X and Y
Andrew Whitehouse, Murray Maybery, Roger Hart, Eugen Mattes, John Newnham, Deborah Sloboda, Fiona Stanley & Martha Hickey
Psychoneuroendocrinology, September 2010, Pages 1259-1264
Abstract:
Prenatal exposure to testosterone has been shown to affect fetal brain maturation as well as postnatal cognition and behavior in animal studies. Although there are well-established sex-differences in the use of social communication (or ‘pragmatic language') in humans, there has been limited investigation of the association between fetal testosterone exposure and postnatal pragmatic language ability. In this prospective study, pragmatic language skills, assessed using a pragmatic language score (PLS), were measured in 78 girls aged 10 years and correlated with testosterone levels in umbilical cord blood. A measure of the biologically active, ‘free' fraction of testosterone, the free androgen index (FAI), was positively correlated with the PLS (R = .3). Regression analyses showed that the FAI was a significant, positive predictor of pragmatic language difficulties in girls after controlling for maternal and infant-health variables (B = 0.02, 95% confidence interval = 0.01-0.04, p = 0.02). This is the first prospective study to identify an association between early life testosterone exposure and pragmatic language difficulties in girls. These novel findings are discussed with reference to the ‘extreme male-brain' theory of autism.
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Women's voice pitch is negatively correlated with health risk factors
Jovana Vukovic, David Feinberg, Lisa DeBruine, Finlay Smith & Benedict Jones
Journal of Evolutionary Psychology, September 2010, Pages 217-225
Abstract:
Previous studies have demonstrated that men prefer women's voices with relatively high pitch to those with low pitch, suggesting that men may use voice pitch as a cue of women's mate quality. However, evidence that voice pitch is a cue to women's long-term health is equivocal. Here we present evidence that women's average speaking voice pitch is negatively correlated with a health risk index derived from principle component analysis of various body measurements that are known to predict long-term health outcomes in women (weight, body mass index, percentage body fat, waist and hip circumference, and waist-hip ratio). Our results suggest that voice pitch is a cue to women's long-term health, supporting mate-choice accounts of men's preferences for raised pitch in women's voices.
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Digit ratio (2D:4D), academic performance in computer science and computer-related anxiety
Mark Brosnan, Victoria Gallop, Nida Iftikhar & Edmund Keogh
Personality and Individual Differences, forthcoming
Abstract:
Being able to use information communication technology (ICT) effectively has become an essential element of participation within an increasingly digital culture. However, there are differences in participation within this digital culture. Prenatal testosterone exposure is thought to influence the development of numeric capabilities and relate to levels of anxiety, both of which contribute towards engagement with ICT. This study examined whether an index of prenatal exposure to testosterone, digit ratio (2D:4D), is related to successful involvement within a computer-technology context - performance in a Java programming course. Three studies (N = 73,75,65) identified a consistent negative correlation between 2D:4D digit ratio and attainment (r ≈ -0.2). A fourth study (N = 119) found that 2D:4D digit ratio positively correlated with two indices of computer-related anxieties, as well as anxiety sensitivity (r = 0.32/0.51). These results suggest that males and females who have been exposed to higher levels of testosterone within the womb perform better upon academic assessments of Java-related programming ability within computer science education, and have lower levels of computer-related anxieties outside computer science education. Thus, the 2D:4D index of prenatal testosterone exposure correlated with the two factors that directly impact upon ICT engagement, which is increasingly essential to effectively participate within educational and occupational environments.
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Can buy me love: Mate attraction goals lead to perceptual readiness for status products
Kim Janssens, Mario Pandelaere, Bram Van den Bergh, Kobe Millet, Inge Lensa & Keith Roe
Journal of Experimental Social Psychology, forthcoming
Abstract:
Exposure to mating cues activates the goal to signal one's mate value to members of the opposite sex. This mate attraction goal may render men perceptually ready for products that signal their mate value to women. As men's mate value is partly determined by their financial prospects, men may be more likely to notice products that would signal their financial resources to women. The current study demonstrates that exposure to a sexily dressed woman increases single men's likelihood of noticing status products in a visual display. Not only do these findings further support the link between conspicuous consumption and male mating strategies, they are the first to demonstrate perceptual readiness for indirect (i.e., products) rather than direct (i.e., opposite sex individuals) means for reproduction.
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Arginine Vasopressin selectively enhances recognition of sexual cues in male humans
Adam Guastella, Amanda Kenyon, Christian Unkelbach, Gail Alvares & Ian Hickie
Psychoneuroendocrinology, forthcoming
Abstract:
Arginine Vasopressin modulates complex social and sexual behavior by enhancing social recognition, pair bonding, and aggression in non-human mammals. The influence of Arginine Vasopressin in human social and sexual behavior is, however, yet to be fully understood. We evaluated whether Arginine Vasopressin nasal spray facilitated recognition of positive and negative social and sexual stimuli over non-social stimuli. We used a recognition task that has already been shown to be sensitive to the influence of Oxytocin nasal spray (Unkelbach et al., 2008). In a double-blind, randomized, placebo-controlled, between-subjects design, 41 healthy male volunteers were administered Arginine Vasopressin (20 IU) or a placebo nasal spray after a 45 min wait period and then completed the recognition task. Results showed that the participants administered Arginine Vasopressin nasal spray were faster to detect sexual words over other types of words. This effect appeared for both positively and negatively valenced words. Results demonstrate for the first time that Arginine Vasopressin selectively enhances human cognition for sexual stimuli, its regardless of valence. They further extend animal and human genetic studies linking Arginine Vasopressin to sexual behavior in males. Findings suggest an important cognitive mechanism that could enhance sexual behaviors in humans.
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Trait inferences about prospective mates: Effects of relationship length and social dominance
Murray Millar
Journal of Evolutionary Psychology, September 2010, Pages 245-259
Abstract:
The study tested the proposition that relationship length influences female perceptions about the co-occurrence of traits in prospective mates. It was hypothesized that females when choosing short-term mates would infer that beautiful males possess positive personality traits and, alternatively, females when choosing long-term mates would infer dominant males possess other positive personality traits. To test the hypothesis, female university students viewed a target male that was available for either a long- or a short-term relationship. The target male's physical attractiveness and dominance was systematically manipulated. As predicted, females inferred physically attractive males were more intelligent and kind when evaluating potential short-term mates. When evaluating potential long-term mates the females inferred socially dominant males were more intelligent and kind.
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Ovulation, Female Competition, and Product Choice: Hormonal Influences on Consumer Behavior
Kristina Durante, Vladas Griskevicius, Sarah Hill, Carin Perilloux & Norman Li
Journal of Consumer Research, forthcoming
Abstract:
Recent research shows that women experience nonconscious shifts across different phases of the monthly ovulatory cycle. For example, women at peak fertility (near ovulation) are attracted to different kinds of men and show increased desire to attend social gatherings. Building on the evolutionary logic behind such effects, we examined how, why, and when hormonal fluctuations associated with ovulation influenced women's product choices. In three experiments, we show that at peak fertility women nonconsciously choose products that enhance appearance (e.g., choosing sexy rather than more conservative clothing). This hormonally regulated effect appears to be driven by a desire to outdo attractive rival women. Consequently, minimizing the salience of attractive women who are potential rivals suppresses the ovulatory effect on product choice. This research provides some of the first evidence of how, why, and when consumer behavior is influenced by hormonal factors.
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Biological and psychosocial correlates of adult gender-variant identities: A review
Jaimie Veale, David Clarke & Terri Lomax
Personality and Individual Differences, March 2010, Pages 357-366
Abstract:
This article reviews research on biological and psychosocial factors relevant to the etiology of gender-variant identities. There is evidence for a genetic component of gender-variant identities through studies of twins and other within-family concordance and through studies of specific genes. Evidence that prenatal androgens play a role comes from studies that have examined finger length ratios (2D:4D), prevalence of polycystic ovary syndrome among female-to-male transsexuals, and individuals with intersex and related conditions who are more likely to have reassigned genders. There is also evidence that transsexuals have parts of their brain structure that is typical of the opposite birth-assigned gender. A greater likelihood of non-right-handedness suggests developmental instability may also contribute as a biological factor. There is a greater tendency for persons with gender-variant identities to report childhood abuse and a poor or absent relationship with parents. It is unclear if this is a cause or effect of a gender-variant identity. Parental encouragement of gender-variance is more common among individuals who later develop a gender-variant identity. We conclude that biological factors, especially prenatal androgen levels, play a role in the development of a gender-variant identity and it is likely that psychosocial variables play a role in interaction with these factors.
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Symmetry and aesthetics in website design: It's a man's business
Alexandre Tuch, Javier Bargas-Avila & Klaus Opwis
Computers in Human Behavior, forthcoming
Abstract:
In recent years the aesthetic appearance of user-interfaces has become a topic of increasing interest in the field of human-computer interaction (HCI). At the same time, it is well known that there are gender-specific effects in HCI. The present study investigates the effect of web page symmetry by taking gender differences into account. A total of 60 people (30 male, 30 female) participated in a laboratory experiment, where 20 website startpages had to be rated regarding symmetry, intuitive beauty, classical and expressive aesthetics. Results show that vertical symmetry is an important factor in aesthetic website design. It has an impact on intuitive straightforward beauty appraisals and on classical and expressive aesthetics judgments. Asymmetrically designed web pages were considered to be less beautiful and achieved lower scores on the classical and expressive dimensions. Moreover, the study indicates that the symmetry effect only occurs among male participants: only men react unfavorably to asymmetrically designed websites, whereas women's judgments are not influenced by symmetry. These findings should be taken into consideration by website designers, especially when they aim to design for target audience consisting of a majority of a certain gender.
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Controlling Anger and Happiness at Work: An Examination of Gender Differences
Melissa Sloan
Gender, Work & Organization, forthcoming
Abstract:
This article examines gender differences in the emotion management of men and women in the workplace. The belief in American culture that women are more emotional than men has limited women's opportunities in many types of work. Because emotional expression is often tightly controlled in the workplace, examining emotion management performed at work presents an opportunity to evaluate gender differences in response to similar working conditions. Previous research suggests that men and women do not differ in their experiences of emotion and the expression of emotion is linked to status positions. An analysis of survey data collected from workers in a diverse group of occupations illustrates that women express anger less and happiness more than men in the workplace. Job and status characteristics explain the association between gender and anger management at work but were unrelated to the management of happiness expressions in the workplace.
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Sari van Anders & Katherine Siciliano
Hormones and Behavior, forthcoming
Abstract:
Cross-cultural evidence links pair bonding and testosterone (T). We investigated what factors account for this link, how casual relationships are implicated, and whether gender/sex moderates these patterns. We gathered saliva samples for radioimmunoassay of T and self-report data on background, health, and social/relational variables from 115 women and 120 men to test our predictions, most of which were supported. Our results show that singles have higher T than LT partnered individuals, and that casual relationships without serious romantic commitment are more like singlehood for men and LT relationships for women in terms of T. We were also able to demonstrate what factors mediate the association between partnering and T: in women, frequency of partnered sexual activity mediated the effect, indicating a relationship status interpretation; in men, interest in more/new partners mediated the effect. This supported our prediction of relationship status interpretations in women, but relationship orientation in men. Results replicated past findings that neither sexual desire nor extrapair sexuality underlie the T-partnering link. We were able to rule out a large number of viable alternative explanations ranging from the lifestyle (e.g. sleep) to the social (e.g. social support). Our data thus demonstrate pattern and mediators for the development of T-pair bonding associations, and emphasize the importance of neither under- nor overstating the importance of gender/sex in research about the evolution of intimacy.
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Personality and testosterone in men from a high-fertility population
Alexandra Alvergne, Markus Jokela, Charlotte Faurie & Virpi Lummaa
Personality and Individual Differences, forthcoming
Abstract:
Extraversion, a personality dimension associated with sociability, activity and dominance, predicts a man's mating effort in various human populations. At a proximate level, individual differences in extraversion are likely to be mediated through testosterone, a strong hormonal correlate of men's reproductive effort. However, the rare attempts to address this question have all been conducted in populations with low-fertility schedules, thus limiting the generality of the results. Using demographic, questionnaire and hormonal data from a high-fertility polygynous human population of Senegal, we first show that extraversion, a personality dimension predicting men's mating behavior in this population, is associated with inter-individual differences in testosterone profiles, with men in the top quartile of extraversion distribution having 29% higher testosterone levels. We then show that personality profiles for neuroticism, openness and agreeableness are independent from testosterone levels. Since extraversion is the only personality dimension predicting men's mating and reproductive success in this population, we suggest that variation in testosterone levels is primarily relevant for personality traits related to reproductive effort. The results have further implications to discuss possible evolutionary scenarios for the maintenance of variation in personality traits.
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Responsiveness of the reproductive axis to a single missed evening meal in young adult males
Benjamin Trumble, Eleanor Brindle, Michalina Kupsik & Kathleen O'Connor
American Journal of Human Biology, forthcoming
Objectives: The male reproductive axis is responsive to energetic deficits, including multiday fasts, but little is known about brief periods of fasting (<24 hours). Reduced testosterone in low-energy balance situations is hypothesized to reflect redirection of resources from reproduction to survival. This study tests the hypothesis that testosterone levels decrease during a minor caloric deficiency by assessing the effects of a single missed (evening) meal on morning testosterone in 23 healthy male participants, age 19-36.
Methods: Participants provided daily saliva and urine samples for two baseline days and the morning following an evening fast (water only after 4 PM). Testosterone, cortisol, and luteinizing hormone were measured with enzyme immunoassays.
Results: Fasting specimens had significantly lower overnight urinary luteinizing hormone (P = 0.045) and morning salivary testosterone than baseline (P = 0.037). In contrast to morning salivary testosterone, there was a significant increase in overnight urinary testosterone (P = 0.000) following the evening fast, suggesting an increase in urinary clearance rates. There was a marginal increase in overnight urinary cortisol (P = 0.100), but not morning salivary cortisol (P = 0.589).
Conclusion: These results suggest the male reproductive axis may react more quickly to energetic imbalances than has been previously appreciated.
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Giving birth to a new brain: Hormone exposures of pregnancy influence human memory
Laura Glynn
Psychoneuroendocrinology, September 2010, Pages 1148-1155
Abstract:
Mammalian pregnancy produces alterations in maternal physiology that are necessary for maintaining gestation, fetal development and parturition. These changes also may prepare the maternal brain for the unique demands of motherhood. Parous rodents exhibit long-term changes in neurological structure and function and human work suggests that other landmark events in the reproductive cycle, such as menarche and menopause, influence cognition. However, the influence of pregnancy on the human brain remains to be elucidated. This study indicates that verbal recall memory (but not recognition or working memory) diminishes during human pregnancy and that these decrements persist after parturition. Further, prenatal glucocorticoids and estrogen are associated with these alterations. To meet the challenges of motherhood, the female brain may be remodeled, a process that appears to be initiated prenatally. However, it is not often that adaptation is achieved without an associated cost. For the human, in the case of the new maternal brain, diminished memory performance may reflect such a cost.
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Jacqueline Holloway, Kevin Beck & Richard Servatius
Behavioural Brain Research, forthcoming
Abstract:
Sex differences in attentional processing and new motor learning remain controversial, and are complicated by the influence of endogenous and exogenous gonadal hormones. Facilitated acquisition of a classically conditioned eyeblink response in oral contraceptive-using women has been reported, as have menstrual cycle-dependent changes in pre-pulse inhibition (PPI). The current study sought to replicate and extend these findings by comparing acquisition of the conditioned eyeblink response and PPI in women currently taking oral contraceptives (OCs), women not taking OCs, as well as men. Women were assigned to participate either during their follicular or luteal menstrual cycle phase. Acquisition was assessed in a two-tone discrimination delay paradigm (500-ms conditional stimulus (CS); 100-ms airpuff unconditional stimulus (US)). PPI was lower in males and OC-users depending on stimulus intensity. Consistent with early classical conditioning research, females acquired an eyeblink conditioned response faster than males. Faster acquisition was associated with larger unconditional responses. Women taking OCs demonstrated accelerated conditioned response acquisition compared to women not taking OCs and males although unconditional responses were comparable to males. Facilitated acquisition of new motor learning in OC-users was replicated in a college-aged population of women and was not secondary to enhanced reactivity to sensory stimuli.
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Jacqueline Goodway, Leah Robinson & Heather Crowe
Research Quarterly for Exercise and Sport, March 2010, Pages 17-24
Abstract:
This study examined the influence of gender and region on object control (OC) and locomotor skill development. Participants were 275 midwestern African American and 194 southwestern Hispanic preschool children who were disadvantaged. All were evaluated on the Test of Gross Motor Development-2 (Ulrich, 2000). Two, 2 Gender (girls, boys) x 2 Region (midwest, southwest) analyses of variance were conducted on OC and locomotor percentile rank. Both midwestern and southwestern preschoolers were developmentally delayed in locomotor and OC skills (< 30th percentile). There was a significant difference for gender (p < .0001) and Gender x Region interaction (p = .02) for OC skills. Boys outperformed girls in the midwestern and southwestern regions. For locomotor skills, there was a significant difference for region (p < .001), with midwestern preschoolers having better locomotor skills.