# Preference for Facial Symmetry Depends on Study Design

^{*}

## Abstract

**:**

## 1. Study 1

#### 1.1. Methods

#### 1.1.1. Participants

#### 1.1.2. Measures and Procedure

#### Two-Alternative Forced Choice Task

#### Rating Task

#### 1.1.3. Statistical Analysis

#### 1.2. Results

#### 1.2.1. Analysis 1: Preference for Facial Symmetry as Measured by the 2AFC Task

#### 1.2.2. Analysis 2: Preference for Facial Symmetry as Measured by the Ratings Task

#### 1.2.3. Analysis 3: Congruency between the 2AFC Task and Ratings Task

#### 1.3. Discussion

## 2. Study 2

#### 2.1. Methods

#### 2.1.1. Participants

#### 2.1.2. Measures, Procedures, and Statistical Analysis

#### 2.2. Results

#### 2.2.1. Analysis 1: Preference for Facial Symmetry as Measured by the 2AFC Task

#### 2.2.2. Analysis 2: Preference for Facial Symmetry as Measured by the Ratings Task

#### 2.2.3. Analysis 3: Congruency between the 2AFC Task and Ratings Task

#### 2.3. Discussion

## 3. Study 3

#### 3.1. Methods

#### 3.1.1. Participants

#### 3.1.2. Measures and Procedure

#### 3.1.3. Statistical Analysis

#### 3.2. Results

#### 3.3. Discussion

## 4. General Discussion

## Supplementary Materials

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## Research Ethics

## References

- Van Valen, L. A study of fluctuating asymmetry. Evolution
**1962**, 16, 125–142. [Google Scholar] [CrossRef] - Grammer, K.; Thornhill, R. Human (Homo sapiens) facial attractiveness and sexual selection: The role of symmetry and averageness. J. Comp. Psychol.
**1994**, 108, 233–242. [Google Scholar] [CrossRef] [PubMed] - Rhodes, G.; Proffitt, F.; Grady, J.M.; Sumich, A. Facial symmetry and the perception of beauty. Psychon. Bull. Rev.
**1998**, 5, 659–669. [Google Scholar] [CrossRef] [Green Version] - Little, A.C.; Jones, B.C. Evidence against perceptual bias views for symmetry preferences in human faces. Proc. R. Soc. B Biol. Sci.
**2003**, 270, 1759–1763. [Google Scholar] [CrossRef] [PubMed] [Green Version] - Møller, A.P.; Swaddle, J.P. Asymmetry, Developmental Stability, and Evolution; Oxford University Press: Oxford, UK, 1997. [Google Scholar]
- Thornhill, R.; Gangestad, S.W. Facial attractivness. Trends Cogn. Sci.
**1999**, 3, 452–460. [Google Scholar] [CrossRef] - Little, A.C. Domain Specificity in Human Symmetry Preferences: Symmetry is Most Pleasant When Looking at Human Faces. Symmetry
**2014**, 6, 222–233. [Google Scholar] [CrossRef] [Green Version] - King, M.; Meyer, G.E.; Tangney, J.; Biederman, I. Shape constancy and a perceptual bias towards symmetry. Percept. Psychophys.
**1976**, 19, 129–136. [Google Scholar] [CrossRef] - Perrett, D.I.; Burt, D.; Penton-Voak, I.; Lee, K.J.; Rowland, D.; Edwards, R. Symmetry and Human Facial Attractiveness. Evol. Hum. Behav.
**1999**, 20, 295–307. [Google Scholar] [CrossRef] - Little, A.C.; Jones, B. Variation in facial masculinity and symmetry preferences across the menstrual cycle is moderated by relationship context. Psychoneuroendocrinology
**2012**, 37, 999–1008. [Google Scholar] [CrossRef] [PubMed] - Little, A.C.; Apicella, C.L.; Marlowe, F.W. Preference for symmetry in human faces in two cultures: Data from the UK and the Hadza, an isolated group of hunter-gatherers. Proc. R. Soc. B Biol. Sci.
**2007**, 274, 3113–3117. [Google Scholar] [CrossRef] [Green Version] - Little, A.C.; DeBruine, L.; Jones, B. Exposure to visual cues of pathogen contagion changes preferences for masculinity and symmetry in opposite-sex faces. Proc. R. Soc. B Biol. Sci.
**2011**, 278, 2032–2039. [Google Scholar] [CrossRef] - Saxton, T.; Debruine, L.; Jones, B.; Little, A.; Roberts, S.C. A longitudinal study of adolescents’ judgments of the attractiveness of facial symmetry, averageness and sexual dimorphism. J. Evol. Psychol.
**2011**, 9, 43–55. [Google Scholar] [CrossRef] [Green Version] - Swaddle, J.P.; Cuthill, I.C. Asymmetry and human facial attractiveness: Symmetry may not always be beautiful. Proc. R. Soc. B Biol. Sci.
**1995**, 261, 111–116. [Google Scholar] [CrossRef] - Koehler, N.; Rhodes, G.; Simmons, L.W. Are human female preferences for symmetrical male faces enhanced when conception is likely? Anim. Behav.
**2002**, 64, 233–238. [Google Scholar] [CrossRef] [Green Version] - Komori, M.; Kawamura, S.; Ishihara, S. Averageness or symmetry: Which is more important for facial attractiveness? Acta Psychol.
**2009**, 131, 136–142. [Google Scholar] [CrossRef] [PubMed] - Penton-Voak, I.S.; Jones, B.C.; Little, A.C.; Baker, S.; Tiddeman, B.; Burt, D.M.; Perrett, D.I. Symmetry, sexual dimorphism in facial proportions and male facial attractiveness. Proc. R. Soc. B Biol. Sci.
**2001**, 268, 1617–1623. [Google Scholar] [CrossRef] [Green Version] - Fink, B.; Neave, N.; Manning, J.T.; Grammer, K. Facial symmetry and judgements of attractiveness, health and personality. Pers. Individ. Differ.
**2006**, 41, 491–499. [Google Scholar] [CrossRef] - Jones, A.; Jaeger, B. Biological Bases of Beauty Revisited: The Effect of Symmetry, Averageness, and Sexual Dimorphism on Female Facial Attractiveness. Symmetry
**2019**, 11, 279. [Google Scholar] [CrossRef] [Green Version] - Holzleitner, I.J.; Lee, A.J.; Hahn, A.C.; Kandrik, M.; Bovet, J.; Renoult, J.P.; Simmons, D.; Garrod, O.; DeBruine, L.M.; Jones, B.C. Comparing theory-driven and data-driven attractiveness models using images of real women’s faces. J. Exp. Psychol. Hum. Percept. Perform.
**2019**, 45, 1589–1595. [Google Scholar] [CrossRef] [PubMed] [Green Version] - Scott, I.M.L.; Clark, A.P.; Boothroyd, L.G.; Penton-Voak, I.S. Do men’s faces really signal heritable immunocompetence? Behav. Ecol.
**2013**, 24, 579–589. [Google Scholar] [CrossRef] - Lewis, M.B. Fertility affects asymmetry detection not symmetry preference in assessments of 3D facial attractiveness. Cognition
**2017**, 166, 130–138. [Google Scholar] [CrossRef] - Little, A.C.; Griffey, J.A.F. Preferring and Detecting Face Symmetry: Comparing Children and Adults Judging Human and Monkey Faces. Symmetry
**2020**, 12, 2112. [Google Scholar] [CrossRef] - Little, A.C.; Jones, B. Attraction independent of detection suggests special mechanisms for symmetry preferences in human face perception. Proc. R. Soc. B Biol. Sci.
**2006**, 273, 3093–3099. [Google Scholar] [CrossRef] [Green Version] - Zebrowitz, L.A.; Rhodes, G. Sensitivity to “bad genes” and the anomalous face overgeneralization effect: Cue validity, cue utilization, and accuracy in judging intelligence and health. J. Nonverbal Behav.
**2004**, 28, 167–185. [Google Scholar] [CrossRef] - Wang, T.T.; Wessels, L.; Hussain, G.; Merten, S. Discriminative thresholds in facial asymmetry: A review of the literature. Aesthet. Surg. J.
**2017**, 37, 375–385. [Google Scholar] [CrossRef] - Anderson, N.D.; Gleddie, C. Comparing Sensitivity to Facial Asymmetry and Facial Identity. i-Perception
**2013**, 4, 396–406. [Google Scholar] [CrossRef] [Green Version] - Ma, D.S.; Correll, J.; Wittenbrink, B. The Chicago face database: A free stimulus set of faces and norming data. Behav. Res. Methods
**2015**, 47, 1122–1135. [Google Scholar] [CrossRef] [Green Version] - De Bruine, L.M.; Tiddeman, B.P. Webmorph. 2016. Available online: http://webmorph.org (accessed on 5 February 2021).
- R Core Team. A Language and Environmental for Statistical Computing; R Foundation for Statistical Computing: Vienna, Austria, 2013. [Google Scholar]
- Bates, D.; Mächler, M.; Bolker, B.; Walker, S. Fitting linear mixed-effects models using lme4. J. Stat. Softw.
**2015**, 67, 1–48. [Google Scholar] [CrossRef] - Kuznetsova, A.; Brockhoff, P.B.; Christensen, R.H.B. lmerTest: Tests for Random and Fixed Effects for Linear Mixed Effect Models. 2015. Available online: https://CRAN.R-project.org/package=lmerTest (accessed on 5 February 2021).
- De Bruine, L.M.; Barr, D.J. Understanding Mixed-Effects Models through Data Simulation. Adv. Methods Pract. Psychol. Sci.
**2021**, 4. [Google Scholar] [CrossRef] - Barr, D.J.; Levy, R.; Scheepers, C.; Tily, H.J. Random effects structure for confirmatory hypothesis testing: Keep it maximal. J. Mem. Lang.
**2013**, 68, 255–278. [Google Scholar] [CrossRef] [PubMed] [Green Version] - Debruine, L.M. Evidence versus speculation on the validity of methods for measuring masculinity preferences: Comment on Scott et al. Behav. Ecol.
**2013**, 24, 591–593. [Google Scholar] [CrossRef] [Green Version] - Lewis, M.B. Challenges to both reliability and validity of masculinity-preference measures in menstrual-cycle-effects research. Cognition
**2020**, 197, 104201. [Google Scholar] [CrossRef] [PubMed] - Pollet, T.; Little, A. Baseline probabilities for two-alternative forced choice tasks when judging stimuli in Evolutionary Psychology: A methodological note. Hum. Ethol. Bull.
**2017**, 32, 53–59. [Google Scholar] [CrossRef] [Green Version]

**Figure 1.**Examples of faces manipulated to be perfectly symmetrical (

**left**), unmanipulated (

**middle**), and manipulated to be more asymmetrical (

**right**; only used in Studies 2 and 3).

**Figure 2.**Proportion of times the perfectly symmetrical face was chosen over the original face in the 2AFC task. Error bars represent 95% confidence intervals.

**Figure 3.**Associations between facial symmetry and mean attractiveness ratings for the ratings task. The grey area represents the 95% confidence interval.

**Figure 4.**The correlation between symmetry preference measured by the 2AFC task (using proportions) and ratings task (using correlations) for females rating male faces. The grey area represents the 95% confidence interval.

**Figure 5.**Proportion of times the original face was chosen over the asymmetrical face for the 2AFC task. The error bars represent the 95% confidence interval.

**Figure 6.**Associations between facial symmetry and mean ratings of attractiveness for the ratings task. The grey area represents the 95% confidence interval.

**Figure 7.**Attractiveness ratings given for different versions of faces that have been manipulated on facial symmetry. The error bars represent 95% confidence intervals.

**Table 1.**Correlation coefficients (r) between symmetry preferences measured by the 2AFC and ratings tasks. Results from males rating female faces (N = 83) are on the bottom triangle, while females rating male faces (N = 257) are on the top triangle.

2AFC: Proportion | 2AFC: Random Effect? | Rating: Correlation | Rating: Random Effects | |
---|---|---|---|---|

2AFC: Proportion | 0.99 (p < 0.001) | 0.18 (p = 0.004) | 0.16 (p = 0.010) | |

2AFC: Random Effect | 0.99 (p < 0.001) | 0.18 (p = 0.005) | 0.16 (p = 0.011) | |

Rating: Correlation | −0.05 (p = 0.656) | −0.04 (p = 0.657) | 0.90 (p < 0.001) | |

Rating: Random Effects | −0.07 (p = 0.503) | −0.07 (p = 0.503) | 0.84 (p < 0.001) |

**Table 2.**Correlation coefficients (r) between symmetry preferences measured by the 2AFC and ratings tasks. Results from males rating female faces (N = 87) are on the bottom triangle, while females rating male faces (N = 169) are on the top triangle.

2AFC: Proportion | 2AFC: Random Effects | Rating: Correlation | Rating: Random Effects | |
---|---|---|---|---|

2AFC: Proportion | 0.99 (p < 0.001) | 0.14 (p = 0.076) | 0.06 (p = 0.463) | |

2AFC: Random Effects | 0.99 (p < 0.001) | 0.15 (p = 0.052) | 0.06 (p = 0.424) | |

Rating: Correlation | 0.09 (p = 0.434) | 0.09 (p = 0.360) | 0.37 (p < 0.001) | |

Rating: Random Effects | 0.12 (p = 0.271) | 0.14 (p = 0.187) | −0.00 (p =0.979) |

**Table 3.**Fixed effects estimates from the linear mixed effects models predicting attractiveness ratings.

Males Rating Female Faces | Females Rating Male Faces | |||||
---|---|---|---|---|---|---|

Estimate (Std. Error) | t (Approx. df) | p-Value | Estimate (Std. Error) | t (Approx. df) | p-Value | |

Intercept | 3.32 (0.15) | 21.54 (92.54) | <0.001 | 3.13 (0.12) | 27.24 (117.30) | <0.001 |

Symmetry Version | 0.06 (0.03) | 2.16 (145.19) | 0.033 | 0.02 (0.02) | 1.02 (47.23) | 0.314 |

Asymmetry Version | −0.42 (0.05) | −8.79 (55.10) | <0.001 | −0.38 (0.05) | −7.74 (79.26) | <0.001 |

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**MDPI and ACS Style**

Lee, A.J.; De La Mare, J.K.; Moore, H.R.; Umeh, P.C.
Preference for Facial Symmetry Depends on Study Design. *Symmetry* **2021**, *13*, 1637.
https://doi.org/10.3390/sym13091637

**AMA Style**

Lee AJ, De La Mare JK, Moore HR, Umeh PC.
Preference for Facial Symmetry Depends on Study Design. *Symmetry*. 2021; 13(9):1637.
https://doi.org/10.3390/sym13091637

**Chicago/Turabian Style**

Lee, Anthony J., Jessica K. De La Mare, Hannah R. Moore, and Pamela C. Umeh.
2021. "Preference for Facial Symmetry Depends on Study Design" *Symmetry* 13, no. 9: 1637.
https://doi.org/10.3390/sym13091637