Jones et al. (2004) paper, "The Relationship Between Shape Symmetry and Perceived Skin Condition in Male Facial Attractiveness”
- Core Question: The study addresses why symmetrical male faces are deemed more attractive, even when cues of symmetry are diminished.
- Proposed Explanation: The researchers propose that correlates of facial symmetry, specifically the apparent healthiness of facial skin, influence attractiveness independently.
- Methodology Summary: They used real and composite male faces.
- Key Findings:
- Males with symmetrical faces were perceived to have healthier skin.
- Facial color and texture were sufficient to maintain attractiveness-symmetry relationships even when facial shape influence was minimized.
- Conclusion: Color and texture cues contribute to the link between attractiveness and symmetry.
Introduction Deep Dive
- Mate Choice Significance: The face is crucial in human mate selection, prompting research into visual cues determining attractiveness.
- Symmetry's Adaptive Role: Facial symmetry reflects an individual's ability to maintain good health, making preferences for symmetry adaptive. Cites Thornhill & Gangestad (1999a; 1999b).
- Prior Symmetry Studies: Manipulated images showed preferences for symmetrical faces (Little et al., 2001; Perrett et al., 1999; Rhodes et al., 1998, Rhodes, Zebrowitz, et al., 2001).
- Correlates Beyond Shape: Even with reduced cues to symmetry, relationships between symmetry and attractiveness persist, suggesting other factors are at play.
- Health as a Covariate: Apparent healthiness of facial skin may covary with symmetry, acting as a cue to general health (Thornhill & Gangestad, 1999a; 1999b).
- Study Aim: Two studies were conducted: (1) exploring the relationship between male facial symmetry and perceived facial skin health in real faces, and (2) using image processing to test if facial color and texture cues can maintain the attractiveness–symmetry link with minimized facial shape influence.
Study 1: Detailed Examination
- Objective: To find a correlation between shape symmetry and ratings of perceived skin health in male faces.
- Methodological Specifics:
- Participants: 113 Caucasian males (20–30 years old).
- Image Acquisition: Digital camera with resolution at 1200 × 1000 pixels under standardized diffuse lighting.
- Standardization: Interpupillary distance standardized to 100 units.
- Symmetry Assessment: Perceptual technique using chimeric faces (Mealey et al., 1999; Penton-Voak et al., 2001; Rhodes, Zebrowitz, et al., 2001).
- Chimeric Face Creation: Texture and color information of each face were made symmetrical prior to generating chimeras (Tiddeman, Burt, & Perrett, 2001) to minimize nonshape differences.
- Raters: Twenty-two female participants (mean age = 24.13, S.D. = 3.83).
- Rating Task: Rated paired chimeric faces for "similarity" (1= very dissimilar, 7 = very similar) and original faces for "healthiness of facial skin" (1 = very unhealthy, 4 = neutral, 7 = very healthy) and "attractiveness" (1 = very unattractive, 4 = neutral, 7 = very attractive).
- Image Presentation: Full-color images were presented on-screen in a fully randomized order. Cropped to minimize influence of clothing, neck, and hairstyle.
- Statistical Analysis: Nonparametric tests (Spearman’s rho) used due to non-normal distribution of measures (N = 113).
- Specific Results:
- Rated symmetry ("similarity") positively correlated with ratings of apparent skin health (rs = .23, P = .015).
- Symmetry significantly correlated with ratings of male facial attractiveness (rs = .21, P = .025).
- Apparent skin health and male facial attractiveness were significantly correlated (rs = .70, P < .0001).
Study 2: In-Depth Review
- Objective: To determine if facial color and texture cues were enough to maintain the attractiveness–symmetry link when facial shape influence was minimized.
- Methodological Details:
- Average Face Generation: Average male face representing mean shape, color, and texture information for all 113 faces (Rowland & Perrett, 1995; Tiddeman et al., 2001).
- Sample Selection: The 30 males with the most asymmetric faces (asymmetric sample) and the 30 with the most symmetric faces (symmetric sample) from Study 1 were identified using similarity ratings.
- Symmetrization: Average faces were made perfectly symmetrical by blending each face with a mirror-reflected version.
- Texture/Color Application: The average color and texture information for the asymmetric and symmetric samples was applied to the average symmetrical shape of all 113 faces (Rowland & Perrett, 1995; Tiddeman et al., 2001).
- Participants: Eighty female participants (mean age = 27.5, S.D. = 4.3; different from Study 1).
- Procedure: Forced-choice paradigms were used to assess which of the two faces was the "most attractive" or looked the "most healthy."
- Results Breakdown:
- The symmetric sample was judged more attractive (33 out of 40 participants, P < .0001).
- The symmetric sample was judged healthier (36 out of 40 participants, P < .0001).
Discussion: Nuances and Implications
- Synthesis of Findings: Apparent healthiness of facial skin correlates with symmetry and contributes to attractiveness independently of facial shape.
- Surface Information Importance: Surface information (color and texture) influences attractiveness in symmetrical faces.
- Possible Mechanisms: Both symmetry and skin condition may indicate general health, with healthy skin suggesting good genes for immunocompetence (Roberts et al., 2003).
- Limitations Acknowledged: Potential "halo" effect where attractive facial shapes influence skin condition judgments.
- Wider Context: Symmetric males may have more attractive voices (Feinberg & Jacobson, 2001; Hughes, Harrison & Gallup, 2002) and body odors (Rikowski & Grammer, 1999; Thornhill & Gangestad, 1999b).
- Overall Significance: Correlates of symmetry might explain why preferences for symmetrical males are evident in female mate choice (Thornhill & Gangestad, 1997) even when symmetry variations are subtle.
