Catharine P. Cross

Sex differences in impulsivity : a meta-analysis.

Men are overrepresented in socially problematic behaviors, such as aggression and criminal behavior, which have been linked to impulsivity. Our review of impulsivity is organized around the tripartite theoretical distinction between reward hypersensitivity, punishment hyposensitivity, and inadequate effortful control. Drawing on evolutionary, criminological, developmental, and personality theories, we predicted that sex differences would be most pronounced in risky activities with men demonstrating greater sensation seeking, greater reward sensitivity, and lower punishment sensitivity. We predicted a small female advantage in effortful control. We analyzed 741 effect sizes from 277 studies, including psychometric and behavioral measures. Women were consistently more punishment sensitive (d = -0.33), but men did not show greater reward sensitivity (d = 0.01). Men showed significantly higher sensation seeking on questionnaire measures (d = 0.41) and on a behavioral risk-taking task (d = 0.36). Questionnaire measures of deficits in effortful control showed a very modest effect size in the male direction (d = 0.08). Sex differences were not found on delay discounting or executive function tasks. The results indicate a stronger sex difference in motivational rather than effortful or executive forms of behavior control. Specifically, they support evolutionary and biological theories of risk taking predicated on sex differences in punishment sensitivity. A clearer understanding of sex differences in impulsivity depends upon recognizing important distinctions between sensation seeking and impulsivity, between executive and effortful forms of control, and between impulsivity as a deficit and as a trait.

Experimental evidence for the co-evolution of hominin tool-making teaching and language

Hominin reliance on Oldowan stone tools – which appear from 2.5mya and are believed to have been socially transmitted – has been hypothesised to have led to the evolution of teaching and language. Here we present an experiment investigating the efficacy of transmission of Oldowan tool-making skills along chains of adult human participants (N=184) using 5 different transmission mechanisms. Across six measures, transmission improves with teaching, and particularly with language, but not with imitation or emulation. Our results support the hypothesis that hominin reliance on stone tool-making generated selection for teaching and language and imply that (i) low-fidelity social transmission, such as imitation/emulation, may have contributed to the ~700,000 year stasis of the Oldowan technocomplex, and (ii) teaching or proto-language may have been pre-requisites for the appearance of Acheulean technology. This work supports a gradual evolution of language, with simple symbolic communication preceding behavioural modernity by hundreds of thousands of years.

Sex differences in sensation-seeking: a meta-analysis

Men score higher than women on measures of sensation-seeking, defined as a willingness to engage in novel or intense activities. This sex difference has been explained in terms of evolved psychological mechanisms or culturally transmitted social norms. We investigated whether sex differences in sensation-seeking have changed over recent years by conducting a meta-analysis of studies using Zuckermans Sensation Seeking Scale, version V (SSS-V). We found that sex differences in total SSS-V scores have remained stable across years, as have sex differences in Disinhibition and Boredom Susceptibility. In contrast, the sex difference in Thrill and Adventure Seeking has declined, possibly due to changes in social norms or out-dated questions on this sub-scale. Our results support the view that men and women differ in their propensity to report sensation-seeking characteristics, while behavioural manifestations of sensation-seeking vary over time. Sex differences in sensation-seeking could reflect genetically influenced predispositions interacting with socially transmitted information.

Gender symmetry in intimate aggression : an effect of intimacy or target sex ?

Mens greater use of direct aggression is not evident in studies of intimate partner aggression. In previous research, the effects of target sex and relationship intimacy have frequently been confounded. This study sought to examine these effects separately. One hundred and seventy-four participants (59 male and 115 female) read vignette scenarios in which they were provoked by a same-sex best friend, an opposite-sex best friend, and a partner. For each target, participants estimated their likely use of direct physical and verbal aggression as well as noninjurious forms of anger expression. Results showed that men lower their aggression in the context of an intimate partnership and that this is an effect of the targets sex. In contrast, women raise their aggression in the context of an intimate partnership and this is an effect of intimacy with the target. The use of noninjurious angry behavior did not vary between targets for either sex of the participant, which suggests that the effects of target are confined to behaviors which carry an intention to harm. Possible effects of social norms and oxytocin-mediated emotional disinhibition on intimate partner aggression are discussed.

Sex Differences in Same-Sex Direct Aggression and Sociosexuality: The Role of Risky Impulsivity

Sex differences in same-sex direct aggression and sociosexuality are among the most robust in the literature. The present article evaluated the hypothesis that both can be explained by a sex difference in the willingness to take impulsive risks. Self-report data were gathered from 3,775 respondents (1,514 female) on same-sex aggression, sociosexuality, and risky impulsivity. Risky impulsivity was higher for men than for women (d = .34) and path analysis showed it to be a common cause of same-sex aggression and sociosexuality for both sexes. However, it did not completely mediate the sex differences in same-sex aggression and sociosexuality. The results suggest that same-sex aggression and sociosexual behavior share a common psychological mechanism, but that fully explaining sex differences in aggression requires a more sensitive assay of impulsive risk and a consideration of dyadic processes.

Human mate-choice copying is domain-general social learning

Women appear to copy other women’s preferences for men’s faces. This ‘mate-choice copying’ is often taken as evidence of psychological adaptations for processing social information related to mate choice, for which facial information is assumed to be particularly salient. No experiment, however, has directly investigated whether women preferentially copy each other’s face preferences more than other preferences. Further, because prior experimental studies used artificial social information, the effect of real social information on attractiveness preferences is unknown. We collected attractiveness ratings of pictures of men’s faces, men’s hands, and abstract art given by heterosexual women, before and after they saw genuine social information gathered in real time from their peers. Ratings of faces were influenced by social information, but no more or less than were images of hands and abstract art. Our results suggest that evidence for domain-specific social learning mechanisms in humans is weaker than previously suggested.

Nothing in Human Behavior Makes Sense Except in the Light of Culture: Shared Interests of Social Psychology and Cultural Evolution

Over the past few decades, evolutionary approaches to understanding human behavior have become more widespread. Here we describe one such approach: cultural evolution. Cultural evolution can be distinguished from other related fields in that it treats culture as a shared body of knowledge that evolves at least partially independently of genes. This creates the opportunity for a variety of interesting dynamics between culture and genetics, referred to as “gene–culture coevolution,” including cultural practices creating selection for particular alleles. As culture is sustained by social transmission of information between individuals, cultural evolutionists are greatly interested in understanding the psychological mechanisms that affect how information flows through groups of individuals, referred to as “social learning strategies,” and it is here that we suggest there is an opportunity for crossovers between social psychology and cultural evolution. Across the rest of the chapter, we review the current state of knowledge concerning social learning strategies, including biases to copy when uncertain, to copy majorities, and to copy successful, prestigious, older, or related individuals. We also discuss maladaptive culture and comparative work with nonhuman animals. Finally, we end the chapter by discussing outstanding questions that could be targeted by both cultural evolutionists and social psychologists.

Violence and Aggression in Women

While women’s aggression is less frequent and dangerous than men’s, it must be addressed in any complete explanatory account of human aggression. In this chapter, we first argue that the sex difference in aggression is the result not only of selection pressures favouring aggressive competition in males but also of selection pressures favouring the avoidance of injury in females. Second, we briefly review evidence for a number of possible proximate psychological mechanisms underlying the sex difference in aggression. We find that fear—rather than anger, impulsivity, or sensation seeking—shows consistent sex differences in the anticipated direction and is the strongest candidate for accounting for women’s relatively low involvement in aggression. Third, we discuss contextual and cultural effects which might modify women’s appraisals of danger and, in turn, influence their fear levels and tendency to use aggressive acts. In particular, we discuss intimate partner aggression: Here, women’s use of aggression appears highly sensitive to cultural effects, with the magnitude of the sex difference varying markedly. Finally, we offer suggestions for extending the study of female aggression using an evolutionary approach which explicitly focuses on interaction between psychological mechanisms and cultural factors.

Sex differences in the use of social information emerge under conditions of risk

Social learning provides an effective route to gaining up-to-date information, particularly when information is costly to obtain asocially. Theoretical work predicts that the willingness to switch between using asocial and social sources of information will vary between individuals according to their risk tolerance. We tested the prediction that, where there are sex differences in risk tolerance, altering the variance of the payoffs of using asocial and social information differentially influences the probability of social information use by sex. In a computer-based task that involved building a virtual spaceship, men and women (N = 88) were given the option of using either asocial or social sources of information to improve their performance. When the asocial option was risky (i.e., the participant’s score could markedly increase or decrease) and the social option was safe (i.e., their score could slightly increase or remain the same), women, but not men, were more likely to use the social option than the asocial option. In all other conditions, both women and men preferentially used the asocial option to a similar degree. We therefore found both a sex difference in risk aversion and a sex difference in the preference for social information when relying on asocial information was risky, consistent with the hypothesis that levels of risk-aversion influence the use of social information.

Father absence and gendered traits in sons and daughters

Research has previously found a number of apparently contradictory patterns in the relationship between ‘father absence’ (having a non-resident father during childhood) and the expression of gender roles, as well as other sexually dimorphic traits such as aggression. In the current study we measured a battery of sexually differentiated traits in relation to family background. 133 men and 558 women from the United States and Australia completed the Bem Sex Role Inventory, the Barrett Impulsivity Scale, the Fear Survey Schedule and the Buss & Perry Aggression Questionnaire. Principal components analysis found two main axes of variation in these traits. Firstly, a general ‘reactivity’ factor, on which aggression, impulsivity, and fear all loaded positively, was weakly associated with father absence in women. Secondly, ‘masculinity’ (consisting of high scores on masculine traits, low fear, and physical and verbal aggression) was not associated with father absence. Participants (except American males) reporting a poor childhood relationship with their parents also had high ‘reactivity’ but not higher ‘masculinity’. We found some evidence of a link between father absence and earlier age of first coitus in American females (although not in Australia), but there was no link with age of menarche in either country. Overall, the current results suggest that previous findings linking gender development with father absence in girls may have arisen from a tendency towards greater externalising and reactive behaviour rather than a change in gender development per se.