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Objective: Mean speed of responding is the most commonly used measure in the assessment of reaction time (RT). An alternative measure is intraindividual variability (IIV): the inconsistency of responding across multiple trials of a test. IIV has been suggested as an important indicator of central nervous system functioning, and as such, there has been increasing interest in the associations between IIV and brain imaging metrics. Results however, have been inconsistent. The present seeks to provide a comprehensive evaluation of the associations between a variety of measures of brain white matter integrity and individual differences in choice RT (CRT) IIV. Method: MRI brain scans of members of the Lothian Birth Cohort 1936 were assessed to obtain measures of the volume and severity of white matter hyperintensities, and the integrity of brain white matter tracts. CRT was assessed with a 4 CRT task on a separate occasion. Data were analyzed using multiple regression (N range = 358–670). Results: Greater volume of hyperintensities and more severe hyperintensities in frontal regions were associated with higher CRT IIV. White matter tract integrity, as assessed by both fractional anisotropy and mean diffusivity, showed the smallest effect sizes in associations with CRT IIV. Associations with hyperintensities were attenuated and no longer significant after controlling for M CRT. Conclusions: Taken together, the results of the present study suggested that IIV was not incrementally predictive of white matter integrity over mean speed. This is in contrast to previous reports, and highlights the need for further study.
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Previous research reported ovulatory changes in women’s appearance, mate preferences, extra- and in-pair sexual desire and behaviour, but has been criticised for small sample sizes, inappropriate designs, and undisclosed flexibility in analyses. In the present study, we sought to address these criticisms by preregistering our hypotheses and analysis plan and by collecting a large diary sample. We gathered over 26 thousand usable online self-reports in a diary format from 1043 women, of which 421 were naturally cycling. We inferred the fertile period from menstrual onset reports. We used hormonal contraceptive users as a quasi-control group, as they experience menstruation, but not ovulation. We probed our results for robustness to different approaches (including different fertility estimates, different exclusion criteria, adjusting for potential confounds, moderation by methodological factors). We found robust evidence supporting previously reported ovulatory increases in extra-pair desire and behaviour, in-pair desire, and self-perceived desirability, as well as no unexpected associations. Yet, we did not find predicted effects on partner mate retention behaviour, clothing choices, or narcissism. Contrary to some of the earlier literature, partners’ sexual attractiveness did not moderate the cycle shifts. Taken together, the replicability of the existing literature on ovulatory changes was mixed. We conclude with simulation-based recommendations for reading the past literature and for designing future large-scale preregistered within-subject studies to understand ovulatory cycle changes and the effects of hormonal contraception. Interindividual differences in the size of ovulatory changes emerge as an important area for further study.
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Recent evidence suggests that in sexual selection on human males, intrasexual competition plays a larger role than female choice. In a sample of men (N = 164), we sought to provide further evidence on the effects of men’s physical dominance and sexual attractiveness on mating success and hence in sexual selection. Objective measures and subjective ratings of male sexually dimorphic traits purportedly under sexual selection (height, vocal and facial masculinity, upper body size from 3D scans, physical strength, and baseline testosterone) and observer perceptions of physical dominance and sexual attractiveness based on self-presentation video recordings were assessed and associated with mating success (sociosexual behaviour and number of potential conceptions) in a partly longitudinal design. Results from structural equation models and selection analyses revealed that physical dominance, but not sexual attractiveness, predicted mating success. Physical dominance mediated associations of upper body size, physical strength, as well as vocal and facial physical dominance and attractiveness with mating success. These findings thus suggest a greater importance of intrasexual competition than female choice in human male sexual selection.
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Increases in men’s testosterone (T) levels after intrasexual competitions and exposure to females facilitate competitive and courtship behaviours, suggesting T reactivity should affect relevant personality state changes. How exactly T reactivity, also under potential buffering effects of cortisol (C), relates to personality state changes is unclear. In a preregistered study, we aimed at inducing T increases in young men (N = 165) through dyadic intrasexual competitions while exposed to a female experimenter. We investigated self-reported and video-based observer-rated personality state changes, captured by the interpersonal circumplex and social impressions, in relation to hormonal levels. Results revealed increases in self-reported competitiveness and observer-rated self-assurance, relative to a control group, moderated by T reactivity and partly by TxC interactions, providing insights into hormone-personality response-link.
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The existence of ovulatory cycle shifts in women’s mate preferences has been discussed controversially. There is evidence that naturally cycling women in their fertile phase, compared to their luteal phase, evaluate specific behavioral cues in men as more attractive for sexual relationships. However, recent research has cast doubt on these findings. We addressed this debate in a large, pre-registered within-subject study including salivary hormone measures and luteinizing hormone tests. One-hundred-fifty-seven female participants rated natural videos of 70 men in dyadic intersexual interactions on sexual and long-term attractiveness. Multilevel comparisons across two ovulatory cycles indicated that women’s mate preferences for men’s behaviors did not shift across the cycle, neither for competitive, nor for courtship behavior. Hormone levels and relationship status did not affect these results. Hormonal mechanisms and implications for estrus theories are discussed.
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Although empirical research has investigated what we ideally seek in a romantic partner for decades, the crucial question of whether ideal partner preferences actually guide our mating decisions in real life has remained largely unanswered. One reason for this is the lack of designs that assess individuals’ ideal partner preferences before entering a relationship and then follow up on them over an extended period. In the Göttingen Mate Choice Study (GMCS), a preregistered, large-scale online study, we employed such a naturalistic prospective design. We investigated partner preferences across four preference domains in a large sample of predominantly heterosexual singles (N = 763, aged 18-40 years) and tracked these individuals across a period of five months upon a possible transition into romantic relationships. Attesting to their predictive validity, partner preferences prospectively predicted the characteristics of later partners. This was equally true for both sexes, except for vitality-attractiveness where men’s preferences were more predictive of their later partners’ standing on this dimension than women’s. Self-perceived mate value did not moderate the preference-partner characteristics relations. Preferences proved to be relatively stable across the five months interval, yet were less stable for those who entered a relationship. Subgroup analyses using a newly developed indicator of preference adjustment towards (vs. away from) partner characteristics revealed that participants adjusted their preferences downwards when partners fell short of initial preferences, but showed no consistent adjustment when partners exceeded them. Results and implications are discussed against the background of ongoing controversies in mate choice and romantic relationship research.
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Relationship satisfaction is the most researched aspect in the study of couple relationships. Very broadly, it refers to a person’s overall evaluation of his or her relationship. This may entail, for example, the degree to which one’s needs and desires for love, support, and security or one’s expectations are met. Researchers are far from consensus regarding relationship satisfaction’s conceptualization. While some have advocated a unidimensional view of global relationship satisfaction, other researchers have called for multidimensional views (such as multiple satisfactions with different aspects of the relationship or different components of relationship quality). This is also mirrored in the variety of satisfaction measures employed in the study of couple relationships.
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Romantic attraction is a complex and multifaceted construct. It refers to positive reactions toward a potential romantic partner, usually at initial or early-stage encounters in which no close relationship has been stablished yet. Positive reactions toward a potential partner may include positive thoughts and beliefs (cognitive component), positive feelings and emotions (affective component), a desire to approach the other (motivational component), and also behavioral reactions, such as standing or sitting closer (behavioral component; Wurst and Back 2018). As romantic attraction may motivate further contact with a potential partner, t can constitute a basis on which new romantic relationships form. Thus, choices such as expressing interest in seeing a potential partner again in dating contexts like speed or online dating can be viewed as indicators of romantic interest. Such initial choices should, however, be clearly distinguished from actual partner choice, i.e., opting for a specific individual to pursue and build a romantic relationship.
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Ovulatory cycle shifts in women’s mate preferences have been documented for several physical and behavioral traits. Research suggests that, at peak fertility, women tend to prefer men with characteristics that reflect good genes for short-term sexual relationships. However, existing findings have been criticized for methodological flexibility and failing attempts to replicate core results. In a large (N=157), pre-registered, within-subject study spanning two ovulatory cycles, we investigated cycle shifts in women’s mate preferences for masculine bodies. Using a large set of natural stimuli, we found that when fertile, women’s ratings of male bodies increased for sexual as well as for long-term attractiveness. Both effects were partially mediated by the estradiol-to-progesterone-ratio. Furthermore, moderation analyses revealed that both shifts were only evident in women in relationships, but not in singles. Contrary to previous findings, male masculine traits did not interact with cycle phase to predict attraction, indicating that women’s preferential priorities do not shift. Taken together, our results do not support women’s mate preference shifts, as assumed by the good genes ovulatory shift hypothesis, but are consistent with shifting motivational priorities throughout the cycle. Implications of these results for female estrus theories and methodological recommendations for future research are discussed.
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Objective: To explore associations between the 5-factor model (FFM; neuroticism, extraversion, openness/intellect, agreeableness, and conscientiousness), personality traits, and measures of whole-brain integrity in a large sample of older people, and to test whether these associations are mediated by health-related behaviors. Method: Participants from the Lothian Birth Cohort 1936 completed the International Personality Item Pool measure, a 5-factor public-domain personality measure (http://ipip.ori.org), and underwent a structural magnetic resonance brain scan at the mean age of 73 years, yielding 3 measures of whole brain integrity: average white matter fractional anisotropy (FA), brain-tissue loss, and white matter hyperintensities (N = 529 to 565). Correlational and mediation analyses were used to test the potential mediating effects of health-related behaviors on the associations between personality and integrity. Results: Lower conscientiousness was consistently associated with brain-tissue loss (β = −0.11, p < 0.01), lower FA (β = 0.16, p < 0.001) and white matter hyperintensities (β = −0.10, p < 0.05). Smoking, alcohol consumption, diet, physical activity, body mass index and a composite health-behavior variable displayed significant associations with measures of brain integrity (range of r = 0.10 to 0.25). The direct effects of conscientiousness on brain integrity were mediated to some degree by health behaviors, with the proportions of explained direct effects ranging from 0.1% to 13.7%. Conclusion: Conscientiousness was associated with all 3 measures of brain integrity, which we tentatively interpret as the effects of personality on brain aging. Small proportions of the direct effects were mediated by individual health behaviors. Results provide initial indications that lifetime stable personality traits may influence brain health in later life through health-promoting behaviors.
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Sir – In a letter to the Editor, D. Oliva has raised the hypothesis that there might be a guiding thread through pheromone communication from unicellular organisms up to humans, which may serve as an expla- nation for human homosexual orientation. Although we do not want to reject this hypothesis in its entirety, as links between olfactory signals and human sexual ori- entation remain poorly understood, the argument seem to be too simplistic in light of evolutionary adaptation- ism and neurobiological research, and requires further investigation and discussion. Our reply should not be regarded as criticism, but rather to encourage further academic discussion.
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Previous research has suggested that offspring sex ratio may be influenced by the actions of prenatal sex steroids, principally androgens. The relative length of the second (index finger) to the fourth digit (ring finger) has been reported to be a proxy to prenatal testosterone levels. This trait is sexually dimorphic, such that males display a significantly lower 2D:4D ratio (indicating higher testosterone exposure), and this dimorphism appears robust across different populations. We suggest that digit ratio (2D:4D) may form a useful marker to help explain variation in sex ratio and sociosexuality.
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Im Tierreich ist olfaktorische Kommunikation, besonders bei der Partnerwahl, weit verbreitet und mittlerweile gut studiert. Mit der wachsenden Anzahl an Studien über die biologischen Rahmenbedingungen/Mechanismen der Partnerwahl und der Entdeckung des Vomeronasalorgan (VNO) beim Menschen hat das wissenschaftliche Interesse an der Bedeutung des Körpergeruchs als mögliches Signalsystem in diesem Kontext deutlich zugenommen. Die Annahme, dass Menschen und andere Primaten vorwiegend visuell gesteuerte Lebewesen sind, die auch im Zuge der Partnerwahl hauptsächlich auf optische Reize angewiesen sind, musste in den letzten Jahren revidiert werden. Jüngste Studien zeigen, dass Pheromone (Geruchsbotenstoffe) eine wichtige Rolle in der Verhaltens- und Fortpflanzungsbiologie des Menschen spielen können, deuten aber auch darauf hin, dass manche Annahmen einer Modifikation bedürfen. Dieser Artikel gibt einen Überblick über die aktuellen Hypothesen und sog. Beweise für die Wirkung von menschlichen Pheromonen und diskutiert deren Bedeutung für das menschliche Sexualverhalten.
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Signaling mate quality through visual adornments is a common phenomenon in animals and humans. However, humans are probably the only species who applies artificial ornaments. Such deliberate alterations of the skin, e.g., tattoos and scarring patterns, have been discussed by researchers as potential handicap signals, but there is still very little information about a potential biological signaling value of body modification. In this study eye-tracking was employed to investigate the signaling value of tattoos and other body modification. Measurement of gaze duration of 50 individuals while watching plain, scarred, accessorized, and tattooed bodies of artificial human images indicated that participants looked significantly longer at tattooed than at scarred, accessorized, and plain bodies. Generally, male participants paid more attention to tattooed stimuli of both sexes. More detailed analyses showed that particularly female tattooed stimuli were looked at longer. These findings are discussed within an evolutionary framework by suggesting that tattoos might have some signaling value which influences the perception of both male and female conspecifics and may hence also affect mating decisions.
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According to evolutionary psychology, the preference for some facial characteristics reflects adaptations for mate choice because they signal aspects of mate quality. Although morphological features such as facial symmetry and sexually dimorphic traits have been studied extensively in recent years, little is known about skin condition in this context. The preferences for young and healthy looking skin could offer an explanation as to why women place such an importance on the condition of their skin and its refinement through e.g., cosmetic products. Recent research showed that facial skin colour distribution significantly influences the perception of age and attractiveness of female faces, independent of skin surface topography cues. However, the relative effect of skin colour distribution and topography cues on age and health perception remains to be investigated. We present data showing that both skin colour distribution and skin surface topography cues not only significantly influence the perception of female facial age and health but also convey differential information with regard to the strength of these effects. Our data indicate that skin surface topography cues account for a large proportion of variation in facial age perception, whereas skin colour distribution seems to be a stronger health cue.
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Neck circumference, measured as the distance around the neck, is a simple and timesaving screening measure to identify obesity in both men and women. It is positively correlated with the components of the metabolic syndrome and obstructive sleep apnea. Furthermore, neck circumference is positively associated with traditional anthropometric measures of body circumferences and indices, such as the body mass index and the waist-to-hip ratio, and other physiological and biochemical measures of cardiovascular risk. It is positively correlated with systolic and diastolic blood pressure, triglycerides and glucose levels and has been used as a clinical predictor of menstrual irregularity, hirsutism, infertility, and insulin resistance. This has led to and increased interest in this measure with regard to its usefulness in clinical and epidemiological studies, but also from biological studies, interested in the possibility of an early predisposition for cardiovascular risk through early sex-steroid exposure. This chapter briefly reviews the reported associations with neck circumference and suggests possible applications also in non-clinical studies.
