A possible confound and the role of olfaction in mouse aggressive interactions

In investigating the olfactory modulation of aggression in mice, a urine-coating technique frequently has been used. Fighters typically have been tested against castrated animals coated with either urine or water. Then, if the fighters are more aggressive toward urine-coated castrates than toward water-coated castrates, it is concluded that olfaction plays a role in this discriminatory response. However, it is possible that the fighers might react to behavioral differences between these two groups of castrates caused by the different experimental treatment. Three experiments were conducted to study this possible confound and the role of olfaction in the control of agonistic encounters. The results indicated that 1) the confound is not likely to operate; 2) even if the confound is allowed to operate, it is not an effective discriminatory cue; and 3) anosmic fighters do not exhibit differential attacks toward castrates treated with different chemo-signals. Therefore, the emission and perception of olfactory cues do play an important role in mouse agonistic interactions.     

Fighting in female mice in lines selected for laterality

Male and female mice from the Collins HI and LO laterality strains were isolated for 3–5 days. Thereafter on Day 1 each was given the Intruder Test followed by a Training Test; the latter was repeated 1 week later. All males of 36 days or older fought vigorously, but without line differences. Females of the HI strain showed higher numbers of fighters and greater intensity of fighting than those of the LO strain, and by the second Training Test these differences were significant at p < 0.01. The HI and LO laterality strains thus provide useful tools for investigating the functions of female agonistic behavior and the possible relationship between laterality and the expression of aggression.     

Agonistic behavior,plasma testosterone,and hypothalamic estradiol binding in male rabbits

The purpose of this study was to establish a relation between agonistic behavior, gonadal hormones, and their receptorial capacity at the central level. Male rabbits were observed in seminatural conditions and three components of their agonistic behavior were recorded: follow, attack, and chase. The three behaviors were mutually correlated and clearly differed among the four members of each group. Within the social group, one rabbit was agonistically more active than the others and his supremacy was associated with an increased level of peripheral testosterone and higher estradiol binding in the hypothalamus. On the whole, the values of the hypothalamic estradiol binding were positively correlated with the behaviors. The results show that, in the male rabbit, agonistic activity is associated with changes in testosterone concentration and in the binding at the central level of its aromatized metabolite estradiol. Aggr. Behav. 23:33–40, 1997. © 1997 Wiley-Liss, Inc.     

Response of colony mice to intruders with different fighting experience

Six male mice placed in a large, moderately complex enclosure formed a stable dominance hierarchy in which two mice defended adjacent floor areas and the remaining four mice were subordinate and did not form territories. Intruder mice with winning or losing experience in prior paired encounters, or those with no fighting experience, were introduced individually into the colony for 30 minute periods. These intruders were attacked by the dominant members of the colony, and the fighting outcomes were strongly dependent upon the fighting experience of the intruder. Intruders with losing or no fighting experience engaged in little mutual fighting with residents, were easily defeated, and terminated attacks by engaging in subordinate behaviors. Intruders with winning experience fought vigorously with residents, attacked and, in many cases, defeated residents. These results suggest that relatively little winning experience gained in earlier paired encounters may be sufficient to overcome the various fighting advantages enjoyed by a dominant territorial holding member of a colony.     

Effects of acute administration of nicotine and lobeline on agonistic encounters in male mice

The effects of acute administration of two nicotinic ligands, (‐)‐nicotine and (‐)‐lobeline were examined on isolation‐induced aggression in mice. Individually housed male mice confronted anosmic “standard opponents” in a neutral arena 10 min after drug administration. Encounters were videotaped and evaluated using an ethologically based analysis facilitating estimation of time allocated to 11 broad behavioral categories. Nicotine did not have significant effects on threat or attack but significantly diminished time allocated to digging. The lowest dose of lobeline significantly diminished attack and induced a slight increase of immobility without significantly diminishing other behaviors with motor components. The intermediate and highest dose of lobeline reduced time allocated to all behaviors with motor components. It is concluded that these two nicotinic agonists produce different behavioral profiles during agonistic encounters in mice but that this test may not facilitate assessing the impact of such drugs on irritability. Aggr. Behav. 26:376–385, 2000. © 2000 Wiley‐Liss, Inc.     

A possible function of the preference for hind nipples in prairie voles (Microtus ochrogaster)

Prairie vole pups (Microtus ochrogaster) in laboratory cages prefer hind nipples. In this research, the author observed 8 litters of prairie voles in a seminatural environment to confirm the preference for hind nipples and to determine if young on hind nipples were groomed more frequently or dislodged less frequently than were young on other nipples. Prairie vole pups in seminatural environments preferred hind nipples; this preference was illustrated by the progressive use of more anterior nipples only as litter size increased and by the reluctance of pups to voluntarily release their hold on hind nipples. Maternal grooming of young did not vary with suckling location. Prairie vole young on hind nipples, however, were dislodged less frequently than were young on other nipples. Less frequent dislodgment from hind nipples during maternal movements may play a role in the preference for hind nipples in prairie voles.     

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

Male and female albino rats were tested for intraspecies aggression without the use of shock. In the first experiment, male pairs showed more biting attacks, offensive sideways movements, and self-grooming than did female pairs; male pairs also showed more stereotyped defensive/submissive behaviors and were wounded more frequently. The second experiment examined the effects of neonatal castration and testosterone propionate (TP) administration 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. The 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.     

Adrenal mediation of intermale aggression maintained by aromatized and reduced metabolites of testosterone

Individually housed CD-1 mice were either sham castrated or castrated and treated with testosterone (T), estradiol benzoate (EB), dihydrotestosterone (DHT), a combination of EB and DHT (EB+DHT), or the injection vehicle. Following 16 days of isolation and subcutaneous injections, animals were tested repeatedly for fighting behavior in paired encounters with nonaggressive stimulus males. Results indicated that the T and EB+DHT groups fought to the same extent as the gonadally intact group. Both the EB and DHT groups fought more than the vehicle-treated group but less than the T, EB+DHT and sham castrated groups. A similar study was subsequently performed with adrenalectomized animsls. Adrenalectomy eliminated agonistic responses in animals receiving metabolites of testosterone (EB, DHT, EB+DHT) but had only slight effects in gonadally intact and T-treated, castrated mice. The results suggested that a) EB and DHT, either singly or in combination, maintain aggression through a synergism with adrenal steroids; b) the combined effects of EB and DHT reflect an additive action rather than synergistic interaction, notwithstanding the synergism with adrenal steroids; c) metabolism of testosterone to estrogen and dihydrotestosterone does not sufficiently account for the action of testosterone.     

利他行为的内隐启动研究

通过视觉与组词任务启动范式的两个实验考察了利他人物形象与利他词语对利他行为的内隐启动效应。结果发现,完成利他人物形象视觉启动(实验1)与完成利他组词任务启动(实验2)的实验组被试,在独裁者分配任务中分配给他人的钱数显著多于控制组被试。研究结果表明:利他人物形象视觉和利他语义组词都可以使个体的利他行为被显著直接无意识启动,即内隐启动。研究对设计能更好地启动人们的利他行为的一般情境有重要的启示。     

Reflexive fighting in the albino rat: Aggressive or defensive behavior?

Specific agonistic responses of albino rats were compared for dominant colony rats and intruders, and for rats in a “reflexive fighting” task. The “reflexive fighters” showed high levels of defensive responses such as boxing and freezing, and very low levels of aggressive behaviors such as piloerection, biting, and the lateral display. This pattern clearly suggests that the behaviors measured in the reflexive fighting task reflect conspecific defensive reactions, rather than “shockelicited aggression.” Moreover, striking responses seen in the reflexive fighting task also occur at a high rate when footshock is given to a solitary rat held in a boxing posture. Thus it appears that “reflexive fighting” primarily involves defensive rather than aggressive responses.     

Dyadic social behaviour in the hamster: Evidence for contextual mediation

Dyadic social interactions among 34 adult male golden hamsters reared in either standard wire cages (Experiment 1) or cages with sandy substrates (Experiment 2) were observed for 15 min on consecutive days in two neutral arenas with either a bare Plexiglas or a sandy substrate. The tests showed that in the arena with the sandy substrate the hamsters spent less time engaged in agonistic encounters, initiated fewer agonistic encounters of all kinds and engaged in fewer agonistic encounters of a potentially physically damaging nature (i.e. violent encounters) than they did in the arena with the Plexiglas substrate. These effects were the same in animals reared under either condition. This finding argues against the behavioural effects being due to the novelty of a sand substrate to laboratory-reared hamsters. Consequently, the social behaviour of hamsters in laboratory settings is highly labile across various contexts. Therefore, it is necessary to examine the behavioural effects of contextual variables if general behavioural principles are to be derived from laboratory indices of social behaviour in hamsters, and possibly a number of other species.     

Setting an egalitarian social norm in the classroom: improving attitudes towards diversity among male engineering students

This study tested the effect of a message describing a social norm of egalitarian attitudes and behaviors in an engineering college on male students’ attitudes and behavioral intentions surrounding diversity in engineering. Participants were first-semester university students enrolled in four sections of an introductory engineering course in two academic terms (Fall 2009 and Fall 2011). At the beginning of the semester, students in two of the four sections received the egalitarian social norms message in the form of an oral presentation given by a senior White male faculty member (social norms message condition). Students in the other two sections did not receive this presentation (control condition). At the end of the semester, all students were invited to complete a survey. Results from a sample of 129 students showed that compared to the control condition, male students in the social norms message condition had stronger intentions to speak out against racist behaviors in their engineering courses and teams, and (among White compared to racial minority men) more positive attitudes toward diversity in engineering. These results suggest that setting a tone of egalitarianism and intolerance of bias for incoming students could help create a more inclusive environment in a White male-dominated educational setting such as a college of engineering.     

Offensive and defensive bite-target topographies in attacks by lactating rats

The attacks by resident lactating Wistar rats on sexually naive conspecifics of both sexes were examined. Male and female intruders were equally attacked in terms of frequency and number of bites, but the topographies of biting seen in these encounters were different. Similarly to male-male agonistic interactions, females were attacked in a fashion which avoided bites to the head and snout (“offensive” attack), whereas males were frequently bitten on such vulnerable regions (“defensive” attack). This dichotomy in bite pattern suggests that different motivations and functions underlay maternal aggression in these situations. The defensive attack on males may be a deterrent to infanticide since only male intruders counterattack lactating females and kill their pups. The attack on females may be concerned with resource competition.     

Agonistic onset marks emotional changes and dispersal propensity in wild house mouse males (Mus domesticus)

The authors investigated implications of agonistic onset for anxiety and dispersive motivation in maturing wild house mouse males (Mus domesticus). Laboratory-kept fraternal pairs either developed agonistic dominance or stayed amicable during their first 2 months of life, when the authors assessed open-field behavior and dispersal propensity. State anxiety was lower in amicable than agonistic males and higher in subordinate than dominant ones. During subsequent dispersal trials, 1 dominant and 1 amicable male from 2 fraternal pairs were concomitantly introduced into seminatural enclosures containing 3 females. One male invariably became territorial. The defeated males, if previously dominant, dispersed at significantly higher rates than if previously amicable. The authors conclude that agonistic onset during development represents an adaptive behavioral switch from a submissive-philopatric to agonistic-dispersive coping strategy.     

不同性别比和童年经济状况对未婚男性性态度的影响

基于进化心理学的生命史理论,通过两个实验探讨性别比和童年经济状况同男性性态度间的关系。实验1和实验2分别采用图片和文字材料启动被试的性别比感知,结果发现感知性别比和童年经济状况对未婚男性的"随意性行为"态度表现出显著的交互效应：童年家庭经济状况差的未婚男性在感知到周围女性数量相对充裕的情境下,其性开放态度会较感知到周围男性数量充裕时明显上升;童年家庭富裕的男性的性开放态度在不同感知性别比下保持相对稳定。     

不同性别比和童年经济状况对未婚男性性态度的影响

基于进化心理学的生命史理论,通过两个实验探讨性别比和童年经济状况同男性性态度间的关系。实验1和实验2分别采用图片和文字材料启动被试的性别比感知,结果发现感知性别比和童年经济状况对未婚男性的"随意性行为"态度表现出显著的交互效应：童年家庭经济状况差的未婚男性在感知到周围女性数量相对充裕的情境下,其性开放态度会较感知到周围男性数量充裕时明显上升;童年家庭富裕的男性的性开放态度在不同感知性别比下保持相对稳定。     

Comparison of agonistic behavior in individually-housed male mice with those cohabiting with females

Videotape recordings of male mice group-housed, individually-housed and cohabiting with females, were rated for their agonistic behavior in a “standard opponent” test. Previously mated male mice showed more fighting than isolated or grouped males. Marked differences in other social and non-social behaviors, which could not be accounted for in terms of increased fighting, were not evident. These results suggest that agonistic behavior may be usefully studied by examining male mice that have cohabited with females. One obvious advantage is that such mice cannot be dismissed as being “socially deprived,” as is sometimes claimed for individually-housed mice. Other advantages are that aggressiveness is induced quickly, at high levels, and the mice appear very sensitive to hormone manipulation following castration.     

Possession Episodes in Young Children's Social Interactions

This naturalistic study examined the relationships between possession episodes and other social behaviors. Twenty children were observed in 240 social interactions that occurred during free play in their preschool classroom. The interactions were analyzed for behaviors related to possession, affiliation, prosociability, and aggression. The findings suggest that possession episodes are positively associated with agonistic behaviors and negatively related to positive social responses both situationally and dispositionally. First, disputes following possession claims frequently resulted in the termination or disruption of the social interaction. Moreover, a comparison between children's behaviors in interactions that contained a possession episode and in those that did not revealed that more aggression and fewer prosocial and affiliative behaviors occurred in the possession interactions. Second, in an analysis of individual social patterns, children who frequently engaged in possession disputes engaged in more aggressive actions and fewer affiliative ones than did their less possession-oriented classmates.     

Behavioral effects of testosterone in relation to social rank in the male rabbit

The role of gonadal androgens in favoring the adaptation to environmental pressure, including social organization, is well known. In the rabbit, testosterone administration increases marking behavior, and its level can be affected by agonistic interaction. In this experiment, we studied the effect of subcutaneous administration of testosterone propionate (TP) (3 mg/d for 6 days) in male rabbits belonging to the same social group (6 groups of 4 animals). In 2 additional groups (4 animals each), males were injected with almond oil. The animals were observed for 6 days in seminatural conditions, then treated with TP (or oil) and observed for another 6 days. The dominant/subordinate frequency ratio of behavioral patterns was used to rank the animals. The testosterone plasma concentration was correlated with agonistic behavior after the first period of social interaction. A significant increase of marking, digging, and defensive activity was observed after TP administration in all animals independent of rank, whereas this increase was not present in animals treated with oil. Agonistic and interactive behaviors increased significantly after TP treatment only in the first‐ranking animals. This indicates the influence of social rank in the modification of behaviors involving interactions among subjects Aggr. Behav. 29:269–278, 2003. © 2003 Wiley‐Liss, Inc.