Eye-tracking women’s preferences for men’s somatotypes

Judging physical attractiveness involves sight, touch, sound and smells. Where visual judgments are concerned, attentional processes may have evolved to prioritize sex-typical traits that reflect cues signaling direct or indirect (i.e. genetic) benefits. Behavioral techniques that measure response times or eye movements provide a powerful test of this assumption by directly assessing how attractiveness influences the deployment of attention. We used eye-tracking to characterize women’s visual attention to men’s back-posed bodies, which varied in overall fat and muscle distribution, while they judged the potential of each model for a short- or long-term relationship. We hypothesized that when judging male bodily attractiveness women would focus more on the upper body musculature of all somatotypes, as it is a signal of metabolic health, immunocompetence and underlying endocrine function. Results showed that mesomorphs (muscular men) received the highest attractiveness ratings, followed by ectomorphs (lean men) and endomorphs (heavily-set men). For eye movements, attention was evenly distributed to the upper and lower back of both ectomorphs and mesomorphs. In contrast, for endomorphs the lower back, including the waist, captured more attention over the viewing period. These patterns in visual attention were evident in the first second of viewing, suggesting that body composition is identified early in viewing and guides attention to body regions that provide salient biological information during judgments of men’s bodily attractiveness.     

Patterns of eye movements when male and female observers judge female attractiveness, body fat and waist-to-hip ratio

Behavioural studies of the perceptual cues for female physical attractiveness have suggested two potentially important features: body fat distribution [the waist-to-hip ratio (WHR)] and overall body fat [often estimated by the body mass index (BMI)]. However, none of these studies tell us directly which regions of the stimulus images inform observers' judgments. Therefore, we recorded the eye movements of three groups of 10 male observers and three groups of 10 female observers, when they rated a set of 46 photographs of female bodies. The first sets of observers rated the images for attractiveness, the second sets rated for body fat and the third sets for WHR. If either WHR and/or body fat is used to judge attractiveness, then observers rating attractiveness should look at those areas of the body which allow assessment of these features, and they should look in the same areas when they are directly asked to estimate WHR and body fat. So we are able to compare the fixation patterns for the explicit judgments with those for attractiveness judgments and infer which features were used for attractiveness. Prior to group analysis of the eye-movement data, the locations of individual eye fixations were transformed into a common reference space to permit comparisons of fixation density at high resolution across all stimuli. This manipulation allowed us to use spatial statistical analysis techniques to show the following: (1) Observers' fixations for attractiveness and body fat clustered in the central and upper abdomen and chest, but not the pelvic or hip areas, consistent with the finding that WHR had little influence over attractiveness judgments. (2) The pattern of fixations for attractiveness ratings was very similar to the fixation patterns for body fat judgments. (3) The fixations for WHR ratings were significantly different from those for attractiveness and body fat.     

Motivational value and salience of images of infants

Researchers have typically reported relatively greater preferences for infants among females than among males, though this varies somewhat across samples and age groups. The mechanism by which this sex difference occurs is not well understood and many studies rely on participants' self-reported preferences rather than measuring motivated behavior or patterns of visual attention directly. The present research consists of two independent studies investigating attention to infants. The aim of these studies was to extend research on the characteristics associated with interest in infants by measuring motivation to view infant faces (Study 1) and visual attention to infants in a complex visual scene (Study 2). In Study 1, participants controlled the length of viewing time for different images. Women demonstrated motivation to extend viewing of infants. Men showed the opposite pattern, working to decrease the length of time they viewed infants. In Study 2, participants were shown complex scenes that contained infants. Patterns of visual attention were measured using eye-tracking technology. Infants did not receive a particularly high proportion of fixations from either sex. However, there were relationships between gender-linked traits, such as digit ratio and self-reported interest in infants, and the percentage of fixations on infants. Additionally, participants who reported being in a romantic relationship demonstrated greater interest in infants. This suggests the long-reported sex difference in interest in infants may relate more to current life circumstances and gender linked traits than an overwhelming tendency among all members of a sex.     

Investigating the link between television viewing and men's preferences for female body size and shape in rural Nicaragua

The different levels of media access in otherwise very similar villages in rural Nicaragua provided a natural laboratory to explore the effect of television (TV) access on men's preferences for female body size and shape. In study 1 we compared the female body ideals of men from three discrete villages who experienced different levels of TV but otherwise inhabited a similar ecological and sociocultural environment. 3D modelling software enabled participants to create their ideal female body with more precision than simply choosing a figure from a limited range of 2D images. In study 2 we further explored local men's perceptions of female physical attractiveness and attitudes towards television using focus group discussions. Results from study 1 showed that men in the high TV villages preferred significantly slimmer bodies compared to those in the low TV village. Regression analyses showed TV access to be a significant predictor of ideal body size and upper body shape, but not of ideal lower body shape. The central theme to emerge from study 2 was the importance of the relationship between lower body shape, movement, and sex in the men's judgments of female attractiveness: the curvaceous body was perceived by the men to be a reliable cue to potential sexual promise, rather than valued simply for its visual aesthetic. Overall, findings suggest that TV access is linked to rural Nicaraguan men's perceptions of ideal female body weight and breast size, but preferences for a curvaceous lower body shape may be driven primarily by judgments of female sexual promise.     

Culture Modulates Eye-Movements to Visual Novelty

Background

When viewing complex scenes, East Asians attend more to contexts whereas Westerners attend more to objects, reflecting cultural differences in holistic and analytic visual processing styles respectively. This eye-tracking study investigated more specific mechanisms and the robustness of these cultural biases in visual processing when salient changes in the objects and backgrounds occur in complex pictures.

Methodology/Principal Findings

Chinese Singaporean (East Asian) and Caucasian US (Western) participants passively viewed pictures containing selectively changing objects and background scenes that strongly captured participants'' attention in a data-driven manner. We found that although participants from both groups responded to object changes in the pictures, there was still evidence for cultural divergence in eye-movements. The number of object fixations in the US participants was more affected by object change than in the Singapore participants. Additionally, despite the picture manipulations, US participants consistently maintained longer durations for both object and background fixations, with eye-movements that generally remained within the focal objects. In contrast, Singapore participants had shorter fixation durations with eye-movements that alternated more between objects and backgrounds.

Conclusions/Significance

The results demonstrate a robust cultural bias in visual processing even when external stimuli draw attention in an opposite manner to the cultural bias. These findings also extend previous studies by revealing more specific, but consistent, effects of culture on the different aspects of visual attention as measured by fixation duration, number of fixations, and saccades between objects and backgrounds.     

Waist-to-hip ratio versus body mass index as predictors of fitness in women

The claim that men prefer women with low waist-to-hip ratios (WHR) has been vigorously disputed. We examine self-report data from 359 primiparous Polish women (with normal singleton births and healthy infants) and show that WHR correlates with at least one component of a woman’s biological fitness (her first child’s birth weight, a variable that significantly affects infant survival rates). However, a woman’s Body Mass Index (BMI) is a better predictor of her child’s neonatal weight in small-bodied women (<54 kg). The failure to find a preference for low WHR in some traditional populations may thus be a consequence of the fact that, even in western populations, body mass is a better predictor of fitness in those cases characterized by low maternal body weight. Boguslaw Pawłowski Ph.D., D.Sc., is a researcher and lecturer in biological anthropology at the University of Wrocław, Poland. His research interests focus on mechanisms of human evolution (with special attention to the evolution of subcutaneous fat tissue distribution) and human mate choice. Robin Dunbar Ph.D., FBA is British Academy Research Professor of Evolutionary Psychology at the University of Liverpool, England, and co-Director of the British Academy Centenary Research Project. His research interests focus on the evolutionary and environmental determinants of social and reproductive strategies, with particular references to humans, nonhuman primates, and ungulates.     

High accumulations of calcium and phosphorus in women’s pubic symphysis

To elucidate compositional changes of the pubic symphysis (PS) by aging, elements of pubic symphyses (PSs) removed from 26 cadavers were determined by inductively coupled plasma atomic-emission spectrometry. It was found that the relative contents (RCs) of calcium and phosphorus in women’s PSs were about three-and five-fold amounts as compared with those in men’s PSs, respectively. In contrast, the RCs of sulfur, magnesium, sodium, and iron in women’s PSs were somewhat lower than those in men’s PSs. The accumulations of calcium (Ca) and phosphorus (P) in women’s PSs occurred mainly beyond the age of 70-yr-old, but did not occur in men’s PSs.     

The role of body fat in female attractiveness

The purpose of the present study was to investigate the role of body fat percentage (BF%) on female attractiveness. To this end, a series of female body images were selected from a collection of dual-energy X-ray absorptiometry scans. Images were stratified by three levels (low, mid, and high) of waist-to-hip ratio (WHR) and seven levels (15%–50%) of BF%. These 21 images were presented in a random order and rated for attractiveness. Results indicate that WHR, BMI, and BF% are all significant predictors of female attractiveness when regressed separately (R²= 0.19, 0.70, and 0.76, respectively). When regressed simultaneously, all three variables accounted for 87% of the variance in image attractiveness, with only BF% and WHR being significant predictors. Further analysis revealed that body fat might disrupt the negative linear relationship between WHR and attractiveness. Men and women differed significantly in most categories of WHR and BF%, with men generally rating images as less attractive than women. These data indicate that BF% appears to be a strong cue for attractiveness and that the impact of WHR and BMI on attractiveness is dependent, in part, on BF%. The appearance of body fat may provide disruption in the visual cues of both shape and size of the female body, potentially impacting behavior.     

Willingness to engage in casual sex

Sexually dimorphic mate selection strategies were examined in 200 university students reporting their willingness to engage in casual sexual encounters with hypothetical individuals of the opposite sex. Using a questionnaire format, the possibility of forming a long-term relationship was manipulated, while risk of disease, pregnancy, and detection was eliminated across all conditions. In addition, potential partners varied in level of attractiveness, and in personality and behavioral characteristics. As expected, men reported a greater anticipated willingness to engage in sexual intercourse across all conditions compared with women. The possibility of forming a long-term relationship elevated women’s, but not men’s, willingness for sexual intercourse. While a potential partner’s attractiveness had a significant positive overall effect on responses, reducing their relative attractiveness had a greater negative impact on men’s responses. Reference to the parental qualities of a potential partner significantly increased women’s, but not men’s, anticipated willingness for sexual intercourse. Describing a hypothetical partner as non-aggressive (safe) marginally increased women’s willingness (p<.09) and did not affect men’s responses. The wording of items relevant to this condition may have resulted in the potential partner sounding "wimpy" rather than nonaggressive, and this may have reduced the expected effect of this manipulation. The possibility that women may trade off personality and behavioral characteristics with attractiveness to a greater degree than men when assessing potential mates is considered.     

Different Visual Preference Patterns in Response to Simple and Complex Dynamic Social Stimuli in Preschool-Aged Children with Autism Spectrum Disorders

Eye-tracking studies in young children with autism spectrum disorder (ASD) have shown a visual attention preference for geometric patterns when viewing paired dynamic social images (DSIs) and dynamic geometric images (DGIs). In the present study, eye-tracking of two different paired presentations of DSIs and DGIs was monitored in a group of 13 children aged 4 to 6 years with ASD and 20 chronologically age-matched typically developing children (TDC). The results indicated that compared with the control group, children with ASD attended significantly less to DSIs showing two or more children playing than to similar DSIs showing a single child. Visual attention preference in 4- to 6-year-old children with ASDs, therefore, appears to be modulated by the type of visual stimuli.     

Where Do Neurologists Look When Viewing Brain CT Images? An Eye-Tracking Study Involving Stroke Cases

The aim of this study was to investigate where neurologists look when they view brain computed tomography (CT) images and to evaluate how they deploy their visual attention by comparing their gaze distribution with saliency maps. Brain CT images showing cerebrovascular accidents were presented to 12 neurologists and 12 control subjects. The subjects' ocular fixation positions were recorded using an eye-tracking device (Eyelink 1000). Heat maps were created based on the eye-fixation patterns of each group and compared between the two groups. The heat maps revealed that the areas on which control subjects frequently fixated often coincided with areas identified as outstanding in saliency maps, while the areas on which neurologists frequently fixated often did not. Dwell time in regions of interest (ROI) was likewise compared between the two groups, revealing that, although dwell time on large lesions was not different between the two groups, dwell time in clinically important areas with low salience was longer in neurologists than in controls. Therefore it appears that neurologists intentionally scan clinically important areas when reading brain CT images showing cerebrovascular accidents. Both neurologists and control subjects used the "bottom-up salience" form of visual attention, although the neurologists more effectively used the "top-down instruction" form.     

Partner Status Influences Women’s Interest in the Opposite Sex

Previous research has demonstrated that hormones, relationship goals, and social context influence interest in the opposite sex. It has not been previously reported, however, whether having a current sexual partner also influences interest in members of the opposite sex. To test this, we obtained explicit and implicit measures of interest by measuring men’s and women’s subjective ratings and response times while they evaluated photos of opposite-sex faces. Fifty-nine men and 56 women rated 510 photos of opposite-sex faces for realism, masculinity, attractiveness, or affect. We found that these subjective ratings were not influenced by partner status in either men or women. However, women who did not report having a current sexual partner spent more time evaluating the photos than women who did have partners, demonstrating greater interest in the photos. Sexual partner status did not predict men’s response times. These findings may reveal that relationship commitment in women suppresses interest in alternative partners.

Age-related changes of bone mineral density in human calcaneus, talus, and scaphoid bone

To examine whether the bone mineral density (BMD) decreases uniformly with aging in any spongy bones, the authors investigated age-related changes of BMD in the calcaneus, talus, and scaphoid bone. After the ordinary dissection by medical students was finished, calcanei, tali, and scaphoid bones were resected from the subjects, and BMDs were measured by dual-energy X-ray absorptiometry. Their BMDs seemed to decrease gradually with aging in the calcanei, tali, and scaphoid bones. It was found that there were statistically significant relationships between age and BMD in the men’s and women’s scaphoid bones, women’s tali, and women’s calcanei, but not in the men’s tali and calcanei. It should be noted that there were significant relationships between age and BMD in both men’s and women’s scaphoid bones. In regard to relationship in BMD between the bones of the upper and lower limbs in individuals, it was found that the relationship between the calcaneus and talus was higher than that between the calcaneus and scaphoid bone. This suggests that there is a higher relationship in BMD between the two tarsal bones compared with that between the tarsal and carpal bones.     

Kinship,Family, and Gender Effects in the Ultimatum Game

Kinship and reciprocity are two main predictors of altruism. The ultimatum game has been used to study altruism in many small-scale societies. We used the ultimatum game to examine effects of individuals’ family and kin relations on altruistic behavior in a kin-based horticultural community in rural Dominica. Results show sex-specific effects of kin on ultimatum game play. Average coefficient of relatedness to the village was negatively associated with women’s ultimatum game proposals and had little effect on men’s proposals. Number of brothers in the village was positively associated with men’s ultimatum game proposals and negatively associated with women’s proposals. Similarly, presence of father in the village was associated with higher proposals by men and lower proposals by women. We interpret the effect of brothers on men’s proposals as a consequence of local competition among brothers. We speculate that daughter-biased parental care in this community creates a sense of entitlement among women with brothers, which may explain the inverse relation between number of brothers and women’s ultimatum game proposals. The pattern of results may be consistent with how matrifocality affects cultural models of fairness differently along gender and family lines.     

BMI not WHR modulates BOLD fMRI responses in a sub-cortical reward network when participants judge the attractiveness of human female bodies

In perceptual terms, the human body is a complex 3d shape which has to be interpreted by the observer to judge its attractiveness. Both body mass and shape have been suggested as strong predictors of female attractiveness. Normally body mass and shape co-vary, and it is difficult to differentiate their separate effects. A recent study suggested that altering body mass does not modulate activity in the reward mechanisms of the brain, but shape does. However, using computer generated female body-shaped greyscale images, based on a Principal Component Analysis of female bodies, we were able to construct images which covary with real female body mass (indexed with BMI) and not with body shape (indexed with WHR), and vice versa. Twelve observers (6 male and 6 female) rated these images for attractiveness during an fMRI study. The attractiveness ratings were correlated with changes in BMI and not WHR. Our primary fMRI results demonstrated that in addition to activation in higher visual areas (such as the extrastriate body area), changing BMI also modulated activity in the caudate nucleus, and other parts of the brain reward system. This shows that BMI, not WHR, modulates reward mechanisms in the brain and we infer that this may have important implications for judgements of ideal body size in eating disordered individuals.     

Visual perception of female physical attractiveness

On the basis of visual assessment of figure drawings and front/profile images, past researchers believed that the waist-hip ratio (WHR) and the body mass index (BMI) were two putative cues to female physical attractiveness. However, this view was not tested on three-dimensional (3D) female images. In the present study, 3D images of 31 Caucasian females having varying body weights (BMI ranged from 16 to 35) were shown to 29 male and 25 female viewers, who were asked to rate the physical attractiveness. The results showed that the body volume divided by the square of the height, defined as volume height index (VHI), is the most important and direct visual determinant of female physical attractiveness. In determining the female attractiveness, human observers may first use VHI as a visual cue, which is also a key indicator of health and fertility owing to its strong linear relation to BMI. To fine-tune the judgement, observers may then use body proportions, the most important of which are the ratio of waist height over the chin height (WHC) (a measure of the length of legs over total tallness) and the deviation of WHR from the ideal ratio. It also appears that the effect of the body's physical parameters on the perception of female physical attractiveness conforms to Stevens' power law of psychophysics.     

Men’s reproductive investment decisions

Using questionnaire data completed by 170 men, we examine variation in paternal investment in relation to the trade-off between mating and parenting. We found that as men’s self-perceived mate value increases, so does their mating effort, and in turn, as mating effort increases, paternal investment decreases. This study also simultaneously examined the influence on parental investment of men’s mating effort, men’s perception of their mates’ fidelity, and their perceived resemblance to their offspring. All predicted investment. The predictors of investment are also tested independently for men who are still in a relationship with the mother of their children and those that are separated from her. Finally we examine how self-perceived mate value affects how men respond to variation in paternity confidence. Men with a self-perceived low mate value were less likely to respond to lowered mate fidelity by reducing their parental investment compared with men with a self-perceived high mate value.     

Loneliness and Hypervigilance to Social Cues in Females: An Eye-Tracking Study

The goal of the present study was to examine whether lonely individuals differ from nonlonely individuals in their overt visual attention to social cues. Previous studies showed that loneliness was related to biased post-attentive processing of social cues (e.g., negative interpretation bias), but research on whether lonely and nonlonely individuals also show differences in an earlier information processing stage (gazing behavior) is very limited. A sample of 25 lonely and 25 nonlonely students took part in an eye-tracking study consisting of four tasks. We measured gazing (duration, number of fixations and first fixation) at the eyes, nose and mouth region of faces expressing emotions (Task 1), at emotion quadrants (anger, fear, happiness and neutral expression) (Task 2), at quadrants with positive and negative social and nonsocial images (Task 3), and at the facial area of actors in video clips with positive and negative content (Task 4). In general, participants tended to gaze most often and longest at areas that conveyed most social information, such as the eye region of the face (T1), and social images (T3). Participants gazed most often and longest at happy faces (T2) in still images, and more often and longer at the facial area in negative than in positive video clips (T4). No differences occurred between lonely and nonlonely participants in their gazing times and frequencies, nor at first fixations at social cues in the four different tasks. Based on this study, we found no evidence that overt visual attention to social cues differs between lonely and nonlonely individuals. This implies that biases in social information processing of lonely individuals may be limited to other phases of social information processing. Alternatively, biased overt attention to social cues may only occur under specific conditions, for specific stimuli or for specific lonely individuals.     

Preferred Women’s Waist-to-Hip Ratio Variation over the Last 2,500 Years

The ratio between the body circumference at the waist and the hips (or WHR) is a secondary sexual trait that is unique to humans and is well known to influence men’s mate preferences. Because a woman''s WHR also provides information about her age, health and fertility, men''s preference concerning this physical feature may possibly be a cognitive adaptation selected in the human lineage. However, it is unclear whether the preferred WHR in western countries reflects a universal ideal, as geographic variation in non-western areas has been found, and discordances about its temporal consistency remain in the literature. We analyzed the WHR of women considered as ideally beautiful who were depicted in western artworks from 500 BCE to the present. These vestiges of the past feminine ideal were then compared to more recent symbols of beauty: Playboy models and winners of several Miss pageants from 1920 to 2014. We found that the ideal WHR has changed over time in western societies: it was constant during almost a millennium in antiquity (from 500 BCE to 400 CE) and has decreased from the 15^th century to the present. Then, based on Playboy models and Miss pageants winners, this decrease appears to slow down or even reverse during the second half of the 20^th century. The universality of an ideal WHR is thus challenged, and historical changes in western societies could have caused these variations in men’s preferences. The potential adaptive explanations for these results are discussed.