Preliminary evidence of an increased susceptibility to face pareidolia in postpartum women

As primates, we are hypersensitive to faces and face-like patterns in the visual environment, hence we often perceive illusory faces in otherwise inanimate objects, such as burnt pieces of toast and the surface of the moon. Although this phenomenon, known as face pareidolia, is a common experience, it is unknown whether our susceptibility to face pareidolia is static across our lifespan or what factors would cause it to change. Given the evidence that behaviour towards face stimuli is modulated by the neuropeptide oxytocin (OT), we reasoned that participants in stages of life associated with high levels of endogenous OT might be more susceptible to face pareidolia than participants in other stages of life. We tested this hypothesis by assessing pareidolia susceptibility in two groups of women; pregnant women (low endogenous OT) and postpartum women (high endogenous OT). We found evidence that postpartum women report seeing face pareidolia more easily than women who are currently pregnant. These data, collected online, suggest that our sensitivity to face-like patterns is not fixed and may change throughout adulthood, providing a crucial proof of concept that requires further research.

Heterogeneity in the Sexual Orientations of Men Who Have Sex with Fa'afafine in Samoa

In Samoa, feminine natal males who possess male-typical genitalia are known locally as fa'afafine. Some Samoan men express sexual interest in fa'afafine, whereas others do not. To assess the sexual orientation of men who are sexually interested in fa'afafine, we collected sexual attraction ratings and viewing times of Samoan men's and women's faces. Study 1 (N = 130) focused on men who were insertive or versatile during anal sex with fa'afafine partners. These men were compared to each other, as well as to males (i.e., men and fa'afafine) who were exclusively sexually interested in either women or men. Study 2 (N = 180) compared men who had sex with fa'afafine and women; men who had sex with fa'afafine, women, and men; and men who had sex with fa'afafine and men. These men were compared to each other, as well as to males who were exclusively sexually interested in either women or men. These studies suggest that men who have sex with fa'afafine are a heterogeneous group. A small portion of the men who are sexually interested in fa'afafine shows a relatively bisexual pattern of sexual attraction ratings and viewing times, namely men who have sex with fa'afafine, men, and women. In contrast, a larger number of men who were sexually interested in fa'afafine responded in a manner similar to men who were exclusively sexually interested in either women or men. The present research suggests that additional insights into male sexual orientation can be garnered by focusing on how sexuality is expressed in non-Western cultural contexts.

Viewing Time and Self-Report Measures of Sexual Attraction in Samoan Cisgender and Transgender Androphilic Males

Across cultures, androphilic males (natal males who are predominantly sexually attracted to adult men, not women) tend to present in one of two forms: cisgender or transgender. Previous research has shown that, although their gender presentation and identities are distinct, the two forms are similar in many other ways. The present study examined whether cisgender and transgender androphilic males exhibit a similar pattern of self-reported sexual attraction and viewing time response to images of men and women, and one that is directly inverse to that of cisgender gynephilic males (natal males who are predominately sexually attracted to adult women, not men). Using measures of self-reported sexual attraction and viewing time, we compared the response patterns of Samoan cisgender males who self-identified as men, were predominantly attracted to men, and had sex only with men (N = 16) and Samoan transgender males who self-identified as fa'afafine, were predominantly attracted to men, and had sex only with men (N = 30). Samoan cisgender males who self-identified as men, were predominantly attracted to women, and had sex only with women (N = 31) served as a comparison group. Androphilic men and fa'afafine reported greater sexual attraction to men than women and viewed the images of men longer than those of women. Gynephilic men showed the inverse pattern. Viewing time discrepancies between participant's preferred gender and their non-preferred gender were greater for gynephilic men compared to the two androphilic groups. The implications of these preliminary findings for the use of viewing time measures of male sexual orientation across different cultural contexts are discussed.

The Association Between Men's Sexist Attitudes and Facial Hair

Facial hair, like many masculine secondary sexual traits, plays a significant role in perceptions of an array of sociosexual traits in men. While there is consensus that beards enhance perceptions of masculinity, age, social dominance, and aggressiveness, the perceived attractiveness of facial hair varies greatly across women. Given the ease with which facial hair can be groomed and removed entirely, why should some men retain beards and others choose to remove them? We hypothesized that men with relatively sexist attitudes would be more likely to allow their facial hair to grow than men with less sexist attitudes. Men from the USA (n = 223) and India (n = 309) completed an online survey measuring demographic variables, ambivalent sexism, and facial hair status. After controlling for demographic variables, men with facial hair were significantly higher in hostile sexism than clean-shaven men; hostile sexism was a significant predictor of facial hair status over and above demographic variables; and facial hair was more frequent among ambivalent and hostile sexists than among benevolent and non-sexists. It is suggested that sexist men choose to grow facial hair because it maximizes sexual dimorphism and augments perceived masculinity and dominance.

Men's Preferences for Female Facial Femininity Decline With Age

OBJECTIVES

Women tend to have a smaller chin, fuller lips, and rounder eyes than men, due in part to the effects of estrogen. These features associated with facial femininity have been found to be positively associated with fertility. Although young men in their 20s typically judge facial femininity as more attractive than facial masculinity, at all ages, men with higher sexual desire and testosterone levels tend to show a marked preference for feminine faces. In the current study, we extend this research using a large cross-national sample to test the hypothesis that facial femininity preferences will be stronger among younger men than among older men. We also tested whether these preferences are influenced by self-reported sexual openness, national health indices, and gross national income.

METHOD

We quantified attractiveness judgments (i.e., preferences) among 2,125 heterosexual men (aged 17-73 years) for female faces that were manipulated to appear more or less feminine using a computer graphics program.

RESULTS

Facial femininity preferences decreased with age, being highest among men in their 30s and lowest among men in their 70s. This pattern was independent of men's sexual openness and cross-national variation in health and socioeconomic development.

DISCUSSION

Our study shows that men's preferences for facial femininity are age dependent. At the proximate level, differences in preferences could reflect age-related declines in testosterone levels. These age-related declines in preferences could benefit older men, who are less able to invest in mating effort, and thus may opt out of competition with younger men for mates with potentially higher fertility.

The Role of Breast Size and Areolar Pigmentation in Perceptions of Women's Sexual Attractiveness, Reproductive Health, Sexual Maturity, Maternal Nurturing Abilities, and Age

Women's breast morphology is thought to have evolved via sexual selection as a signal of maturity, health, and fecundity. While research demonstrates that breast morphology is important in men's judgments of women's attractiveness, it remains to be determined how perceptions might differ when considering a larger suite of mate relevant attributes. Here, we tested how variation in breast size and areolar pigmentation affected perceptions of women's sexual attractiveness, reproductive health, sexual maturity, maternal nurturing abilities, and age. Participants (100 men; 100 women) rated images of female torsos modeled to vary in breast size (very small, small, medium, and large) and areolar pigmentation (light, medium, and dark) for each of the five attributes listed above. Sexual attractiveness ratings increased linearly with breast size, but large breasts were not judged to be significantly more attractive than medium-sized breasts. Small and medium-sized breasts were rated as most attractive if they included light or medium colored areolae, whereas large breasts were more attractive if they had medium or dark areolae. Ratings for perceived age, sexual maturity, and nurturing ability also increased with breast size. Darkening the areolae reduced ratings of the reproductive health of medium and small breasts, whereas it increased ratings for large breasts. There were no significant sex differences in ratings of any of the perceptual measures. These results demonstrate that breast size and areolar pigmentation interact to determine ratings for a suite of sociosexual attributes, each of which may be relevant to mate choice in men and intra-sexual competition in women.

Evidence from Meta-Analyses of the Facial Width-to-Height Ratio as an Evolved Cue of Threat

The facial width-to-height ratio (FWHR) is the width of the face divided by the height of the upper face. There is mixed evidence for the hypothesis that the FWHR is a cue of threat and dominance in the human face. We conducted a systematic review and meta-analyses of all peer-reviewed studies (and 2 unpublished studies) to estimate the magnitude of the sex difference in the FWHR, and the magnitude of the relationship between the FWHR and threatening and dominant behaviours and perceptions. Studies were eligible for inclusion if the authors reported an analysis involving the FWHR. Our analyses revealed that the FWHR was larger in men than in women (d¯ = .11, n = 10,853), cued judgements of masculinity in men (r¯ = .35, n of faces = 487; n of observers = 339), and was related to body mass index (r¯ = .31, n = 2,506). Further, the FWHR predicted both threat behaviour in men (r¯ = .16, n = 4,603) and dominance behaviour in both sexes (r¯ = .12, n = 948) across a variety of indices. Individuals with larger FWHRs were judged by observers as more threatening (r¯ = .46, n of faces = 1,691; n of observers = 2,076) and more dominant (r¯ = .20, n of faces = 603; n of observers = 236) than those with smaller FWHRs. Individuals with larger FWHRs were also judged as less attractive (r¯ = -.26, n of faces = 721; n of observers = 335), especially when women made the judgements. These findings provide some support for the hypothesis that the FWHR is part of an evolved cueing system of intra-sexual threat and dominance in men. A limitation of the meta-analyses on perceptions of threat and dominance were the low number of stimuli involving female and older adult faces.

Viewing time measures of sexual orientation in Samoan cisgender men who engage in sexual interactions with fa'afafine

Androphilia refers to attraction to adult males, whereas gynephilia refers to attraction to adult females. The current study employed self-report and viewing time (response time latency) measures of sexual attraction to determine the sexual orientation of Samoan cisgender men (i.e., males whose gender presentation and identity is concordant with their biological sex) who engage in sexual interactions with transgender male androphiles (known locally as fa’afafine) compared to: (1) Samoan cisgender men who only engage in sexual interactions with women, and (2) fa’afafine. As expected, both measures indicated that cisgender men who only engaged in sexual interactions with women exhibited a gynephilic pattern of sexual attraction, whereas fa’afafine exhibited an androphilic one. In contrast, both measures indicated that cisgender men who engaged in sexual interactions with fa’afafine demonstrated a bisexual pattern of sexual attraction. Most of the cisgender men who exhibited bisexual viewing times did not engage in sexual activity with both men and women indicating that the manner in which bisexual patterns of sexual attraction manifest behaviorally vary from one culture to the next.

Cross-cultural variation in men's preference for sexual dimorphism in women's faces

Both attractiveness judgements and mate preferences vary considerably cross-culturally. We investigated whether men's preference for femininity in women's faces varies between 28 countries with diverse health conditions by analysing responses of 1972 heterosexual participants. Although men in all countries preferred feminized over masculinized female faces, we found substantial differences between countries in the magnitude of men's preferences. Using an average femininity preference for each country, we found men's facial femininity preferences correlated positively with the health of the nation, which explained 50.4% of the variation among countries. The weakest preferences for femininity were found in Nepal and strongest in Japan. As high femininity in women is associated with lower success in competition for resources and lower dominance, it is possible that in harsher environments, men prefer cues to resource holding potential over high fecundity.

Negative frequency-dependent preferences and variation in male facial hair

Negative frequency-dependent sexual selection maintains striking polymorphisms in secondary sexual traits in several animal species. Here, we test whether frequency of beardedness modulates perceived attractiveness of men's facial hair, a secondary sexual trait subject to considerable cultural variation. We first showed participants a suite of faces, within which we manipulated the frequency of beard thicknesses and then measured preferences for four standard levels of beardedness. Women and men judged heavy stubble and full beards more attractive when presented in treatments where beards were rare than when they were common, with intermediate preferences when intermediate frequencies of beardedness were presented. Likewise, clean-shaven faces were least attractive when clean-shaven faces were most common and more attractive when rare. This pattern in preferences is consistent with negative frequency-dependent selection.

Men's preferences for women's breast morphology in New Zealand, Samoa, and Papua New Guinea

Sexual selection via mate choice may have influenced the evolution of women's breast morphology. We conducted an image-based questionnaire quantifying and comparing the preferences of men from Papua New Guinea (PNG), Samoa, and New Zealand (NZ) for images of women's breast size, breast symmetry, areola size, and areolar pigmentation. Results showed that men from PNG preferred larger breasts to a greater extent than men from Samoa and NZ, providing some support for the hypothesis that men from subsistence living cultures have a greater preference for morphological cues indicative of caloric reserves. Symmetrical breasts were most attractive to men in each culture. However, preferences were highest among NZ men, followed by men from Samoa, and were lowest among men from PNG. These results did not support the hypothesis that people living in higher pathogen environments have a greater preference for traits indicative of pathogen resistance and developmental stability. Large areolae were preferred among men from PNG, and to a lesser extent in Samoa, while in NZ men preferred medium-sized areolae. Thus, men's preferences for women's areolar size appear to be highly culturally specific. Darkly pigmented areolae were most attractive to men from Samoa and PNG, whereas men from NZ preferred areolae with medium pigmentation. These findings suggest that areolar pigmentation indicative of sexual maturity is preferred by men rather than lighter pigmentation, which may signal that a woman is in the early years of reproductive maturity. This study highlights the importance of cross-cultural research when testing the role of morphological cues in mate choice.

Whatever the weather: ambient temperature does not influence the proportion of males born in New Zealand

Background

The proportion of male births has been shown to be over 50% in temperate climates around the world. Given that fluctuations in ambient temperature have previously been shown to affect sex allocation in humans, we examined the hypothesis that ambient temperature predicts fluctuations in the proportion of male births in New Zealand.

Methodology/Principal Findings

We tested three main hypotheses using time series analyses. Firstly, we used historical annual data in New Zealand spanning 1876–2009 to test for a positive effect of ambient temperature on the proportion of male births. The proportion of males born ranged by 3.17%, from 0.504 to 0.520, but no significant relationship was observed between male birth rates and mean annual temperature in the concurrent or previous years. Secondly, we examined whether changes in annual ambient temperature were negatively related to the proportion of male stillbirths from 1929–2009 and whether the proportion of male stillbirths negatively affected the proportion of male live births. We found no evidence that fewer male stillbirths occurred during warmer concurrent or previous years, though a declining trend in the proportion of male stillbirths was observed throughout the data. Thirdly, we tested whether seasonal ambient temperatures, or deviations from those seasonal patterns, were positively related to the proportion of male births using monthly data from 1980–2009. Patterns of male and female births are seasonal, but very similar throughout the year, resulting in a non-seasonal proportion of male births. However, no cross correlations between proportion of male births and lags of temperature were significant.

Conclusions

Results showed, across all hypotheses under examination, that ambient temperatures were not related to the proportion of male births or the proportion of male stillbirths in New Zealand. While there is evidence that temperature may influence human sex allocation elsewhere, such effects of temperature are not universal.

Eye tracking of men's preferences for female breast size and areola pigmentation

Sexual selection via male mate choice has often been implicated in the evolution of permanently enlarged breasts in women. While questionnaire studies have shown that men find female breasts visually attractive, there is very little information about how they make such visual judgments. In this study, we used eye-tracking technology to test two hypotheses: (1) that larger breasts should receive the greatest number of visual fixations and longest dwell times, as well as being rated as most attractive; (2) that lightly pigmented areolae, indicative of youth and nubility, should receive most visual attention and be rated as most attractive. Results showed that men rated images with medium-sized or large breasts as significantly more attractive than small breasts. Images with dark and medium areolar pigmentation were rated as more attractive than images with light areolae. However, variations in breast size had no significant effect on eye-tracking measures (initial visual fixations, number of fixations, and dwell times). The majority of initial fixations during eye-tracking tests were on the areolae. However, areolar pigmentation did not affect measures of visual attention. While these results demonstrate that cues indicative of female sexual maturity (large breasts and dark areolae) are more attractive to men, patterns of eye movements did not differ based on breast size or areolar pigmentation. We conclude that areolar pigmentation, as well as breast size, plays a significant role in men's judgments of female attractiveness. However, fine-grained measures of men's visual attention to these morphological traits do not correlate, in a simplistic way, with their attractiveness judgments.

Eye-tracking of men's preferences for waist-to-hip ratio and breast size of women

Studies of human physical traits and mate preferences often use questionnaires asking participants to rate the attractiveness of images. Female waist-to-hip ratio (WHR), breast size, and facial appearance have all been implicated in assessments by men of female attractiveness. However, very little is known about how men make fine-grained visual assessments of such images. We used eye-tracking techniques to measure the numbers of visual fixations, dwell times, and initial fixations made by men who viewed front-posed photographs of the same woman, computer-morphed so as to differ in her WHR (0.7 or 0.9) and breast size (small, medium, or large). Men also rated these images for attractiveness. Results showed that the initial visual fixation (occurring within 200 ms from the start of each 5 s test) involved either the breasts or the waist. Both these body areas received more first fixations than the face or the lower body (pubic area and legs). Men looked more often and for longer at the breasts, irrespective of the WHR of the images. However, men rated images with an hourglass shape and a slim waist (0.7 WHR) as most attractive, irrespective of breast size. These results provide quantitative data on eye movements that occur during male judgments of the attractiveness of female images, and indicate that assessments of the female hourglass figure probably occur very rapidly.

Male preferences for female waist-to-hip ratio and body mass index in the highlands of Papua New Guinea

One hundred men, living in three villages in a remote region of the Eastern Highlands of Papua New Guinea were asked to judge the attractiveness of photographs of women who had undergone micrograft surgery to reduce their waist-to-hip ratios (WHRs). Micrograft surgery involves harvesting adipose tissue from the waist and reshaping the buttocks to produce a low WHR and an "hourglass" female figure. Men consistently chose postoperative photographs as being more attractive than preoperative photographs of the same women. Some women gained, and some lost weight, postoperatively, with resultant changes in body mass index (BMI). However, changes in BMI were not related to men's judgments of attractiveness. These results show that the hourglass female figure is rated as attractive by men living in a remote, indigenous community, and that when controlling for BMI, WHR plays a crucial role in their attractiveness judgments.

Human physique and sexual attractiveness in men and women: a New Zealand-U.S. comparative study

Men and women living in New Zealand and California completed five studies regarding human physique and sexual attractiveness. In Studies 1-3, women rated images of male stimuli and, in Studies 4-5, men rated female stimuli. In Study 1, women in both countries rated mesomorphic (muscular) and average male somatotypes as most attractive, followed by ectomorphic (slim) and endomorphic (heavily built) figures. In Study 2, amount and distribution of masculine trunk hair (chest and abdominal) was altered progressively in a series of front-posed male figures. In both countries, the image lacking any trunk hair was rated as the most attractive, with a steady decline in attractiveness as hirsutism became more pronounced. Study 3 assessed attractiveness of front-posed male figures that varied only in the length of the non-erect penis. Five lengths were presented: The smallest penile size was rated as less attractive than three intermediate sizes. The largest penile size was not the most attractive, but received higher scores than the unaltered and smallest penile size. In Study 4, men rated the attractiveness of back-posed female images varying in waist-to-hip ratio (WHR) (from 0.5 to 1.0). The 0.7 WHR figure was rated more attractive in New Zealand and the 0.6 WHR in California. Study 5 measured the attractiveness of female skin color; men expressed preferences for lighter skinned female figures in New Zealand and California. Results indicate very similar preferences for sexually dimorphic physical traits among men and women of European extraction, living in two culturally and geographically different environments.

Human physique and sexual attractiveness: sexual preferences of men and women in Bakossiland, Cameroon

Men and women living in a rural community in Bakossiland, Cameroon were asked to rate the attractiveness of images of male or female figures manipulated to vary in somatotype, waist-to-hip ratio (WHR), secondary sexual traits, and other features. In Study 1, women rated mesomorphic (muscular) and average male somatotypes as most attractive, followed by ectomorphic (slim) and endomorphic (heavily built) figures. In Study 2, amount and distribution of masculine trunk (chest and abdominal) hair was altered progressively in a series of front-posed male figures. A significant preference for one of these images was found, but the most hirsute figure was not judged as most attractive. Study 3 assessed attractiveness of front-posed male figures which varied only in length of the non-erect penis. Extremes of penile size (smallest and largest of five images) were rated as significantly less attractive than three intermediate sizes. In Study 4, Bakossi men rated the attractiveness of back-posed female images varying in WHR (from 0.5-1.0). The 0.8 WHR figure was rated markedly more attractive than others. Study 5 rated the attractiveness of female skin color. Men expressed no consistent preference for either lighter or darker female figures. These results are the first of their kind reported for a Central African community and provide a useful cross-cultural perspective to published accounts on sexual selection, human morphology and attractiveness in the U.S., Europe, and elsewhere.

Studies of human physique and sexual attractiveness: sexual preferences of men and women in China

Men and women at Northwest University (n = 631), Xi'an, China, were asked to rate the attractiveness of male or female figures manipulated to vary somatotype, waist-to-hip ratio (WHR), secondary sexual traits, and other features. In study 1, women rated the average masculine somatotype as most attractive, followed by the mesomorphic (muscular), ectomorphic (slim), and endomorphic (heavily built) somatotypes, in descending order of preference. In study 2, the amount and distribution of masculine trunk (chest and abdominal) hair were altered progressively in a series of front-posed figures. Women rated figures with no or little trunk hair as most attractive. Study 3 assessed the attractiveness of front-posed male figures which varied only in length of their nonerect penis. Numerical ratings for this trait were low, but moderate lengthening of the penis (22% or 33% above average) resulted in a significant increase in scores for attractiveness. In study 4, Chinese men rated the attractiveness of back-posed female images varying in waist-to-hip ratio (WHR from 0.5-1.0). The 0.6 WHR figure was most preferred, followed by 0.7, while figures with higher ratios (0.9 or 1.0) were significantly less attractive. Study 5 rated the attractiveness of female skin color: men expressed a marked preference for images which were lighter in color, as compared to images of average or darker skin colors. These results, the first of their kind reported for a Chinese population, support the view that sexual selection has influenced the evolution of human physique and sexual attractiveness in men and women.