Can exposure to prenatal sex hormones (2D:4D) predict cognitive reflection?

Sex Differences in Cognitive Reflection: A Meta-Analysis

The current study presents a meta-analytic review of the differences between men and women in cognitive reflection (CR). The study also explores whether the type of CR test (i.e., numerical tests and verbal tests) moderates the relationship between CR and sex. The results showed that men score higher than women on CR, although the magnitude of these differences was small. We also found out that the type of CR test moderates the sex differences in CR, especially in the numerical tests. In addition, the results showed that the length of numerical tests (i.e., number of items) does not affect the differences between men and women in CR. Finally, the implications of these results are discussed, and future research is suggested.

Finger-Length Ratios and Sexual Orientation in Southern Spain: A Large Sample Study on Sex-Linked Personality and Cognitive Traits

Some similarities between sex differences and sexual orientation differences, with gay men shifted in female-typical directions and lesbians shifted in male-typical directions, have been hypothesized to reflect the effects of prenatal androgen exposure. This report assessed sex-linked personality and cognitive traits in a Spanish sample of 1117 straight (i.e., heterosexual) and non-straight (i.e., non-heterosexual) men and women, using finger-length ratio (2D:4D) as an index of prenatal androgen exposure. Observed sex differences were in the expected direction: Measures of right-hand 2D:4D, left-hand 2D:4D, and anxiety were higher in straight women than men, whereas impulsivity, dominance, cognitive reflection, and mathematical proficiency were higher in straight men than women. Gay men proved to be shifted in a female-typical direction compared to straight men for right-hand 2D:4D, left-hand 2D:4D, anxiety, and cognitive reflection; they were intermediate for dominance and mathematics, and were shifted in a male-typical direction for impulsivity. Lesbians were shifted in a male-typical direction compared to straight women for left-hand 2D:4D, anxiety, cognitive reflection, and mathematics; and they were shifted in a highly female-typical direction for impulsivity and dominance (scoring lower than straight women). Observed sex-linked shifts in gay men and lesbians were larger for psychological traits that displayed larger sex differences, and smallest for impulsivity (which displayed the smallest sex difference). Evidence also suggested that sex-related measures were linked to 2D:4D in theoretically meaningful ways. In conclusion, this report suggests a plausible role of androgens as prenatal determinants of sex-linked personality and cognitive traits in straight and non-straight men and women.

In and out of unemployment-Labour market transitions and the role of testosterone

Biological processes have provided new insights into diverging labour market trajectories. This paper uses population variation in testosterone levels to explain transition probabilities into and out of unemployment. We examine labour market transitions for 2004 initially employed and 111 initially unemployed British men from the UK Household Longitudinal Study ("Understanding Society") between 2011 and 2013. We address the endogeneity of testosterone levels by using genetic variation as instrumental variables (Mendelian Randomization). We find that for both initially unemployed men as well as initially employed men, higher testosterone levels reduce the risk of unemployment. Based on previous studies and descriptive evidence, we argue that these effects are likely driven by differences in cognitive and non-cognitive skills as well as job search behaviour of men with higher testosterone levels. Our findings suggest that latent biological processes can affect job search behaviour and labour market outcomes without necessarily relating to illness and disability.

Trustors' disregard for trustees deciding quickly or slowly in three experiments with time constraints

Many decisions in the economic and social domain are made under time constraints, be it under time pressure or forced delay. Requiring individuals to decide quickly or slowly often elicit different responses. Time pressure has been associated with inefficiency in market settings and market regulation often requires individuals to delay their decisions via cooling-off periods. Yet, recent research suggests that people who make reflective decisions are met with distrust. If this extends to external time constraints, then forcing individuals to delay their decisions may be counterproductive in scenarios where trust considerations are important, such as in market and organizational design. In three Trust Game experiments (total number of participants = 1872), including within- and between-subjects designs, we test whether individuals trust (more) someone who is forced to respond quickly (intuitively) or slowly (reflectively). We find that trustors do not adjust their behavior (or their beliefs) to the trustee’s time conditions. This seems to be an appropriate response because time constraints do not affect trustees’ behavior, at least when the game decisions are binary (trust vs. don’t trust; reciprocate vs. don’t reciprocate) and therefore mistakes cannot explain choices. Thus, delayed decisions per se do not seem to elicit distrust.

2D:4D Digit Ratios in Adults with Gender Dysphoria: A Comparison to Their Unaffected Same-Sex Heterosexual Siblings, Cisgender Heterosexual Men, and Cisgender Heterosexual Women

We compared gender dysphoria (GD) patients and their same-sex siblings in terms of their 2D:4D ratios, which may reflect prenatal exposure to androgen, one of the possible etiological mechanisms underlying GD. Sixty-eight GD patients (46 Female-to-Male [FtM]; 22 Male-to-Female [MtF]), 68 siblings (46 sisters of FtMs; 22 brothers of MtFs), and 118 heterosexual controls (62 female; 56 male) were included in the study. FtMs were gynephilic and MtFs were androphilic. We found that 2D:4D ratios in the both right hand (p < .001) and the left hand (p = .003) were lower in male controls than in female controls. Regarding right hands, FtM GD patients had lower 2D:4D ratios than female controls (p < .001) but their ratios did not differ from those of their sisters or male controls. FtM GD patients had no significant difference in their left-hand 2D:4D ratios compared to their sisters or female and male controls. While there was no significant difference in right hands between FtM's sisters and male controls, left-hand 2D:4D ratios were significantly higher in FtM's sisters (p = .017). MtF GD patients had lower right-hand 2D:4D ratios than female controls (p <.001), but their right-hand ratios did not differ from those of their brothers and male controls. There was no significant difference in left-hand 2D:4D ratios between MtF GD patients, and their brothers, or female and male controls. FtM GD patients showed significantly masculinized right-hand 2D:4D ratios, while there was no evidence of feminization in MtF GD patients.

"You're wrong!": The impact of accuracy feedback on the bat-and-ball problem

The popular bat-and-ball problem is a relatively simple math riddle on which people are easily biased by intuitive or heuristic thinking. In two studies we tested the impact of a simple but somewhat neglected manipulation - the impact of minimal accuracy feedback - on bat-and-ball performance. Participants solved a total of 15 standard and 15 control versions of the bat-and-ball problem in three consecutive blocks. Half of the participants received accuracy feedback in the intermediate block. Results of both studies indicated that the feedback had, on average, no significant effect on bat-and-ball accuracy over and above mere repeated presentation. We did observe a consistent improvement for a small number of individual participants. Explorative analyses indicated that this improved group showed a more pronounced conflict detection effect (i.e., latency increase) at the pretest and took more deliberation time after receiving the negative feedback compared to the unimproved group.

Lower Digit Ratio (2D:4D) Indicative of Excess Prenatal Androgen Is Associated With Increased Sociability and Greater Social Capital

Positive social interactions are crucial for human well-being. Elevated prenatal exposure to testosterone as indicated by a low second-to-fourth finger length ratio (2D:4D) relates to more aggressive/hostile behavior in men of low 2D:4D, especially in challenging situations. How much people enjoy interacting with others is determined by the personality trait sociability. Given its role in approach and avoidance behavior, sociability might also be influenced by prenatal sex hormones, but studies are inconclusive so far. Here, we investigated the association between 2D:4D and the personality trait sociability complemented by personal social capital and personal social network size, in a population-based cohort of 4998 men. Lower 2D:4D correlated significantly with higher trait sociability, bigger personal social capital, and larger personal social network size. These effects were consistent across both hands separately and their mean value. Furthermore, both factors of sociability (1) liking party and company of friends and (2) isolation intolerance, correlated significantly with the prenatal testosterone marker. The exploratory analysis revealed no link between 2D:4D and responses to the personality trait aggression items or items of anti-social-personality disorder. Our data suggest that prenatal androgen exposure organizes the brain with lasting effects on social behavior.

Neural basis of romantic partners' decisions about participation in leisure activity

Leisure activity is one of key ingredients for individual happiness and life satisfaction. Enjoying leisure activity with one’s partner can increase marital satisfaction. This study aimed to identify the neural basis of making decisions on participation in a leisure activity with one’s romantic partner as well as the relationship between leisure activity and satisfaction with life. Thirty-seven soon-to-be married heterosexual couples were participated in functional MRI while deciding participation in specific leisure activities in the individual, partner, with-friend, and with-partner conditions. We constructed analysis of variance models and investigated couple characteristics such as personality similarity, leisure activity matching rate, and spatial similarity in the bilateral frontoparietal network. The results showed decreased activity in the bilateral hippocampus during the task in the with-partner condition. Individual leisure activity was correlated with quality of life in males, whereas participation in leisure activity might require more cognitive loading on the dorsolateral prefrontal cortex in females. The leisure activity matching rate was correlated with courtship period, personality similarity, and spatial similarity of the right frontoparietal network during the task. These findings suggest that although there are different activation pattern in making decisions on leisure activity between romantic couples, spatial similarity of the partner’s social brain networks may be a marker that predicts how well the couple enjoys leisure activity together. In addition, our couples’ data analysis provides a scientific basis for the saying that romantic couples become more similar the longer they are together.

Gender role orientation, thinking style preference and facets of adult paranormality: A mediation analysis

This study examines the extent to which masculine and feminine gender role orientations predict self-reported anomalous experiences, belief, ability and fear once relevant correlates including biological sex are controlled for. The extent to which rational versus intuitive thinking style preference mediates these relationships is also examined. Path analysis (n = 332) found heightened femininity directly predicts stronger intuitive preference plus more anomalous experiences, belief and fear with, additionally, intuitive preference mediating several gender role-paranormality relationships. By comparison, heightened masculinity directly predicts both thinking styles plus lower anomalous fear. The latter relationship is also shaped by the nature of mediators with (a) more anomalous experiences and belief associated with more anomalous fear and (b) either heightened rationality else more anomalous ability linked to, conversely, less anomalous fear. The extent to which findings support a gender (or social) role account of adult paranormality, together with methodological limitations and ideas for future research, is discussed.

Digit ratio (2D : 4D) and prosocial behaviour in economic games: no direct correlation with generosity, bargaining or trust-related behaviours

Prenatal exposure to sex hormones exerts organizational effects on the brain which have observable behavioural correlates in adult life. There are reasons to expect that social behaviours-fundamental for the evolutionary success of humans-might be related to biological factors such as prenatal sex hormone exposure. Nevertheless, the existing literature is inconclusive as to whether and how prenatal exposure to testosterone and oestrogen, proxied by the second-to-fourth digit ratio (2D : 4D), may predict non-selfish behaviour. Here, we investigate this question using economic experiments with real monetary stakes and analyse five different dimensions of social behaviour in a comparatively large sample of Caucasian participants (n = 560). For both males and females, our results show no robust association between right- or left-hand 2D : 4D and generosity, bargaining or trust-related behaviours. Moreover, no differences in behaviour were found according to sex. We conclude that there is no direct correlation between 2D : 4D and these social behaviours.

Effect of response format on cognitive reflection: Validating a two- and four-option multiple choice question version of the Cognitive Reflection Test

The Cognitive Reflection Test, measuring intuition inhibition and cognitive reflection, has become extremely popular because it reliably predicts reasoning performance, decision-making, and beliefs. Across studies, the response format of CRT items sometimes differs, based on the assumed construct equivalence of tests with open-ended versus multiple-choice items (the equivalence hypothesis). Evidence and theoretical reasons, however, suggest that the cognitive processes measured by these response formats and their associated performances might differ (the nonequivalence hypothesis). We tested the two hypotheses experimentally by assessing the performance in tests with different response formats and by comparing their predictive and construct validity. In a between-subjects experiment (n = 452), participants answered stem-equivalent CRT items in an open-ended, a two-option, or a four-option response format and then completed tasks on belief bias, denominator neglect, and paranormal beliefs (benchmark indicators of predictive validity), as well as on actively open-minded thinking and numeracy (benchmark indicators of construct validity). We found no significant differences between the three response formats in the numbers of correct responses, the numbers of intuitive responses (with the exception of the two-option version, which had a higher number than the other tests), and the correlational patterns of the indicators of predictive and construct validity. All three test versions were similarly reliable, but the multiple-choice formats were completed more quickly. We speculate that the specific nature of the CRT items helps build construct equivalence among the different response formats. We recommend using the validated multiple-choice version of the CRT presented here, particularly the four-option CRT, for practical and methodological reasons. Supplementary materials and data are available at https://osf.io/mzhyc/ .

Cognitive reflection, 2D:4D and social value orientation

The current study seeks confirmation for the hypothesis that 2D:4D (positively) predicts prosociality when people are more likely to rely on intuition than deliberation. We assess intuition and deliberation using the Cognitive Reflection Test (CRT) and measure prosociality via the validated Social Value Orientation (SVO) slider measure. Although our results do not provide collective evidence for our main proposition, we observe in the data that for low (right) 2D:4D men, the more intuitive they are, the less prosocial they become, whereas for high (right) 2D:4D men the thinking style does not affect their prosociality. Importantly, we find that two alternative measures of cognitive reflection, CRT and CRT-2, differently relate to prosocial decision making such that only CRT-2 (but not the classic CRT) positively predicts prosociality. Given that previous research on the role of cognitive reflection and 2D:4D in prosocial decision making provided inconsistent results, the present study findings are highly valuable to get a better understanding in this domain of study. Furthermore, some of our findings invite further confirmatory tests, thereby opening up multiple avenues for further research.

Deliberate reasoning is not affected by language

BACKGROUND

Millions of people use a second language every day. Does this have an effect on their decision-making? Are decisions in a second language more deliberate? Two mechanisms have been proposed: reduced emotionality or increased deliberation. Most studies so far used problems where both mechanisms could contribute to a foreign language effect. Here, we aimed to identify whether deliberate reasoning increases for problems that are devoid of any emotional connotation when using a second language or having to switch between native and second language.

METHOD

We measured deliberate reasoning with items from the cognitive reflection test, ratio bias, a probability matching task, and base rate neglect items. We recruited over 500 participants from Norway and the Netherlands that had English as their second language. Participants were randomly assigned to either the native, switching or second language condition. We measured: number of correctly answered items-deliberate reasoning score, perceived effort, perceived accuracy or confidence, and language proficiency.

RESULTS

Deliberate reasoning was not increased when using a second language or when having to switch between native and second language. All three groups performed equally well. Significant predictors of deliberate reasoning were age, gender, education, perceived effort, and confidence but not the language context. Participants with low English proficiency spent more time reading compared to more fluent speakers.

CONCLUSION

There is no advantage of second language on deliberate reasoning in the absence of time pressure. Deliberation was not increased by providing items in a second language, but through the willingness to spend cognitive effort and time to read carefully.

Testosterone is not associated with traits of optimism or pessimism: Observational evidence from the prospective DETECT study

Background

Previous experimental research on testosterone (T) and psychological traits is inconclusive. Thus, we performed the first large-scale observational study of the association between T and dispositional optimism / pessimism.

Methods

We used prospective data from 6,493 primary-care patients (3,840 women) of the DETECT study (Diabetes Cardiovascular Risk-Evaluation: Targets and Essential Data for Commitment of Treatment), including repeated immunoassay-based measurement of serum T and optimism / pessimism assessed by the revised Life-Orientation Test (LOT-R). Cross-sectional and longitudinal associations of baseline T and one-year change in T with optimism and pessimism were investigated using age- and multivariable-adjusted regression models.

Results

Cross-sectional analyses showed no association of T with optimism or pessimism in both sexes. Longitudinal analyses also showed no association of baseline T with optimism or pessimism at four-year follow-up. Multivariable analyses of total LOT-R score yielded similarly non-significant results (β-coefficient per unit change in T for men: -0.01 (95% CI: -0.24–0.22), women: 0.08 (-0.03–0.20)). Furthermore, change in T was not related to optimism or pessimism at four-year follow-up.

Conclusions

The present observational study of a large-scale prospective sample showed no association of T with optimism or pessimism. Integrating further experimental and interventional evidence from alternative methodological approaches would strengthen this conclusion and establish stronger evidence about the potential hormonal basis of psychological traits.

Second-to-fourth digit length ratio is associated with negative and affective symptoms in schizophrenia patients

BACKGROUND

Higher levels of circulating oestrogens in women and testosterone in men have been shown to have a protective effect against the clinical manifestations of schizophrenia, mostly with respect to negative symptomatology. Certain studies suggest that they also have a protective effect against the neuropsychological impairment observed in the disease. We investigated whether greater prenatal exposure to estrogens in women and to testosterone in men, reflected by the 2D:4D ratio, was similarly associated with decreased negative symptomatology and improved neuropsychological functioning in patients.

METHOD

51 schizophrenia patients and 50 healthy participants were administered a neuropsychological battery. The 2D:4D ratio was measured in all participants. Positive, negative, and affective symptoms were assessed in patients. Regression analyses were conducted separately in male and female subgroups.

RESULTS

No associations with positive symptoms were revealed. In male patients, the 2D:4D ratio was positively associated with avolition and inversely associated with anxiety. In female patients, it was inversely associated with alogia, and tended to be positively associated with depression. No association between higher prenatal concentration of the relevant sex hormone and improved neuropsychological performance emerged in patients.

CONCLUSIONS

Higher concentrations of prenatal testosterone in male patients, and prenatal oestrogens in female patients, are associated with a decrement in certain aspects of negative symptomatology. In addition, prenatal sex hormone concentration seems to be associated with predisposition to anxiety in male patients, and to depression in female patients.

The androgen model of suicide completion

Suicide is a devastating public health issue that imposes severe psychological, social, and economic burdens not only for the individuals but also for their relatives, friends, clinicians, and the general public. Among the different suicidal behaviors, suicide completion is the worst and the most relevant outcome. The knowledge of biological etiopathological mechanisms involved in suicide completion is limited. Hitherto, no objective markers, either alone or in combination, can reliably predict who will complete a suicide. However, such parameters are strongly needed to establish and optimize prediction and prevention. We introduce here a novel ideation-to-completion framework in suicide research and discuss the problems of studies aiming at identifying and validating clinically useful markers. The male gender is a specific risk factor for suicide, which suggests that androgen effects are implicated in the transition from suicidal ideation to suicide completion. We present multiple lines of direct and indirect evidence showing that both an increased prenatal androgen load (with subsequent permanent neuroadaptations) and increased adult androgen activity are involved in suicide completion. We also review data arguing that modifiable maternal behavioral traits during pregnancy contribute to the offspring's prenatal androgen load and increase the risk for suicide completion later in life. We conclude that in utero androgen exposure and adult androgen levels facilitate suicide completion in an synergistic manner. The androgen model of suicide completion provides the basis for the development of novel predictive and preventive strategies in the future.

Testosterone, Cortisol and Financial Risk-Taking

Both testosterone and cortisol have major actions on financial decision-making closely related to their primary biological functions, reproductive success and response to stress, respectively. Financial risk-taking represents a particular example of strategic decisions made in the context of choice under conditions of uncertainty. Such decisions have multiple components, and this article considers how much we know of how either hormone affects risk-appetite, reward value, information processing and estimation of the costs and benefits of potential success or failure, both personal and social. It also considers how far we can map these actions on neural mechanisms underlying risk appetite and decision-making, with particular reference to areas of the brain concerned in either cognitive or emotional functions.

Decision-making, financial risk aversion, and behavioral biases: The role of testosterone and stress

We examine the relation between testosterone, cortisol, and financial decisions in a sample of naïve investors. We find that testosterone level is positively related to excess risk-taking, whereas cortisol level is negatively related to excess risk-taking (correlation coefficient [r]: 0.75 and -0.21, respectively). Additionally, we find support for the dual-hormone hypothesis in a financial context. Specifically, the testosterone-to-cortisol ratio is significantly related to loss aversion. Individuals with a higher ratio are 3.4 times more likely to sell losing stocks (standard error [SE]: 1.63). Furthermore, we find a positive feedback loop between financial success, testosterone, and cortisol. Specifically, financial success is significantly related to higher post-trial testosterone and cortisol by a factor of 0.53 (SE: 0.14). Finally, we find that in a competitive environment, testosterone level increases significantly, leading to greater risk-taking than in noncompetitive environment. Overall, this study underscores the importance of the endocrine system on financial decision-making. The results of this study are relevant to a broad audience, including investors looking to optimize financial performance, industry human resources, market regulators, and researchers.

Self-confidence, Overconfidence and Prenatal Testosterone Exposure: Evidence from the Lab

This paper examines whether foetal testosterone exposure predicts the extent of confidence and over-confidence in own absolute ability in adulthood. To study this question, we elicited incentive-compatible measures of confidence and over-confidence in the lab and correlate them with measures of right hand 2D:4D, used as as a marker for the strength of prenatal testosterone exposure. We provide evidence that men with higher prenatal testosterone exposure (i.e., low 2D:4D ratio) are less likely to set unrealistically high expectations about their own performance. This in turn helps them to gain higher monetary rewards. Men exposed to low prenatal testosterone levels, instead, set unrealistically high expectations which results in self-defeating behavior.

Discounting and Digit Ratio: Low 2D:4D Predicts Patience for a Sample of Females

Inter-temporal trade-offs are ubiquitous in human decision making. We study the relationship between preferences over such trade-offs and the ratio of the second digit to that of the forth (2D:4D), a marker for pre-natal exposure to sex hormones. Specifically, we study whether 2D:4D affects discounting. Our sample consists of 419 female participants of a Guatemalan conditional cash transfer program who take part in an experiment. Their choices in the convex time budget (CTB) experimental task allow us to make inferences regarding their patience (discounting), while controlling for present-biasedness and preference for smoothing consumption (utility curvature). We find that women with lower digit ratios tend to be more patient.

A Context Dependent Interpretation of Inconsistencies in 2D:4D Findings: The Moderating Role of Status Relevance

Whereas direct relationships between 2D:4D and dominance related attitudes or behavior often turn out to be weak, some literature suggests that the relation between 2D:4D and dominance is context-specific. That is, especially in status-challenging situations 2D:4D may be related to dominant behavior and its correlates. Based on this perspective, we interpret inconsistencies in the literature on the relation between 2D:4D and risk taking, aggression and dominance related outcomes and investigate in our empirical study how attitudes in low 2D:4D men may change as a function of the status relevance of the context. We provide evidence for the idea that status relevance of the particular situation at hand influences the attitude towards performance-enhancing means for low 2D:4D men, but not for high 2D:4D men. We argue that 2D:4D may be related to any behavior that is functional to attain status in a specific context. Implications for (economic) decision making are discussed.

Investigating Gender Differences under Time Pressure in Financial Risk Taking

There is a significant gender imbalance on financial trading floors. This motivated us to investigate gender differences in financial risk taking under pressure. We used a well-established approach from behavior economics to analyze a series of risky monetary choices by male and female participants with and without time pressure. We also used second to fourth digit ratio (2D:4D) and face width-to-height ratio (fWHR) as correlates of pre-natal exposure to testosterone. We constructed a structural model and estimated the participants' risk attitudes and probability perceptions via maximum likelihood estimation under both expected utility (EU) and rank-dependent utility (RDU) models. In line with existing research, we found that male participants are less risk averse and that the gender gap in risk attitudes increases under moderate time pressure. We found that female participants with lower 2D:4D ratios and higher fWHR are less risk averse in RDU estimates. Males with lower 2D:4D ratios were less risk averse in EU estimations, but more risk averse using RDU estimates. We also observe that men whose ratios indicate a greater prenatal exposure to testosterone exhibit a greater optimism and overestimation of small probabilities of success.

Men Who Compliment a Woman's Appearance Using Metaphorical Language: Associations with Creativity, Masculinity, Intelligence and Attractiveness

Language may have evolved as a signal of mental fitness. However, it remains unclear what language form and topic men use to covertly signal mate quality. In this study 69 men created compliments to impress unfamiliar women they chose to either date or work with and provided hand scans to compute 2D4D ratio as a proxy for prenatal testosterone exposure and masculinity indicator. Compliments were coded in terms of form (literal vs. metaphorical) and topic (women's appearance vs. non-appearance), with metaphorical ones being subsequently rated by 114 women for psycholinguistic features, indices of intelligence and willingness to have a romantic relationship with the author. Results showed that in a dating context, men produced more metaphorical form compliments targeting appearance compared to the working context and they were associated with men's art creativity and negatively with 2D4D ratio (i.e., positively with masculinity). Women preferred establishing a romantic relationship with a higher proportion of the men producing metaphorical compliments in a dating than a working context. Furthermore, in the dating but not the working context, women perceived men producing such compliments as being more intelligent, and importantly this correlated with the men's actual verbal intelligence. Overall, findings suggest that men may use metaphorical language compliments targeting women's appearance in a dating context to signal covertly their mate quality.

Prenatal Temperature Shocks Reduce Cooperation: Evidence from Public Goods Games in Uganda

Climate change has not only led to a sustained rise in mean global temperature over the past decades, but also increased the frequency of extreme weather events. This paper explores the effect of temperature shocks in utero on later-life taste for cooperation. Using historical climate data combined with data on child and adult behavior in public goods games, I show that abnormally high ambient temperatures during gestation are associated with decreased individual contributions to the public good in a statistically and economically significant way. A 1 standard deviation rise in mean ambient temperature during gestation is associated with a 10% point decrease in children's cooperation rate in a dichotomous public goods game, and the reduced taste for cooperation lasts into adulthood.

The Effect of Testosterone Administration and Digit Ratio (2D:4D) on Implicit Preference for Status Goods in Healthy Males

Testosterone has been linked to social status seeking in humans. The present study investigated the effects of testosterone administration on implicit and explicit preferences for status goods in healthy male participants (n = 64), using a double-blind, placebo-controlled, between-subjects design. We also investigated the interactive effect between second-to-fourth digit ratio (2D:4D; i.e., a proximal index of prenatal testosterone) and testosterone treatment on status preferences. Results showed that testosterone administration has no discernable influence on self-reported willingness-to-pay (i.e., the explicit measure) or implicit attitudes towards status goods. Individuals with lower 2D:4D (i.e., more masculine) had more positive attitudes for high-status goods on an Implicit Association Task, and this association was abolished with testosterone administration. These data suggest interactive effects of acute testosterone administration and prenatal testosterone exposure on human social status seeking, and highlight the utility of implicit methods for measuring status-related behavior.

Single-Dose Testosterone Administration Impairs Cognitive Reflection in Men

In nonhumans, the sex steroid testosterone regulates reproductive behaviors such as fighting between males and mating. In humans, correlational studies have linked testosterone with aggression and disorders associated with poor impulse control, but the neuropsychological processes at work are poorly understood. Building on a dual-process framework, we propose a mechanism underlying testosterone’s behavioral effects in humans: reduction in cognitive reflection. In the largest study of behavioral effects of testosterone administration to date, 243 men received either testosterone or placebo and took the Cognitive Reflection Test (CRT), which estimates the capacity to override incorrect intuitive judgments with deliberate correct responses. Testosterone administration reduced CRT scores. The effect remained after we controlled for age, mood, math skills, whether participants believed they had received the placebo or testosterone, and the effects of 14 additional hormones, and it held for each of the CRT questions in isolation. Our findings suggest a mechanism underlying testosterone’s diverse effects on humans’ judgments and decision making and provide novel, clear, and testable predictions.

Deliberation favours social efficiency by making people disregard their relative shares: evidence from USA and India

Groups make decisions on both the production and the distribution of resources. These decisions typically involve a tension between increasing the total level of group resources (i.e. social efficiency) and distributing these resources among group members (i.e. individuals' relative shares). This is the case because the redistribution process may destroy part of the resources, thus resulting in socially inefficient allocations. Here we apply a dual-process approach to understand the cognitive underpinnings of this fundamental tension. We conducted a set of experiments to examine the extent to which different allocation decisions respond to intuition or deliberation. In a newly developed approach, we assess intuition and deliberation at both the trait level (using the Cognitive Reflection Test, henceforth CRT) and the state level (through the experimental manipulation of response times). To test for robustness, experiments were conducted in two countries: the USA and India. Despite absolute-level differences across countries, in both locations we show that: (i) time pressure and low CRT scores are associated with individuals' concerns for their relative shares and (ii) time delay and high CRT scores are associated with individuals' concerns for social efficiency. These findings demonstrate that deliberation favours social efficiency by overriding individuals' intuitive tendency to focus on relative shares.

Creativity and Cognitive Skills among Millennials: Thinking Too Much and Creating Too Little

Organizations crucially need the creative talent of millennials but are reluctant to hire them because of their supposed lack of diligence. Recent studies have shown that hiring diligent millennials requires selecting those who score high on the Cognitive Reflection Test (CRT) and thus rely on effortful thinking rather than intuition. A central question is to assess whether the push for recruiting diligent millennials using criteria such as cognitive reflection can ultimately hamper the recruitment of creative workers. To answer this question, we study the relationship between millennials' creativity and their performance on fluid intelligence (Raven) and cognitive reflection (CRT) tests. The good news for recruiters is that we report, in line with previous research, evidence of a positive relationship of fluid intelligence, and to a lesser extent cognitive reflection, with convergent creative thinking. In addition, we observe a positive effect of fluid intelligence on originality and elaboration measures of divergent creative thinking. The bad news for recruiters is the inverted U-shape relationship between cognitive reflection and fluency and flexibility measures of divergent creative thinking. This suggests that thinking too much may hinder important dimensions of creative thinking. Diligent and creative workers may thus be a rare find.

Self-identified Obese People Request Less Money: A Field Experiment

Empirical evidence suggests that obese people are discriminated in different social environments, such as the work place. Yet, the degree to which obese people are internalizing and adjusting their own behavior as a result of this discriminatory behavior has not been thoroughly studied. We develop a proxy for measuring experimentally the "self-weight bias" by giving to both self-identified obese (n = 90) and non-obese (n = 180) individuals the opportunity to request a positive amount of money after having performed an identical task. Consistent with the System Justification Theory, we find that self-identified obese individuals, due to a preexisting false consciousness, request significantly lower amounts of money than non-obese ones. A within subject comparison between self-reports and external monitors' evaluations reveals that the excessive weight felt by the "self" but not reported by evaluators captures the self-weight bias not only for obese but also for non-obese individuals. Linking our experimental results to the supply side of the labor market, we argue that self-weight bias, as expressed by lower salary requests, enhances discriminatory behavior against individuals who feel, but may not actually be, obese and consequently exacerbates the wage gap across weight.

Fluid Intelligence and Cognitive Reflection in a Strategic Environment: Evidence from Dominance-Solvable Games

Dominance solvability is one of the most straightforward solution concepts in game theory. It is based on two principles: dominance (according to which players always use their dominant strategy) and iterated dominance (according to which players always act as if others apply the principle of dominance). However, existing experimental evidence questions the empirical accuracy of dominance solvability. In this study, we study the relationships between the key facets of dominance solvability and two cognitive skills, cognitive reflection, and fluid intelligence. We provide evidence that the behaviors in accordance with dominance and one-step iterated dominance are both predicted by one's fluid intelligence rather than cognitive reflection. Individual cognitive skills, however, only explain a small fraction of the observed failure of dominance solvability. The accuracy of theoretical predictions on strategic decision making thus not only depends on individual cognitive characteristics, but also, perhaps more importantly, on the decision making environment itself.

Cognitive reflection and antibiotic prescribing for acute respiratory infections

BACKGROUND

Variation in clinical decision-making could be explained by clinicians' tendency to make 'snap-decisions' versus making more reflective decisions. One common clinical decision with unexplained variation is the prescription of antibiotics for acute respiratory infections (ARIs).

OBJECTIVE

We hypothesized that clinicians who tended toward greater cognitive reflection would be less likely to prescribe antibiotics for ARIs.

METHODS

The Cognitive Reflection Test (CRT) is a psychological test with three questions with intuitive but incorrect answers that respondents reach if they do not consider the question carefully. The CRT is scored from 0 to 3, representing the number of correct answers. A higher score indicates greater cognitive reflection. We administered the CRT to 187 clinicians in 50 primary care practices. From billing and electronic health record data, we calculated clinician-level antibiotic prescribing rates for ARIs in 3 categories: all ARIs, antibiotic-appropriate ARIs and non-antibiotic-appropriate ARIs.

RESULTS

A total of 57 clinicians (31%) scored 0 points on the CRT; 38 (20%) scored 1; 51 (27%) scored 2; and 41 (22%) scored 3. We found a roughly U-shaped association between cognitive reflection and antibiotic prescribing. The antibiotic prescribing rate for CRT scores of 0, 1, 2 and 3 for all ARIs (n = 37080 visits) was 32%, 26%, 25% and 30% (P = 0.10); for antibiotic-appropriate ARIs (n = 11220 visits) was 60%, 55%, 54% and 58% (P = 0.63); and for non-antibiotic-appropriate ARIs (n = 25860 visits) was 21%, 17%, 13% and 18%, respectively (P = 0.03).

CONCLUSIONS

In contrast to our hypothesis, there appears to be a 'sweet-spot' of cognitive reflection for antibiotic prescribing for non-antibiotic-appropriate ARIs. Differences in clinicians' cognitive reflection may be associated with other variations in care.

Overconfidence, Incentives and Digit Ratio

This paper contributes to a better understanding of the biological underpinnings of overconfidence by analyzing performance predictions in the Cognitive Reflection Test with and without monetary incentives. In line with the existing literature we find that the participants are too optimistic about their performance on average; incentives lead to higher performance; and males score higher than females on this particular task. The novelty of this paper is an analysis of the relation between participants’ performance prediction accuracy and their second to fourth digit ratio. It has been reported that the digit ratio is a negatively correlated bio-marker of prenatal testosterone exposure. In the un-incentivized treatment, we find that males with low digit ratios, on average, are significantly more overconfident about their performance. In the incentivized treatment, however, we observe that males with low digit ratios, on average, are less overconfident about their performance. These effects are not observed in females. We discuss how these findings fit into the literature on testosterone and decision making and how they might help to explain seemingly opposing evidence.

The Influence of Facial Characteristics on the Relation between Male 2D:4D and Dominance

Although relations between 2D:4D and dominance rank in both baboons and rhesus macaques have been observed, evidence in humans is mixed. Whereas behavioral patterns in humans have been discovered that are consistent with these animal findings, the evidence for a relation between dominance and 2D:4D is weak or inconsistent. The present study provides experimental evidence that male 2D:4D is related to dominance after (fictitious) male-male interaction when the other man has a dominant, but not a submissive or neutral face. This finding provides evidence that the relationship between 2D:4D and dominance emerges in particular, predictable situations and that merely dominant facial characteristics of another person are enough to activate supposed relationships between 2D:4D and dominance.

The cognitive basis of social behavior: cognitive reflection overrides antisocial but not always prosocial motives

Even though human social behavior has received considerable scientific attention in the last decades, its cognitive underpinnings are still poorly understood. Applying a dual-process framework to the study of social preferences, we show in two studies that individuals with a more reflective/deliberative cognitive style, as measured by scores on the Cognitive Reflection Test (CRT), are more likely to make choices consistent with “mild” altruism in simple non-strategic decisions. Such choices increase social welfare by increasing the other person's payoff at very low or no cost for the individual. The choices of less reflective individuals (i.e., those who rely more heavily on intuition), on the other hand, are more likely to be associated with either egalitarian or spiteful motives. We also identify a negative link between reflection and choices characterized by “strong” altruism, but this result holds only in Study 2. Moreover, we provide evidence that the relationship between social preferences and CRT scores is not driven by general intelligence. We discuss how our results can reconcile some previous conflicting findings on the cognitive basis of social behavior.

Digit ratio (2D:4D) and altruism: evidence from a large, multi-ethnic sample

We look at the links between the Digit Ratio—the ratio of the length of the index finger to the length of the ring finger—for both right and left hands, and giving in a Dictator Game. Unlike previous studies with exclusively Caucasian subjects, we consider a large, ethnically diverse sample. Our main results are as follows. First, for Caucasian subjects we estimate a significant positive regression coefficient for the right hand digit ratio and a significant negative coefficient for its squared measure. These results replicate the findings of Brañas-Garza et al. (2013), who also observe an inverted U-shaped relationship for Caucasian subjects. Second, we are not able to find any significant association of the right hand digit ratio with giving in the Dictator Game for the other main ethnic groups in our sample, nor in the pooled sample. Third, we find no significant association between giving in the Dictator Game and the left hand digit ratio.

In utero exposure to mixtures of xenoestrogens and child neuropsychological development

BACKGROUND

To date, no epidemiological studies have explored the impact and persistence of in utero exposure to mixtures of xenoestrogens on the developing brain. We aimed to assess whether the cumulative effect of xenoestrogens in the placenta is associated with altered infant neuropsychological functioning at two and at four years of age, and if associations differ among boys and girls.

METHODS

Cumulative prenatal exposure to xenoestrogens was quantified in the placenta using the biomarker Total Effective Xenoestrogen Burden (TEXB-alpha) in 489 participants from the INMA (Childhood and the Environment) Project. TEXB-alpha was split in tertiles to test its association with the mental and psychomotor scores of the Bayley Scales of Infant Development (BSID) at 1-2 years of age, and with the McCarthy Scales of Children׳s Abilities (MSCA) general cognitive index and motor scale assessed at 4-5 years of age. Interactions with sex were investigated.

RESULTS

After adjustment for potential confounders, no association was observed between TEXB-alpha and mental scores at 1-2 years of age. We found a significant interactions with sex for the association between TEXB-alpha and infant psychomotor development (interaction p-value=0.029). Boys in the third tertile of exposure scored on average 5.2 points less than those in the first tertile on tests of motor development at 1-2 years of age (p-value=0.052), while no associations were observed in girls. However, this association disappeared in children at 4-5 years of age and no association between TEXB-alpha and children׳s cognition was found.

CONCLUSIONS

Our results suggest that boys' early motor development might be more vulnerable to prenatal exposure to mixtures of xenoestrogens, but associations do not persist in preschool children.

Risk preferences and prenatal exposure to sex hormones for ladinos

Risk preferences drive much of human decision making including investment, career and health choices and many more. Thus, understanding the determinants of risk preferences refines our understanding of choice in a broad array of environments. We assess the relationship between risk preferences, prenatal exposure to sex hormones and gender for a sample of Ladinos, which is an ethnic group comprising 62.86% of the population of Guatemala. Prenatal exposure to sex hormones has organizational effects on brain development, and has been shown to partially explain risk preferences for Caucasians. We measure prenatal exposure to sex hormones using the ratio of the length of the index finger to the length of the ring finger (2D:4D), which is negatively (positively) correlated with prenatal exposure to testosterone (estrogen). We find that Ladino males are less risk averse than Ladino females, and that Ladino males have lower 2D:4D ratios than Ladino females on both hands. We find that the 2D:4D ratio does not explain risk preferences for Ladinos. This is true for both genders, and both hands. Our results highlight the importance of exploring the behavioral significance of 2D:4D in non-Caucasian racial groups.