No Evidence that 2D:4D is Related to the Number of CAG Repeats in the Androgen Receptor Gene

The length ratio of the second to the fourth digit (2D:4D) is a putative marker of prenatal testosterone (T) effects. The number of CAG repeats (CAGn) in the AR gene is negatively correlated with T sensitivity in vitro. Results regarding the relationship between 2D:4D and CAGn are mixed but have featured prominently in arguments for and against the validity of 2D:4D. Here, I present random-effects meta-analyses on 14 relevant samples with altogether 1,904 subjects. Results were homogeneous across studies. Even liberal estimates (upper limit of the 95% CI) were close to zero and therefore suggested no substantial relationship of CAGn with either right-hand 2D:4D, left-hand 2D:4D, or the difference between the two. However, closer analysis of the effects of CAGn on T dependent gene activation in vitro and of relationships between CAGn and T dependent phenotypic characteristics suggest that normal variability of CAGn has mostly no, very small, or inconsistent effects. Therefore, the lack of a clear association between CAGn and 2D:4D has no negative implications for the latter’s validity as a marker of prenatal T effects

Heterogeneity of Research Results: A New Perspective From Which to Assess and Promote Progress in Psychological Science

Heterogeneity emerges when multiple close or conceptual replications on the same subject produce results that vary more than expected from the sampling error. Here we argue that unexplained heterogeneity reflects a lack of coherence between the concepts applied and data observed and therefore a lack of understanding of the subject matter. Typical levels of heterogeneity thus offer a useful but neglected perspective on the levels of understanding achieved in psychological science. Focusing on continuous outcome variables, we surveyed heterogeneity in 150 meta-analyses from cognitive, organizational, and social psychology and 57 multiple close replications. Heterogeneity proved to be very high in meta-analyses, with powerful moderators being conspicuously absent. Population effects in the average meta-analysis vary from small to very large for reasons that are typically not understood. In contrast, heterogeneity was moderate in close replications. A newly identified relationship between heterogeneity and effect size allowed us to make predictions about expected heterogeneity levels. We discuss important implications for the formulation and evaluation of theories in psychology. On the basis of insights from the history and philosophy of science, we argue that the reduction of heterogeneity is important for progress in psychology and its practical applications, and we suggest changes to our collective research practice toward this end

Sometimes the impact factor outshines the H index

Journal impact factor (which reflects a particular journal's quality) and H index (which reflects the number and quality of an author's publications) are two measures of research quality. It has been argued that the H index outperforms the impact factor for evaluation purposes. Using articles first-authored or last-authored by board members of Retrovirology, we show here that the reverse is true when the future success of an article is to be predicted. The H index proved unsuitable for this specific task because, surprisingly, an article's odds of becoming a 'hit' appear independent of the pre-eminence of its author. We discuss implications for the peer-review process

2D:4D Suggests a Role of Prenatal Testosterone in Gender Dysphoria

Gender dysphoria (GD) reflects distress caused by incongruence between one’s experienced gender identity and one’s natal (assigned) gender. Previous studies suggest that high levels of prenatal testosterone (T) in natal females and low levels in natal males might contribute to GD. Here, we investigated if the 2D:4D digit ratio, a biomarker of prenatal T effects, is related to GD. We first report results from a large Iranian sample, comparing 2D:4D in 104 transwomen and 89 transmen against controls of the same natal sex. We found significantly lower (less masculine) 2D:4D in transwomen compared to control men. We then conducted random-effects meta-analyses of relevant studies including our own (k = 6, N = 925 for transwomen and k = 6, N = 757 for transmen). In line with the hypothesized prenatal T effects, transwomen showed significantly feminized 2D:4D (d ≈ 0.24). Conversely, transmen showed masculinized 2D:4D (d ≈ − 0.28); however, large unaccounted heterogeneity across studies emerged, which makes this effect less meaningful. These findings support the idea that high levels of prenatal T in natal females and low levels in natal males play a part in the etiology of GD. As we discuss, this adds to the evidence demonstrating the convergent validity of 2D:4D as a marker of prenatal T effects

Heterogeneity estimates in a biased world

Meta-analyses typically quantify heterogeneity of results, thus providing information about the consistency of the investigated effect across studies. Numerous heterogeneity estimators have been devised. Past evaluations of their performance typically presumed lack of bias in the set of studies being meta-analysed, which is often unrealistic. The present study used computer simulations to evaluate five heterogeneity estimators under a range of research conditions broadly representative of meta-analyses in psychology, with the aim to assess the impact of biases in sets of primary studies on estimates of both mean effect size and heterogeneity in meta-analyses of continuous outcome measures. To this end, six orthogonal design factors were manipulated: Strength of publication bias; 1-tailed vs. 2-tailed publication bias; prevalence of p-hacking; true heterogeneity of the effect studied; true average size of the studied effect; and number of studies per meta-analysis. Our results showed that biases in sets of primary studies caused much greater problems for the estimation of effect size than for the estimation of heterogeneity. For the latter, estimation bias remained small or moderate under most circumstances. Effect size estimations remained virtually unaffected by the choice of heterogeneity estimator. For heterogeneity estimates, however, relevant differences emerged. For unbiased primary studies, the REML estimator and (to a lesser extent) the Paule-Mandel performed well in terms of bias and variance. In biased sets of primary studies however, the Paule-Mandel estimator performed poorly, whereas the DerSimonian-Laird estimator and (to a slightly lesser extent) the REML estimator performed well. The complexity of results notwithstanding, we suggest that the REML estimator remains a good choice for meta-analyses of continuous outcome measures across varied circumstances

Women’s Preferences for Men’s Facial Masculinity and Anticipations of Grandparental Care Provision

Women vary in the extent to which they prefer facial masculinity in a male partner, and much research has focused on explaining this variation systematically, with reference to the significance of men’s facial masculinity. Masculine-faced men provide some benefits (either real or perceived) as a romantic partner, but are perceived as less investing as parents. Accordingly, we investigated whether a UK-based sample of women (n = 366) had stronger preferences for male facial masculinity if they anticipated that their own parents would provide more time, money, and emotional investment in future grandchildren (i.e. the women’s future offspring), thereby alleviating any potential shortfall from the child’s father. In line with our hypothesis, we found that women had stronger preferences for men’s facial masculinity if the women anticipated that their fathers would provide more financial investment in their future grandchildren. We also found that women anticipated time, money, and emotional investment from their parents (particularly their mother) in their role as grandparents; given existing research on grandparental investment, participants’ anticipations are likely to be at least somewhat realistic

Digit ratio (2D:4D) and male facial attractiveness: New data and a meta-analysis

Digit ratio (2D:4D) appears to correlate negatively with prenatal testosterone (T) effects in humans. As T probably increases facial masculinity, which in turn might be positively related to male facial attractiveness, a number of studies have looked into the relationship between 2D:4D and male facial attractiveness, showing equivocal results. Here, I present the largest and third largest samples so far, which investigate the relationship between 2D:4D and male facial attractiveness in adolescents ( n = 115) and young men ( n = 80). I then present random-effects meta-analyses of the available data (seven to eight samples, overall n = 362 to 469). These showed small ( r ≈ −.09), statistically non-significant relationships between 2D:4D measures and male facial attractiveness. Thus, 2D:4D studies offer no convincing evidence at present that prenatal T has a positive effect on male facial attractiveness. However, a consideration of confidence intervals shows that, at present, a theoretically meaningful relationship between 2D:4D and male facial attractiveness cannot be ruled out either

Visuo-Spatial Performance in Autism: A Meta-analysis

Visuo-spatial skills are believed to be enhanced in autism spectrum disorders (ASDs). This meta-analysis tests the current state of evidence for Figure Disembedding, Block Design, Mental Rotation and Navon tasks in ASD and neurotypicals. Block Design (d = 0.32) and Figure Disembedding (d = 0.26) showed superior performance for ASD with large heterogeneity that is unaccounted for. No clear differences were found for Mental Rotation. ASD samples showed a stronger local processing preference for Navon tasks (d = 0.35); less clear evidence for performance differences of a similar magnitude emerged. We discuss the meta-analysis results together with other findings relating to visuo-spatial processing and three cognitive theories of ASD: Weak Central Coherence, Enhanced Perceptual Functioning and Extreme Male Brain theory

Relationships between digit ratio 2D:4D and self-reported aggression and risk taking in an online study

2D:4D, the length ratio of the second to the fourth digit, is a putative measure of prenatal testosterone, which may have effects on aggression and risk taking. Participants in a German online study (>1000females, >1200 males) submitted their self-measured digit lengths and self-report measures on verbal and physical aggression and risk taking. For males, left-hand 2D:4D and verbal aggression correlated significantly(r = [1].10, after correction for age and reduced reliability in self-measured 2D:4D), with other relationships being similar but non-significant. For females, no relationships between aggression and 2D:4D were found. Risk taking and right-hand 2D:4D correlated significantly in women (r = [1].10, after correction for age and reduced reliability in self-measured 2D:4D); similar, but statistically non-significant, relationships were found in men. The result corroborates an emerging view that 2D:4D is negatively related to aggression in males and that 2D:4D is negatively related to risk taking. This tentatively points to effects of prenatal testosterone on these characteristics

Once more: is beauty in the eye of the beholder? Relative contributions of private and shared taste to judgements of facial attractiveness

Misconstruing the meaning of Cronbach's alpha, experts on facial attractiveness have conveyed the impression that facial-attractiveness judgment standards are largely shared. This claim is unsubstantiated, because information necessary for deciding whether judgments of facial attractiveness are more influenced by commonly shared or by privately held evaluation standards is lacking. Three experiments, using diverse face and rater samples to investigate the relative contributions of private and shared taste to judgments of facial attractiveness, are reported. These experiments show that for a variety of ancillary conditions, and contrary to the prevalent notion in the literature, private taste is about as powerful as shared taste. Important implications for scientific research strategy and laypeople's self-esteem are discussed. Misconstruing the meaning of Cronbach's alpha, experts on facial attractiveness have conveyed the impression that facial-attractiveness judgment standards are largely shared. This claim is unsubstantiated, because information necessary for deciding whether judgments of facial attractiveness are more influenced by commonly shared or by privately held evaluation standards is lacking. Three experiments, using diverse face and rater samples to investigate the relative contributions of private and shared taste to judgments of facial attractiveness, are reported. These experiments show that for a variety of ancillary conditions, and contrary to the prevalent notion in the literature, private taste is about as powerful as shared taste. Important implications for scientific research strategy and laypeople's selfesteem are discussed