Quantitative chromatographic profiling of odours associated with dominance in male laboratory mice

Triads of male NMRI mice were housed together and dominance hierarchies allowed to form. At age 19 weeks the mice were ranked on the basis of wins in spontaneous aggressive encounters, and whole-body volatiles were sampled by the dynamic solvent effect and quantitatively analysed by capillary gas chromatography. At age 26 weeks the mice were again ranked on the basis of wins in aggressive encounters, number of aggressive encounters initiated, and scent marking patterns, and whole-body volatiles were sampled and analysed. Chromatographic odour profile ranks agreed perfectly with aggressive initiator ranks and poorly with encounter winner ranks. Eight components of the whole-body odour were identified by gas chromatography-mass spectrometry; two of these are known semiochemicals. The results demonstrate that murine semiochemicals are accessible to quantitative analysis at the level of the individual.     

Predatory aggression in the mink (Mustela vison): Roles of serotonin and food satiation

5-Hydroxytrypotophan at a dose of 50 mg/kg intraperitoneally (i.p.) sharply increased neural serotonin (5-HT) levels in mink and considerably inhibited that animal's predatory attack on rats. Intraperitoneal injection of 5-HT (10 and 20 mg/kg) did not influence such rat-killing. Neural levels of 5-HT or 5-hydroxyindoleacetic acid (5-HIAA) and subsequent aggression by the predator did not change to any great degree after ingestion of a single meal. Abundance of natural mink food for 3 days was associated with an increased level of 5-HIAA in the lateral hypothalamus and the amygdala as well as with an increased latency to attack and to kill rats. 5-HT seems to represent an endogenous factor that inhibits predatory attack by the mink; this effect appears to function through increased metabolism of 5-HT in some brain regions, which is evident after abundant intake of tryptophan with the natural diet.     

Is indirect aggression typical of females? gender differences in aggressiveness in 11- to 12-year-old children

Gender differences regarding aggressive behaviour were investigated in 167 school children, 11 to 12 years of age, through peer-rating techniques supported by self-ratings and interviews. The social structure of the peer groups also was studied. The principal finding was that girls made greater use of indirect means of aggression, whereas the boys tended to employ direct means. Gender differences in verbal aggression were less pronounced. The social structure of peer groups was found to be tighter among girls, making it easier for them to exploit relationships and harm their victims by indirect manipulative aggression. Because indirect aggression has rarely been satisfactorily studied with tests of aggression, this finding may help to explain 1) the generally lower correlation found between peer-rated and self-rated aggression in girls than among boys (indirect means not being so readily recognized by the subject as a kind of aggression) and 2) the low stability of aggressiveness in girls often found in developmental studies.     

Facet-level analysis of the relations between personality and laboratory aggression

Multiple reviews and meta-analyses have identified the low pole of the Five-Factor Model (FFM) Agreeableness (also called Antagonism) as the primary domain-level personality correlates of aggression across self-report and behavioral methodologies. In the current study, we expand on this literature by investigating the relations between FFM facets and aggressive behavior as measured by laboratory competitive reaction time tasks (CRTTs). Across three samples (total N = 639), we conducted weighted mean analyses, multiple regression analyses, and dominance analyses to determine which FFM facets were the strongest predictors of aggression within and across domains. These analyses suggested that facets of Agreeableness were among the strongest consistent predictors of CRTT aggression, including Sympathy (r = −.21) and Cooperation (r = −.14), but facets from other FFM domains also yielded meaningful relations (e.g., Anger from Neuroticism; r = .17). We conclude by discussing these results in the context of controversies surrounding laboratory aggression paradigms and emphasizing the importance of considering small effect sizes in the prediction of societally harmful behavior like aggression.     

Internalizing problems and their impact on the relation between callous-unemotional traits,narcissism, and aggression

Narcissism and callous-unemotional (CU) traits have demonstrated relations with youth aggression across studies. However, different forms of narcissism and internalizing problems may exacerbate the relation between CU traits and aggression. To that end, the current study examined the degree to which interactions among internalizing problems, CU traits, and dimensions of narcissism related to aggression in a sample of 219 adolescents (83.1% males), ages 16–19, enrolled in a military-style residential program. Consistent with previous research, psychopathy-linked narcissism significantly moderated the relation between CU traits and aggression. Addtionally, self-reported aggression was highest among adolescents who endorsed high levels of CU traits, psychopathy-linked narcissism, and internalizing problems. The same pattern of results was not evident for other forms of narcissism. These results suggest that internalizing problems further increase the probability of aggression among adolescents with psychopathic tendencies (i.e., CU traits, psychopathy-linked narcissism). Further implications are discussed.     

Cyberbullying,cyber aggression,and cyber victimization in relation to adolescents’ dating and sexual behavior: An evolutionary perspective

This study examined adolescents’ cyberbullying, cyber aggression, and cyber victimization from an evolutionary perspective, extending previous research showing that traditional forms of bullying, aggression, and victimization are associated with reproductively relevant outcomes. Consistent with hypotheses based on theory and research linking bullying and aggression to intrasexual competition for mates, results indicated that cyber victimization was positively associated with a number of dating and sexual partners. Findings for cyber aggression were more complex, depending on the degree of cyber victimization experienced by the perpetrator, and the balance of power between the perpetrator and victim. Specifically, nonbullying cyber aggression by perpetrators with equal or less power than the victim had stronger positive relations with the number of dating or sexual partners when perpetrators experienced a high level of cyber victimhood. In contrast, cyberbullying by perpetrators with more power than the victim was negatively associated with the number of dating partners when the perpetrators’ exposure to cyber victimization was low. Although cyber aggression and cyber victimization are new forms of aggression that involve the use of modern electronic devices, the results of this study demonstrate the usefulness of viewing this behavior from an evolutionary perspective and show that adolescents are likely to use cyber aggression against rivals in the context of intrasexual competition for mates.     

A combination of combat experience,early abduction,and severe traumatization fuels appetitive aggression and violence among abductees of rebel war in Northern Uganda

Individuals who perpetrate violence may likely perceive violence as appealing and infliction of violence to derive pleasure is termed as appetitive aggression. Individuals who were abducted as children into an armed group often experience a higher number of traumatic event types, that is traumatic load and are usually socialized in a violence-endorsing environment. This study aims to investigate the interaction between age at initial abduction with that of traumatic load, and their influence on appetitive aggression along with perpetration of violent acts by former members of an armed rebel group of both sexes. Semi-structured interviews were conducted among a target group of formerly abducted rebel-war survivors (including participants with and without combat experience) from Northern Uganda. Participants included 596 women and 570 men with N = 1,166 (M_age = 32.58, SD_age = 9.76, range: 18–80 years). We conducted robust linear regression models to investigate the influence of age at initial abduction, traumatic load, combat experience, and biological sex on appetitive aggression as well as their perpetrated violent acts. Our study shows, appetitive aggression and the number of perpetrated violent acts were specifically increased in individuals who were abducted young, experienced several traumatic events in their lifetime, and with previous combat experience. For perpetrated violence men showed increased levels whereas for appetitive aggression the association was independent of biological sex. Therefore, early abducted individuals with a higher traumatic load, who have combat experience, need to be given special intervention to prevent any further violence.     

Relations between forms and functions of aggression and moral judgments of aggressive transgressions

The present study sought to examine the influence of aggressive behavior, psychopathy, and gender on moral judgments of aggressive transgressions. A two-dimensional conceptualization of aggression was used, such that proactive relational aggression, reactive relational aggression, proactive physical aggression, and reactive physical aggression were treated as distinct subtypes of aggression and also as distinct subtypes of moral judgments of aggression. Participants were 421 emerging adults (215 women). Self-report measures of aggression, psychopathy, and moral judgments were collected. Peer-reports of aggression and psychopathy were obtained from a randomly assigned subsample of 73 participants (46 women) for validity purposes. Unique associations were found between subtypes of aggression and corresponding moral judgments of the same subtypes.     

Making Americans Feel Great Again? Personal Significance Predicts Political Intentions of Losers and Winners of the 2016 U.S. Election

Reactions of losers and winners of political elections have important consequences for the political system during times of power transition. In four studies conducted immediately before and after the 2016 U.S. presidential elections, we investigated how personal significance induced by success or failure of one's candidate is related to hostile versus benevolent intentions toward political adversaries. We found that the less significant supporters of Hillary Clinton and supporters of Donald Trump felt after an imagined (Study 1A) or actual (Study 2) electoral failure the more they were willing to engage in peaceful actions against the elected president and the less they were willing to accept the results of the elections. However, while significance gain due to an imagined or actual electoral success was related to more benevolent intentions among Clinton supporters (Study 1B), it was related to more hostile intentions among Trump supporters (Studies 1B, 2, and 3).     

Antecedents of fathers’ perception of child behavior at child age 12 months

This study investigates whether fathers’ adverse childhood experiences (ACE) and attachment style reported during pregnancy predict fathers’ perception of child behavior assessed 12 months postpartum, expressed by the Parenting Stress Index (PSI), Child Domain. Prospective fathers (N = 835) were recruited to “The Little in Norway (LiN) study” (Moe & Smith) at nine well-baby clinics in Norway, with data collection composed of five time points during pregnancy and two time points postpartum (6 and 12 months). The main analyses included linear regression, path-analysis modeling, and intraclass correlation based on mixed effects modeling. First, linear regression analyses showed that neither fathers’ ACE nor attachment style significantly predicted perceived child behavior postpartum directly. Furthermore, path analyses showed that ACE and less secure attachment style (especially avoidant attachment) measured early in pregnancy strongly predicted negatively perceived child behavior, mediated by fathers’ mental health symptoms during pregnancy and partner disharmony postpartum. Second, intraclass correlation analyses showed that fathers’ perceived child behavior showed substantial stability between 6 and 12 months postpartum. Family interventions beginning in pregnancy may be most beneficial given that fathers’ early experiences and perceptions of attachment in pregnancy were associated with later partner disharmony and stress.