Commentary: Facial Width-to-Height Ratio (fWHR) Is Not Associated with Adolescent Testosterone Levels

Accuracy and Bias in Facial Trustworthiness Appraisals in Borderline Personality Disorder

Individuals with borderline personality disorder (BPD) have shown a negativity bias, whereas the general population has shown a positivity bias in their trustworthiness appraisal of others. We tested if individuals with BPD are more negative but also more realistic with their appraisals. Trustworthiness was objectified on an external criterion. The influence of childhood trauma was investigated. Facial photographs of peace prize laureates and sentenced murderers were presented. Participants with BPD and healthy controls (HC) rated the trustworthiness of the targets. Bias and sensitivity were measured using signal detection theory. The BPD group was more negatively biased compared to HC, but not more sensitive in discriminating between the two groups. When correcting for experienced childhood abuse and neglect, the authors found that group differences in bias disappeared. Individuals with BPD might not be more sensitive in discriminating between, on average, more or less trustworthy targets, but they have developed a negativity bias to ensure the detection of untrustworthiness.

Relationships of the Ulna-to-fibula Ratio to Baseline and Reactive Steroid Hormone Levels: An Exploratory Study

Objective

Organizational hormone effects on the human brain and behavior are often retrospectively assessed via morphological markers of prenatal (e.g., 2D:4D digit ratio) or pubertal (e.g., facial width-to-height ratio, fWHR) hormone exposure. It has been argued that markers should relate to circulating hormones particularly in challenging, dominance/status-relevant situations. However, meta-analytic research indicates that fWHR, a frequently used pubertal marker, is neither reliably sex-dimorphic nor related to steroid hormones. This casts doubt on fWHR’s validity for reflecting hormone levels. Ulna-to-fibula ratio (UFR), an alternative, long-bone-length-based pubertal marker, is sex-dimorphic and associated with dominance motivation. However, its hormonal associations were never tested before. We therefore explored UFR’s relationships to baseline and reactive hormone levels.

Methods

We measured ulna and fibula length as well as shoulder/waist/hip circumference of 81 participants (49 women; after exclusions) via anthropometry. Salivary hormone levels (estradiol, testosterone) at baseline and after a gross-motor one-on-one balancing contest were measured via radioimmunoassay.

Results

We replicated UFR’s dimorphism, unrelatedness to height, and correlations to other putative markers of organizational hormone effects. On an exploratory basis, we found UFR to be related to overall baseline testosterone and to competition-induced reactive surges in steroid hormones (estradiol, testosterone) overall and in women.

Conclusions

Our results hint at UFR’s relationship to baseline testosterone and may indicate functional connections between outcomes of pubertal organizational hormone effects and contest-induced steroid reactivity. Pubertal organizational hormone effects may prepare the endocrine system for dominance and status contests. However, the small sample and the exploratory nature of our research demands replication.

Was facial width-to-height ratio subject to sexual selection pressures? A life course approach

Sexual selection researchers have traditionally focused on adult sex differences; however, the schedule and pattern of sex-specific ontogeny can provide insights unobtainable from an exclusive focus on adults. Recently, it has been debated whether facial width-to-height ratio (fWHR; bi-zygomatic breadth divided by midface height) is a human secondary sexual characteristic (SSC). Here, we review current evidence, then address this debate using ontogenetic evidence, which has been under-explored in fWHR research. Facial measurements were collected from 3D surface images of males and females aged 3 to 40 (Study 1; US European-descent, n = 2449), and from 2D photographs of males and females aged 7 to 21 (Study 2; Bolivian Tsimane, n = 179), which were used to calculate three fWHR variants (which we call fWHRnasion, fWHRstomion, and fWHRbrow) and two other common facial masculinity ratios (facial width-to-lower-face-height ratio, fWHRlower, and cheekbone prominence). We test whether the observed pattern of facial development exhibits patterns indicative of SSCs, i.e., differential adolescent growth in either male or female facial morphology leading to an adult sex difference. Results showed that only fWHRlower exhibited both adult sex differences as well as the classic pattern of ontogeny for SSCs-greater lower-face growth in male adolescents relative to females. fWHRbrow was significantly wider among both pre- and post-pubertal males in the Bolivian Tsimane sample; post-hoc analyses revealed that the effect was driven by large sex differences in brow height, with females having higher placed brows than males across ages. In both samples, all fWHR measures were inversely associated with age; that is, human facial growth is characterized by greater relative elongation in the mid-face and lower face relative to facial width. This trend continues even into middle adulthood. BMI was also a positive predictor of most of the ratios across ages, with greater BMI associated with wider faces. Researchers collecting data on fWHR should target fWHRlower and fWHRbrow and should control for both age and BMI. Researchers should also compare ratio approaches with multivariate techniques, such as geometric morphometrics, to examine whether the latter have greater utility for understanding the evolution of facial sexual dimorphism.

Observers use facial masculinity to make physical dominance assessments following 100-ms exposure

Research has consistently demonstrated that faces manipulated to appear more masculine are perceived as more dominant. These studies, however, have used forced-choice paradigms, in which a pair of masculinized and feminized faces was presented side by side. These studies are susceptible to demand characteristics, because participants may be able to draw the conclusion that faces which appear more masculine should be rated as more dominant. To prevent this, we tested if dominance could be perceived when masculinized or feminized faces were presented individually for only 100 ms. We predicted higher dominance ratings to masculinized faces and better memory of them in a surprise recognition memory test. In the experiment, 96 men rated the physical dominance of 40 facial photographs (masculinized = 20, feminized = 20), which were randomly drawn from a larger set of faces. This was followed by a surprise recognition memory test. Half of the participants were assigned to a condition in which the contours of the facial photographs were set to an oval to control for sexual dimorphism in face shape. Overall, men assigned higher dominance ratings to masculinized faces, suggesting that they can appraise differences in facial sexual dimorphism following very brief exposure. This effect occurred regardless of whether the outline of the face was set to an oval, suggesting that masculinized internal facial features were sufficient to affect dominance ratings. However, participants' recognition memory did not differ for masculinized and feminized faces, which could be due to a floor effect.

Facial features and unethical behavior - Doped athletes show higher facial width-to-height ratios than non-doping sanctioned athletes

Past research has emphasized the role of facial structures in predicting social behavior. In particular the facial width-to-height ratio (fWHR) was found to be a reliable predictor for antisocial and unethical behavior. The current study was aimed at examining this association in the field of sports: FWHRs of 146 doping sanctioned athletes in athletics (37 male/38 female) and weightlifting (44 male/27 female) were compared to the fWHRs of randomly chosen non-doping sanctioned athletes of the Top Ten at the World Championship 2017 and Olympic Games 2016 in both sports (146 athletes). The results showed that doping sanctioned athletes due to the use of anabolic steroids had larger fWHRs than non-doping sanctioned athletes. However, doping sanctioned athletes due to other doping rule violations than the use of anabolic steroids, did not show this effect. The study provides empirical evidence for the relation between fWHR and unethical behavior in a real-world setting and contributes to the discussion about fWHR’s biological origin, emphasizing the role of anabolic steroids. A mutual interaction between fWHR and doping behavior is discussed, at which a larger fWHR might signify a higher tendency to behave unethically, whereas the consequential intake of anabolic steroids might also shape individuals’ faces.

An Exploration of the Relationships Among Facial Dimensions, Age, Sex, Dominance Status, and Personality in Rhesus Macaques (Macaca mulatta)

Aspects of personality in nonhuman primates have been linked to health, social relationships, and life history outcomes. In humans as well as nonhuman primates, facial morphology is associated with assertiveness, aggression, and measures of dominance status. In this study we aimed to examine the relationship among facial morphology, age, sex, dominance status, and ratings on the personality dimensions Confidence, Openness, Assertiveness, Friendliness, Activity, and Anxiety in rhesus macaques (Macaca mulatta). We measured facial width-to-height ratio (fWHR) and lower-height/full-height ratio (fLHFH) using photographs from 109 captive rhesus macaques, which observers also assessed for dominance status and personality, and explored the associations among facial morphology, age, sex, dominance status, and personality. fWHR and fLHFH personality associations depended on age category: Assertiveness was associated with higher fWHR and fLHFH, and Confidence was associated with lower fWHR and fLHFH, but all these associations were consistent only in individuals <8 yr. of age. We found fWHR and fLHFH to not be consistently associated with sex or dominance status; compared to younger individuals, we found few associations with fWHR and fLHFH for individuals older than 8 yr., which may be due to limited sample size. Our results indicate that in macaques <8 yr. old, facial morphology is associated with the Assertiveness and Confidence personality dimensions, which is consistent with results suggesting a relationship between fWHR and trait aggression in humans and assertiveness in brown capuchins, all of which implies that fWHR might be a cue to assertive and aggressive traits.

Facial width-to-height ratio is associated with agonistic and affiliative dominance in bonobos (Pan paniscus)

Facial width-to-height ratio (fWHR) is associated with social dominance in human and non-human primates, which may reflect the effects of testosterone on facial morphology and behaviour. Given that testosterone facilitates status-seeking motivation, the association between fWHR and behaviour should be contingent on the relative costs and benefits of particular dominance strategies across species and socioecological contexts. We tested this hypothesis in bonobos (Pan paniscus), who exhibit female dominance and rely on both affiliation and aggression to achieve status. We measured fWHR from facial photographs, affiliative dominance with Assertiveness personality scores and agonistic dominance with behavioural data. Consistent with our hypothesis, agonistic and affiliative dominance predicted fWHR in both sexes independent of age and body weight, supporting the role of status-seeking motivation in producing the link between fWHR and socioecologically relevant dominance behaviour across primates.

Sex Affects the Relationship Between Third Party Punishment and Cooperation

Prosocial third-party punishment (3PP) is a punitive behavior against antisocial individuals, which might explain extended cooperativeness in humans. 3PP shows sexual dimorphism, being more frequent in men than in women. We studied whether sexually dimorphic features related to sexual hormones during development (facial dimorphism and 2D:4D) influence the tendency to engage in 3PP in a sample of 511 women and 328 men. After playing a Prisoner's Dilemma, participants had to decide whether to penalize the defection of a third player who had exploited his/her counterpart's cooperation. In line with previous studies, we observe that men are more prone to engage in 3PP than women. We find that this sex difference is due to cooperative men being more likely to punish than cooperative women. In addition, men with higher facial masculinity are less likely to engage in 3PP, whereas no features influence 3PP in women. We discuss the possibility that sex differences in the motivations and fitness implications underlying 3PP might be driving the observed results.

The influence of income and testosterone on the validity of facial width-to-height ratio as a biomarker for dominance

Research has indicated that men's facial width-to-height ratio (fWHR) is part of an evolved system of social dominance, aggression, and power. fWHR has been linked to antisocial behavior, measured by self-reported aggression, but recent studies have failed to replicate this finding. To overcome these inconsistencies, influencing factors such as social status have to be taken into account in order to explain the relationship between fWHR and aggression. In particular, income has been shown to be an important influencing factor in this relationship. Furthermore, previous findings suggested that testosterone is linked to fWHR and might be associated with fWHR and dominance-related outcomes. Therefore, this study examined the influence of both social status defined by income and salivary testosterone on the association between fWHR and self-reported dominance-related behavioral traits. In particular, links between fWHR and self-report measures of aggression and the Dark Triad (encompassing psychopathy, Machiavellianism, and narcissism) were investigated in N = 109 men aged 40 to 75 years. fWHR was significantly associated with physical aggression and two of the Dark Triad traits (psychopathy and Machiavellianism) in men reporting low income. The relationship between fWHR and narcissism was moderated by testosterone. The findings highlight the importance of considering social status and neuroendocrine parameters such as testosterone when examining associations between fWHR and complex psychological traits and behaviors.

Body mass index, facial width-to-height ratio, and perceived formidability in female Ultimate Fighting Championship (UFC) fighters

Both facial width-to-height ratio (fWHR) and body mass index (BMI) have been associated with aggressive behavior in women but how they influence perception of their potential threat remain unclear. Here, we assessed the effects of fWHR and BMI on perceived formidability from faces of 42 female Ultimate Fighting Championship (UFC) fighters. In study 1, BMI, but not fWHR, positively predicted participants' ratings of aggressiveness and fighting ability from facial photographs. In study 2, both high fWHR and high BMI composite faces were rated as more aggressive, tougher, and more likely to win a fight than low fWHR and low BMI composite faces, respectively. Further analyses revealed that the high BMI composite face was rated as more aggressive and tougher than the high fWHR composite face. Taken together, these results suggest that compared to fWHR, BMI may be a more salient cue to women's formidability.

Sexually Dimorphic Faciometrics in Black Racial Groups From Early Adulthood to Late Middle Age

An increasing body of research focusing on gender-related traits has utilized faciometrics in order to consider sexual dimorphism: Aspects as diverse as social heuristics, facial attractiveness, sexual orientation, aggression, and trustworthiness have all been investigated. However, the majority of these studies have tended to focus on White or Caucasian student populations and have paid little regard to either older populations or racial background. The current study therefore investigated sexual dimorphism in 450 participants (225 women) from a Black population across four age groups (20s, 30s, 40s, and 50s). In line with much previous research using White or Caucasian faces, the expected sexual dimorphism was seen in the younger age-group in three of the four indices (cheekbone prominence, facial width to lower facial height, and lower face height to full face height). However, consistent with more recent literature, the facial width to height ratio (fWHR) was not found to be significantly different between men and women in this age-group. Contrary to previous research, when considering broader age groups, the three established measures of facial sexual dimorphism, when looked at independently, remained static over time, but this was not true for fWHR. It is concluded that facial structure does not follow the same aging trajectory in all populations and care should be taken in choice of facial metric, depending on the nature of the sample under investigation.

Detecting implicit cues of aggressiveness in male faces in revictimized female PTSD patients and healthy controls

Victimized women are thought to have impairments in identifying risk and to have dysfunctional reactions to threatening situations, which increase the risk for revictimization. To investigate possible deficits in revictimized women, we used a method examining women's perceptions of an implicit facial cue of aggressiveness - the facial Width-to-Height Ratio (fWHR). We tested whether revictimized women show impairments in detecting aggressiveness in male faces by neglecting cues of fWHR and choosing a smaller preferred distance to men. Fifty-two revictimized PTSD patients and 52 healthy controls provided ratings of aggressiveness and attractiveness for 65 photographed men and chose their preferred distance towards 11 pictured men. Multiple regression analyses indicated that revictimized women do not show impairments in perceiving and reacting to cues of aggression accurately. Hierarchical linear models, however, indicated that revictimized women rated all men as less aggressive. Revictimized women with histories of intimate partner violence (IPV) rated men with larger fWHRs and higher values of actual aggression to be more attractive than did revictimized women without IPV histories. A reduced appraisal of threat signals as threatening and an attraction to wider-faced and more aggressive men might increase the risk for revictimization.

No evidence that facial width-to-height ratio (fWHR) is associated with women's sexual desire

Facial width-to-height ratio (fWHR) has been linked to many different behavioral tendencies. However, not all of these correlations have replicated well across samples. Arnocky et al. (in press, Archives of Sexual Behavior) recently reported that sexual desire was correlated with fWHR. The current study aimed to test this relationship in a large sample of women. fWHR was measured from face images of 754 women. Each woman completed the Sexual Desire Inventory, which measures total, dyadic, and solitary sexual desire. Analyses revealed no significant correlations between fWHR and any of our measures of sexual desire. These null results do not support the hypothesis that fWHR is related to women’s sexual desire. Additionally, we found no evidence that women’s face-shape sexual dimorphism was related to their sociosexual orientation.

The Facial Width-to-Height Ratio Predicts Sex Drive, Sociosexuality, and Intended Infidelity

Previous research has linked the facial width-to-height ratio (FWHR) to a host of psychological and behavioral characteristics, primarily in men. In two studies, we examined novel links between FWHR and sex drive. In Study 1, a sample of 145 undergraduate students revealed that FWHR positively predicted sex drive. There were no significant FWHR × sex interactions, suggesting that FWHR is linked to sexuality among both men and women. Study 2 replicated and extended these findings in a sample of 314 students collected from a different Canadian city, which again demonstrated links between the FWHR and sex drive (also in both men and women), as well as sociosexuality and intended infidelity (men only). Internal meta-analytic results confirm the link between FWHR and sex drive among both men and women. These results suggest that FWHR may be an important morphological index of human sexuality.

No Robust Association between Static Markers of Testosterone and Facets of Socio-Economic Decision Making

Digit ratio (2D:4D) and facial width-to-height ratio (WHR) are supposedly static indicators of testosterone exposition during prenatal and pubertal lifetime, respectively. Both measures have been linked to aggressive and assertive behavior in laboratory economic games, as well as in real world scenarios. Most of the research-often limited to male subjects-considers the associations between these behaviors, traits, and hormonal markers separately for 2D:4D and WHR. Reported associations are weak and volatile. In the present study we had independent raters assess 2D:4D and WHR in a sample of N = 175 participants who played the ultimatum game (UG). Respondent behavior in UG captures the tendency to reject unfair offers (negative reciprocity). If unfair UG offers are seen as provocations, then individuals with stronger testosterone exposition may be more prone to reject such offers. Economists argue that negative reciprocity reflects altruistic punishment, since the rejecting individual is sacrificing own resources. However, recent studies suggest that self-interest, in terms of status defense plays a substantial role in decisions to reject unfair offers. We also assessed social preferences by social value orientation and assertiveness via self-report. By applying structural equation modeling we estimated the latent level association of 2D:4D and WHR with negative reciprocity, assertiveness and prosociality in both sexes. Results revealed no robust association between any of the trait measures and hormonal markers. The measures of 2D:4D and WHR were not related with each other. Multigroup models based on sex suggested invariance of factor loadings allowing to compare hormone-behavior relationships of females and males. Only when collapsing across sex greater WHR was weakly associated with assertiveness, suggesting that individuals with wider faces tend to express greater status defense. Only the right hand 2D:4D was weakly associated with prosocial behavior, indicating that individuals with lower prenatal testosterone exposure are more cooperative. Rejection behavior in UG was not related with 2D:4D nor WHR in any of the models. There were also no curvilinear associations between 2D:4D and prosociality as theorized in the literature. Our results suggest that previous studies over-estimated the role of static markers of testosterone in accounting for aggression and competition behavior in males.

Functional significance of men's testosterone reactivity to social stimuli

Rapid testosterone fluctuations in response to social stimuli are observed across a wide range of species, and the highly conserved nature of these fluctuations suggests an adaptive function. This paper reviews the current literature on testosterone reactivity, primarily in human males, and illustrates how life-history theory provides an adequate theoretical framework to interpret findings. The review is structured around supporting evidence suggesting that situations implicated in mating effort either directly (e.g., interactions with a mate) or indirectly (e.g., intrasexual competition) are generally associated with a brief elevation of testosterone, while situations implicated in parenting effort (e.g., nurturant interactions with offspring) are generally associated with a decline in testosterone. Further, we discuss how these fluctuations in testosterone have been linked to future behaviors, and how situational, motivational, and physiological variables moderate the interplay between social stimuli, testosterone reactivity, and behavior. Supporting the notion that testosterone can play a causal role in modulating behavior in response to social stimuli, we also summarize recent single administration studies examining the effects of testosterone on physiology, neurobiology, and behavior. A conceptual model provides links between supported findings, and hypothesized pathways requiring future testing.