Influence of timing of post-weaning isolation on play fighting and serious aggression in the male golden hamster (Mesocricetus auratus)

Effects of timing of social isolation on play fighting and serious fighting were studied at different ages in male golden hamsters. Litters were isolated at 21, 35, and 65 days of age, and tested in a resident-intruder paradigm. Behaviors were compared within grous and with a fourth group of socially reared conspecifics. The earlier the pups were isolated, the more they engaged in play activities. Later, in adulthood, the aggression level of the same animals was retested using the same paradigm. The three isolated groups showed a high level of aggression, with significant differences among them. When compared with socially reared subjects, a reliable difference in the level of aggression was also found. These results support the view that early social experience is important, suggesting that isolation during early critical periods of socialization has a significant impact on play fighting, whereas short periods of isolation may be enough to trigger adult agonistic behavior. © 1994 Wiley-Liss, Inc.     

Hostile masculinity,sexual aggresion,and gender-biased domineeringness in conversations

This study assessed the ability of certain variables to predict which men would be more domineering in conversations with a woman and/or with a man. The variables included men's self-reported sexually aggressive behavior and several components comprising a personality profile labeled “Hostile Masculinity.” As expected, these variables successfully predicted domineering behavior toward the female but not toward the male. These findings supported theories hypothesizing that men's desire to control women and men's antisocial behavior toward them are due to specific rather than to general factors (i. e., evolutionary and feminist theorizing). © 1994 Wiley-Liss, Inc.     

Individual differences in the study of human aggression

Excessive concern for simplicity has often led us to underestimate the complexity of aggression. Over the years, several scales related to aggression have been identified and validated both on adults and on children. Ultimately, two main higher order dimensions, emotional responsivity and proneness to aggression, repeatedly emerged in a series of second-order factor analysis. These dimensions are rather similar to two of the big five factors of personality: neuroticism/emotinal stability and hostility/agreeableness, respectively. Several studies corroborate the plausibility of a higher level bidimensional conceptualization of aggression that, while preserving the heuristic validity of looking for more specific constructs of aggression, can link the field of aggression to the field of personality. © 1994 Wiley-Liss, Inc.     

Behavioral changes over several successful agonistic encounters between male mice: Effects of type of “standard opponent”

This study assessed whether two types of non-aggressive “standard opponents” (“intact” and “anosmic” group-housed males) produced similar behavioral changes in isolated OF1 male mice given several experiences of victory. Experimental groups confronted either intact or anosmic opponents every two days until they had completed four encounters. The behavioral changes were recorded using a detailed ethologically inspired analysis. These changes were clearly different depending on the opponent type. When intact opponents were used, experimental subjects increased the time spent in digging, non-social exploration, explore from a distance, and attack over encounters, but showed decreased time spent in threat and a decreased latency to the first attack. In encounters with anosmic opponents, only declines in the latencies to threat and attack were noted. Moreover, the experimental groups differed in their behaviors over encounters. Those confronting intact opponents spent less time in social investigation, more time in explore from a distance and threat, and showed a shorter latencies to threat and attack than counterparts confronting anosmics. These results suggest that, although both types of “standard opponents” are similar in their non-aggressiveness, they elicit rather different behavioral responses in their adversaries. These findings provide additional support for the view that the type of opponent used in studies on intermale aggression is of paramount importance. Indeed, the use of different types of “standardized non-aggressive opponents” appears to be an important source of variability between studies. © 1994 Wiley-Liss, Inc.     

Variation in aggressive behavior and anatomo-physiological correlates generated by crowding without physical contact in the house mouse

Behavioral, physiological (i.e., endocrine), and anatomical consequences of crowding in mice were studied in a situation where animals were in auditory, visual, olfactory, and tactile contact but restrained from full physical interactions, to prevent overt aggression. Males that cohabited with females undisturbed by neighboring conspecifics showed greater propensity to attack same-sex intruders and had higher plasma testosterone levels than did their “crowded” counterparts, that is, males cohabiting with females and housed adjacent to other male/female pairs. In this respect, the latter animals resembled submissive males. However, a significant increase in weight of androgen-dependent target organs (i.e., seminal vesicles and preputial glands) was found in crowded males. These data indicate that despite the observed inhibition of social aggression these males are not physiologically comparable (homologous) to male mice that experienced defeat and the stress of submission during fighting. The intriguing possibility that different conversion pathway of testosterone are accelerated, as a result of social communication, in males living in these two environments and the behavioral implications of these possibilities are discussed. Finally, the parental behavior of crowded animals, although not freely interacting with each other, was disrupted, causing a marked decrease in reproductive success. In this situation a high incidence of infanticide of their offspring by both parents was observed, whereas this behavior was virtually absent in non-crowded male/female pairs.     

Relative deprivation: A mechanism for the ostracism–aggression link

In five studies, we tested whether ostracism triggers feelings of relative deprivation and whether relative deprivation accounts for the impact of ostracism on aggression. Relative to participants who recalled either inclusive or neutral experiences, participants who recalled ostracism experiences reported higher levels of relative deprivation (Study 1). Furthermore, the feeling of relative deprivation mediated the effect of ostracism on aggression (Studies 2, 3a, and 3b). Framing ostracism as an experience of nondeprivation weakened the connection between ostracism and aggression (Study 4), which suggests an effective way of reducing aggression following an ostracism experience. Together, these findings highlight the significance of relative deprivation in shaping people's responses toward ostracism.     

Associations of temperament and personality traits with frequency of physical activity in adulthood

Temperament and physical activity (PA) have been examined in children and adolescents, but little is known about these associations in adulthood. Personality traits, however, are known to contribute to PA in adults. This study, which examined both temperament and personality characteristics at age 42 in relation to frequency of PA at age 50 (JYLS, n = 214–261), also found associations with temperament traits. Positive associations were found between Orienting sensitivity and overall PA and between Extraversion and vigorous PA among women and between low Negative affectivity and overall and vigorous PA among men. Furthermore, Orienting sensitivity and Agreeableness were associated with vigorous PA among men. Temperament and personality characteristics also showed gender-specific associations with rambling in nature and watching sports.     

How our work influences who we are: Testing a theory of vocational and personality development over fifty years

This study examines the developmental influences of occupational environments on personality traits from childhood to adulthood. We test aspects of a theory of vocational and personality development, proposing that traits develop in response to work experience following corresponsive and noncorresponsive mechanisms. We describe these pathways in the context of situations of vocational gravitation and inhabitation. In a sample from the Hawaii personality and health cohort (N = 596), we examined associations of childhood and adulthood personality traits, with occupational environments profiled on the RIASEC model. Mediations tests confirmed that work influenced personality development from childhood to adulthood for Openness/Intellect. We observed multiple reactivity effects of occupation environments on adulthood traits that were not associated with corresponding selection effects.     

An empirically derived scoring system for intermale aggression in mice

Scoring systems used to assess intermale aggression have been characterized by arbitrary scales and wide variability in the behaviors selected for measurement. The use of such different systems severely limits the ability of investigators to make meaningful comparisons among studies and indicates that there is a need for a common, statistically derived evaluative system for intermale aggression. We measured the frequency and duration of five major components of agonistic behavior exhibited by intact males toward olfactory bulbectomized stimulus males and then analyzed the data using a number of univariate and multivariate procedures. The results were used to generate two statistically based scoring systems, one a short-form index and the other a composite index for more detailed studies of aggression. It is hoped that these statistically derived systems will be adopted by other investigators to increase methodological congruence in the field.