Brian M. Bird

Effects of competition outcome on testosterone concentrations in humans: An updated meta-analysis.

Abstract A contribution to a special issue on Hormones and Human Competition. Since Archers (2006) influential meta‐analysis, there has been a major increase in the number of studies investigating the effect of competition outcome on testosterone reactivity patterns in humans. Despite this increased research output, there remains debate as to whether competition outcome modulates testosterone concentrations. The present paper examines this question using a meta‐analytic approach including papers published over the last 35 years. Moreover, it provides the first meta‐analytic estimate of the effect of competition outcome on testosterone concentrations in women. Results from a meta‐analysis involving 60 effect sizes and >2500 participants indicated that winners of a competition demonstrated a larger increase in testosterone concentrations relative to losers (D = 0.20)—an effect that was highly heterogeneous. This ‘winner‐loser’ effect was most robust in studies conducted outside the lab (e.g., in sport venues) (D = 0.43); for studies conducted in the lab, the effect of competition outcome on testosterone reactivity patterns was relatively weak (D = 0.08), and only found in studies of men (D = 0.15; in women: D = −0.04). Further, the ‘winner‐loser’ effect was stronger among studies in which pre‐competition testosterone was sampled earlier than (D = 0.38, after trim and fill correction) rather than within (D = 0.09) 10 min of the start of the competition. Therefore, these results also provide important insight regarding study design and methodology, and will be a valuable resource for researchers conducting subsequent studies on the ‘winner loser’ effect. HighlightsWe performed a meta‐analysis on the effect of competition outcome on testosterone reactivity patterns in men and women.Winners had elevated testosterone concentrations relative to losers.This ‘winner‐loser’ effect was most robust in studies conducted outside the laboratory.

Exogenous Testosterone Rapidly Increases Aggressive Behavior in Dominant and Impulsive Men

BACKGROUND Although traditional wisdom suggests that baseline levels of testosterone (T) promote aggressive behavior, decades of research have produced findings that have been largely weak and inconsistent. However, more recent experimental work suggests that exogenous administration of T rapidly potentiates amygdala and hypothalamus responses to angry facial expressions. Notably, these brain regions are rich in androgen receptors and play a key role in modulating aggressive behavior in animal models. METHODS The present experiment extends this work by examining whether acutely increasing T potentiates aggressive behavior in men. In a double-blind, placebo-controlled, between-subject design, healthy adult men (n = 121) were administered either T or placebo, and subsequently engaged in a well-validated decision-making game that measures aggressive behavior in response to social provocation. In light of prior correlational research, we also assessed the extent to which Ts effects on aggressive behavior would depend on variability in trait dominance and/or trait self-control. RESULTS Exogenous T on its own did not modulate aggressive behavior. However, Ts effects on aggression were strongly influenced by variation in trait dominance and trait self-control. Specifically, T caused an increase in aggressive behavior, but only among men scoring relatively high in trait dominance or low in trait self-control. CONCLUSIONS These findings are the first to demonstrate that T can rapidly (within 60 minutes) potentiate aggressive behavior, but only among men with dominant or impulsive personality styles.

Exogenous testosterone increases men's perceptions of their own physical dominance.

Mens testosterone is associated with several constructs that are linked to dominance rank, such as risk-taking, mating success, and aggression. However, no study has directly tested the relationship between mens self-perceived dominance and testosterone using an experimental design. We employed a within-subjects, double-blind, placebo-controlled paradigm to assess whether testosterone influences mens self-perceived dominance. Exogenous testosterone or a placebo was administered to healthy adult men and self-perceptions of physical dominance were subsequently assessed by having participants select what they believed to be their true face from an array of images digitally manipulated in masculinity. Men picked a more masculine version of their own face after testosterone versus placebo--an effect that was particularly pronounced among men with relatively low baseline testosterone. These findings indicate that a single administration of testosterone can rapidly modulate mens perceptions of their own physical dominance, which may explain links between testosterone and dominance-related behaviors.

Functional significance of men’s testosterone reactivity to social stimuli

Rapid testosterone fluctuations in response to social stimuli are observed across a wide range of species, and the highly conserved nature of these fluctuations suggests an adaptive function. This paper reviews the current literature on testosterone reactivity, primarily in human males, and illustrates how life-history theory provides an adequate theoretical framework to interpret findings. The review is structured around supporting evidence suggesting that situations implicated in mating effort either directly (e.g., interactions with a mate) or indirectly (e.g., intrasexual competition) are generally associated with a brief elevation of testosterone, while situations implicated in parenting effort (e.g., nurturant interactions with offspring) are generally associated with a decline in testosterone. Further, we discuss how these fluctuations in testosterone have been linked to future behaviors, and how situational, motivational, and physiological variables moderate the interplay between social stimuli, testosterone reactivity, and behavior. Supporting the notion that testosterone can play a causal role in modulating behavior in response to social stimuli, we also summarize recent single administration studies examining the effects of testosterone on physiology, neurobiology, and behavior. A conceptual model provides links between supported findings, and hypothesized pathways requiring future testing.

Effects of exogenous testosterone and mating context on men's preferences for female facial femininity

Correlational research suggests that men show greater attraction to feminine female faces when their testosterone (T) levels are high. Mens preferences for feminine faces also seem to vary as a function of relationship context (short versus long-term). However, the relationship between T and preferences for female facial femininity has yet to be tested experimentally. In the current paper, we report the results of two experiments examining the causal role of T in modulating preferences for facial femininity across both short and long-term mating contexts. Results of Experiment 1 (within-subject design, n=24) showed that participants significantly preferred feminized versus masculinized versions of womens faces. Further, participants showed a stronger preference for feminine faces in the short versus the long-term context after they received T, but not after they received placebo. Post-hoc analyses suggested that this effect was driven by a lower preference for feminine faces in the long-term context when on T relative to placebo, and this effect was found exclusively for men who received placebo on the first day of testing, and T on the second day of testing (i.e., Order x Drug x Mating context interaction). In Experiment 2 (between-subject design, n=93), men demonstrated a significant preference for feminized female faces in the short versus the long-term context after T, but not after placebo administration. Collectively, these findings provide the first causal evidence that T modulates mens preferences for facial femininity as a function of mating context.

Commentary: Facial Width-to-Height Ratio (fWHR) Is Not Associated with Adolescent Testosterone Levels

Facial width-to-height ratio (fWHR), the ratio of the distance between the left and right zygomatic bones to the distance between the upper lip and brow, predicts many traits, displays, and behaviors, including male aggression, trustworthiness, risk-taking, and physical formidability (e.g., Carre et al., 2009; Stirrat and Perrett, 2010; Welker et al., 2015; Zilioli et al., 2015). One theorized mechanism for linking fWHR to these behavioral traits and displays is pubertal exposure to testosterone, which may reflect androgenic organizational effects on neural circuitry related to these behaviors (Carre and McCormick, 2008). Lending support to this possibility, some work suggests that low-dose administrations of testosterone modulate craniofacial growth in boys with delayed puberty (Verdonck et al., 1999), but until now, research has not examined this association.

Psychedelic use and intimate partner violence: The role of emotion regulation:

Background: Recent evidence suggests that psychedelic use predicts reduced perpetration of intimate partner violence among men involved in the criminal justice system. However, the extent to which this association generalizes to community samples has not been examined, and potential mechanisms underlying this association have not been directly explored. Aims: The present study examined the association between lifetime psychedelic use and intimate partner violence among a community sample of men and women. The study also tested the extent to which the associations were mediated by improved emotion regulation. Methods: We surveyed 1266 community members aged 16–70 (mean age=22.78, standard deviation=7.71) using an online questionnaire that queried substance use, emotional regulation, and intimate partner violence. Respondents were coded as psychedelic users if they reported one or more instance of using lysergic acid diethylamide and/or psilocybin mushrooms in their lifetime. Results/outcomes: Males reporting any experience using lysergic acid diethylamide and/or psilocybin mushrooms had decreased odds of perpetrating physical violence against their current partner (odds ratio=0.42, p<0.05). Furthermore, our analyses revealed that male psychedelic users reported better emotion regulation when compared to males with no history of psychedelic use. Better emotion regulation mediated the relationship between psychedelic use and lower perpetration of intimate partner violence. This relationship did not extend to females within our sample. Conclusions/interpretation: These findings extend prior research showing a negative relationship between psychedelic use and intimate partner violence, and highlight the potential role of emotion regulation in this association.

Effect of exogenous testosterone on cooperation depends on personality and time pressure

The social heuristic hypothesis posits that human cooperation is an intuitive response that is expressed especially under conditions of time-constraint. Conversely, it proposes that for individuals given an opportunity for reflection, cooperation is more likely to be curtailed by an optimizing process calibrated to maximize individual benefit in a given situation. Notably, the steroid hormone testosterone has also been implicated in intuitive decision-making, including both prosocial and anti-social behaviors, with effects strongest in men with particular dispositional characteristics. This raises the possibility that increased testosterone may augment the effects predicted by the social heuristic hypothesis, particularly among men higher in specific dispositional characteristics (dominance, impulsivity, independent self-construal: high risk for testosterone-induced antisocial behavior). Here, in a testosterone administration study with a relatively large sample of men (N = 400), we test this possibility in a double-blind, placebo-controlled paradigm, with men randomly assigned to play a one-shot public goods game either under time-pressure (forced intuition) or with a time delay (forced reflection). Results revealed that within the placebo group, time-pressure (versus forced delay) increased cooperation among low risk men, but decreased cooperation among high risk men. Testosterone further moderated this pattern by abolishing the time-pressure effect in low risk men and—in high risk men—reversing the effect by selectively reducing offers (compared to placebo) under forced delay. This is the first evidence that testosterone and personality can interact with time-pressure and delay to predict human cooperation.

A Comparison of Voluntary and Involuntary Child and Adolescent Inpatient Psychiatry Admissions

ABSTRACT The study compares voluntary and involuntary groups of patients and provides the first detailed description of involuntary admissions to a Canadian child and adolescent inpatient psychiatry setting. The involuntary group was found to have a higher percentage of adolescents, patients with suicide risk, patients living away from families, and patients presenting outside of regular office hours. Involuntary patients were more likely to be provided with secure transportation to inpatient care than voluntary patients. No differences were found between groups in terms of gender, culture, problem severity, global functioning, or medication. Inpatient psychiatry assessed lower prevalence of suicide risk relative to referral sources, kept involuntary patients for shorter stays than voluntary patients, and rapidly terminated involuntary status for the majority. Based upon the study findings, it appears that involuntary referrals may provide reassuring admission after emergency department screening identifies possible severe risk of suicide. But, this reassurance may come at the cost of admitting a significant proportion of individuals without serious mental illness, and who may not require involuntary status or who may not go on to profit from inpatient care. Research is required to evaluate the determinants, costs, and benefits of involuntary admissions for patients and the mental health system.