Relationships between digit ratio (2D:4D) and sex-typed play behavior in pre-school children

Juvenile play shows sex differences in animals and humans. Animal studies and a recent study in humans suggest that testosterone exposure during early development plays a key role. Here we report on the relationship between children’s sex-typed play behavior and digit ratio (2D:4D), a putative negative correlate of prenatal testosterone. 2D:4D and sex-typed play behavior as assessed by parents were negatively correlated in a sample of 83 pre-school boys but not in a sample of 93 girls. This finding lends some support to the ideas that early testosterone has a masculinising effect upon sex-typed play behavior in humans and that 2D:4D is a valuable tool for studying effects of early testosterone on human behavior.     

Objective aerobic fitness level and neuropsychological functioning in healthy adolescents and emerging adults: Unique sex effects

ObjectiveResearch suggests positive relationships between aerobic fitness and cognition in older adults; however, limited research has adequately investigated the relationship between objectively measured aerobic fitness and broad cognitive functioning in healthy adolescents and young adults without psychiatric or physical health disorders. Further, studies to date have disproportionately examined males and failed to examine sex differences. Here we examine the relationship between aerobic fitness and neuropsychological functioning in physically healthy youth and whether sex moderates these findings.DesignSixty-four healthy emerging adults (16-25 years-old; 32 female) underwent measurement of objective aerobic fitness (VO₂ max) and neuropsychological assessment. Exclusion criteria included: left-handedness, prenatal medical issues or alcohol/illicit drug exposure, Axis-I psychiatric disorders, major medical disorders including metabolic conditions such as diabetes, hypertension, hyperlipidemia, major neurologic disorders, LOS greater than 2 min, intellectual disability or learning disability, regular substance use (e.g., greater than bi-weekly use of cannabis) or positive drug toxicology testing.MethodMultiple regressions examined VO₂ max, sex, sex*VO₂interaction in relation to neurocognition, controlling for objectively measured body fat percentage.ResultsPrior to including body fat percentage, higher VO₂ max related to improved working memory (Letter-Number Sequencing; p = .03) and selective attention (CPT-II hit response time standard error; p = .03). Aerobic fitness significantly interacted with sex, as higher-fit males had better performance on two sustained attention tasks while females did not demonstrate this pattern (CPT-II variability standard error, p = .047; Ruff 2&7 Total Speed, p = .02). Body fat percentage was positively slower cognitive flexibility (D-KEFS color-word switching/inhibition, p = .046).ConclusionsVO₂ independently predicted better working memory and selective attention. Increased aerobic fitness level related to increased performance on sustained attention tasks in males but not females. Therefore, aerobic fitness may be positively related to better cognitive functioning in physically healthy adolescents and emerging adults without metabolic conditions. Further research into factors (e.g., intensity or type of activity) that may relate to beneficial outcomes by sex are needed.     

Digit ratio (2D:4D) and sensation seeking: New data and meta-analysis

Previously reported associations between low (male-typical) digit ratio (2D:4D), a putative pointer to prenatal testosterone exposure, and high (male-typical) sensation seeking have been inconsistent across studies (alternately present for men, women, either sex, or neither). Addressing this question again in three new studies (N = 198, 188, 1118) produced similarly erratic findings. Meta-analysis of the entire literature (13 studies with nearly 3000 individuals, including unpublished accounts) showed that the current cumulative evidence does not support any negative correlations between 2D:4D and sensation seeking traits. The only significant meta-analytical finding was for right-hand 2D:4D and the experience seeking facet of sensation seeking in both sexes, but this effect accounted for merely 0.4% attributable variance, and moreover was directionally opposite to expectation (i.e., a positive correlation). Discussed are inherent limitations of narrow-scoped approaches (such as via 2D:4D) for elucidating the biological bases of individual difference variables with evidentially intricate neurochemical underpinnings (such as sensation seeking).     

Dominance styles mediate sex differences in Dark Triad traits

We sought to determine what styles of social dominance are associated with Dark Triad traits (i.e., narcissism, psychopathy, and Machiavellianism) and whether sex differences in Dark Triad traits are mediated by dominance styles measured by the Dominance and Prestige Scale, and the Rank Styles with Peers Questionnaire. Machiavellianism, psychopathy, and narcissism are strongly associated with dominance-striving, but only narcissism is consistently correlated with prestige-striving. Dark Triad traits are negatively correlated with coalition-building, but positively correlated with dominant leadership and ruthless self-advancement. Sex differences in Dark Triad traits were mediated by various dominance styles, but mainly by dominance-striving and ruthless self-advancement. These results suggest that particular styles of social dominance are utilized by both men and women with Dark Triad traits.     

Prenatal exposure to sex hormones predicts gratitude intervention use. Examination of digit ratio,motivational beliefs,and online activities

Men are less grateful than women and less likely to intentionally enhance gratitude via interventions. Yet, little is known if sex differences in gratitude result from biological influences such as prenatal testosterone and estrogen levels – hormones that control the development of sex-specific characteristics. In two studies, we examined how sex and second-to-fourth digit ratio (2D:4D) – an indicator of prenatal sex hormones exposure – predicts gratitude intervention use. In the first study, we tested whether lower 2D:4D (i.e., higher masculinization) would suppress gratitude intervention use. Contrary to expectations, after controlling for sex, women and men with more male-type fingers were more motivated and likely to complete the intervention. In the second study, we replicated these findings using a larger sample and different 2D:4D metric. Our research suggests that motivation towards gratitude interventions is facilitated by female sex and masculinity. These findings provide initial evidence for the biological grounding of individual differences in gratitude behavior.     

Revisiting correlates of sociosexuality for men and women: The role of love relationships and psychological maladjustment

The purpose of this work was to examine the links between sociosexuality, and love relationships and psychological maladjustment. Although males and females vary in connection with the sociocultural orientations, the involvements of this variation may not be similar for both sexes. The sample included 475 participants, 42% women and 58% men. Ages ranged from 18 through 80 (M = 37.28, SD = 16.27). Measures assessed sociosexuality, love styles, love satisfaction, compassionate love, commitment, romantic loneliness, and negative affect. Men displayed a more unrestricted sociosexual orientation than women. We found both sex similarities and differences in the associations between sociosexuality and love relationships and psychological maladjustment. For both sexes a similar pattern of correlations was found regarding erotic love, love satisfaction, and commitment. It seems that unrestricted women experience more psychological maladjustment, evidenced by romantic loneliness and negative affect than men. The findings are discussed with reference to past research and some suggestions for further work are also noted.     

On the reception of the concept of the death drive in Germany: expressing and resisting an ‘evil principle’?

With Beyond the Pleasure Principle, Freud attempted ‘to describe and to account for the facts of daily observation in our field of study’ (1920, p. 7), in particular concerning destructive clinical phenomena that confront us in the analytic situation: traumatic neuroses, melancholic states, negative‐therapeutic reactions, masochism, repetition compulsion and so on. The author demonstrates in the first section how Freud's own resistance – later self‐diagnosed – to recognizing these unwelcome facts was expressed in the terminological and conceptual ambiguities of the death drive hypothesis then introduced, ambiguities that to some extent continue to impede the reception of its clinical usefulness to this day. As soon as Freud had demonstrated the connection with clinical practice more directly in The Ego and the Id (1923), some contemporaries adopted it as a helpful clinical concept, while others believed that they could (and must) refute it. The second part outlines its reception in the 1920s and 1930s, which was part of an international discussion that was, of course, initially conducted mainly in German. The beginnings of an important further development of the death drive hypothesis are described in a separate section because it originated from Melanie Klein's earliest experiences in analysing children in Berlin in the early to mid‐1920s. She referred at that time to an ‘evil principle’, and in 1932 published her view of the death drive hypothesis, which was further developed in subsequent decades by her and her followers in London. In this period, conditions changed dramatically: in Germany Freud's books (among others) were burnt, crimes against humanity were instigated and psychoanalysis ceased to exist in this country. Almost all the analysts who published on the death drive had to emigrate. From then on, entirely different discourses took place in the various regions. In Germany, the death drive hypothesis was (largely) disregarded or rejected for decades after the Holocaust. Frank demonstrates how the uncritical recourse in relevant works to this day to an article by Brun in 1953 that considered the death drive to have been comprehensively refuted on the basis of (apparently) comprehensive literature research can be understood as a symptom. Pursuing some reflections by Beland (1988) and Cycon (1995), the author expounds her thesis that in Germany the clinical usefulness of the death drive hypothesis could not be considered as long as destructive impulses were still an immediate social reality. According to the author's observations, in stating that there had been a ‘definite reaction formation against death drive hypotheses’, Brun had unintentionally made an accurate diagnosis. It was not until the realization of inevitable perpetrator identifications (‘Hitler in us’) in this country became (more widely) possible that a concern with the death drive hypothesis could also resume. In the final section, the author takes up one line of this development and traces how some German analysts in the 1980s came into contact with Kleinian developments that had since occurred and how these found and find their way into their analytic working. She closes by asking whether it might be appropriate to consider Melanie Klein's concept of an evil principle – along with the pleasure and reality principles – as a less ambiguous one for the phenomena under consideration.