Sex Differences in Direct Aggression: The Role of Impulsivity, Target Sex, and Intimacy with the Target

Men are, as a sex, more aggressive than women. Evolutionary accounts of the sex difference in direct aggression focus on the differing costs and benefits of aggression for men and women, and posit that male aggression and female non-aggression are both part of a suite of adaptations to sex-specific selection pressures. However, greater male aggression is not evident in studies of intimate partner aggression conducted in Western cultures. The present thesis sought to integrate evolutionary accounts of the sex difference in direct aggression with research on intimate partner aggression showing gender symmetry in aggressive acts. The proposed proximate mechanisms for the sex difference in direct aggression are myriad, but one of the most extensively investigated is impulsivity. The present thesis therefore sought to establish the presence or absence of sex differences in impulsivity, and identify the forms of impulsivity most likely to mediate the sex difference in aggression. Chapter Two presents a meta-analysis of sex differences in psychometric and behavioural measures of impulsivity. Sex differences are consistently present on those forms of impulsivity which are affective or motivational as opposed to cognitive in nature, and which incorporate some element of risk. Risky impulsivity, a personality trait reflecting a tendency to take risks without prior thought, was identified as a strong candidate for mediating the sex difference in aggression. In Chapter Three, the role of risky impulsivity in same-sex aggression and sociosexuality, both of which are related to the pursuit of reproductive success in the face of risk, was examined. Results from this chapter indicate that risky impulsivity might represent a common proximate mechanism for individual differences in aggression and sociosexuality, but that explaining sex differences in direct aggression requires consideration of processes at the dyadic, as well as the intrapsychic, level. Finally, the reasons for the absence of a sex difference in intimate partner aggression were examined more closely in Chapter Four. Participants were asked about hypothetical responses to provocation by same-sex friends, opposite-sex friends, and partners. Self-report data were also gathered on participants' actual aggressive behaviour towards partners, same-sex friends and strangers, and opposite-sex friends and strangers. There was good concordance between vignette responses and self-reports. Results indicated that men's aggression is inhibited towards all female targets relative to male ones, but that women's aggression is disinhibited specifically towards partners. In other words, men's lowered aggression towards intimate partners is an effect of target sex, while women's raised aggression towards intimate partners is an effect of intimacy with the target. It is argued that gender parity in intimate aggression is the result of sex-specific influences on rates of perpetration. It is further argued that any complete account of sex differences in aggression must be able to account for gender symmetry in aggression towards intimate partners. To this end, due consideration should be given to sex differences in low-level emotional and motivational processes, particularly fear, as well as the effects of sex differences in styles of anger expression. Specifically, men's reduction in intimate partner aggression might be best explained by the effects of Western social norms which proscribe aggression towards all women, while women's raised intimate partner aggression might be best explained by an oxytocin-mediated reduction in fear which is specific to intimate partners

Integrating approaches requires more than a division of labour: commentary on Wӧlfer & Hewstone

Wӧlfer and Hewstone (2015; hereafter W&H) argue that evolutionary psychology (EP) is useful for understanding sex differences in same-sex aggression, while social role theory (SRT) is best applied to sex differences in opposite-sex aggression. W&H tested this proposal using a rich dataset on high school students’ peer-reported aggression. They regressed classroom-level sex differences in same- and opposite-sex aggression onto five variables drawn from the two theoretical positions. Three variables (gender and masculinity norms, derived from SRT and body dimorphism, derived from EP) did not differ in their association with the two forms of aggression. Another variable (sex ratio: EP) was not interpretable because it was confounded with number of available targets, leaving a fifth (male hierarchy: EP) predicting sex differences in same-sex but not opposite-sex aggression. Our focus is not on the study itself, but on their proposal that theoretical disputes between EP and SRT can be resolved by assigning one form of aggression to EP and another to SRT. We believe that this argument mischaracterises both theories, reinforces the ‘evolutionary vs social’ divide, and falls short of integration.PostprintPeer reviewe

The effects of intimacy and target sex on direct aggression: Further evidence

The effects on aggression of target sex and relationship with the target were investigated using self-report data. One hundred and seventy-four participants (115 female) reported on acts of direct aggression in the last two years towards: intimate partners, known and unknown same-sex targets, and known and unknown opposite-sex targets. Women’s self-reported aggression was higher towards partners than other targets, replicating previous findings regarding women’s intimate partner aggression. Women’s aggression was consistently higher towards same-sex than opposite-sex targets, but the effect of knowing the target was inconsistent. Men’s self-reported aggression was more frequent towards same-sex than opposite-sex targets – including intimate partners – and more frequent towards known than unknown targets. Results are discussed with reference to a partner-specific reduction in women’s fear, and sex differences in threshold for classifying someone as ‘known well.’ Limitations of the present sample and suggestions for future work are discussed.PreprintPeer reviewe

Sex differences in direct aggression : the role of impulsivity, target sex, and intimacy with the target

Men are, as a sex, more aggressive than women. Evolutionary accounts of the sex difference in direct aggression focus on the differing costs and benefits of aggression for men and women, and posit that male aggression and female non-aggression are both part of a suite of adaptations to sex-specific selection pressures. However, greater male aggression is not evident in studies of intimate partner aggression conducted in Western cultures. The present thesis sought to integrate evolutionary accounts of the sex difference in direct aggression with research on intimate partner aggression showing gender symmetry in aggressive acts. The proposed proximate mechanisms for the sex difference in direct aggression are myriad, but one of the most extensively investigated is impulsivity. The present thesis therefore sought to establish the presence or absence of sex differences in impulsivity, and identify the forms of impulsivity most likely to mediate the sex difference in aggression. Chapter Two presents a meta-analysis of sex differences in psychometric and behavioural measures of impulsivity. Sex differences are consistently present on those forms of impulsivity which are affective or motivational as opposed to cognitive in nature, and which incorporate some element of risk. Risky impulsivity, a personality trait reflecting a tendency to take risks without prior thought, was identified as a strong candidate for mediating the sex difference in aggression. In Chapter Three, the role of risky impulsivity in same-sex aggression and sociosexuality, both of which are related to the pursuit of reproductive success in the face of risk, was examined. Results from this chapter indicate that risky impulsivity might represent a common proximate mechanism for individual differences in aggression and sociosexuality, but that explaining sex differences in direct aggression requires consideration of processes at the dyadic, as well as the intrapsychic, level. Finally, the reasons for the absence of a sex difference in intimate partner aggression were examined more closely in Chapter Four. Participants were asked about hypothetical responses to provocation by same-sex friends, opposite-sex friends, and partners. Self-report data were also gathered on participants' actual aggressive behaviour towards partners, same-sex friends and strangers, and opposite-sex friends and strangers. There was good concordance between vignette responses and self-reports. Results indicated that men's aggression is inhibited towards all female targets relative to male ones, but that women's aggression is disinhibited specifically towards partners. In other words, men's lowered aggression towards intimate partners is an effect of target sex, while women's raised aggression towards intimate partners is an effect of intimacy with the target. It is argued that gender parity in intimate aggression is the result of sex-specific influences on rates of perpetration. It is further argued that any complete account of sex differences in aggression must be able to account for gender symmetry in aggression towards intimate partners. To this end, due consideration should be given to sex differences in low-level emotional and motivational processes, particularly fear, as well as the effects of sex differences in styles of anger expression. Specifically, men's reduction in intimate partner aggression might be best explained by the effects of Western social norms which proscribe aggression towards all women, while women's raised intimate partner aggression might be best explained by an oxytocin-mediated reduction in fear which is specific to intimate partners.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

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 Zuckerman's 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.Publisher PDFPeer reviewe

The effects of intimacy and target sex on direct aggression: Further evidence

The effects on aggression of target sex and relationship with the target were investigated using self-report data. One hundred and seventy-four participants (115 female) reported on acts of direct aggression in the last two years towards: intimate partners, known and unknown same-sex targets, and known and unknown opposite-sex targets. Women’s self-reported aggression was higher towards partners than other targets, replicating previous findings regarding women’s intimate partner aggression. Women’s aggression was consistently higher towards same-sex than opposite-sex targets, but the effect of knowing the target was inconsistent. Men’s self-reported aggression was more frequent towards same-sex than opposite-sex targets – including intimate partners – and more frequent towards known than unknown targets. Results are discussed with reference to a partner-specific reduction in women’s fear, and sex differences in threshold for classifying someone as ‘known well.’ Limitations of the present sample and suggestions for future work are discussed.</p

Dataset: 'Sex differences in confidence influence patterns of conformity'

Raw data collected in the two experiments run for this study