Aggressive behavior during the breeding season of adult female rhesus monkeys (Macaca mulatta)

The aggressive behavior of eight adult female rhesus living in a captive social group was studied prior to and during a breeding season extended by vasectomizing all the adult males in the group. Female reproductive status was ascertained by: recording all adult female-adult male copulations; detecting menstruation by vaginal swabbing; and analyzing serum progesterone levels by radioimmunoassay. Females showed more non-contact aggression during the breeding season, but wounding did not increase. Individual cycling females directed more frequent aggression to: particular adult males subordinate to them, subordinate females also in estrus, and (in a few cases) juveniles and infants.     

Vengeance: Effects of gender,age, and religious background

Vengeance can be commonly defined as the infliction of harm in return for perceived injury or insult or as simply getting back at another person. Three hundred fifty‐three participants responded to eight hypothetical scenarios that may elicit vengeful behavior in which the offending party was either a romantic partner, a friend, a coworker, or a stranger. Participants also completed a vengeance scale and a measure of biblical literalism. Participants were most vengeful toward coworkers and least vengeful toward romantic partners. Age, religious conservatism, and gender were significant predictors of attitudes toward vengeance. Although men were more likely than women to be accepting of vengeful attitudes as measured by the vengeance scale, only age was a significant predictor of behavior in the vengeance scenarios. The current research provides a basis for a systematic investigation of vengeance within the structure of human relationships and interactions. Aggr. Behav. 27:343–350, 2001. © 2001 Wiley‐Liss, Inc.     

Children's verbalizations and cheating behavior during game playing: the role of sociometric status,aggression, and gender

The first goal of this study was to investigate sociometric status, aggression, and gender differences in children's verbalizations and cheating behavior during game playing using a fine-grained observational coding system. The second goal was to control for the effects of differential peer treatment and bias on children's behavior by observing children in a standardized procedure with unfamiliar peer confederates. Participants were 111 second-grade African American children, half average and half rejected sociometric status, half aggressive and half nonaggressive based on peer nominations, and half boys and half girls. Rejected children engaged in more cheating behavior and made more negative and argumentative verbalizations than average status children. Boys made more negative and argumentative verbalizations than girls. Aggressive children did not differ from nonaggressive children, in terms of either verbalizations or cheating behavior.     

Dominance-subordinance in cohabiting pairs of adult rats: Effects on Aggressive behavior

Following an initial intruder aggression test, 10 pairs of adult male rats matched on aggressiveness were formed. The first 20 min of paired cohabitation were used to determine dominance and subordinance between pau members. Residents judged to be dominant from this observation session gained significantly more weight during cohabitation and exhibited significantly more aggression on the second aggression test than their subordinate counterparts. Significant correlations among various measures of aggression were found, but open field performance did not correlate, with the measures of aggression nor did changes in open field scores reflect changes in aggression.     

Relationships among individualism--collectivism, gender, and ingroup/outgroup status, and responses to conflict: a study in China and the United States

Responses to conflict were studied in samples of college students from a highly collectivistic society (China, n = 207) and a highly individualistic society (United States n = 209). As predicted, the collectivistic society reported more conflict-reducing behaviors and less verbal or physical aggression. However, the effect of individualism/collectivism was moderated by both the ingroup/outgroup status of the target and gender of the participant. Chinese and US women did not differ on any measure. However, of the four groups, Chinese men reported the most conflict-reducing behaviors and the least physical aggression, whereas US men reported the fewest conflict-reducing behaviors and the greatest physical aggression. As predicted, conflict-reducing behaviors were more common in the ingroup condition and both verbal and physical aggression was more common in the outgroup condition. However, the latter were moderated by gender of the participant. US men reported greater physical aggression than any other group. Neither gender nor society had any effect on the level of indirect aggression. There were no gender or individualism/collectivism effects on indirect aggression. Observed gender effects were attributed to differences in how collectivistic and individualistic societies conceptualize masculinity. The effect sizes associated with the ingroup/outgroup condition were consistently and substantially larger than effect sizes associated with individualism/collectivism or gender.     

Development of co-feeding behavior in young wild Japanese macaques (Macaca fuscata)

This study describes the developmental course of the social context of feeding behavior in infants and yearlings of Japanese macaques in a provisioned free-ranging troop. Results of this longitudinal study revealed that infants and yearlings exhibited synchronous feeding behavior in the majority of cases in which they had feeding neighbors within 1 m. They consistently showed feeding behavior more often when their closest neighbor fed than when they did not. In feeding situations, infants tended mainly to be in close proximity with their mothers in the early stages of life and, later, also with peers. The results imply that potential opportunities for the social transmission of food selection habits are available for young Japanese macaques in the wild.     

Aggressive behavior among girls and boys during middle childhood: predictors and sequelae of trajectory group membership

Using longitudinal data spanning early elementary through middle school, aggression behavior trajectory groups were identified for boys and girls. Early elementary school predictors of trajectory group membership were examined as well as whether trajectory group predicted physical aggression, covert delinquency, and substance use in 9th grade. Semiparametric group modeling identified aggression behavior trajectory groups. We identified four aggression trajectory groups for both genders described as “not involved,” “low,” “moderate,” and “high.” Attention problems, family conflict, and low school commitment and attachment were predictors of membership in higher aggression groups for both boys and girls. Low family involvement and low parental education predicted membership in higher aggression groups for boys; while depression, low‐income status, and having a single parent predicted higher aggression group membership for girls. For both boys and girls, few risk predictors distinguished between the moderate and high aggression trajectories except that low school commitment and having a teen mother were significant predictors of being in the high group for girls, and low parental education and income were significant predictors of being in the high group for boys. Membership in the higher aggression trajectory groups predicted involvement in violent behaviors, covert delinquency, and substance use in 9th grade. Findings suggest that children who display an early trajectory of high levels of aggressive behavior are more likely to continue involvement in later problem behaviors. Second‐grade predictors suggest commonality of risk across genders and provide evidence of modifiable targets for preventive interventions. Aggr. Behav. 32:1–15. 2006. © 2006 Wiley‐Liss, Inc.     

Physical,verbal, and relational forms of bullying among German students: age trends,gender differences,and correlates

A revised version of the Bully/Victim Questionnaire [Olweus, 1991] was given to 2,086 fifth–tenth grader students from schools in two German federal states. The results were analysed in terms of frequencies of self‐reports of different forms of bullying (physical, verbal, relational/indirect; for bullies and for victims), gender and grade differences. Overall, 12.1% of the students reported bullying others and 11.1% reported being bullied (victimisation). We classified 2.3% of the students as bully/victims due to their self‐report. Significantly more boys reported bullying others, regardless of bullying form, and significantly more boys than girls were classified as bully/victims. Although there was no gender difference for victimisation at all, boys reported significantly more often than girls being bullied physically. Besides, self‐reports of pure and overlapping forms of bullying behaviour (relational, verbal, physical) were analysed. With regard to age trends, students from middle grades reported the highest rates of bullying. Self‐reported rates of victimisation were higher for younger students, regardless of form of victimisation. Furthermore, class size was not linked to reports of bullying and victimisation. Results from logistic regression analyses emphasised that the variables “gender” and “grade” add significantly to the prediction of self‐reported bullying; “grade” and variables measuring impaired psychosocial “well‐being” of students at school (e.g., feeling of not being popular, negative attitude towards breaks) add significantly to the prediction of self‐reported victimisation. The results are discussed against the background of other study findings, accentuating the significance of gender‐ and age‐specific forms of bullying/victimisation. Aggr. Behav. 32:1–15, 2006. © 2006 Wiley‐Liss, Inc.     

Relationship Quality of Aggressive Children and Their Siblings: A Multiinformant, Multimeasure Investigation

Sibling influence on the learning and enactment of aggressive behavior has been consistently demonstrated in studies of sibling relationships. Available evidence suggests that, compared with nonaggressive children's sibling interactions, the sibling interactions of aggressive children are marked by more frequent, intense, and prolonged aggressive behaviors. Although research on normative and aggressive children's sibling interactions has increased recently, a number of limitations in this literature were addressed in this study by: (1) including both an aggressive and nonaggressive comparison group, (2) examining both positive and negative features of sibling relationships, (3) employing a multimethod/multiinformant approach to data collection, and (4) utilizing an improved self-report method. In support of our hypotheses and consistent with previous research, results showed that aggressive children's sibling relationships were marked by higher levels of observed conflict and lower levels of self-reported positive features. When gender was examined, results showed that older brother/younger sister dyads were characterized by higher levels of negative features and lower levels of positive features.     

A meta-analysis of aggression in the presence of violent cues: Effects of gender differences and aversive provocation

Meta-analytically examines experimental studies that include violent cues in the setting and assesses the effects of aversive provocation on gender differences in aggression. The results show that when violent cues are present, men are more aggressive than women under neutral unprovoked conditions. However, when they are exposed to both violent cues and aversive provocation, men and women are equally aggressive. Differences in individual reactivity to violent cues as well as the type of aggressive response and the sex of the target also affected the magnitude of gender differences in the presence of violent cues. Aggr. Behav. 23:447–456, 1997. © 1997 Wiley-Liss, Inc.     

Aggressive behavior of pigeons: Suppression by archistriatal lesions

The agonistic responses of pigeons to the introduction of a stick and the experimenter's hand into their home cages is described. The effects of lesions of the archistriatum, a presumed homologue of the mammalian amygdala, of lesions of the overlying neostriatum and of control sham operations on this behavior in selected aggressive pigeons are reported. Only archistriatal lesions lead to a persistent depression of the aggressive and a converse increment of the avoidance components of the pigeon's response to both test stimuli. The results are discussed in relation to other evidence on the role of the avian archistriatum and this structure's correspondence with the amygdala.     

Emotional arousal and gender differences in aggression: A meta‐analysis

This meta‐analysis investigated the possibility that gender differences in aggression, and the variability in these differences, are a function of gender differences in the regulation of arousal generated in emotionally evocative contexts. The sample of studies for this analysis was based on an exhaustive search of the relevant research reports from 1965–1999. Studies were excluded from the sample if they were case studies; investigated spousal/familial or societal violence, war, suicide, or political violence; involved clinical or deviant participants; included fewer than 10 participants; included all male, all female, all non‐Caucasian, or non‐US/non‐Canadian participants. Based on previous evidence that males may be more easily aroused by aggressive‐relevant emotional stimuli than females, and that males may have more difficulty regulating emotionally arousing states than females, we hypothesized that the magnitude of the gender differences in aggression would covary, in a nonlinear manner, with the emotional evocativeness of the study context. Consistent with our hypothesis, the magnitude of gender differences in aggression was relatively small in research contexts that appeared to produce no or large increments in emotional arousal and larger (favoring males) in contexts that appeared to produce small or medium increments in emotional arousal. Aggr. Behav. 28:366–393, 2002. © 2002 Wiley‐Liss, Inc.     

Relations between different types of children's aggressive behavior and sociometric status among peers of the same and opposite gender

Croatian elementary school children in grades 4 to 6 (N= 151) reported on direct and indirect aggressive behaviors of their classmates. Acceptance and rejection by classmates were also assessed, employing the sociometric nomination technique. Correlational analyses revealed that both forms of aggression were related to peer rejection, but unrelated to peer acceptance. Girls' aggression was more strongly related to peer rejection than boys' aggression, independent of the type of aggression. Aggressive children of both genders tended to be more rejected by their same-gender classmates than by classmates of the opposite gender. Results were discussed in terms of children's attitudes towards aggression, and gender stereotyped perception of appropriateness of aggressive behavior. A need to examine developmental changes and cultural differences in relationships between aggression and peer status was emphasized.     

Variability in behavior frequencies and consistency in transactions across seasons in captive Japanese macaques (Macaca fuscata)

Consistent interspecific differences are found in macaque species, ranging from highly hierarchical and nepotistic societies to more tolerant and open social organizations. It still remains to be demonstrated whether intraspecific variation is narrower than interspecific variation. Herein, we quantified social behavior in a captive group of Japanese macaques (Macaca fuscata) to estimate the range of intraspecific variation for a full array of measurements in three different seasons. Despite an increased frequency of aggression found on the part of males during the mating season, the form of the behaviors performed remained relatively unchanged. Transactions during conflicts, approaches, or grooming did not undergo significant variations in relation to season. Frequencies and durations seemed more sensitive to demographic and environmental variations. The values measured in the study group are representative of the Japanese macaque. The results validate the use of transaction measurements in interspecific comparisons, providing that additional factors such as age and sex are taken into account. Aggr. Behav. 29:81–93, 2003. © 2003 Wiley‐Liss, Inc.     

Reconciliation and variation in post-conflict stress in Japanese macaques (Macaca fuscata fuscata): testing the integrated hypothesis

Reconciliation in primates, a post-conflict affiliative interaction between former opponents, appears to have two functions: (1) to repair relationship damaged by aggression such that animals who share more valuable relationships are more likely to reconcile, and (2) to reduce the post-conflict uncertainty and stress of former combatants. The 'integrated hypothesis' of reconciliation links these functions by arguing that the disturbance of a valuable relationship by aggression should result in particularly high levels of stress, which in turn should facilitate efforts to reconcile and thus gain relief from post-conflict stress. A key prediction of the integrated hypothesis is that victims of aggression suffer more stress following conflicts with individuals with whom they share a valuable relationship. In this article, we test the integrated hypothesis by observing the post-conflict behaviour of victims among a free-ranging provisioned troop of Japanese macaques (Macaca fuscata fuscata) living in Shiga Heights, Nagano, Japan. In this troop, monkeys reconciled roughly one in seven conflicts. The only factor that we could significantly relate to the occurrence of reconciliation was kinship; kin reconciled more frequently than non-kin did. Receiving aggression increased and reconciliation reduced the probability of being re-attacked after aggressive interactions, supporting the hypothesis that reconciliation repairs relationships. Victims' self-directed behaviour (SDB) – a behavioural index of stress comprising increases in scratching, self-grooming, and body-shaking – was elevated following aggression but decreased rapidly following reconciliation, supporting the idea that reconciliation functions to reduce post-conflict stress. Post-conflict SDB varied as follows: (1) victims showed a higher level of stress following aggression with kin than with non-kin, and (2) juvenile victims were less distressed than adults. The level of post-conflict SDB performed by juveniles following conflicts with kin was indistinguishable from that performed by adults but was greatly reduced following attacks from non-kin. These results indicate that post-conflict SDB keenly reflects the value of relationships between opponents, and that the post-conflict behaviour of free-ranging Japanese macaques fits the predictions of the integrated hypothesis. Accepted after revision: 11 September 2001 Electronic Publication     

The stimulating and inhibiting effects of weapons on Aggressive behavior

Evidence is presented suggesting that firearms violence is an important social problem. Research strongly suggests that the effectiveness of firearms as a cause of death and injury may be due to their widespread availability, their lethality, and the impulsivity of their use. The investigation of a possible causal link between firearms and impulsive aggression led to Berkowitz and LePage's (1967) weapons effect experiment. The results suggested that weapons can increase the instigation to aggression in aroused an uninhibited individuals. The researchers reasoned that weapons might stimulate aggression by classical conditioning processes resulting from learned associations between aggressive acts and weapons. Although a few studies have failed to reproduce an aggression-enhancing effect of weapons, the original finding has been replicated in several countries with diverse subject groups both in field and laboratory settings. However, these studies also indicate that many individuals may react with anxiety or fear in the presence of weapons and inhibit aggressive reactions. Manipulations of evaluation apprehension, subject suspiciousness, and/or hypothesis awareness about the purpose of the weapons in the experiments all seem to lead to reduced levels of aggressive response in the presence of weapons. These findings offer a possible explanation for the few failures to replicate the original weapons effect; if researchers used apprehensive subjects or subjects who were aware of possible experimental deceptions, they were more likely to observe an inhibitory reaction rather than an aggression-enhancing effect of weapons.     

Patterns of agonistic interactions in three species of macaque (Macaca mulatta,M fascicularis,M tonkeana)

Patterns of aggression and response to aggression were studied in three groups of macaques living in semiliberty, each group representing a different species: Macaca mulatta, M fascicularis, and M tonkeana. In Macaca mulatta, intensity of aggression is high (biting is frequent) and symmetry in aggression is low: the aggressee most often flees or submits. In Macaca tonkeana, in contrast, biting is exceptional, aggression is very often bidirectional, and appeasement behaviors are frequently observed. Intermediate patterns are found in Macaca fascicularis with, in addition, especially frequent mild forms of submission. It is argued that relationships exist between intensity of aggression, symmetry in aggression, and development of behaviors controlling aggresssion. Whether balances between these variables are species-specific is discussed.