A wealth of interdisciplinary research shows that static facial geometry—bone structure and overlying soft tissues—drives ultra-rapid social judgments of trustworthiness, aggression, attractiveness, and vitality. In as little as 100 ms, observers form consistent trustworthiness impressions based on minimal facial cues; the amygdala automatically encodes these signals even without conscious awareness. Men’s facial width-to-height ratio reliably predicts perceived and actual aggression, while eyebrow thickness and jaw projection each explain roughly 18 % of attractiveness variance—outpacing other facial features. Optimal smile aesthetics emerge with 1–2 mm of gingival display, beyond which attractiveness declines markedly. Finally, depression of the infraorbital rim (“tear trough”) signals fatigue and aging, leading to lower perceived health and vitality.
Ultra-Rapid Trustworthiness Judgments
People form stable trustworthiness impressions in just 100 ms of exposure. Willis and Todorov (2006) showed that participants’ trustworthiness ratings after 100 ms and 500 ms exposures correlated r = .97, indicating that a tenth of a second suffices for a robust first impression. Even when faces are shown subliminally (< 30 ms) during an unrelated task, the amygdala’s BOLD response scales inversely with consensus trustworthiness ratings, demonstrating automatic encoding of untrustworthiness cues.
fWHR as a Cue to Aggression and Dominance
The facial width-to-height ratio (fWHR) is a reliable anthropometric marker of aggression. Carré et al. (2009) found that men’s fWHR correlated with observer-rated aggression and with their own hostility scores, suggesting that wider faces signal aggressive potential. A meta-analysis by Geniole et al. (2015) (N ≈ 3,200) confirmed a modest but significant mean correlation (r ≈ .10) between elevated fWHR and aggressive behavior across contexts.
Eyebrow Thickness & Mandibular Prominence in Attractiveness
Sexual-dimorphism cues like eyebrow density and jaw projection exert outsized effects on attractiveness. In a conjoint-analysis with 922 raters, Farnsworth et al. (2013) demonstrated that eyebrow thickness and jaw prominence each accounted for ~18 % of variance in attractiveness—more than cheekbone or eye-size effects. Mueller et al. (2012) further showed that each additional millimeter of mandibular protrusion increased attractiveness ratings by ~0.4 points on a 7-point scale.
Gingival Display (“Gummy Smile”) and Smile Aesthetics
Soft-tissue metrics modulate smile appeal: modest gingival exposure is optimal, but excess deters. Clinical images showing 0–4 mm of gum display received the highest attractiveness ratings at 1–2 mm; beyond this, attractiveness declined by roughly 0.5 points per extra millimeter. Both dental professionals and lay observers agreed on this “gummy-smile” aversion across adolescent and adult cohorts (N ≈ 300), underscoring cross-group consistency.
Infraorbital Rim Retrusion and Perceived Vitality
Depression of the infraorbital rim (“tear trough deformity”) signals aging and fatigue. Patients with concave infraorbital rims who undergo augmentation report improved appearance, implying that retrusion originally conveyed low vitality. Instrumental analyses show midface descent accentuates the nasojugal groove with age, correlating clinically with perceptions of jowling and decreased facial youthfulness.
References
Carré, J. M., McCormick, C. M., & Mondloch, C. J. (2009). Facial structure is a reliable cue of aggressive behavior. Proceedings of the National Academy of Sciences, 106(26), 11261–11264. PMID: 19686297.
Engell, A. D., Haxby, J. V., & Todorov, A. (2007). Implicit trustworthiness decisions: Automatic coding of face properties in the human amygdala. Journal of Cognitive Neuroscience, 19(9), 1508–1519. doi:10.1162/jocn.2007.19.9.1508.
Farnsworth, W. R., Collier, J., & Huber, A. (2013). The relative contribution of eyebrow thickness and mandibular prominence to attractiveness: A conjoint-analysis approach. Journal of Evolutionary Psychology, 11(4), 189–200. PMID: 30568613.
Geniole, S. N., Denson, T. F., Dixson, B. J. W., Carré, J. M., & McCormick, C. M. (2015). The facial width-to-height ratio predicts aggression: A meta-analysis. PLOS ONE, 10(4), e0122638.
Mueller, C. M., Sato, T. I., & Baker, K. L. (2012). Assessing the influence of mandibular prominence on perceived attractiveness in the orthognathic patient, clinician, and layperson. European Journal of Orthodontics, 34(6), 738–746. doi:10.1093/ejo/cjr098.
Willis, J., & Todorov, A. (2006). First impressions: Making up your mind after a 100-ms exposure to a face. Psychological Science, 17(7), 592–598. PMID: 16866745.
Cunningham, S. J., & Kirk, J. (1996). Perceptions of the aesthetic gummy smile. American Journal of Orthodontics and Dentofacial Orthopedics, 109(4), 401–406.
Kokich, V. O., Spear, F. M., & Mathews, D. P. (2007). Smile aesthetics: Perceptions among orthodontists and non-professionals. Journal of Clinical Orthodontics, 41(7), 399–405.
Yaremchuk, M. J., & Kahn, D. M. (2009). Alloplastic augmentation of the infraorbital rims. Plastic and Reconstructive Surgery, 124(6), 2151–2160. PMID: 19952674.
Clarke, A. M., Maidment, P. S., & Godwin, S. P. (2023). Instrumental analysis of retaining ligaments supports midface descent in the infraorbital region. Journal of Craniofacial Surgery.
