Magnitude Of Sex Differences Research Articles

Sex differences in emotion recognition: investigating the moderating effects of stimulus features

ABSTRACT Emotion recognition – a prerequisite for social interactions – varies among individuals. Sex differences have been proposed as a central source of individual differences, although the existing evidence is rather heterogeneous. In the current study (N = 426), we investigated the potential moderating effects of stimulus features, including modality, emotion specificity, and the sex of the encoder (referring to the sex of the actor) on the magnitude of sex differences in emotion recognition. Our findings replicated women’s overall better emotion recognition, particularly evident for negative expressions (fear and anger) compared to men. This outperformance was observed across all modalities, with the largest differences for audiovisually expressed emotions, while the sex of the encoder had no impact. Given our findings, future studies should consider these and other potential moderator variables to better estimate sex differences.

Sex differences in the Dark Triad are sensitive to socioeconomic conditions: the adaptive value of narcissism in the UK, Greece, and China

Research has shown that levels of the Dark Triad (i.e., traits of Machiavellianism, narcissism, and psychopathy) vary across sex and age, with males and younger people reporting higher scores. The Dark Triad has also been found to be associated with personal economic status. We investigated whether sex and age differences in the Dark Triad varied across countries of different socioeconomic conditions. We further explored whether the dark traits predicted personal income to different extent across countries. We utilized three samples from the UK, Greece, and China (total N = 5,854), whose socioeconomic status varied from more to less developed according to the Human Development Index. Men scored higher than women on the Dark Triad, with the magnitude of sex differences being largest in the UK, followed by Greece and China. Younger people scored higher than older people on the Dark Triad, with the effect of age varying across countries. Narcissism positively predicted income, with its predictive power being significant in China and Greece but null in the UK. The results are consistent with the view that Dark Triad traits may be adaptive responses to environmental challenges. Specifically, the results suggest that sex differences in the Dark Triad and the relation between narcissism and personal income are responsive to socioeconomic conditions at the country level.

Comparing brain asymmetries independently of brain size

Studies examining cerebral asymmetries typically divide the l-R Measure (e.g., Left–Right Volume) by the L + R Measure to obtain an Asymmetry Index (AI). However, contrary to widespread belief, such a division fails to render the AI independent from the L + R Measure and/or from total brain size. As a result, variations in brain size may bias correlation estimates with the AI or group differences in AI. We investigated how to analyze brain asymmetries in to distinguish global from regional effects, and report unbiased group differences in cerebral asymmetries in the UK Biobank (N = 40, 028).We used 306 global and regional brain measures provided by the UK Biobank. Global gray and white matter volumes were taken from Freesurfer ASEG, subcortical gray matter volumes from Freesurfer ASEG and subsegmentation, cortical gray matter volumes, mean thicknesses, and surface areas from the Destrieux atlas applied on T1-and T2-weighted images, cerebellar gray matter volumes from FAST FSL, and regional white matter volumes from Freesurfer ASEG.We analyzed the extent to which the L + R Measure, Total Cerebral Measure (TCM, e.g., Total Brain Volume), and l-R TCM predict regional asymmetries. As a case study, we assessed the consequences of omitting each of these predictors on the magnitude and significance of sex differences in asymmetries.We found that the L + R Measure, the TCM, and the l-R TCM predicted the AI of more than 89% of regions and that their relationships were generally linear. Removing any of these predictors changed the significance of sex differences in 33% of regions and the magnitude of sex differences across 13–42% of regions. Although we generally report similar sex and age effects on cerebral asymmetries to those of previous large-scale studies, properly adjusting for regional and global brain size revealed additional sex and age effects on brain asymmetry.

A meta-analysis of sex differences in animal personality: no evidence for the greater male variability hypothesis.

The notion that men are more variable than women has become embedded into scientific thinking. For mental traits like personality, greater male variability has been partly attributed to biology, underpinned by claims that there is generally greater variation among males than females in non-human animals due to stronger sexual selection on males. However, evidence for greater male variability is limited to morphological traits, and there is little information regarding sex differences in personality-like behaviours for non-human animals. Here, we meta-analysed sex differences in means and variances for over 2100 effects (204 studies) from 220 species (covering five broad taxonomic groups) across five personality traits: boldness, aggression, activity, sociality and exploration. We also tested if sexual size dimorphism, a proxy for sex-specific sexual selection, explains variation in the magnitude of sex differences in personality. We found no significant differences in personality between the sexes. In addition, sexual size dimorphism did not explain variation in the magnitude of the observed sex differences in the mean or variance in personality for any taxonomic group. In sum, we find no evidence for widespread sex differences in variability in non-human animal personality.

Access to Resources Shapes Sex Differences Between Caring Parents

In species where both parents cooperate to care for their joint offspring, one sex often provides more care than the other. The magnitude of such sex differences often varies both between and within species and may depend on environmental conditions, such as access to resources, predation risk and interspecific competition. Here we investigated the impact of one such environmental variable – access to resources for breeding – on the magnitude of sex differences in parental care in the burying beetleNicrophorus vespilloides. This species breeds on the carcasses of small vertebrates, which are the sole food source for parents and offspring during breeding. We manipulated access to resources by providing pairs with mouse carcasses from a broad mass range (3.65–26.15 g). We then monitored subsequent effects on the duration and amount of care provided by males and females, male and female food consumption and weight change during breeding, and larval traits related to offspring performance. We found that males increased their duration of care as carcass mass increased, while females remained with the brood until it had completed its development irrespective of carcass mass. There were thus more pronounced sex differences in parental care when parents had access to fewer resources for breeding. Overall, our findings show that sex differences between caring parents vary depending on access to resources during breeding. The finding that males extended their duration of care on larger carcasses suggests that access to more resources leads to a shift toward more cooperation between caring parents.

Sex differences in the pelvis did not evolve de novo in modern humans.

It is commonly assumed that the strong sexual dimorphism of the human pelvis evolved for delivering the relatively large human foetuses. Here we compare pelvic sex differences across modern humans and chimpanzees using a comprehensive geometric morphometric approach. Even though the magnitude of sex differences in pelvis shape was two times larger in humans than in chimpanzees, we found that the pattern is almost identical in the two species. We conclude that this pattern of pelvic sex differences did not evolve de novo in modern humans and must have been present in the common ancestor of humans and chimpanzees, and thus also in the extinct Homo species. We further suggest that this shared pattern was already present in early mammals and propose a hypothesis of facilitated variation as an explanation: the conserved mammalian endocrine system strongly constrains the evolution of the pattern of pelvic differences but enables rapid evolutionary change of the magnitude of sexual dimorphism, which in turn facilitated the rapid increase in hominin brain size.

Using a Continuous Measure of Genderedness to Assess Sex Differences in the Attitudes of the Political Elite

We investigated the attitudes of the 11,410 candidates in the Finnish 2017 municipal elections who had responded to a Voting Advice Application. Women candidates were, both in terms of economic and social attitudes, more progressive than men. Building on the gender diagnosticity approach, we used responses to the attitude items to construct a dimensional measure of political genderedness; i.e., a measure of the femininity–masculinity of the individual’s political attitudes. We used this measure to investigate the magnitude of sex differences across parties and the determinants of these differences. Sex differences were larger in parties with more economically right-oriented, socially conservative, well-off, and male candidates. Moreover, these differences were caused by men in these parties being different from other candidates. A similar methodology, in which a continuous measure of genderedness is used to assess sex differences, could be used in other domains of research on political behavior.

Absence of Consistent Sex Differences in Outcomes From Symptomatic Carotid Endarterectomy and Stenting Randomized Trials.

CREST (Carotid Revascularization Endarterectomy Versus Stenting Trial) reported a higher periprocedural risk for any stroke, death, or myocardial infarction for women randomized to carotid artery stenting (CAS) compared with women randomized to carotid endarterectomy (CEA). No difference in risk by treatment was detected for women relative to men in the 4-year primary outcome. We aimed to conduct a pooled analysis among symptomatic patients in large randomized trials to provide more precise estimates of sex differences in the CAS-to-CEA risk for any stroke or death during the 120-day periprocedural period and ipsilateral stroke thereafter. Data from the Carotid Stenosis Trialists' Collaboration included outcomes from symptomatic patients in EVA-3S (Endarterectomy Versus Angioplasty in Patients With Symptomatic Severe Carotid Stenosis), SPACE (Stent-Protected Angioplasty Versus Carotid Endarterectomy in Symptomatic Patients), ICSS (International Carotid Stenting Study), and CREST. The primary outcome was any stroke or death within 120 days after randomization and ipsilateral stroke thereafter. Event rates and relative risks were estimated using Poisson regression; effect modification by sex was assessed with a sex-by-treatment-by-trial interaction term, with significant interaction defined a priori as P≤0.10. Over a median 2.7 years of follow-up, 433 outcomes occurred in 3317 men and 1437 women. The CAS-to-CEA relative risk of the primary outcome was significantly lower for women compared with men in 1 trial, nominally lower in another, and nominally higher in the other two. The sex-by-treatment-by-trial interaction term was significant (P=0.065), indicating heterogeneity among trials. Contributors to this heterogeneity are primarily differences in periprocedural period. When the trials are nevertheless pooled, there were no significant sex differences in risk in any follow-up period. There were significant differences between trials in the magnitude of sex differences in treatment effect (CAS-to-CEA relative risk), indicating pooling data from these trials to estimate sex differences might not be valid. Whether sex is acting as an effect modifier of the CAS-to-CEA treatment effect in symptomatic patients remains uncertain. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00190398 (EVA-3S) and NCT00004732 (CREST). URL: https://www.isrctn.com; Unique identifier: ISRCTN57874028 (SPACE) and ISRCTN25337470 (ICSS).

Sex Differences Concerning Prosocial Behavior in Social Dilemmas Are (Partially) Mediated by Risk Preferences But Not Social Preferences

Abstract. Previous results on the prosociality of men and women in social dilemmas are mixed. Studies find more prosocial behavior for men and women; and a meta-analysis ( Balliet et al., 2011 ) reports an overall null effect. Including samples ( N = 1,903) from 10 countries that vary concerning gender inequality (e.g., China, Colombia, Sweden), we investigated sex differences in social dilemmas and drivers of these potential differences. We found that men behaved more prosocially, in that they transferred more of their endowment to their interaction partner. This sex difference was descriptively observed for all countries and was partially mediated by differences in risk but not social preferences. Gender inequality did not predict the difference in magnitude of sex differences between countries.

Sex differences in infant health following ART-treated, subfertile, and fertile deliveries

Among infants following ART-treated, subfertile, and fertile deliveries to determine (1) the presence and magnitude of sex differences in health outcomes and (2) whether the presence of sex differences varied among maternal fertility groups. Retrospective cohort analysis of infants born in Massachusetts (MA) in 2004-2013 who were conceived by ART. The Society for Assisted Reproductive Technology Clinic Outcome Reporting System was linked to the Pregnancy to Early Life Longitudinal data system, which links birth certificates to hospital discharge records for MA mothers and infants. Included were singletons born via ART-treated, subfertile, and fertile deliveries. Multivariable logistic regression was used to model the association between infant sex and health outcomes, controlling for maternal demographic and health characteristics. A total of 16,034 ART-treated, 13,277 subfertile, and 620,375 fertile singleton live births were included. For all three groups, males had greater odds of being preterm (AOR range 1.15-1.2), having birth defects (AOR range 1.31-1.71), experiencing respiratory (AOR range 1.33-1.35) and neurologic (AOR range 1.24-1.3) conditions, and prolonged hospital stay (AOR range 1.19-1.25) compared to females. The interaction between maternal fertility group and infant sex for all infant outcomes was nonsignificant, denoting that the presence of sex differences among fertile, subfertile, and ART groups did not vary. Sex differences in birth outcomes of infants following ART-treated, subfertile, and fertile deliveries exist but the magnitude of these differences does not vary among these maternal fertility groups.

Magnitude of sex differences in visual search varies with target eccentricity

A recent meta-analysis found no support for the popular theory that superior visuospatial ability in males is attributable to their relatively greater hemispheric asymmetry of neural functions. However, the issue of whether differences in hemispheric laterality could account for differences in visual perception between the sexes has not been systematically investigated. Visual search is an ideal task for such an investigation, as target-position can be systematically varied across the visual field allowing for a detailed analysis of how performance varies with visual field and eccentricity. We recruited 539 undergraduate participants (150 male) and administered a visual search task that required them to identify the presence of a uniquely-oriented triangle amongst distractors. Crucially, target location was systematically varied over the visual field across trials. Males displayed both superior accuracy and shorter reaction time when targets were presented in the left visual field, whilst sex differences systematically diminished when the target was located further rightward. These behavioural results are in line with the notion that greater hemispheric asymmetry in males influences task performance to a varying extent across the visual field, and illustrates the importance of considering task parameters and the influence of sex in behavioural research.

Country-level correlates of the Dark Triad traits in 49 countries.

The Dark Triad traits (i.e., narcissism, psychopathy, Machiavellianism) capture individual differences in aversive personality to complement work on other taxonomies, such as the Big Five traits. However, the literature on the Dark Triad traits relies mostly on samples from English-speaking (i.e., Westernized) countries. We broadened the scope of this literature by sampling from a wider array of countries. We drew on data from 49 countries (N=11,723; 65.8% female; AgeMean =21.53) to examine how an extensive net of country-level variables in economic status (e.g., Human Development Index), social relations (e.g., gender equality), political orientations (e.g., democracy), and cultural values (e.g., embeddedness) relate to country-level rates of the Dark Triad traits, as well as variance in the magnitude of sex differences in them. Narcissism was especially sensitive to country-level variables. Countries with more embedded and hierarchical cultural systems were more narcissistic. Also, sex differences in narcissism were larger in more developed societies: Women were less likely to be narcissistic in developed (vs. less developed) countries. We discuss the results based on evolutionary and social role models of personality and sex differences. That higher country-level narcissism was more common in less developed countries, whereas sex differences in narcissism were larger in more developed countries, is more consistent with evolutionary than social role models.

Sex Differences in Youth Elite Swimming

The timing and magnitude of sex differences in athletic performance during early human development, prior to adulthood, is unknown.ObjectiveTo compare swimming velocity of boys and girls for all Olympic‐length freestyle swimming events to determine the age of divergence in swimming performance.MethodsWe collected the all‐time top 100 U.S. freestyle swimming performance times of boys and girls age 5 to 18 years for the 50m to 1500m events.ResultsSwimming performance improved with increasing age for boys and girls (p<0.001) until reaching a plateau, which initiated at a younger age for girls (15 years) than boys (17 years; sex×age; p<0.001). Prior to age 10, the top 5 swimming records for girls were 3% faster than the top boys (p<0.001). For the 10th–50th places, however, there were no sex‐related differences in swimming performance prior to age 10 (p=0.227). For both the top 5 and 10th–50th places, the sex difference in performance increased from age 10 (top 5, 2.5%; 10th–50th places, 1.0%) until age 17 (top 5, 7.6%; 10th–50th places, 8.0%). For all places, the sex difference in performance at age 18 was larger for sprint events (9.6%; 50–200m) than endurance events (7.1%; 400–1500m; p<0.001). Additionally, the sex‐related difference in performance increased across age and US ranking from 2.4% for 1st place to 4.3% for 100th place (p<0.001), indicating less depth of performance in girls than boys. However, annual participation was ~20% higher in girls than boys for all ages (p<0.001).ConclusionThe top 5 girls demonstrated faster swimming velocities and the 10th–50th place girls demonstrated similar swimming velocities than boys (until ~10 years). After age 10, however, boys demonstrated increasingly faster swimming velocities than girls until 17 years. Collectively, these data suggest girls are faster, or at least not slower, than boys prior to the performance‐enhancing effects of puberty.Support or Funding InformationThis study was supported by the National Institutes of Health R‐35‐HL139854‐02 (MJJ), HL139854‐02S1 (AJC), 5T32DK007352‐40 (JWS), and the Mayo Foundation.Elite swimming performance.Mean swimming velocity from 5 to 18 years of the top 100 fastest US boys (blue circles) and girls (red triangles) for the 50, 100, 200, 400, 800 and 1500m freestyle swimming distances.Figure 1Sex differences in performance of the top 5 places.The primary plot (heat map) displays the sex differences in swimming velocity (% boy’s swimming velocity) of the top 5 US rankings in each freestyle event distance and age, negative values (red) indicate faster performance of girls. The top displays the mean sex difference across age, and the right plot displays the mean sex difference across swimming event distance.Figure 2

Sex differences in youth elite swimming.

BackgroundThe timing and magnitude of sex differences in athletic performance during early human development, prior to adulthood, is unknown.ObjectiveTo compare swimming velocity of boys and girls for all Olympic-length freestyle swimming events to determine the age of divergence in swimming performance.MethodsWe collected the all-time top 100 U.S. freestyle swimming performance times of boys and girls age 5 to 18 years for the 50m to 1500m events.ResultsSwimming performance improved with increasing age for boys and girls (p<0.001) until reaching a plateau, which initiated at a younger age for girls (15 years) than boys (17 years; sex×age; p<0.001). Prior to age 10, the top 5 swimming records for girls were 3% faster than the top boys (p<0.001). For the 10th-50th places, however, there were no sex-related differences in swimming performance prior to age 10 (p = 0.227). For both the top 5 and 10th-50th places, the sex difference in performance increased from age 10 (top 5, 2.5%; 10th-50th places, 1.0%) until age 17 (top 5, 7.6%; 10th-50th places, 8.0%). For all places, the sex difference in performance at age 18 was larger for sprint events (9.6%; 50-200m) than endurance events (7.1%; 400-1500m; p<0.001). Additionally, the sex-related difference in performance increased across age and US ranking from 2.4% for 1st place to 4.3% for 100th place (p<0.001), indicating less depth of performance in girls than boys. However, annual participation was ~20% higher in girls than boys for all ages (p<0.001).ConclusionThe top 5 girls demonstrated faster swimming velocities and the 10th-50th place girls demonstrated similar swimming velocities than boys (until ~10 years). After age 10, however, boys demonstrated increasingly faster swimming velocities than girls until 17 years. Collectively, these data suggest girls are faster, or at least not slower, than boys prior to the performance-enhancing effects of puberty.

Mate Preferences in Three Muslim-Majority Countries: Sex Differences and Personality Correlates

Cross-cultural research on long-term mate preferences in Muslim-majority countries is scarce. The research described here aims to examine the KASER (kindness/dependability, attractiveness/sexuality, status/resources, education/intelligence, and religiosity/chastity) model of mate preferences in Iran, Pakistan, and Turkey (N = 1,089). We examined structural validity, measurement invariance between men and women, sex differences, cultural differences, and Big Five personality correlates of these dimensions of mate preferences. Findings supported preregistered hypotheses regarding sex differences in mate preferences. Multilevel models suggested that the magnitude of sex differences was invariant across cultures. Personality correlates of mate preferences varied across cultures, but agreeableness consistently predicted the preference for kind and dependable partners across cultures. In sum, sex differences in mate preferences within and across three Muslim-majority countries described here replicate previous findings, but evidence for personality correlates of mate preferences is mixed, variable across cultures, and in need of further examination in non-Western samples.

A meta-analysis of sex differences in human navigation skills.

There are inconsistent reports regarding behavioral sex differences in the human navigation literature. This meta-analysis quantifies the overall magnitude of sex differences in large-scale navigation skills in a variety of paradigms and populations, and examines potential moderators, using 694 effect sizes from 266 studies and a multilevel analytic approach. Overall, male participants outperform female participants, with a small to medium effect size (d = 0.34 to 0.38). The type of task, the type of dependent variable and the testing environment significantly contribute to variability in effect sizes, although there are only a few situations in which differences are either nonexistent or very large. Pointing and recall tasks (and the deviation scores associated with them) show larger sex differences than distance estimation tasks or learning to criterion. Studies with children younger than 13 years showed much smaller effect sizes (d = .15) than older age groups. We discuss the implications of these findings for understanding sex differences in human spatial navigation and identify avenues for future navigation research.

The magnitude of sex differences in verbal episodic memory increases with social progress: Data from 54 countries across 40 years.

Sex differences in episodic memory have been reported. We investigate (1) the existence of sex differences in verbal and other episodic memory tasks in 54 countries, and (2) the association between the time- and country-specific social progress indicators (a) female to male ratio in education and labor force participation, (b) population education and employment, and (c) GDP per capita, and magnitude of sex differences in verbal episodic memory tasks. Data were retrieved from 612 studies, published 1973–2013. Results showed that females outperformed (Cohen’s d > 0) males in verbal (42 out of 45 countries) and other (28 out of 45 countries) episodic memory tasks. Although all three social progress indicators were, separately, positively associated with the female advantage in verbal episodic memory performance, only population education and employment remained significant when considering the social indicators together. Results suggest that women’s verbal episodic memory performance benefits more than men’s from education and employment.

Sex differences in the Big Five model personality traits: A behavior genetics exploration

The importance of genetic influences for the Five Factor/Big Five Model (BFM) traits is well established. Relatively understudied, however, are the presence and magnitude of sex differences in genetic and environmental variance of these traits. The current study tested if men and women differ (1) qualitatively in the genetic mechanisms, or (2) quantitatively, on the genetic and environmental variance, contributing to BFM personality domains. Results from a nationally representative U.S. adult twin sample (N = 973 pairs) supported phenotypic (i.e., mean level) sex differences in three of five personality traits (Neuroticism, Agreeableness, Conscientiousness) but did not support genetic or environmental sex differences in any trait.

Learning environment, attitudes and anxiety across the transition from primary to secondary school mathematics

Past research has revealed that, relative to primary-school students, high-school students have less-positive attitudes to mathematics and perceive their classroom environments and teacher–student relationships less favourably. This study involved the transition experience of 541 students in 47 classes in 15 primary (year 7) and secondary (year 8) government and Catholic schools in metropolitan and regional South Australia. Scales were adapted from three established instruments, namely, the What Is Happening In this Class?, Test of Mathematics Related Attitudes and Revised Mathematics Anxiety Ratings Scale, to identify changes across the transition from primary to secondary school in terms of the classroom learning environment and students’ attitude/anxiety towards mathematics. Relative to year 7 students, year 8 students reported less Involvement, less positive Attitude to Mathematical Inquiry, less Enjoyment of Mathematics and greater Mathematics Anxiety. Differences between students in Years 7 and 8 were very similar for male and female students, although the magnitude of sex differences in attitudes was slightly different in Years 7 and 8.

Timing and sex effects on the “Spatial Orientation Test”: A World War II map reading test

ABSTRACTThe present study aimed to document the psychometric properties of a recently declassified map reading test used in World War II, known as the Spatial Orientation Test (SOT), which measures mostly the ability to match map and aerial images. We also examined the influence of timing conditions and sex of the participants as correlates of performance. A total of 101 participants (41 males, 60 females) completed the SOT, along with other spatial tests and spatial affect scales (tapping spatial anxiety and confidence). Results showed a significant male advantage on this rediscovered map reading test. Additionally, timing affected overall performance but not the magnitude of sex differences. Finally, significant correlations were found between the SOT and other spatial tests and scales. The processes underlying this test and its potential for future use are discussed.