Habituation as a mechanism of reduced aggression between neighboring territorial male bullfrogs (Rana catesbeiana)

Territorial animals often exhibit relatively lower levels of aggression toward familiar territorial neighbors than toward strangers. Habituation to a neighbor or its communication signals has been proposed to account for this reduced aggression between adjacent territorial neighbors. The authors asked whether discrimination between neighbors and strangers by territorial male bullfrogs (Rana catesbeiana) could result from habituation of the aggressive response to repeated presentations of the acoustic communication signals of a simulated new neighbor calling from an adjacent territory. In 3 field playback experiments, the authors found evidence for 5 response characteristics that operationally define habituation. Moreover, aggressive response decrements persisted between nights of chorusing and were specific to an individually distinct property of male advertisement calls. The authors suggest that reduced aggression between neighboring territorial male bullfrogs could result from long-term, stimulus-specific habituation to the advertisement calls of a new neighbor.     

Mouse aggression and the intruder-familiarity effect: evidence for multiple-factor determination c57bl

Male house mice attack their familiar cagemates less than novel intruders-an effect often attributed to habituation of aggression toward odors emanating from the cagemate. This interpretation is overly simplistic in that the effects of familiarizing preexposure depend additionally upon two factors. One factor is the aggression-inhibiting odors emanating from the test male that are deposited onto the cagemate by cohabitation. Supporting evidence is that attack inhibition to the cagemate failed to generalize to noncohabiting same-strain intruders and that eliminating physical contact between subject and cagemate during preexposure prevented the usual postexposure decline in aggression. The second factor is nonolfactory social stimuli emanating from the cagemate during aggressive encounters. The same intruder odors that elicited aggression when placed on a socially active mouse elicited only investigation when placed on models. When subjects were preexposed to an intruder's odor while prevented from socially interacting with the intruder, this investigation subsequently declined while aggression paradoxically increased.     

Agonistic rank,aggression, social context,and testosterone in male pigtail monkeys

Two groups of pigtail monkeys were merged, a third was formed, and individual males were introduced into a group in a series of experiments examining the effects of social context upon agonistic rank, aggressive expression, and testosterone levels. In the first experiment, two heterosexual groups, containing adult males unfamiliar to the other group, were merged. The two groups fought, and the smaller group was defeated. The alpha and beta males of the defeated group were singled out for repeated attack and both showed significant drops in circulating levels of testosterone. Both males were removed from the group during the first day, but testosterone levels did not recover to baseline levels for several days. The alpha male of the victorious group, on the other hand, showed a significant rise in testosterone, which was apparent only on the day following the merger. In order to study the influence of previous social familiarity on male reception into a group, another group was formed by removing males from the victorious group and placing them in a separate enclosure. The males in the new group established a dominance hierarchy unrelated to their previous social ranks with one another. Three months later, each of the six adult males remaining in the parent group was individually introduced into the new group for one day or less. Each of the males introduced into the new group accepted a social position at the lower end of the dominance hierarchy without regard to his previous rank relationships with the host males when they were all in the parent group. Even the alpha and beta males of the parent group were relegated to low rank positions in the new group, despite having ranked over each of the host males since birth. In contrast to the aggression directed at the unfamiliar males in the first experiment, a minimum of aggression was directed to the familiar males introduced into the new group in the second experiment. Although the males introduced accepted low social ranks, it appeared that each was readily integrated into the group with a minimum of aggressive interaction during the time he was scheduled to remain in the group. There were no significant changes in circulating levels of testosterone in any of the males during the introductions of familiar males to one another.     

Female behavior in populations of mice in the presence and absence of male hierarchy

Female aggression may be the regulator of population size in small mammals. Freely growing populations of house mice showed several differences in aggressive female behavior in the presence and the absence of a male hierarchy. Territoriality in females and not in males appeared to maintain social order and regulate population density. Certain females were seen patrolling and guarding the territory and chasing and fighting with both male and female intruders. These females did not fight amongst themselves, suggesting that they were not fighting for rank (as do the males) but for territory. Although these aggressive females produced young, the pups were neglected, and few were weaned. The non-aggressive females were the successful breeders. Aggression by the females only occurred when there was reproduction and increased densities. Assembled females with no males present never show this aggression. The occurrence of “male-type” behavior became most apparent when the males were removed at peak population densities. The removed males were then castrated and injected with testosterone cyprionate. Doses were increased by population cage, and therefore all males returned to each freely growing population were given the same dose. The males given oil placebo injections showed no return of a male hierarchy and the females showed high levels of aggression toward them. Males injected with testosterone cyprionate showed return of male aggression and fighting and mounting of females. But the new “dominant” females continued their patrols and chased males away from their territories and did not permit these males to mount. Male-male fighting consisted primarily of frontal attacks to the face and roll and tumble fights. Female-male aggression consisted primarily of attacks to the posterior region targeted at the base of the tail and the genitals of the male. The males were rarely seen attacking females and then only during mating. Females only attacked each other in defense of their territories.     

Role of female behavior in controlling population growth in mice

Sex ratio does not appear to be a factor in generating the characteristic population growth curve. Freely growing populations of house mice, consisting of all females and one male, stopped their growth at approximately the same densities as normal sexratio populations used as references. The mechanism(s) of female control of population dynamics may be related to female aggressive behavior. As the all-female/one-male populations approached their maximum size, the females began to show wounding patterns and social hierarchies in much the same manner as males in populations with normal sex ratios. The male in each of the populations was severely wounded in the posterior region, and each lost its tail as a result of injuries which could have been inflicted only by the females. The female social hierarchy can be seen only when there has been reproduction and population growth. Assembled populations of all females rarely exhibit aggressive behavior. Female aggression becomes apparent only when the population approaches its maximum size and thereafter. These data are consistent with the hypothesis that males are competitive among themselves for territory and social rank, and ultimately to mate with the females. Other investigators have indicated that females respond to population size, which may reflect increased competition between the females with the establishment of territories. Thus female agression may control population growth, a role previously ascribed to male aggression.     

Witnessed aggression: influence of an observer's sex and values on aggressive responding.

Two experiments investigated the effects of the presence of an observer on aggressive responding. In one experiment, male subjects observed by a male aggressed more than those observed by a female. When the male observer was removed from the situation, subjects' level of aggressiveness more closely matched the level manifested by the opponent. The removal of the female observer had little effect on the subjects' behavior. In the second experiment, the male or female observer of the subject's behavior was disguised as a member of an organization with explicit values (aggressive or pacifistic) regarding the use of aggression. In this case, significant differences in aggression were associated with the observer's values but not the observer's sex. Following the departure of the observer, the shock settings of subjects in the two aggressive-value observer groups showed a signifcant decrease. The average shock setting of subjects in the two pacifistic-value observer groups remained at about the same level. In sum, the results indicated that the subjects' aggressive behavior was apparently a function of their expectations of approval for such behavior, based on the inferred or explicit values of the observer. The results were further discussed in terms of social learning theory.     

Norm-Narrowing and Self- and Other-Perceived Aggression in Early-Adolescent Same-Sex and Mixed-Sex Cliques

We examined the relations between group context and self- and other-perceptions of aggressive behavior in an ethnically-diverse sample of 168 male and female grade 7 adolescents. We used self- and peer-reports of aggression in high- and average-aggressive mixed-sex and same-sex cliques to examine whether group members would assimilate their self-report of aggression to the aggression report of their peers by way of perceived homophily or, conversely, engage in contrast and see their level of aggression as comparatively low in the face of high-aggression peers. Among boys in mixed-sex groups, comparison with highly-aggressive others resulted in a self-perception of lower levels of aggression than those perceived by their peers. Conversely, girls in mixed-sex groups reported their own levels of aggression to be higher than those perceived by their peers. We interpret these findings in terms of the notion of “norm narrowing”: rather than being set by the larger social environment, such as the school, norms are more narrowly determined within one's immediate peer group.     

虚拟化身对攻击性的启动效应:游戏暴力性、玩家性别的影响

虚拟化身是个体在虚拟环境中的自我呈现,化身形象是与特定刻板印象相联系的虚拟化身的外在表象。虚拟化身与攻击性的关系已得到证实,但还有一些问题尚需探讨。本研究通过2个实验,采用线索启动的方法,考察了化身形象、游戏暴力性和玩家性别对化身认同和攻击性的影响,以及化身认同和攻击性之间的关系。实验1结果表明:化身形象与游戏暴力性交互影响化身认同和攻击性。在暴力游戏中,化身形象对化身认同和攻击性有显著影响;在非暴力游戏中,化身形象对化身认同的影响边缘显著,但对攻击性无显著影响。对不同化身形象的认同会诱发不同的攻击性,但受游戏暴力性的影响。实验2结果表明:在暴力游戏中,化身形象与玩家性别交互影响化身认同和攻击性。女性在化身认同方面比男性更易受化身形象影响;男性在攻击性方面比女性更易受化身形象影响。对不同化身形象的认同会导致不同的攻击性,但受性别的影响。     

Face structure predicts cooperation: men with wider faces are more generous to their in-group when out-group competition is salient

Male facial width-to-height ratio appears to correlate with antisocial tendencies, such as aggression, exploitation, cheating, and deception. We present evidence that male facial width-to-height ratio is also associated with a stereotypically male prosocial tendency: to increase cooperation with other in-group members during intergroup competition. We found that men who had wider faces, compared with men who had narrower faces, showed more self-sacrificing cooperation to help their group members when there was competition with another group. We propose that this finding makes sense given the evolutionary functions of social helpfulness and aggression.     

Olfaction and Human Social Behavior: Effects of Pleasant Scents on Physical Aggression

Forty-eight male undergraduates participated in an experiment designed to investigate the effects of pleasant scents on physical aggression. Subjects were first angered or not angered by a male or female confederate, and then provided with an opportunity to aggress against this person. One third aggressed in the presence of a very pleasant scent (perfume), a second third aggressed in the presence of a mildly pleasant scent (pine-scented aerosol). The remaining subjects aggressed in the absence of any pleasant aroma. Results indicated that when the victim was male, aggression was enhanced by the presence of perfume if subjects had been angered, but reduced by this scent d they had not been provoked, in contrast, when the victim was female, aggression was enhanced by the presence of perfume regardless of whether subjects had previously been angered. The pine-scented aerosol failed to exert any significant effects upon subjects' behavior. These findings were interpreted as consistent with the suggestion that the impact of pleasant scents on social behavior may stem from several different mediating mechanisms, including heightened arousal and shifts in social perception.     

Gender-specific social experiences and the development of aggressive and sexual behavior in male mice

This study examined influences of gender-specific social experiences on the development of aggressive and sexual behavior in male mice. To determine the effects of gender-specific social experience three different types of groups were constituted after the animals had been weaned. The subjects were randomly assigned to different treatments. Female groups were composed of one experimental male and three female cohabitants. Male groups were composed of five experimental males each, and the mixed-sex groups were composed of two experimental males and of two females. The experimental subjects stayed in these groups until the age of approximately three months, when the testing for sexual and aggressive behavior commenced. For the sexuality tests, a receptive female was placed in the home cage of the experimental male for ten minutes. A nonaggressive male was placed in the home cage of the experimental male for seven minutes for the aggression tests. The experimental males were administered both sexuality and aggression tests, the sequence of testing sexual and aggressive behavior was systematically varied in order to control the influence of the two different types of behavioral tests. The results showed that males with only male social experiences showed fewer responses and were less active in both the aggression and sexuality tests than the males from the two other types of groups. Significant positive correlations between activity during aggression and sexual tests were obtained for all three groups. © 1994 Wiley-Liss, Inc.     

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.     

Effects of prior destructive behavior, anonymity, and group presence on deindividuation and aggression.

Three of Zimbardo's deindividuation input variables (group presence, anonymity, and arousal) were manipulated in laboratory experiment, and their effects on aggression and deindividuation were measured. Only arousal produced a significant increase in aggression (p less than .05), while group presence produced a significant decrease in aggression (p less than .01). Anonymity had no significant effect on subjects' aggressiveness. Deindividuation per se was measured on a postsession questionnaire that assessed subjects' memory for their own aggressive behavior, self-consciousness, concern for social evaluation, and memory for central and peripheral cues. Only arousal condition participants showed deindividuation changes, but a factor analysis revealed that the deindividuation changes did not comprise a unified factor. Also it did not appear that the internal changes caused aggressive behavior, since the correlation between the two was low.     

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

Men's 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 target's 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.     

Gender,Driver Aggression,and Driver Violence: An Applied Evaluation

Drivers completed a questionnaire assessing the likelihood of engaging in mild forms of driver aggression, the frequency of past driver violence, and a disposition toward driver stress. Both male and female drivers reported similar levels of mild driver aggression, supporting the notion that context is important in arousing female aggression. In contrast, driver violence was more frequent among male drivers, demonstrating the relevance of behavioral form within gender linked aggression research. Suggestions for the existence of a gender difference in driver violence, but not mild driver aggression are offered. Finally, driver stress susceptibility was linked to both mild driver aggression and driver violence.     

Relationship between maternal aggression and maternal care in the rat

Aggression among female rats is almost entirely confined to the period of late pregnancy and lactation. Behaviorally it is similar to the aggression of males including piloerection and lateral attacks, but it differs in its function. Unlike male aggression which serves to establish a social hierarchy and a territory, i. e., is competitive, maternal aggression is protective, i. e., it serves to prevent predation of the mother's offspring. In this respect it is closely related temporally and causally to maternal care; if the offspring are removed maternal aggression wanes almost immediately–its function no longer exists! Studies on aggression by mothers, among rats, from the author's laboratory are reviewed and comparisons made with maternal care. As noted, maternal aggression and maternal care are closely related during the cycle of maternal behavior and they share a similar hormonal basis and possibly the effect of uterine stimulation, but maternal care requires prolactin and the decline of progesterone while maternal aggression appears independent of pituitary hormones and does not require a decline in progesterone. Maternal aggression like maternal care appears to be organized into a hormonal phase, during pregnancy, parturition, and for about a week postpartum and a nonhormonal phase thereafter. Bilateral radiofrequency lesions of the lateral midbrain peripeduncular nucleus (PPN) produce deficits in maternal aggression if made on lactation day 7 (L7), but not earlier, without producing significant deficits in maternal behavior. Experiments showed that the PPN does not mediate hormonally stimulated maternal aggression; it appears to mediate only nonhormonally stimulated maternal aggression. Studies on the role of pregnancy hormones on long-term retention of maternal aggression and the role of olfaction in maternal aggression are also reviewed. © 1994 Wiley-Liss, Inc.     

Habituation of aggressive behavior in mice: A parametric study

The decline of aggression as a result of repeated episodes of fighting may represent a habituation phenomenon. The frequency of biting and sideways threat by male mice toward conspecific intruders declined over ten 5-min confrontations. Aggression returned to about 50% of original levels when a new intruder was introduced. Variations in length or frequency of confrontation indicated that the rate of decline of attack bites and sideways threats depended on these confrontation parameters. The condition that provided the fewest opportunities to fight provided the least decline in the frequency of attack and threat. The frequency of attack bites and sideways threats elicited by the presentation of a new intruder after repeated confrontations was greater than the frequency of attack bite and sideways threat in the last confrontation with the original intruder, when the resident and intruder were relatively inexperienced. Spontaneous recovery of attack and threat occurred but rate of recovery did not depend on confrontation parameters. The results indicate that the decrement of aggression in mice in repeated confrontations may be the result of habituation but fatigue is an important cofactor.     

Interpersonal antecedents of drivers' aggression

The theory of social information processing, which suggests that attributions affect aggressive reactions to another person's provocative behavior, was applied to the context of driving. Respondents were 150 male drivers, who were presented with three scenarios describing frustrating driving situations caused by another driver, male or female. Hostile and non-hostile attributions, and the preference for either aggressive or non-aggressive reactions were measured for each scenario. Aggregate image of drivers as well as driving-related emotions were also measured. A path analysis showed that irritability and competitiveness mediate the relationship between aggressive reactions, on the one hand, and hostility, anxiety, and drivers' image, on the other. Hostile attributions were found to be directed more toward male than toward female drivers and were related to a negative image of drivers. The results are discussed with regard to interpersonal aspects of driving behavior.     

Modulation of aggression toward an intruder during the reproductive cycle of white king pigeons (columba livia)

For three of four mated male pigeons, intrusion of a still, two-dimensional image of a conspecific into the reproductive situation initiated aggressive behavior over months of daily testing with little habituation. There was a transient increase in aggressive contacts against the head of the target within two days prior to or following the occurrence of the second egg. Such an increase did not occur with extended daily testing of the male alone and was more closely synchronized to egg laying than time since the introduction of the female. The results are consistent with previous studies of reproductive and schedule-induced aggression in birds.     

Overt and covert aggression in work settings in relation to the subjective well‐being of employees

Aggressive behavior was studied in workplaces having (1) predominantly male, (2) predominantly female, or (3) both male and female employees in equal or near equal frequencies. In addition to examining the occurrence of different types of aggression in these workplaces, the question of whether being a target of aggression is related to employees’ subjective well‐being was addressed. One hundred sixty‐nine participants (mainly 30–50 years of age) employed in a wide range of organizations in the public sector completed a questionnaire measuring four types of observed and experienced aggression: direct overt, indirect manipulative, covert insinuative, and rational‐appearing aggression. Indirect manipulative and rational‐appearing aggression were perceived to be the most widely used aggression styles in the work context. In the predominantly male workplaces, the men were perceived to use more of all types of aggression than in the predominantly female workplaces. The women’s aggression was not related to the relative number of females and males with whom they worked. Participants were divided into two groups on the basis of the extent to which they estimated themselves to be targets of workplace aggression. Those who considered themselves to be victims of workplace aggression suffered significantly more from psychosocial problems and physical symptoms than those who had been victimized to a lesser extent or not at all. The victimized group also considered the aggression they had suffered to be the reason for their psychosocial and health problems. Aggr. Behav. 27:360–371, 2001. © 2001 Wiley‐Liss, Inc.