Pathogen disgust sensitivity changes according to the perceived harshness of the environment.

Much research has explored behaviours that are linked with disgust sensitivity. Few studies, however, have been devoted to understanding how fixed or variable disgust sensitivity is. We therefore aimed to examine whether disgust sensitivity can change with the environment by repeatedly testing students whose environment was not changing as well as student cadets undergoing intensive training at an army camp. We found that an increase in the perceived harshness of the environment was associated with a decrease in pathogen disgust sensitivity. Our results support the idea that disgust sensitivity is malleable depending on the environment. More specifically, we propose that in a harsh environment, where survival may be more difficult, pathogen disgust sensitivity may decrease to allow the consumption of available resources.

The Value of Averageness in Aesthetic Rhinoplasty: Humans Like Average Noses.

BACKGROUND: The aesthetic ideal of the nose eludes clear definition. Averageness may be an important determinant of ideal nasal shape: research has shown that averageness plays an important role in the human perception of facial attractiveness. OBJECTIVES: The aim of this study was to test whether an averaged nasal shape is attractive, and whether deviation away from average is associated with decreased attractiveness. METHODS: Photographic series of the face were obtained from 80 Caucasian female volunteers aged 25-40 years. A mathematically averaged composite image was created from the first 40 volunteers. Forty-one panel members were recruited to judge the attractiveness of the nose of each original image and the composite, based on a 5-point Likert scale ranging from 1 (very ugly) to 5 (very pretty). Deviation of nasal shape from average was calculated by principal components analysis of standardized nasal landmarks. RESULTS: Twenty-one respondents were male (51%). The mean age of the respondents was 35.3 [15.6] years. The rating of the composite was significantly higher than the distribution of ratings for the 80 original nose images (4.2 vs 2.8, t = 31.24, P < 0.001). The rating of the original nose images correlated negatively with deviation from average shape (r = -0.40, n = 80, P < 0.001). CONCLUSIONS: In Caucasian females, a mathematically averaged nose is an attractive nose. Furthermore, the more an individual nose shape resembles the average shape, the more attractive it is rated. Calculating deviation from average before and after rhinoplasty may aid in objectively measuring aesthetic rhinoplasty outcome.

The effect of sleep deprivation on objective and subjective measures of facial appearance.

The faces of people who are sleep deprived are perceived by others as looking paler, less healthy and less attractive compared to when well rested. However, there is little research using objective measures to investigate sleep-loss-related changes in facial appearance. We aimed to assess the effects of sleep deprivation on skin colour, eye openness, mouth curvature and periorbital darkness using objective measures, as well as to replicate previous findings for subjective ratings. We also investigated the extent to which these facial features predicted ratings of fatigue by others and could be used to classify the sleep condition of the person. Subjects (n = 181) were randomised to one night of total sleep deprivation or a night of normal sleep (8-9 hr in bed). The following day facial photographs were taken and, in a subset (n = 141), skin colour was measured using spectrophotometry. A separate set of participants (n = 63) later rated the photographs in terms of health, paleness and fatigue. The photographs were also digitally analysed with respect to eye openness, mouth curvature and periorbital darkness. The results showed that neither sleep deprivation nor the subjects' sleepiness was related to differences in any facial variable. Similarly, there was no difference in subjective ratings between the groups. Decreased skin yellowness, less eye openness, downward mouth curvature and periorbital darkness all predicted increased fatigue ratings by others. However, the combination of appearance variables could not be accurately used to classify sleep condition. These findings have implications for both face-to-face and computerised visual assessment of sleep loss and fatigue.

A Web-Based Photo-Alteration Intervention to Promote Sleep: Randomized Controlled Trial.

BACKGROUND: Receiving insufficient sleep has wide-ranging consequences for health and well-being. Although educational programs have been developed to promote sleep, these have had limited success in extending sleep duration. To address this gap, we developed a Web-based program emphasizing how physical appearances change with varying amounts of sleep. OBJECTIVE: The aims of this study were to evaluate (1) whether participants can detect changes in appearances as a function of sleep and (2) whether this intervention can alter habitual sleep patterns. METHODS: We conducted a 5-week, parallel-group, randomized controlled trial among 70 habitual short sleepers (healthy adults who reported having <7 hours of sleep routinely). Upon study enrollment, participants were randomly assigned (1:1) to receive either standard information or an appearance-based intervention. Both groups received educational materials about sleep, but those in the appearance group also viewed a website containing digitally edited photographs that showed how they would look with varying amounts of sleep. As the outcome variables, sleep duration was monitored objectively via actigraphy (at baseline and at postintervention weeks 1 and 4), and participants completed a measure of sleep hygiene (at baseline and at postintervention weeks 2, 4, and 5). For each outcome, we ran intention-to-treat analyses using linear mixed-effects models. RESULTS: In total, 35 participants were assigned to each group. Validating the intervention, participants in the appearance group (1) were able to identify what they looked like at baseline and (2) judged that they would look more attractive with a longer sleep duration (t26=10.35, P<.001). In turn, this translated to changes in sleep hygiene. Whereas participants in the appearance group showed improvements following the intervention (F1,107.99=9.05, P=.003), those in the information group did not (F1,84.7=0.19, P=.66). Finally, there was no significant effect of group nor interaction of group and time on actigraphy-measured sleep duration (smallest P=.26). CONCLUSIONS: Our findings suggest that an appearance-based intervention, while not sufficient as a stand-alone, could have an adjunctive role in sleep promotion. TRIAL REGISTRATION: ClinicalTrials.gov NCT02491138; https://clinicaltrials.gov/ct2/show/study/NCT02491138.

Do Masculine Men Smell Better? An Association Between Skin Color Masculinity and Female Preferences for Body Odor.

A recent study claimed face skin color as a sexually dimorphic variable that influences attractiveness preferences in mate choice. Thereby, skin color may assume the role of a mate quality signal influencing attractiveness preferences. As body odor is linked to attractiveness, this study aimed to explore whether the odors of men with more masculine facial skin color would be evaluated more positively than odors from less masculine men. Female raters were presented with body odors of 18 men and were asked to rate them in various characteristics. Multilevel modeling revealed that the odors of the donors with more masculine color were rated not only as more attractive, more pleasant, and sexier, but also healthier. This indicates that odor associated with men with more masculine skin color is attractive, just as other sexually dimorphic traits. Furthermore, we found a negative relation between skin color masculinity and perceived odor maleness. Regarding this last finding, a new discussion is introduced with respect to the influence of cognitive stereotypes in odor judgments. Altogether, the study supports the possibility that chemosensory signals may be communicating signs of mate quality associated with masculinity.

Skin colour changes during experimentally-induced sickness.

Skin colour may be an important cue to detect sickness in humans but how skin colour changes with acute sickness is currently unknown. To determine possible colour changes, 22 healthy Caucasian participants were injected twice, once with lipopolysaccharide (LPS, at a dose of 2ng/kg body weight) and once with placebo (saline), in a randomised cross-over design study. Skin colour across 3 arm and 3 face locations was recorded spectrophotometrically over a period of 8h in terms of lightness (L∗), redness (a∗) and yellowness (b∗) in a manner that is consistent with human colour perception. In addition, carotenoid status was assessed as we predicted that a decrease it skin yellowness would reflect a drop in skin carotenoids. We found an early change in skin colouration 1-3h post LPS injection with facial skin becoming lighter and less red whilst arm skin become darker but also less red and less yellow. The LPS injection also caused a drop in plasma carotenoids from 3h onwards. However, the timing of the carotenoid changes was not consistent with the skin colour changes suggesting that other mechanisms, such as a reduction of blood perfusion, oxygenation or composition. This is the first experimental study characterising skin colour associated with acute illness, and shows that changes occur early in the development of the sickness response. Colour changes may serve as a cue to health, prompting actions from others in terms of care-giving or disease avoidance. Specific mechanisms underlying these colour changes require further investigation.

Facial Redness Increases Men's Perceived Healthiness and Attractiveness.

Past research has shown that peripheral and facial redness influences perceptions of attractiveness for men viewing women. The current research investigated whether a parallel effect is present when women rate men with varying facial redness. In four experiments, women judged the attractiveness of men's faces, which were presented with varying degrees of redness. We also examined perceived healthiness and other candidate variables as mediators of the red-attractiveness effect. The results show that facial redness positively influences ratings of men's attractiveness. Additionally, perceived healthiness was documented as a mediator of this effect, independent of other potential mediator variables. The current research emphasizes facial coloration as an important feature of social judgments.

Women's Facial Redness Increases Their Perceived Attractiveness: Mediation Through Perceived Healthiness.

In the present research, we investigated whether the red-attraction relation that has been observed for men viewing women may also be observed with regard to women's facial redness. We manipulated facial redness by slightly increasing or decreasing the redness on the faces of baseline pictures of target women, and then had men judge the attractiveness of the women. We also examined healthiness perceptions as a mediator of the redness-attraction relation, along with several other candidate mediator variables. A series of experiments showed that increased redness led to increased ratings of attractiveness, and decreased redness led to decreased ratings of attractiveness. Perceived healthiness was documented as a mediator of the influence of female facial redness on male perceptions of attractiveness, and this mediation was independent of other candidate mediator variables. The findings highlight the importance of attending to facial coloration as an attraction-relevant cue and point to interesting areas for subsequent research.

Menstrual cycle phase affects discrimination of infant cuteness.

Recent studies have shown that women are more sensitive than men to subtle cuteness differences in infant faces. It has been suggested that raised levels in estradiol and progesterone may be responsible for this advantage. We compared young women's sensitivity to computer-manipulated baby faces varying in cuteness. Thirty-six women were tested once during ovulation and once during the luteal phase of their menstrual cycle. In a two alternative forced-choice experiment, participants chose the baby which they thought was cuter (Task 1), younger (Task 2), or the baby that they would prefer to babysit (Task 3). Saliva samples to assess levels of estradiol, progesterone and testosterone were collected at each test session. During ovulation, women were more likely to choose the cuter baby than during the luteal phase, in all three tasks. These results suggest that cuteness discrimination may be driven by cyclic hormonal shifts. However none of the measured hormones were related to increased cuteness sensitivity. We speculate that other hormones than the ones measured here might be responsible for the increased sensitivity to subtle cuteness differences during ovulation.

Judging a man by the width of his face: the role of facial ratios and dominance in mate choice at speed-dating events.

Previous research has shown that men with higher facial width-to-height ratios (fWHRs) have higher testosterone and are more aggressive, more powerful, and more financially successful. We tested whether they are also more attractive to women in the ecologically valid mating context of speed dating. Men's fWHR was positively associated with their perceived dominance, likelihood of being chosen for a second date, and attractiveness to women for short-term, but not long-term, relationships. Perceived dominance (by itself and through physical attractiveness) mediated the relationship between fWHR and attractiveness to women for short-term relationships. Furthermore, men's perceptions of their own dominance showed patterns of association with mating desirability similar to those of fWHR. These results support the idea that fWHR is a physical marker of dominance. This is the first study to show that male dominance and higher fWHRs are attractive to women for short-term relationships in a controlled and interactive situation that could actually lead to mating and dating.

Hebbian Learning is about contingency, not contiguity, and explains the emergence of predictive mirror neurons.

Hebbian Learning should not be reduced to contiguity, as it detects contingency and causality. Hebbian Learning accounts of mirror neurons make predictions that differ from associative learning: Through Hebbian Learning, mirror neurons become dynamic networks that calculate predictions and prediction errors and relate to ideomotor theories. The social force of imitation is important for mirror neuron emergence and suggests canalization.

Father absence and age at first birth in a Western sample.

OBJECTIVES: Although a large literature has shown links between "father absence" during early childhood, and earlier puberty and sexual behavior in girls in Western populations, there are only a few studies which have looked at timing of reproduction, and only one of these fully incorporated childless respondents to investigate whether father absence is associated with increased hazard of becoming a parent at one time point (early) more than another. Here we sought to clarify exactly when, if at all, father absence increased the likelihood of first birth in a Western sample. METHODS: An online sample of 954 women reported on their childhood living circumstances, their age of menarche, first coitus, first pregnancy, and first birth. RESULTS: Cox regression and Kaplan-Meier plots showed an increased risk of becoming a parent for father absent women in their 20s, but no overall greater likelihood of parenthood. CONCLUSION: These data support the suggestion that father absence is associated with an acceleration of reproductive behavior in Western samples, rather than a simple increase in likelihood of reproduction.

When he smiles: Attractiveness preferences for male faces expressing emotions.

The impact of sexual dimorphism on facial attractiveness has been controversial owing to contradictory results, particularly in studies on female preferences. Given that sexually dimorphic facial features, especially more masculine ones, have been previously related to the perception of anger, we investigated the bi-directional influence of emotional expressions and facial masculinity and explored their impact on women's preferences for facial masculinity. We confirmed the effect of facial sexual dimorphism on the perception of emotional cues (happiness and anger) and explored whether smiling or angry expressions influence women's perception of masculinity in male faces. Additionally, we examined women's preferences for emotionally expressive male faces altered along a continuum of masculinity. The results showed that masculinised faces are perceived as angrier, while feminised faces are perceived as happier (Experiment 1), and that angry faces are perceived as more masculine when compared with happy faces (Experiment 2). It is noteworthy that our Experiment 3 uncovered a pivotal finding: women prefer reduced feminisation in happy faces compared with neutral/angry faces. This suggests that the avoidance response observed towards masculinity is attenuated by a smiling expression. The current study introduces a new perspective to be considered when exploring the role of facial masculinity in women's attractiveness preferences.

Maternal tendencies in women are associated with estrogen levels and facial femininity.

Previous studies have shown that women with higher maternal tendencies are shorter and have lower testosterone levels than those with lower maternal tendencies. Here we report two studies that investigated the relationships between maternal tendencies and two further measures of physical masculinization/feminization; urinary estrogen metabolite (estrone-3-glucuronide: E1-3G) levels (Study 1) and rated facial femininity (Study 2). In Study 1, nulliparous women reported both their ideal number of children and ideal own age at first child and also provided urine samples. There was a significant positive correlation between measured late-follicular estrogen levels and reported ideal number of children. In Study 2, analyses of facial cues in two independent samples of women showed that the average facial characteristics of women who reported desiring many children were rated as more feminine than those desiring fewer children. Collectively, these results support the proposal that maternal tendencies are related to physical feminization and that this effect may, at least in part, reflect the influence of the hormone estrogen.

Appealing to vanity: could potential appearance improvement motivate fruit and vegetable consumption?

Fruit and vegetable consumption is inadequate among adults in the United States; this contributes to preventable morbidity and mortality. More effective dietary intervention strategies are needed. Recently, interventions that advertise the consequences of behavior for appearance have been successful in modifying sun-exposure habits and tobacco use. Such an approach might also facilitate dietary improvement. Consumption of carotenoid-rich fruit and vegetables positively affects skin color, which influences perceptions of health and attractiveness, and promoting such an effect may motivate target audiences to increase consumption of this important food group. This approach represents a novel direction for the field and is potentially suitable for cost-effective, population-level dissemination through the visual media.

Hot or not? Thermal reactions to social contact.

Previous studies using thermal imaging have suggested that face and body temperature increase during periods of sexual arousal. Additionally, facial skin temperature changes are associated with other forms of emotional arousal, including fear and stress. This study investigated whether interpersonal social contact can elicit facial temperature changes. Study 1: infrared images were taken during a standardized interaction with a same- and opposite-sex experimenter using skin contact in a number of potentially high-intimate (face and chest) and low-intimate (arm and palm) locations. Facial skin temperatures significantly increased from baseline during the face and chest contact, and these temperature shifts were larger when contact was made by an opposite-sex experimenter. Study 2: the topography of facial temperature change was investigated in five regions: forehead, periorbital, nose, mouth and cheeks. Increased temperature in the periorbital, nose and mouth regions predicted overall facial temperature shifts to social contact. Our findings demonstrate skin temperature changes are a sensitive index of arousal during interpersonal interactions.

How head posture affects perceived cooperativeness: A cross-cultural perspective.

Previous research has tested whether culture moderates the relationship between head tilt and perceptions of a cooperation-relevant construct. In this paper, we replicated the effects of head posture on perceived traits and compared Chinese and American participants to explore whether difference in cultural background (collectivist and individualist) affects perceptual attribution. Specifically, we investigated how head posture (level, up or down) affects perceptions of cooperativeness. In Experiment 1, Chinese and American participants rated Asian and Caucasian faces in three postures for perceived cooperativeness on a seven-point Likert scale. In Experiment 2, participants ranked the cooperativeness of the three postures of the same faces. In Experiment 3, participants scrolled through face images and manually manipulated vertical head angle to maximise apparent cooperativeness. We found that for both Chinese and American participants a neutral head level posture was perceived as more cooperative than head up and down postures. The optimal head posture for maximised apparent cooperativeness was close to level but with a slight downward rotation. While there was cross-cultural consistency in perceptions, Chinese participants exhibited greater sensitivity to postural cues in their judgments of cooperation compared to American participants. Our results suggest a profound effect of posture on the perception of cooperativeness that is common across cultures and that there are additional subtle cross-cultural differences in the cues to cooperativeness.

Implied motion activation in cortical area MT can be explained by visual low-level features.

To investigate form-related activity in motion-sensitive cortical areas, we recorded cell responses to animate implied motion in macaque middle temporal (MT) and medial superior temporal (MST) cortex and investigated these areas using fMRI in humans. In the single-cell studies, we compared responses with static images of human or monkey figures walking or running left or right with responses to the same human and monkey figures standing or sitting still. We also investigated whether the view of the animate figure (facing left or right) that elicited the highest response was correlated with the preferred direction for moving random dot patterns. First, figures were presented inside the cell's receptive field. Subsequently, figures were presented at the fovea while a dynamic noise pattern was presented at the cell's receptive field location. The results show that MT neurons did not discriminate between figures on the basis of the implied motion content. Instead, response preferences for implied motion correlated with preferences for low-level visual features such as orientation and size. No correlation was found between the preferred view of figures implying motion and the preferred direction for moving random dot patterns. Similar findings were obtained in a smaller population of MST cortical neurons. Testing human MT+ responses with fMRI further corroborated the notion that low-level stimulus features might explain implied motion activation in human MT+. Together, these results suggest that prior human imaging studies demonstrating animate implied motion processing in area MT+ can be best explained by sensitivity for low-level features rather than sensitivity for the motion implied by animate figures.

The world smiles at me: self-referential positivity bias when interpreting direction of attention.

Recent research suggests that eye-gaze direction modulates perceived emotional expression. Here we explore the extent to which emotion affects interpretation of attention direction. We captured three-dimensional face models of 8 actors expressing happy, fearful, angry and neutral emotions. From these 3D models 9 views were extracted (0°, 2°, 4°, 6°, 8° to the left and right). These stimuli were randomly presented for 150 ms. Using a forced-choice paradigm 28 participants judged for each face whether or not it was attending to them. Two conditions were tested: either the whole face was visible, or the eyes were covered. In both conditions happy faces elicited most "attending-to-me" answers. Thus, emotional expression has a more general effect than an influence on gaze direction: emotion affects interpretation of attention direction. We interpret these results as a self-referential positivity bias, suggesting a general preference to associate a happy face with the self.