Fabian Probst

Preference for Cute Infants Does Not Depend on Their Ethnicity or Species: Evidence from Hypothetical Adoption and Donation Paradigms

Results of previous work suggest a preference of adult observers for cute compared to less cute infants. In Study 1 we investigated whether the preference for cute infants depends on the ethnicity and species of the infant. We simultaneously presented two faces (one cute and one less cute) and asked Caucasian participants to choose the infant to whom they would rather give a toy (Task 1) and which infant they would rather adopt (Task 2). The infants were Caucasian or African human babies or dog puppies. For all face categories and in both tasks we found a strong preference for cute infants. A possible reason for preferring cute infants may be that cute infants look healthier than less cute infants. To investigate whether cuteness is associated with the assessment of health we conducted Study 2. Faces of Caucasian and African infants and dog puppies were rated for cuteness and health. The findings revealed a significant relationship between health and cuteness evaluation across all stimuli. We suggest that one reason why cute infants are preferred might be because they are perceived as being healthier.

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 womens 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.

Testosterone-to-oestradiol ratio is associated with female facial attractiveness

The relationship between facial shape and attractiveness has been extensively studied, yet few studies have investigated the underlying biological factors of an attractive face. Many researchers have proposed a link between female attractiveness and sex hormones, but there is little empirical evidence in support of this assumption. In the present study we investigated the relationship between circulating sex hormones and attractiveness. We created prototypes by separately averaging photographs of 15 women with high and low levels of testosterone, oestradiol, and testosterone-to-oestradiol ratio levels, respectively. An independent set of facial images was then shape transformed toward these prototypes. We paired the resulting images in such a way that one face depicted a female with high hormone level and the other one with a low hormone level. Fifty participants were asked to choose the more attractive face of each pair. We found that low testosterone-to-oestradiol ratio and low testosterone were positively associated with female facial attractiveness. There was no preference for faces with high oestradiol levels. In an additional experiment with 36 participants we confirmed that a low testosterone-to-oestradiol ratio plays a larger role than low testosterone alone. These results provide empirical evidence that an attractive female face is shaped by interacting effects of testosterone and oestradiol.

Men's preferences for women's body odours are not associated with human leucocyte antigen

Body odours reportedly portray information about an individuals genotype at the major histocompatibility complex (MHC, called human leucocyte antigen, HLA, in humans). While there is strong experimental support for MHC-associated mating behaviour in animals, the situation in humans is more complex. A lot of effort has been spent on testing HLA-associated odour preferences of women. To date, only very few studies have looked at HLA-linked olfactory preferences in men and these studies have revealed inconsistent results. Here, we investigate mens HLA-associated preferences for womens body odours. Importantly, and in contrast to previous studies, these odours were gathered at peak fertility (i.e. just before ovulation) when any HLA-associated odour preferences should be strongest. We scrutinized whether mens preference for womens body odours is influenced by (i) the number of shared HLA alleles between men and women, (ii) HLA heterozygosity, and (iii) the frequency of rare HLA alleles. We found that men could readily differentiate between odours they found attractive and odours they found less attractive, but that these preferences were not associated with HLA. Specifically, men did not prefer odours from women who are HLA dissimilar, HLA heterozygous, or who have rare HLA alleles. Together, these findings suggest that HLA has no effect on mens odour preferences.

Can women detect cues to ovulation in other women's faces?

Recent research suggests that men find portraits of ovulatory women more attractive than photographs of the same women taken during the luteal phase. Only few studies have investigated whether the same is true for women. The ovulatory phase matters to men because women around ovulation are most likely to conceive, and might matter to women because fertile women might pose a reproductive threat. In an online study 160 women were shown face pairs, one of which was assimilated to the shape of a late follicular prototype and the other to a luteal prototype, and were asked to indicate which face they found more attractive. A further 60 women were tested in the laboratory using a similar procedure. In addition to choosing the more attractive face, these participants were asked which woman would be more likely to steal their own date. Because gonadal hormones influence competitive behaviour, we also examined whether oestradiol, testosterone and progesterone levels predict womens choices. The women found neither the late follicular nor the luteal version more attractive. However, naturally cycling women with higher oestradiol levels were more likely to choose the ovulatory woman as the one who would entice their date than women with lower oestradiol levels. These results imply a role of oestradiol when evaluating other women who are competing for reproduction.

Reactive aggression tracks within‐participant changes in women's salivary testosterone

The relation between testosterone and aggression has been relatively well documented in men, but it is less well understood in women. Here we assessed the relationship between salivary testosterone and reactive aggression (i.e., rejection rate for unfair offers) in the Ultimatum Game. Forty naturally cycling women were tested twice, once in the late follicular phase (around ovulation) and once during the luteal phase. Ovulation was determined using urine test strips measuring luteinizing hormone levels. Salivary samples were assayed for testosterone, estradiol, progesterone, and cortisol at both test sessions. There was no association with the cycle, but multilevel modeling revealed a significant within-participant association between testosterone and rejection rate for extremely unfair offers (i.e., high reactive aggression), indicating that women showed greater reactive aggression when their testosterone levels were higher. Additionally, we found that women with relatively high individual concentrations of testosterone were more likely to reject extremely unfair offers than women with relatively low concentrations of testosterone. This study is the first to demonstrate that women react more aggressively in response to provocation when their testosterone level is high than when their testosterone is low, suggesting that testosterone plays an important role in the regulation of womens aggressive behavior following social provocation.

Do women tend while men fight or flee? Differential emotive reactions of stressed men and women while viewing newborn infants

Infant care often is carried out under stressful circumstances. Little is known about differences in caretaking motivation between men and women under stress. In the present study, stress was induced in 40 participants (21 women, 19 men) by means of the cold pressor stress test, 40 (22 women, 18 men) serving as controls. Participants then rated their urge to care for newborn infants shown on 20 short video clips. The infants in the videos were either crying (N=10) or were showing typical neonatal facial movements (N=10). Skin conductance was obtained while participants viewed the videos and salivary cortisol was measured to capture stress responses. We found sex differences in caretaking motivation, such that stress led to decreased caretaking motivation in men but not in women. Furthermore, stressed men elicited a stronger skin conductance change while viewing infant videos than stressed women. These findings provide further evidence for differential stress reactions in men and women and may have crucial implications for parental care.

Accumulating evidence suggests that men do not find body odours of human leucocyte antigen-dissimilar women more attractive

In our recent study published in Proceedings of the Royal Society B [1], we investigated the effects of major histocompatibility complex (MHC; or human leucocyte antigen system, HLA in humans) on mens preferences for womens body odours. Using rigorous methods, we found no evidence that men find body odours of HLA-dissimilar women more attractive than odours of HLA-similar women. In his comment, Wedekind [2] claims that our conclusions were premature, because he found (using our data) a stronger negative relationship between pleasantness and intensity for HLA-dissimilar odours than for similar ones. Although this is an interesting finding, it cannot be considered as a support for HLA-related mate preferences. Wedekinds comment is rather misleading, for various reasons. First, empirical evidence for HLA-mediated body odour preferences in humans is not nearly as clear as the author would like to assume. In the 20 years since Wedekind et al .s seminal work [3], various studies examining HLA-influences on body odour preferences in humans have been published and the reported findings are mixed. In fact, a recent meta-analysis by Winternitz, Abbate [4] revealed that over all studies with human and non-human primates, results on MHC-mediated body odour preferences are inconsistent and non-significant. It is important to note that Wedekind [2] misinterprets the meta-analysis by Winternitz et al . [4]: These authors found preferences for MHC heterozygosity but not for …

Reactive aggression tracks within-participant changes in women's salivary testosterone

Correspondence concerning this article should be addressed to: Janek Lobmaier, University of Bern, Institute of Psychology, Fabrikstrasse 8, 3012 Bern, Switzerland. Email: janek.lobmaier@psy.unibe.ch; Telephone: +41 (0)31 631 40 24. Acknowledgments This study was supported by a grant from the Swiss National Science Foundation awarded to JL (grant number PP00P1_139072/1). The authors declare no conflict of interest.

Men's preferences for women's body odours are not associated with HLA

Objective: Body odours allegedly portray information about an individuals genotype at the major histocompatibility complex (MHC, called HLA in humans). While there is strong experimental support for MHC-associated mating behaviour in animals, the situation in humans is more complex. Previous studies have suggested that women prefer the scent of men with dissimilar HLA to their own. To date only very few studies have looked at HLA-linked olfactory preferences in men and these studies have revealed inconsistent results. Here we investigate mens HLA-associated preferences for womens body odours. Methods: In contrast to previous studies, body odours were gathered at peak fertility (i.e., just before ovulation) when any HLA-associated odour preferences should be strongest. We scrutinized whether mens preference for womens body odours is modulated by (1) the number of shared HLA alleles between men and women, (2) HLA heterozygosity, and (3) the frequency of rare HLA alleles. Results: We found that men could readily differentiate between odours they found attractive and odours they found less attractive, but that these preferences were not associated with HLA. Specifically, men did not prefer odours from women who are HLA dissimilar, HLA heterozygous, or who have rare HLA alleles. Conclusions: Despite adopting rigorous methodology and a large sample size, we found no evidence that men prefer odours from women who are MHC dissimilar, MHC heterozygous, or who have rare MHC alleles. Together, these findings suggest that HLA has no effect on mens mate preferences.