upward tilt of the lateral canthus, was rated as most attractive (P ⬍ 0.001), showing that lateral asymmetries do not necessarily impair overall attractiveness (Figs. 3 and 4).
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the results of the assessment and the gender of the person shown on the photos.
DISCUSSION
FIGURE 4. The assessment of attractiveness of canthal tilts as assessed by visual analogue scale (ordinate; most attractive: 100, least attractive ⫽ 0; n ⫽ 250 participants). Each bar represents mean values ⫾ 1 standard deviation. Gray squares are asymmetric unilateral canthal tilts; white squares are symmetric bilateral tilts. Bars with black dots (Re) are reference images. Negative values (eg, ⫺9 degrees) indicate a downward tilt; positive values (eg, ⫹9 degrees) indicate upward tilts. Please note that the reference pictures (Ref) had a natural 5-degree upward tilt of the lateral canthus, which must be added to all the values mentioned.
Upward or downward tilts of the lateral canthus (center of motion medially) were significantly more attractive than upward or downward tilts of the medial canthus, ie, lateral movements had less of a negative impact on attractiveness than did medial movements (P ⬍ 0.001) (Figs. 3 and 4). Asymmetric (⫽ unilateral) tilts of the intercanthal axis resulted in a greater impairment in attractiveness when performed medially rather than laterally (P ⬍ 0.001). Upward tilts of the medial canthus were perceived significantly more positively than downward tilts (P ⬍ 0.001). Movements of 6 degrees or more laterally, and 4 degrees or more medially, were perceived significantly more positively when they were symmetric (bilateral) rather than asymmetric (unilateral) (P ⬍ 0.001).
Parts A and B All findings were found to be reproducible through the conduction of a second survey (part A: rp ⫽ 0.813, P ⬍ 0.001, 2-sided; part B: rp ⫽ 0.814, P ⬍ 0.001, 2-sided). There was no significant difference in the assessment provided by medical professionals, art professionals, and people of other professions (groups 1–3) in part A and part B of this study. No significant difference was found when comparing the assessments of attractiveness provided by judges of different ages (age groups: 15.0 –26.0 years (part B: 20.0 –26.0 years), 27.0 –39.0 years, 40.0 –53.0 years, 54.0 – 64.0 years). No significant differences were found between the assessments of the 3 participant groups concerning their well-being as measured by the von Zerssen and Koeller19 well-being test. No significant differences were found between the assessment of female and male judges. Finally, there was no relation between
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It is a widely held view that the more symmetric a face is, the more attractive it is to behold. The aim of this study was to ascertain possible exceptions to this theory. Knowledge of acceptable facial asymmetries is not only of interest in the understanding of human behavioral biology.3–5,11–13,16 The position of nevi is determined by genetic and embryological factors. It is very challenging to change the canthal position surgically. Nonetheless, understanding the rules of facial symmetry is of potential value in reconstructive maxillofacial or plastic facial surgery.17,18,21–25 For more than a century studies of human facial attractiveness have focused on photographic and digital composites of faces. This has supported the theory that attractive faces approximate those features seen on facial composites (“averageness” hypothesis).8 Using composite faces, other authors then showed that the mean shape of a set of attractive faces is preferred to the mean shape of the entire sample from which the faces were selected.2 These models, although of enormous value in the understanding of facial attractiveness, have in common the feature that composites of faces are symmetric. This has not allowed the study of the effect of minor asymmetries on the degree of facial attractiveness. No composite image of many faces contains the small irregularities seen on individual faces, such as “beauty spots” or an asymmetrically tilted eye. Other authors have already shown that symmetric faces are the most attractive; however, there remain other characteristics that are yet to have been defined objectively (such as skin texture).7 One option, as we have used, is to study the effect of certain variations of physical appearance on attractiveness using computer-manipulated images and a visual analogue scale.26 –28 The gender of those shown in the images or of the judges assessing those images did not have a significant effect on the results of this study. Scheib and coworkers29 studied phenotypic cues that are used by women in their choice of mates and found that women did consider certain faces attractive even when only the left or right half of the face was presented. Even the assessment of these half-faces revealed a relationship between facial attractiveness and symmetry, which naturally was not present.29 These findings suggest that it is not only symmetry that is used by individuals in their assessment of the phenotypic fitness of another individual. With regard to the assessment of the attractiveness of male faces by women, one such cue found was facial masculinity, ie, cheek-bone prominence and a relatively longer lower face.29 Other authors showed that people prefer feminized to average shapes of a female face and feminized to average or masculinized shapes of a male face.30 In the course of the review process, one reviewer suggested that proportionality (the relationship of 2 measurements) of the face is the most important element in our judgment of attractiveness, regardless of symmetry or minor asymmetries. It has been suggested that the intercanthal axis should demonstrate an approximate 4-degree upward lateral tilt as © 2007 Lippincott Williams & Wilkins
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compared with the true horizontal plane and that this upward tilt of the intercanthal axis is one of the most distinctive qualities of the truly beautiful eye.17,18 In the course of a pilot study, we found an average of 5-degree upward tilt of the lateral canthus in a set of 360 standardized pictures. Here, we provide evidence that the reference images (symmetric with a natural 5-degree upward tilt of the lateral canthus17,18) and the computer-manipulated images with an additional 4-degree tilt (⫽ total of 9 degrees of upward tilt of the lateral canthus) are indeed significantly better rated than the rest of the images and statistically within the most attractive level. We have not disproved that symmetry is a major characteristic of the attractive face, but we have shown that there are significant exceptions to the rule and certain paradoxes. We have demonstrated that slight but visible lateral orbital asymmetries (4-degree unilateral upward tilts of the lateral canthus) do not diminish attractiveness and that lateral asymmetries are significantly more attractive than those close to the midline (P ⬍ 0.001). Slight asymmetries close to the midline (4 degrees or more tilts of the medial canthus in any direction) do impair attractiveness significantly. Downward tilts (4 degrees and more, asymmetric and symmetric) of the lateral canthus also impair attractiveness, whereas upward tilts are significantly more attractive. Upward displacements are significantly less attractive when close to the midline than distant to the midline (P ⬍ 0.001). In general, we have shown that attractiveness diminishes the greater the extent of any asymmetry and the closer that asymmetry is to the midline. We suggest that this emphasizes the need for accurate reconstruction of the midfacial area in traumatized patients and that incisions close to the facial midline should be avoided in plastic and reconstructive surgery whenever possible. Downward displacement is significantly worse than upward displacement of the orbital structures (P ⬍ 0.001). It is interesting to compare these findings with one of the described effects of aging: the downward displacement of lateral facial structures (“lateral facial sagging”).31 A “beauty spot” may therefore be regarded as a nevus located laterally on the face as such a location does not impair attractiveness as compared with a similar symmetric face without a nevus. A laterally located nevus is significantly more attractive than a nevus close to the midline (P ⬍ 0.001). A pair of 2 bilaterally completely symmetrically positioned but otherwise small and unobtrusive nevi in the “beauty spot position” received the worst ratings (P ⬍ 0.001). This suggests that under certain conditions, symmetry has an adverse effect on attractiveness. We speculate that symmetric bilateral nevi subconsciously suggest the presence of a syndromal disease or “unhealthy” genotype.32,33 Moreover, the finding that symmetric nevi do get very bad ratings may contradict the theory that symmetry is always associated with good health. In general, the esthetic result after surgical reconstruction of bilateral symmetric cleft lips is considered to be inferior as compared with the esthetic result after reconstruction of unilateral cleft lips. It is possible that this may be due to the more advantageous surgical techniques available for unilateral clefts. However, considering the results of this survey, we suggest that bilateral abnormalities are perceived © 2007 Lippincott Williams & Wilkins
Visual Impact of Symmetry
as less attractive than unilateral abnormalities, even if facial symmetry is disturbed. What is perceived as beautiful is not just of interest to reconstructive surgeons. The impact on society of beauty and what is perceived as such is easily gauged by even a casual appraisal of the cosmetics and fashion industries and their marketing through mass media. The potential impact of research into what constitutes our perception of beauty is beyond the scope of this paper yet deserves to be mentioned. Research into beauty has the potential to both define and influence sociocultural standards which are propagated in part by mass media through the marketing of cosmetic medical treatments. Research findings on the character of beauty and the correlation between attractiveness and self-esteem and improved social interactions have been implicated in contributing to the increased popularity of cosmetic medicine.34,35 It has been suggested that past research into beauty has confirmed what people who seek cosmetic procedures have suspected: that if they are more physically attractive, they will be seen and treated more positively.34,35
CONCLUSIONS The impact of changes to the symmetry of the orbital region on facial attractiveness increases from lateral to medial and from cranial to caudal. Small but visible lateral asymmetric variations of the orbital region do not influence attractiveness, whereas asymmetries of an equivalent extent close to the midline are rated as significantly less attractive. Attractiveness of the orbital region diminishes the larger asymmetries are, the lesser their distance is to the midline, and the more they are oriented downward. A unilateral nevus of the face may be considered a “beauty spot,” whereas a symmetric nevus in the same position receives the worst ratings of all. The closer a unilateral nevus is to the midline, the less attractive it is. Specifically, unilateral nevi located within Mertens’ triangle were found to be less attractive than nevi located outside. All findings of the present study were found to be significant (P ⬍ 0.001). Symmetry is a characteristic of the attractive face, but there seem to be exceptions to the rule. The impact of facial symmetry increases significantly when approaching the midline. The more distant an irregularity is from the midline, the less it affects perceived attractiveness. There are indeed very attractive asymmetries and very unattractive symmetries.
ACKNOWLEDGMENTS The authors are grateful to Professor Dr. W.-D. Gerber, Department of Medical Psychology, University of Kiel, Germany, for assistance in the design of this study. REFERENCES 1. Langlois JH, Kalakanis L, Rubenstein AJ, et al. Maxims or myths of beauty? A meta-analytic and theoretical review. Psychol Bull. 2000;126: 390 – 423. 2. Perrett DI, May KA, Yoshikawa S. Facial shape and judgements of female attractiveness. Nature. 1994;368:239 –242. 3. Enquist M, Arak A. Symmetry, beauty and evolution. Nature. 1994;372: 169 –172. 4. Swaddle JP, Cuthill IC. Preference for symmetric males by female zebra finches. Nature. 1994;367:165–166.
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5. Moller AP. Female swallow preference for symmetrical male sexual ornaments. Nature. 1992;357:238 –240. 6. Rhodes G, Peters M, Lee K, et al. Higher-level mechanisms detect facial symmetry. Proc Biol Sci. 2005;272:1379 –1384. 7. Penton-Voak IS, Jones BC, Little AC, et al. Symmetry, sexual dimorphism in facial proportions and male facial attractiveness. Proc Biol Sci. 2001;268:1617–1623. 8. Langlois JH, Roggman LA. Attractive faces are only average. Psychol Sci. 1990;1:115–121. 9. Brown WM, Cronk L, Grochow K, et al. Dance reveals symmetry especially in young men. Nature. 2005;438:1148 –1150. 10. Mertens I, Siegmund H, Grusser OJ. Gaze motor asymmetries in the perception of faces during a memory task. Neuropsychologia. 1993;31:989 –998. 11. Rhodes G, Geddes K, Jeffery L, et al. Are average and symmetric faces attractive to infants? Discrimination and looking preferences. Perception. 2002;31:315–321. 12. Rodriguez I, Gumbert A, Hempel de Ibarra N, et al. Symmetry is in the eye of the beeholder: innate preference for bilateral symmetry in flowernaive bumblebees. Naturwissenschaften. 2004;91:374 –377. 13. Rhodes G. The evolutionary psychology of facial beauty. Annu Rev Psychol. 2006;57:199 –226. 14. Zaidel DW, Cohen JA. The face, beauty, and symmetry: perceiving asymmetry in beautiful faces. Int J Neurosci. 2005;115:1165–1173. 15. Little AC, Jones BC. Evidence against perceptual bias views for symmetry preferences in human faces. Proc Biol Sci. 2003;270:1759 –1763. 16. Johnstone RA. Female preference for symmetrical males as a by-product of selection for mate recognition. Nature. 1994;372:172–175. 17. Volpe CR, Ramirez OM. The beautiful eye. Facial Plast Surg Clin North Am. 2005;13:493–504. 18. Bartlett SP, Wornom I 3rd, Whitaker LA. Evaluation of facial skeletal aesthetics and surgical planning. Clin Plast Surg. 1991;18:1–9. 19. von Zerssen D, Koeller D-M. Klinische Selbstbeurteilungs-Skalen (KSB-S) aus dem Muenchener Psychiatrischen Informations-System. Weilheim: Die Befindlichkeitsskala; 1976. 20. Weissman MM, Bland RC, Canino GJ, et al. Cross-national epidemiology of major depression and bipolar disorder. JAMA. 1996;276:293–299. 21. Cuccia G, Shelley O, d’Alcontres FS, et al. A comparison of temporalis transfer and free latissimus dorsi transfer in lower facial reanimation following unilateral longstanding facial palsy. Ann Plast Surg. 2005;54: 66 –70.
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22. Wang X, Qiao Q, Liu Z, et al. Free anterolateral thigh adipofascial flap for hemifacial atrophy. Ann Plast Surg. 2005;55:617– 622. 23. Marchac D, Britto JA. Remodelling the upper eyelid in the management of orbitopalpebral neurofibromatosis. Br J Plast Surg. 2005;58:944 – 956. 24. Kaufman AJ. Periorbital reconstruction with adjacent-tissue skin grafts. Dermatol Surg. 2005;31:1704 –1706. 25. Chen SH, Mardini S, Chen HC, et al. Strategies for a successful corrective Asian blepharoplasty after previously failed revisions. Plast Reconstr Surg. 2004;114:1270 –1277; discussion 1278 –1279. 26. Wolfart S, Brunzel S, Freitag S, et al. Assessment of dental appearance following changes in incisor angulation. Int J Prosthodont. 2004;17: 150 –154. 27. Wolfart S, Thormann H, Freitag S, et al. Assessment of dental appearance following changes in incisor proportions. Eur J Oral Sci. 2005; 113:159 –165. 28. Shaw WC, Rees G, Dawe M, et al. The influence of dentofacial appearance on the social attractiveness of young adults. Am J Orthod. 1985;87:21–26. 29. Scheib JE, Gangestad SW, Thornhill R. Facial attractiveness, symmetry and cues of good genes. Proc Biol Sci. 1999;266:1913–1917. 30. Perrett DI, Lee KJ, Penton-Voak I, et al. Effects of sexual dimorphism on facial attractiveness. Nature. 1998;394:884 – 887. 31. Mentz HA 3rd, Ruiz-Razura A, Patronella CK, et al. Facelift: measurement of superficial muscular aponeurotic system advancement with and without zygomaticus major muscle release. Aesthetic Plast Surg. 2005; 29:353–362. 32. Morris RD, Morris KL, Morris JA. The mathematical basis of sexual attraction. Med Hypotheses. 2002;59:475– 481. 33. Warnke PH, Hauschild A, Schimmelpenning GW, et al. The sebaceous nevus as part of the Schimmelpenning-Feuerstein-Mims Syndrome: an obvious phacomatosis first documented in 1927. J Cutan Pathol. 2003; 30:470 – 472. 34. Sarwer DB, Pruzinsky T, Cash TF, et al. Psychological Aspects of Reconstructive and Cosmetic Plastic Surgery: Clinical, Empirical and Ethical Perspectives. Lippincott Williams & Wilkins; 2005. 35. Sarwer DB, Magee L, Clark VL. Physical appearance and cosmetic medical treatments: physiological and socio-cultural influences. J Cosmetic Dermatol. 2003;2:29 –39.
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