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.     

Infant positioning: A brief review

The American Academy of Pediatrics (2016a) has made several recommendations regarding the safe positioning of infants by caregivers, including placing infants in a supine position for sleep and in prone for supervised periods of tummy time. However, caregivers may have difficulty adhering with these recommendations. A small, but growing, number of behavior analytic studies have examined these infant safety recommendations and strategies for increasing adherence. This review describes behavior analytic research on infant positioning and provides suggestions for future research.     

A preliminary evaluation of treatment duration on the resurgence of destructive behavior

Quantitative models of resurgence (e.g., Behavioral Momentum Theory, Resurgence as Choice) suggest that resurgence is partly a function of the duration of extinction exposure, with longer histories of extinction producing less resurgence. This prediction is supported by some laboratory research and has been partially supported by clinical translations that did not isolate the effects of extinction exposure prior to testing for resurgence. The degree to which different histories of extinction impact the likelihood of treatment relapse in therapeutic applications of differential reinforcement is of great interest to the clinical community, including insurance carriers and other financial providers. In the present study, we isolated the effects of extinction history for severe destructive behavior across 6 participants referred for treatment services and examined resurgence of destructive behavior when alternative reinforcement terminated. Our within-subject evaluation showed no difference in the level of resurgence or persistence of destructive behavior following short and long exposures to differential reinforcement with extinction. We discuss our failure to replicate in relation to experimental-design considerations for investigating this and other relapse phenomena in future research with clinical populations.     

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.     

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.