Male aggression in the presence of an estrous female.

20 100-day-old dominant male albino Holtzman rats were individually exposed to an inaccessible female rat in a specially constructed apparatus. The males were then given free-forced trials to an empty compartment or a compartment housing a submissive male. Results indicate that following exposure to an estrous female, dominant males increased their percentage of choices to the submissive male. Moreover, the incidences of aggressions by the dominant S toward the submissive S increased sharply after prior exposure to the estrous female. Data suggest that one antecedent source of aggression among male rodents may be the presence of a sexually receptive female. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stomach acid secretion in submissive and aggressive rats.

Conducted 4 experiments with 60 female and 162 male Long-Evans rats to determine whether aggressive and submissive behavior are related to either an increase or a decrease in gastric secretion. In Exp I, intruder rats placed in an established male–female colony and attacked by a dominant alpha male secreted less acid than intruders exposed to nonaggressive males and females. In Exp II, intruders exposed to attack and subsequently returned to the encounter site, but protected from physical attack, still demonstrated a gastric hyposecretion. Ss with chronic gastric cannulas in Exp III also revealed an acid inhibition when attacked and later when exposed to, but protected from, attack. Both intruders and attacking males were prepared with gastric cannulas in Exp IV. Both demonstrated secretory inhibition following attack and attack-protected sessions. The inhibitory effect was greater and more persistent for intruders than for aggressive Ss. It is suggested that the inhibition occurring during the attack-protected sessions may have been mediated by some conditioning processes, and other possible associative mechanisms, including a learning model or a direct sensory model, are discussed. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Facilitation of intermale aggression in mice through exposure to receptive females.

Examined intermale aggression after different exposures to receptive females. In Exp I, socially isolated or grouped CD-1 and Swiss-Webster mice each confronted a target male after either no exposure to or 3 intromissions with an estrous female. High levels of aggression were observed in isolated males after exposure to a female, provided the female was removed when the target male was introduced. In Exp II, variation of duration and quality of exposure to females indicated that aggression increased with more advanced prior sexual activity. In Exp III, sexual activity was not greatly influenced by prior aggressive activity. These data suggest a preparedness to fight following sexual activity, but a prepotence of sexual activity over aggression. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Complainant behavioral tone, ambivalent sexism, and perceptions of sexual harassment.

Previous research has examined the impact of the law on decisions made about social sexual interactions in the workplace in the context of a variety of individual difference variables including gender of the observer and sexist attitudes, as well as situational factors including legal standard and prior exposure to aggressive and submissive complainants. The current study continued this line of inquiry by testing whether hostile or benevolent sexist attitudes behaved differently under manipulated exposure to aggressive and submissive complainants. Full-time workers watched 1 videotape in which aggressive, submissive, or neutral (i.e., businesslike) women complained that male coworkers sexually harassed them; then, participants viewed a second complainant who always acted in a neutral behavioral tone. In the first case, participants high in hostile sexism who took a reasonable person perspective (but not those with a reasonable woman point of view) and all men who viewed an aggressive complainant found less evidence of harassment. With the second set of allegations, female workers who were exposed to a submissive complainant in the first case found less evidence of harassment against the neutral complainant, suggesting that exposure to a submissive complainant triggered some type of victim blaming in female workers. Policy and training implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of parasite-induced immunodepression, rank and social environment in the modulation of behaviour and hormone concentration in male laboratory mice (Mus musculus)

Peripheral immune responsiveness in male laboratory mice was reduced by infection with the trichostrongyloid nematode Heligmosomoides polygyrus. Responsiveness was also lower among high-ranking (aggressive) males regardless of infection status. Reduced responsiveness in both infected animals and high rankers was associated with elevated serum corticosterone concentration (a potential immunodepressant) and was compounded among high-ranking males by subsequent high aggressiveness. As in previous experiments, only low rankers modulated testosterone secretion in relation to current immunocompetence and corticosterone concentration. The lack of any downregulation of aggression in response to parasite-induced immunodepression contrasted with previous results using antithymocyte serum and may be due to the more localized nature of immunodepression during H. polygyrus infection. However, the additional increase in corticosterone concentration resulting from exposure to female odour and destabilized aggressive social relationships did result in downregulation of aggression among high rankers and of testosterone among mice generally, suggesting that modulation rules of thumb are at least partly dependent on the proximate cues associated with immunodepression.     

Conspecific urine markings in male rats (Rattus norvegicus) selected for relative aggressiveness.

Male laboratory rats were selected for relative aggressiveness and tested individually and in pairs to examine conspecific marking in relation to object marking. Urine deposited on the other animal and in the environment was rendered visible and quantifiable with sodium fluorescein and filter paper, respectively. Moderately aggressive males were used in Experiment 1, and despite individual differences in both forms of marking, there was a high positive correlation between quantity of marks in the environment and on a conspecific. In Experiment 2, aggressive males marked the environment and their nonaggressive partners more than vice versa. Nonaggressive males were paired successfully with an aggressive and another nonaggressive male in Experiment 3 to examine the crawl-over response, the behavior used by rats to deposit scents on another rat. Nonaggressive males deposited more urine with each crawl over an aggressive than over a nonaggressive male, but they crawled over the nonaggressive male more often than the aggressive male. These data are interpreted as suggesting that conspecific marking is modified by limitations imposed on the behavior by the social relation of the interacting animals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Affiliation in highly aggressive domesticated rats.

Conducted 2 experiments with 131 male Long-Evans rats to examine the relationship between agonistic behavior and the subsequent probability of approaching a conspecific. Highly agressive Ss were given a choice in a –T maze to interact with another male or enter an empty compartment (Exp I) or to interact with 1 of 2 conspecifics (Exp II). In the 1st experiment, the experimental Ss consistently chose the social alternative over the empty goal area. The preference for affiliation was notably strong, not only when the waiting S was a submissive male but also when it was a highly aggressive stimulus male. The aggressive Ss of Exp II were allowed to choose between an equally aggressive male or a submissive male. Ss preferred to interact with the less aggressive male. It was suprising, however, that the Ss often chose to interact with the highly aggressive target S. Data suggest that even after an aversive agonistic attack, the affiliation-response in highly social rodents is remarkably persistent. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Male-female differences and the influence of neonatal and adult testosterone on intraspecies aggression in rats.

Tested Sprague-Dawley male and female albino rats for intraspecies aggression without the use of shock. In the 1st experiment, 6 male pairs showed more biting attacks, offensive sideways movements, and self-grooming than did 6 female pairs; male pairs also showed more stereotyped defensive/submissive behaviors and were wounded more frequently. The 2nd experiment with 103 Ss examined the effects of neonatal castration and testosterone propionate (TP) on fighting. Males castrated at birth attacked other males less frequently than did controls when tested with TP treatment as adults. The TP given at birth to neonatally castrated males restored attacks to control levels. Females given TP as neonates did not differ from either male or female controls. Other aggressive/defensive behaviors, however, did not show this pattern. Results suggest that while the presence of testosterone during a brief postnatal period and during adulthood is necessary for attack behavior to occur, other related behaviors may not be affected in a similar manner. (11/2 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Male-male and male-female aggression may influence mating associations in wild octopuses (Abdopus aculeatus).

Abdopus aculeatus engages in frequent aggression and copulation, exhibits male mate-choice, and employs multiple mating tactics. Here we draw upon established hypotheses to compare male–male aggression (MMA) and male–female aggression (MFA), as they relate to their mating behavior in the wild. When contesting for females, males appear to balance mate preference (resource value) with perceived chances of winning contests (resource holding potential). Although males spent more time mating with and contesting for large “Adjacent Guarded” females (those occupying a den within arm’s reach of a large “Adjacent Guarding” male), they exhibited higher rates of aggression over nonadjacent “Temporarily Guarded” females that may be more accessible. The major determinant of male?male aggressive success was size, and this factor may dictate the expression of conditional mating tactics in males. “Adjacent Guarding” males were the largest and most aggressively successful males, earning the most time copulating with females. They are considered to have the highest resource holding potential (RHP) in MMA. By contrast, in MFA, some larger individuals fled from smaller individuals, indicating that RHP appears to be a function of both size and sex in intersexual aggression. This result suggests variation in aggressiveness, or potential for severe injury—even sexual cannibalism during MFA. Male–female aggression may also be influenced by the sexual nonreceptivity of some individuals, or attempts by both sexes to increase foraging behavior by delaying mate-guarding activity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hormonal dynamics during mate choice in the northern pintail: a test of the 'challenge' hypothesis

In previous mate choice experiments, we found no relationship between dominance rank and pairing success in male northern pintails, Anas acutaOnce chosen by a female, however, males became aggressive, initiated fights with higher-ranked males and quickly established dominance. In the present study, we tested a variation of the 'challenge' hypothesis, that the behavioural stimuli associated with acquiring and defending a mate induce an increase in testosterone level, which in turn facilitates aggressive behaviours required for males to establish dominance. We measured plasma hormone levels (testosterone, dihydrotestosterone, luteinizing hormone and corticosterone) before and after mate choice in two experiments in which males competed for a single female (experiments 1 and 2) and in a control experiment in which no female was introduced (experiment 3). We used groups of either three adult males (experiment 1) or one adult and two yearling males (experiments 2 and 3). Contrary to expectation, in experiment 1, plasma levels of corticosterone increased significantly and testosterone levels decreased in chosen males following mate choice. The magnitude of change in corticosterone was positively correlated with the rate of aggression by males. Chosen adult males in experiment 2 showed similar patterns of hormone change (corticosterone increase and testosterone decrease), although not all changes were significant. Hormone levels of unchosen yearlings in experiment 2 and control adults and yearlings in experiment 3 showed no changes. The results are consistent with the hypothesis that behavioural stimuli associated with successful pair formation induce a transitory increase in circulating levels of corticosterone, which in turn mediates the behavioural response of increased aggression leading to the establishment of dominance following mate choice. A short-term increase in corticosterone may be adaptive in this situation because it would mobilize energy stores needed by the male to defend the new pair bond and establish dominance.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour     

Avoidance of Relatively Aggressive Male Japanese Quail (Coturnix japonica) by Sexually Experienced Conspecific Females.

Sexually experienced female Japanese quail (Coturnix japonica) that are offered a choice between 2 conspecific males previously observed engaging in an aggressive encounter prefer to affiliate with the less aggressive male. The authors determined whether this apparent preference for less aggressive males results from females approaching less aggressive individuals or avoiding more aggressive individuals. The authors found that females that had seen 2 males fight before choosing, in counterbalanced order, between each of them and a neutral stimulus were indifferent to less aggressive males but avoided more aggressive males. The results are consistent with the view that in species in which male courtship and mating are potentially harmful to females, females keep away from relatively aggressive males in order to avoid the physical punishment that can result from contact with them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit stereotyping in person judgment.

Three experiments demonstrated implicit gender stereotyping. A target's social category determined the use of previously primed stereotyped information, without Ss' awareness of such influence. After unscrambling sentences describing neutral or stereotyped behaviors about dependence or aggression, Ss evaluated a female or male target. Although ratings of female and male targets did not differ after exposure to neutral primes, Ss exposed to dependence primes rated a female target as more dependent than a male target who performed identical behaviors (Exp 1A). Likewise, Ss rated a male, but not a female, target as more aggressive after exposure to aggression primes compared with neutral primes (Exp 1B). Exp 2 replicated the implicit stereotyping effect and additionally showed no relationship between explicit memory for primes and judgment of target's dependence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Classical conditioning provides paternity advantage for territorial male blue gouramis (Trichogaster trichopterus).

An irony of territorial behavior is that successful territory defense requires males to be aggressive, but highly aggressive males often inadvertently repel females, potential mates that the territory was created to attract. The authors provide empirical evidence that learning to anticipate the arrival of a female not only can overcome this well-recognized cost of territorial behavior but also can provide a significant paternity advantage. Following a short training period in which male blue gourami fish (Trichogaster trichopterus) either received classically conditioned pairings of a signal and a receptive female or received unpaired presentations of the signal and a female, male subjects were given an opportunity to mate. Signaling of female accessibility not only enabled classically conditioned males to attenuate their initial aggressive response to arriving females but, more important, classically conditioned males were able to spawn with females sooner, clasp females more often, and produce more young than males that did not have the benefit of a signal. Results provide the first demonstration of direct reproductive benefits resulting from classical conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Female-enhanced aggression in male rats: Effects of genital anesthesia, castration, or preoptic lesions.

Male rats that had cohabited with ovariectomized females for 2 weeks became more aggressive toward male intruders after a novel estrous female had been placed in their home cages for a period of 4 hr on the previous day. No increase in aggression was seen in males exposed to anestrous females. Genital anesthesia did not attenuate the female-enhanced aggression effect. By contrast, no enhancement of aggression was observed in long-term castrated males after 24 hr of exposure to estrous females. Rats with bilateral electrolytic lesions in the medial preoptic area showed a normal female-enhanced aggression effect. The observations that exposure to females facilitates aggression in males subjected to genital anesthesia and in males with preoptic lesions raise the possibility that copulatory cues are not always required for the effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of the repeated experience of aggression in daily confrontations on the individual and social behavior of male mice

The influence of repeated experience of aggression in daily intermale confrontations on individual and social behaviour was studied in male mice of C57BL/6J (C57) and CBA/Lac (CBA) strains. Repeated experience of aggression led to a decrease of emotionality in males of highly emotional CBA strain and increase in exploratory activity in the open field and exploratory activity tests, decrease of immobility time in Porsolt's test and pain sensitivity estimated by the "hot plate" test. Low emotional C57 males did not change their individual behaviour in different situations under the influence of repeated experience of aggression. However, aggressive C57 mice demonstrated anxiety-like behaviour estimated in the plus-maze test. In the partition test aggressive mice of both strains showed an increase in communicative level (as a reaction to a familiar male) in comparison with their behaviour before aggressive confrontations. Behavioural reaction to a receptive female under unfamiliar conditions decreased which testified to a decrease in sexual motivation. It is concluded that formation of the aggressive type of social behaviour is accompanied by changes in the individual and social behaviour of male mice. Characteristics of these changes are genetically determined and depend on the duration of confrontations.     

Nonverbal behavior, gender, and influence.

Participants viewed a videotape of either a male or female confederate delivering a persuasive message using a high task, social, submissive, or dominant nonverbal style. Participants were influenced more after viewing the social and task styles than the dominant or submissive styles. Participants liked task and social confederates more than dominant confederates and considered submissive confederates to be less competent than the other 3 styles. Although both likableness and competence were predictive of influence, likableness was a more important determinant of influence for female than male speakers when the audience was male. Consequently, with a male audience, women exhibiting a task style were less influential and likable than men exhibiting that style. Men were not more influential than women when displaying dominance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Another hamster paradox: more males carry pups and fewer kill and cannibalize young than do females

The response of virgin male and female golden hamsters to young was studied. In contrast to most species, males are more likely to carry pups than are females. All males carried pups, but approximately 50% of females cannibalized the young. The females that did not cannibalize the pups carried them with less hesitation and after shorter latencies than did the males. The response of females to young was not correlated with the aggressiveness displayed toward adult males during separate tests. Tests with gonadectomized females indicated that the maintenance of pup-killing behavior is not dependent on concurrent gonadal hormones. Progesterone injections did not significantly increase pup killing in males that had previously carried young. Speculations on the adaptive significance of the male and female hamster's response to pups are presented.     

Dominance in intermale encounters and subsequent sexual success in mice.

In Exp I, when previously isolated male CD-1 mice (n?=?26) were paired and given a female, they fought before beginning to mount, and the more aggressive male ejaculated somewhat more frequently. Males housed together (n?=?26) for several days showed little aggression when jointly given a female, but those that were more aggressive in the home cage clearly ejaculated more frequently. In Exp II, with 144 Ss, males were paired for 4 days after a period of isolation. More aggressive males showed more ejaculations when subsequently tested individually with females, but not when pair members conjointly encountered females. In Exp III, 60 males were paired for several weeks before encountering females. In cases in which home cage dominance was constant, the more aggressive males ejaculated more frequently both when tested individually and when tested as pairs. Findings indicate that success in reproductive behavior in mice is contingent on dominance in intermale aggressive encounters. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Consort bonding and operant behavior by female rhesus monkeys.

An operant conditioning situation was used to relate the leverpressing performance of female rhesus monkeys to different measures of social, sexual, and agonistic behavior that underlie the formation and dissolution of consort bonds. Nine females were trained to press a lever 250 times to gain access to a male partner. After access, a standard 60-min behavioral test took place (1,440 tests). Data were analyzed independently of the stage of the menstrual cycle. Eight females were tested with 2 males, and every female gained access faster with 1 male (i.e, preferred partner). For all 8 females, the preferred male was the one that spent more time grooming the female. For 5 females, the preferred partner was also the one that ejaculated more frequently. For 4 females, where agonistic interactions with males could be evaluated, the preferred male was the one that elicited fewer submissive behavioral patterns. These results indicate that the operant behavior of female rhesus monkeys is positively reinforced by social and sexual factors and negatively reinforced by agonistic interactions and may thus provide a measure of the strength of consort bonds. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does aggression cause a preference for viewing media violence?

Two experiments tested the hypotheses that physical aggression and fantasy aggression would lead to a preference for viewing violence. In Exp I, 45 female and 42 male undergraduates were induced to express aggressive, nonaggressive, or no fantasies and were then given an opportunity to select film clips for viewing. The films chosen by men contained more violence than those chosen by women. In addition, aggressive fantasies in males, compared to nonaggressive fantasies, increased the preference for viewing violence. Exp II, with 64 males, replicated the results of Exp I and also found that men who were given an opportunity to aggress physically, compared to those who had no such opportunity, were more likely to choose to view films containing violent content. Results suggest that just as the viewing of violence may increase aggression, so, too, aggressive behavior may increase the preference for viewing violence. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)