Are attractive men's faces masculine or feminine? The importance of type of facial stimuli.

The authors investigated whether differences in facial stimuli could explain the inconsistencies in the facial attractiveness literature regarding whether adults prefer more masculine- or more feminine-looking male faces. Their results demonstrated that use of a female average to dimorphically transform a male facial average produced stimuli that did not accurately reflect the relationship between masculinity and attractiveness. In contrast, use of averages of masculine males and averages of feminine males produced stimuli that did accurately reflect the relationship between masculinity and attractiveness. Their findings suggest that masculinity contributes more to male facial attractiveness than does femininity, but future research should investigate how various combinations of facial cues contribute to male facial attractiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eye-mouth-eye angle as a good indicator of face masculinization, asymmetry, and attractiveness (Homo sapiens).

Past research on male facial attractiveness has been limited by the reliance on facialmetric measures that are less than ideal. In particular, some of these measures are face size dependent and show only weak sexual dimorphism, which limits the ability to identify the relationship between masculinization and attractiveness. Here, the authors show that eye-mouth-eye (EME) angle is a quantitative and face size independent trait that is sexually dimorphic and a good indicator of masculinity and face symmetry. Using frontal photographs of female and male faces, the authors first confirmed that the EME angle (measured with the vertex in the middle of the mouth and the arms crossing the centers of pupils) was highly sexually dimorphic. Then, using pictures of young male faces whose attractiveness was assessed on a 7-point scale by young women, the authors showed that attractiveness rate was negatively correlated with EME angle and with the angle asymmetry. The results are compared with those that could be obtained with interpupilary or upper face height measurements. The authors discuss the relationship between attractiveness and both EME angle and its symmetry in the light of evolutionary psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Female condition influences preferences for sexual dimorphism in faces of male humans (Homo sapiens).

In some species, female condition correlates positively with preferences for male secondary sexual traits. Women's preferences for sexually dimorphic characteristics in male faces (facial masculinity) have recently been reported to covary with self-reported attractiveness. As women's attractiveness has been proposed to signal reproductive condition, the findings in human (Homo sapiens) and other species may reflect similar processes. The current study investigated whether the covariation between condition and preferences for masculinity would generalize to 2 further measures of female attractiveness: other-rated facial attractiveness and waist-to-hip ratio (WHR). Women with high (unattractive) WHR and/or relatively low other-rated facial attractiveness preferred more "feminine" male faces when choosing faces for a long-term relationship than when choosing for a short-term relationship, possibly reflecting diverse tactics in female mate choice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrasonic vocalizing by adult female mice (Mus musculus).

Conducted 5 experiments, using 1,029 female and 805 male mice, to examine adult female mouse ultrasound emission. Results indicate female ultrasonic vocalizing to be (a) typically displayed among female mouse dyads and (b) comparable to the ultrasonic vocalizing levels obtained among male–female pairs. Genotypically based variations in the production of ultrasounds by females were also noted. Like males, socially naive females readily ultrasonically vocalized to anesthetized female conspecifics and rarely vocalized to anesthetized males. Unlike males, socially experienced females emitted few ultrasounds to either female urine or female-soiled cage shavings. Although social experience increased the ultrasound emission of males to female sex cues, the production of ultrasounds by females to these cues was decreased by social experience. Implications with regard to the existence of a behavioral/functional sexual dimorphism in adult mouse ultrasonic vocalizing are discussed. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexual dimorphism in the face of Australopithecus africanus

Recently discovered crania of Australopithecus africanus from Sterkfontein Member 4 and Makapansgat enlarge the size range of the species and encourage a reappraisal of both the degree and pattern of sexual dimorphism. Resampling methodology (bootstrapping) is used here to establish that A. africanus has a greater craniofacial size range than chimpanzees or modern humans, a range which is best attributed to a moderately high degree of sexual dimorphism. Compared to other fossil hominins, this variation is similar to that of Homo habilis (sensu lato) but less than that of A. boisei. The finding of moderately high dimorphism is corroborated by a CV-based estimate and ratios between those specimens considered to be male and those considered to be female. Inferences about the pattern of craniofacial dimorphism in the A. africanus face currently rely on the relationship of morphology and size. Larger specimens, particularly Stw 505, show prominent superciliary eminences and glabellar regions, but in features related in part to canine size, such as the curvature of the infraorbital surface, large and small specimens of A. africanus are similar. In this respect, the pattern resembles that of modern humans more so than chimpanzees or lowland gorillas. A. africanus may also show novel patterns of sexual dimorphism when compared to extant hominines, such as in the form of the anterior pillar. However, males of the species do not exhibit characteristics of more derived hominins, such as A. robustus.     

Dissociating averageness and attractiveness: Attractive faces are not always average.

Although the averageness hypothesis of facial attractiveness proposes that the attractiveness of faces is mostly a consequence of their averageness, 1 study has shown that caricaturing highly attractive faces makes them mathematically less average but more attractive. Here the authors systematically test the averageness hypothesis in 5 experiments using both rating and visual adaptation paradigms. Visual adaptation has previously been shown to increase both preferences for previously viewed face types (i.e., attractiveness) and their perceived normality (i.e., averageness). The authors used a visual adaptation procedure to test whether facial attractiveness is dependent upon faces' proximity to average (averageness hypothesis) or their location relative to average along an attractiveness dimension in face space (contrast hypothesis). While the typical pattern of change due to visual adaptation was found for judgments of normality, judgments of attractiveness resulted in a very different pattern. The results of these 5 experiments conclusively support the proposal that there are specific nonaverage characteristics that are particularly attractive. The authors discuss important implications for the interpretation of studies using a visual adaptation paradigm to investigate attractiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The confounded nature of angry men and happy women.

Findings of 7 studies suggested that decisions about the sex of a face and the emotional expressions of anger or happiness are not independent: Participants were faster and more accurate at detecting angry expressions on male faces and at detecting happy expressions on female faces. These findings were robust across different stimulus sets and judgment tasks and indicated bottom-up perceptual processes rather than just top-down conceptually driven ones. Results from additional studies in which neutrally expressive faces were used suggested that the connections between masculine features and angry expressions and between feminine features and happy expressions might be a property of the sexual dimorphism of the face itself and not merely a result of gender stereotypes biasing the perception. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Sex and physical attractiveness of raters and applicants as determinants of resumé evaluations.

110 male and female student "interviewers," classified as either high, moderate, or low on physical attractiveness, evaluated 12 bogus job applicants for whom sex, physical attractiveness, and qualifications had been varied. A 2?×?3?×?2?×?3?×?2 analysis of variance was computed, with the 1st 2 variables (interviewer sex and attractiveness) constituting between-group factors, and the last 3 variables (applicant sex, attractiveness, and qualifications) constituting repeated measures factors. Regardless of interviewer sex and attractiveness, highly qualified applicants were preferred over poorly qualified applicants, male applicants were preferred over female applicants, and attractive candidates were preferred over unattractive candidates. Discrimination in employment decisions was attributed to sex-role and physical attractiveness stereotypes. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nonverbal behavior and perceived counselor attractiveness and persuasiveness.

Investigated the perception of counselor attractiveness and persuasiveness through the expression of nonverbal behavior. Ss were 20 male and 20 female psychology undergraduates. 2 male and female counselors were trained to portray "affiliative" manner and "unaffiliative" manner. In a repeated measures design, Ss saw 4 different counselors and then rated them on scales measuring perceived attractiveness and persuasiveness. Results indicate that counselors in the affiliative manner condition were perceived as significantly more attractive and persuasive than counselors in the unaffiliative condition. Ss attributed greater attractiveness and persuasiveness to the same nonverbal cues encoded into the roles. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Male mouse (Mus musculus) attraction to airborne urinary odors of conspecifics and to food odors: Effects of food deprivation.

Five experiments demonstrated that 112 male mice were strongly attracted to the urinary odors of females, and that male urinary odors were considerably less attractive. The strong attraction to female urinary odors did not require that the males have postweaning experience with females. Males with continuous access to food and water were much more strongly attracted to female urinary odors than to the airborne food odors. Female urinary odors remained more attractive than food odors after 24-hr food deprivation, and only after 48-hr deprivation did the attractiveness of food odors approximate that of female urine. Although 48-hr food deprivation appeared to equalize the attractiveness of urinary and food odors, this regimen did so not by diminishing the attractiveness of female urine but rather by increasing the attractiveness of food odors. It is argued that the attraction that male mice exhibited to female urinary odors in this odor-testing apparatus reflected, at least in part, a biologically important precopulatory communication system. (29 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The role of vaginal secretion in hamster sexual behavior: Males' responses to normal and vaginectomized females and their odors.

Two experiments (with 60 adult male hamsters and 4 sexually naive male hamsters) examined the importance of vaginal secretion relative to other feminine odors for attraction of males and elicitation of copulatory behavior by comparing the behavior of males toward normal females with that toward vaginectomized Ss. Males were more attracted to intact females than to vaginectomized Ss when odors were the only cues available and also when auditory, visual, and odor cues were available but contact was prevented. There were no differences in the attractiveness of estrous and diestrous Ss whether intact or vaginectomized. When males and females were allowed to interact, there were no differences in any measures of male sexual behavior toward normal vs vaginectomized females, which indicates that the presence of vaginal secretion is not necessary for male sexual behavior. The significance for conceptions of pheromone action in mammals is discussed. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Female preference for swords in Xiphophorus helleri reflects a bias for large apparent size

Swordtail fish (Poeciliidae: genus Xiphophorus) are a paradigmatic case of sexual selection by sensory exploitation. Female preference for males with a conspicuous "sword" ornament is ancestral, suggesting that male morphology has evolved in response to a preexisting bias. The perceptual mechanisms underlying female mate choice have not been identified, complicating efforts to understand the selection pressures acting on ornament design. We consider two alternative models of receiver behavior, each consistent with previous results. Females could respond either to specific characteristics of the sword or to more general cues, such as the apparent size of potential mates. We showed female swordtails a series of computer-altered video sequences depicting a courting male. Footage of an intact male was preferred strongly to otherwise identical sequences in which portions of the sword had been deleted selectively, but a disembodied courting sword was less attractive than an intact male. There was no difference between responses to an isolated sword and to a swordless male of comparable length, or between an isolated sword and a homogenous background. Female preference for a sworded male was abolished by enlarging the image of a swordless male to compensate for the reduction in length caused by removing the ornament. This pattern of results is consistent with mate choice being mediated by a general preference for large males rather than by specific characters. Similar processes may account for the evolution of exaggerated traits in other systems.     

Odor preferences of female house mice (Mus domesticus) in seminatural enclosures.

Preferences for male odors by female house mice (Mus domesticus) were examined with respect to age, dominance status, and spatial relationships. Mice were free living in 6 field enclosures. Estrous or nonestrous females were placed in an aquarium with soiled bedding from live traps as the odor source. Females were tested for preferences between (1) adult and juvenile male odors, (2) dominant and subordinate male odors, and (3) "near" and "far" male odors. In dominance odor tests, estrous females preferred odors from dominant males; nonestrous females exhibited no significant preferences. In adult juvenile and spatial odor tests, there were no significant differences between odor preferences of estrous and nonestrous females. However, most females preferred odors from adult and "near" males. Male dominance status appears to be the strongest influence on female odor preference in these seminatural enclosures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexually stimulating signals of canary ( Serinus canaria) songs: Evidence for a female-specific auditory representation in the HVc nucleus during the breeding season.

During the breeding season under long-day conditions, male canaries sing sexually attractive songs and females respond behaviorally to such songs. This study assessed whether auditory response properties of neurons in nucleus HVc of female and male canaries are tuned to sexually salient song features: special song phrases and canary song segmentation. In sexually receptive female canaries, neurons responded to special song phrases with a decreased spike rate and were sensitive to canary song segmentation. The nonreceptive females showed no clear response to special song phrases. In females on short days, neurons responded to song phrases with an increase in activity. In males on long days, they exhibited phasic responses after the phrase onset, whatever the song phrase and song segmentation. This study demonstrates both a plasticity in relation to females' sexual responsiveness and a sexual dimorphism in the auditory processing performed in the HVc. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Facial resemblance to emotions: Group differences, impression effects, and race stereotypes.

The authors used connectionist modeling to extend previous research on emotion overgeneralization effects. Study 1 demonstrated that neutral expression male faces objectively resemble angry expressions more than female faces do, female faces objectively resemble surprise expressions more than male faces do, White faces objectively resemble angry expressions more than Black or Korean faces do, and Black faces objectively resemble happy and surprise expressions more than White faces do. Study 2 demonstrated that objective resemblance to emotion expressions influences trait impressions even when statistically controlling possible confounding influences of attractiveness and babyfaceness. It further demonstrated that emotion overgeneralization is moderated by face race and that racial differences in emotion resemblance contribute to White perceivers’ stereotypes of Blacks and Asians. These results suggest that intergroup relations may be strained not only by cultural stereotypes but also by adaptive responses to emotion expressions that are overgeneralized to groups whose faces subtly resemble particular emotions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assortative mating and female clutch investment in black grouse

Variation in female behaviour has only recently received attention in studies of sexual selection. It has been suggested that females may invest differentially in their offspring in relation to the quality of their mate. This may lead to females that mate with high-quality and/or attractive males laying larger clutches. Females may also differ in their ability to choose between males. For example, females in good physical condition may make better choices. If physical condition and clutch size are positively correlated, this hypothesis could also produce a relationship between male attractiveness and female clutch size. We found, in lekking black grouse, Tetrao tetrix, that females mated to the highest ranked males laid the largest clutches. Furthermore we found, regardless of female age, a positive relationship between a measure of female condition and male rank but not between female condition and her clutch size. In addition, females in good condition visited a larger number of different male territories, and old females produced the largest clutches. Our results suggest two mechanisms to explain our findings. First, females in good physical condition tend to mate with the top males, suggesting an assortative mating pattern. Second, females mating with the highest ranked males lay larger clutches as a consequence of their choice. In general, our result calls for caution in evaluating studies that look at the consequences of mate choice. It may be that differences in female quality produce effects that may be wrongly interpreted as male quality effects. (c) 1998 The Association for the Study of Animal Behaviour.     

Sexual dimorphism in facial shapes and their discrimination in Japanese monkeys (Macaca fuscata).

The authors examined the ability of Japanese monkeys (Macaca fuscata) to discriminate between sexes based on facial features. The shape and position of facial features (facial morphology) were measured to quantify the differences between sexes. The distance between the chin and nose was longer in males than females, and the outline of the face around the upper jaw and upper face differed between sexes. Using operant conditioning, 2 monkeys succeeded in discriminating sex based on facial pictures. Furthermore, they successfully generalized the discrimination to novel pictures of faces. Tests with morphed pictures of faces revealed that the monkeys used facial morphology to discriminate between males and females. Our results suggest that Japanese monkeys have sexual dimorphism in facial shape and they can use the morphological differences to discriminate conspecific sex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Magnesium and the transport system

For the purpose of studying the sex differences of the human face we collected five separate images, which consist of several parts of the face, from frontal view photographs of 48 male and 52 female college students. We traced outlines of their faces with simple lines (traced items), and made reproductions of the photographs of their eyes, mouth and nose by using a copying machine (reproduced items). The test subjects were 16 males and 8 females. They looked at parts of the face shown in each image, and categorized them individually by judging on their sex. Then, we calculated the percentages of correct judgments (percentage correct) for each image. By comparing the percentage correct between male and female we concluded that the sex of the subjects did not affect the results of their judgments. In the traced items the percentage correct for the face as a whole, which contained the outlines of the eyes, mouth, nose and the lower jaw, was 69%, but it decreased to 61% when the outline of the lower jaw was removed. Hence, the outline of the lower jaw apparently has a characteristic shape easily noticed by males. In the reproduced items the percentage correct was 65% for the eyes, 68% for the mouth and 58% for the nose. The mouth, therefore, has more distinguishing characteristics than the eyes or nose, especially with females. On the other hand, there is no correlation between the percentage correct for the eye, mouth and nose items. Hence, we concluded that the sexual specificity for the shape of the young Japanese face appears on their parts independently.     

Impressions of counselors as a function of counselor physical attractiveness.

Assessed the effects of counselor physical attractiveness and interactions between attractiveness and counselor and S sex. 40 male and 40 female undergraduates rated their 1st impressions of a counselor and their expectations for counseling outcome on the basis of a photograph of either an attractive or an unattractive person and a brief, audiotaped self-introduction by either a male or a female counseling psychologist. Attractiveness did not show main effects but did interact with sex variables, which did show several main effects. Female counselors, particularly in the attractive condition, received higher ratings than male counselors on several impression variables, and female Ss gave higher ratings on impression variables than did male Ss. Both attractive and unattractive counselors were within the normal range of attractiveness, however. It is suggested that within the natural setting, sex of counselor and client may play a more important role independently and in conjunction with attractiveness than does attractiveness alone in influencing impressions and expectations. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in parasite infections: patterns and processes

Sex differences in parasite infection rates, intensities, or population patterns are common in a wide range of taxa. These differences are usually attributed to 1 of 2 causes: (1) ecological (sociological in humans); and (2) physiological, usually hormonal in origin. Examples of the first cause include differential exposure to pathogens because of sex-specific behavior or morphology. The second cause may stem from the well-documented association between testosterone and the immune system; sexually mature male vertebrates are often more susceptible to infection and carry higher parasite burdens in the field. Although many researchers favor one explanation over the other, the requisite controlled experiments to rule out confounding variables are often neglected. We suggest that sex differences in disease have evolved just as sex differences in morphology and behavior, and are the result of selection acting differently on males and females. Research has often focused on proximate mechanistic explanations for the sex difference in infection rates, but it is equally important to understand the generality of the patterns in an evolutionary context. Because males potentially gain more than females by taking risks and engaging in competition, sexual selection pressure has shaped male behavior and appearance to maximize competitive ability and attractiveness. Many of the classic male attributes such as antlers on deer are testosterone-dependent, putting males in what appears to be a cruel bind: become vulnerable to disease by developing an attractive secondary sexual ornament, or risk lowered mating success by reducing it. A variety of hypotheses have been put forward to explain why males have not circumvented this dilemma. The mating system of the host species will influence the likelihood of sex differences in parasite infection, because males in monogamous species are subject to weaker sexual selection than males in polygynous species. Whether these evolutionary generalizations apply to invertebrates, which lack testosterone, remains to be seen.