Social interactions between peromyscus leucopus and P. gossypinus in captivity

In evaluating the role of behavioral interactions in the maintenance of ecological and ethological isolation in sympatric populations of P. leucopus and P. gossypinus, the interspecific behavior of 94 animals in all possible sex pair combinations was observed in 84 staged dyadic trials of 15-minutes duration. Qualitatively the patterns of behavior differed little between sexes or species. Despite a high inter-individual variability and the high proportion of amicable interactions, the mean frequency of occurrence of aggressive behavior as well as the number of trials in which aggressive behavior occurred was greater in trials of animals from areas of range sympatry in comparison with those of the control animals from areas of range allopatry. Although the dominance relationships in many trials were unclear, gossypinus nonetheless consistently dominated leucopus. These data combined with examination of the habitats of these mice where their ranges do not overlap suggest that agonistic interactions may implement species integrity either primarily by Limiting or preventing the occupancy by leucopus of areas in which gossypinus occurs or secondarily by reducing the chances of pair bond formation.     

Interpersonal violence and its relationship to some personality measures

One hundred and fifteen patients in a psychiatric hospital for criminal offenders volunteered to be tested with the overcontrolled hostility scale, the self focus sentence completion, and an emotional empathy measure. The subjects were divided into five groups on the basis of criminal offenses (murder, assault with a deadly weapon, rape, pedophilia, and nonviolent property offenses). It was also possible to divide the sample on the basis of diagnostic features (psychosis, personality disorder, and brain syndrome). The results failed to support the hypothesis that more violent (by nature of their offense) individuals would-as a group-score higher on the overcontrolled hostility scale than less aggressive counterparts. There was some evidence that psychotics showed more self focus at the expense of external focus. The empathy measure failed to reveal any meaningful differences. It is suggested that more validation data are called for to establish the generality of the overcontrolled hostility scale and that, in view of the therapeutic importance which empathy training may have for violent individuals, further effort should be expanded to find a generally valid empathy measure.     

Predatory aggression: Midbrain-pontine junction rather than hypothalamus as the critical structure?

Electrical stimulation of sites in the region of the ventromedial periaqueductal gray substance at the level of the midbrain–pontine junction was found to elicit a predatory attack by a cat upon a rat. The intensity of stimulation required to elicit the attack was three to four times less than that required to elicit similar behavior by hypothalamic stimulation. The results suggest that anatomically distinct regions of the periaqueductal gray substance are concerned with the regulation of predatory and affective forms of aggressive behavior. The difficulty in reconciling these results with the preeminent role assigned the hypothalamus in the organization of predatory behavior is also discussed.     

The reinforcing properties of aggressive vs nonaggressive social interactions in isolated male ICR mice (Mus musculus)

Isolated male ICR mice in a T-maze consistently selected the goal box which enabled them to fight another mouse if the alternative goal box allowed no social interaction (Experiment 1). However, if the alternative choice enabled the isolated mice to interact with another mouse through a mesh screen which prevented fighting, the preference for the opportunity to fight did not appear (Experiment 2). Because the visual, olfactory, and auditory stimuli available through the screen appeared to be as attractive as the stimuli provided by the additional opportunity to fight, it is not necessary to conclude that the stimuli reinforcing the choice behavior in Experiment 1 were provided by fighting. Since there is no compelling reason to conclude that fighting is a primary reinforcer for these isolated mice, it is not necessary to argue that the high incidence of isolation-induced fighting is the reflection of a primary aggressive motive.     

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.     

The influence of chemical cues on the territorial prior residence effect in convict cichlids (cichlasoma nigrofasciatum Günther)

The importance of accumulated chemical cues on the occurrence of the territorial prior residence effect was investigated in two experiments using adult convict cichlids (Cichlasonul nigrofasciatum). In the first experiment, pairs of fish, matched on a number of criteria, were randomly assigned to three independent treatment conditions in which (1) the territorial marker (pot or clump of plants) was removed just prior to a direct encounter in the aquarium of the resident (pair member in whose aquarium the encounter took place) with accumulated chemical cues remaining intact; (2) the marker was removed, as well as the chemical cues; or (3) the marker was present, but the chemical cues were removed. Results showed that a significant prior residence effect occurred when the marker was present, but did not occur in either condition in which the marker was removed. A second experiment, in which the marker was removed and the gravel substrate altered, also did not reveal a signficant prior residence effect. Apparently, the territorial resident recognizes his territory by using certain visual cues, with accumulated chemical cues being neither necessary nor sufficient in this process.     

The control of alcohol-related aggression: Redirecting the inebriate's attention to socially appropriate conduct

Forty male undergraduates ingested either a high dose of alcohol or a placebo, and were either provided with a nonaggressive norm or not, prior to being provoked by an opponent during a competitive reaction time task. Aggression was assessed by the intensity of shocks administered by the subject to the bogus opponent. Results suggest that the provision of an explicit nonaggressive norm enabled highly intoxicated subjects to moderate their aggressive responding even in a highly competitive situation. These findings are discussed in terms of current cognitive disruption models of alcohol-related aggression which assume intoxicated persons are unable to process information concerning appropriate standards of conduct.     

The aggression test as a possible taxonomic tool in the Formica rufa group

The intra- and interspecific aggressive behavior of Formica polyctena, a species of the Formica rufa group, was analyzed and quantified both in the laboratory and in the field. This behavior was used as a potential taxonomic tool for gaining a better understanding of the phyletic relationships among the species within the group. No overt aggression was recorded toward members of the same species. To examine interspecific relationships, F. polyctena was first confronted with F. cunicularia, to ascertain its aggressiveness toward a distantly related species. All such encounters led immediately to overt and prolonged attacks with virtually no initial mutual inspection. This suggests that recognition of strangeness of the unrelated species is almost immediate in F. polyctena, as previously observed in F. lugubris and F. rufa toward the same antagonist. Subsequently, F. polyctena was contrasted with F. lugubris and F. rufa (also belonging to the F. rufa group) in order to compare these related species. Fierce attacks accompanied by all the elements of conflict behavior were observed in all encounters. Moreover, the degree of aggression in the field was higher than in laboratory-paired ants, possibly because of a territorial effect. These data and our previous and similar research indicate that the relationships between F. lugubris and F. rufa are closer than between these two species and F. polyctena. In considering different viewpoints on this problem, the validity of the aggression test is discussed and the opportunity to compare levels of aggressiveness among strictly sympatric samples of red wood ant species gathered from the same ecological environment are considered.     

Effects of selective breeding for high and low aggressiveness and of fighting experience on odor discrimination in mice

The present study was designed to determine whether male and female mice, selectively bred for high (TA) and low (TNA) aggressiveness, react in different ways when exposed to odors from males of the same strains. The effects of losing or winning fights on odor preferences in the TA males were also studied. The low aggressive TNA males were found to avoid areas soiled by the highly aggressive TA males. The TA males, on the other hand, were most interested in the areas soiled by other highly aggressive TA males. Along with decreasing aggressiveness, losing fights radically changed the odor preferences of the TA males, the soiled bedding from winner TA males now having a strong aversive effect. TNA females preferred the odors of TA males, while the TA females preferred the odors of TNA males. The genotype of the receiver of odor cues is important for the preference choices; this effect can, however, be changed through experience.     

The offensive nature of maternal aggression in mice: Effects of fluprazine hydrochloride

The phenylpiperazine fluprazine hydrochloride was used to test the hypothesis that maternal aggression in laboratory mice reflects offensive motivation. Lactating females (n = 8 per condition) tested for aggression following drug treatment (1.0 mg/kg and 5.0 mg/kg of fluprasine) were significantly less aggressive than saline controls according to all measures used. The findings support the hypothesis that maternal aggression is offensive in nature, and provide no evidence that maternal attack is a mixture of offensive and defensive tendencies.