Characterizing aggressive behavior

In the research literature, aggressive behavior has traditionally been classified into two distinct subtypes, impulsive or premeditated. Impulsive aggression is defined as a hair-trigger aggressive response to provocation with loss of behavioral control. Premeditated aggression is defined as a planned or conscious aggressive act, not spontaneous or related to an agitated state. The present study outlines the development of a clinically useful self-report instrument, the Impulsive/Premeditated Aggression Scales (IPAS), designed to characterize aggressive behavior as predominately impulsive or predominately premeditated in nature. The IPAS showed strong reliability and validity. Analysis of the IPASscores demonstrated thepresence of two types of aggressive behavior, impulsive and premeditated, in men referred for anger problems. The aggression of most individuals in the present sample was characterized as predominately impulsive in nature (90%).     

Predictors of aggressive behavior

A multiple factor approach was used to test additive and multiplicative models as well as to isolate a best predictive model of physical aggression. The variables of aggressive learning history, provocation, sex of target, sex of subject, sex-role orientation, and aggressive tendencies were selected. Eighty-three males and 117 females participated in the experimental session. Multiple regression analyses indicated that multiple predictor models were able to account for significantly more variance than were single predictor models; however, multiplicative models were unable to increase predictive efficacy. A model composed of sex of target, masculinity, and aggressive tendencies was established as the best predictive model for unprovoked aggression; provocation, masculinity, and aggressive tendencies made up the best predictive model of provoked aggression. © 1992 Wiley-Liss, Inc.     

Instrumental conditioning of aggressive behavior in rats

A method has been developed for bringing an aggressive response under stimulus control. It was found that the number of conditioned aggyessive responses was maximal when low-weight target rats were used. The latencies of the conditioned responses toward target animals of 124 gm were significantly lower than those toward animals of 221 and 284 gm. The application of an extinction procedure on the conditioned aggressive response substantially increased the total number of emitted aggressive responses.     

Impact of distressed and aggressive behavior

Two studies examined the hypothesis that distressed behavior induces negative emotions in others but also prompts solicitousness and deters aggression. In Study 1, 48 marital dyads rated various behaviors in terms of their feelings and reactions toward a spouse engaging in each behavior. Distressed behavior prompted both negative and solicitous emotions, but deterred hostile reactions. Aggressive behavior prompted negative feelings and hostile and argumentative reactions. In Study 2, 41 couples rated videotaped examples of a woman engaging in distressed, aggressive, or neutral behavior, with variations in verbal content and nonverbal affect. Examples of distressed behavior prompted more negative feelings and more solicitous feelings than neutral behavior. Aggressive examples prompted more negative feelings and hostile reactions. The studies indicate the importance of distinguishing between distressed and aggressive behavior.     

Predictors of women's aggressive driving behavior

Predictors of women's aggressive driving behavior were explored in a study involving 256 female motorists. Sex role orientation, dispositional aggressiveness, age, and annual mileage were measured as independent variables, and aggressive driving behavior was included as the dependent variable. Stepwise hierarchical regression analysis showed that age was negatively related to driving aggression, whereas annual mileage had a positive relationship with driving aggression. Dispositional aggressiveness was a significant predictor of driving aggression. Of the two components of sex role orientation, only femininity was associated with driving aggression, with higher femininity scores predicting lower aggressive driving scores. Masculinity failed to predict aggressive driving, as did the interaction of masculinity and femininity. In combination, the predictors explained 29% of the variance in women's aggressive driving. The results are discussed with respect to the role of dispositional variables as predictors of driving aggression in women. Aggress. Behav. 00:1–10, 2005. © 2005 Wiley‐Liss, Inc.     

Intellectual ability and aggressive behavior in nonclinical-nonforensic males

The purpose of this study was to test the relationship between IQ and physical aggression in a nonclinical-nonforensic male sample in a laboratory setting. Thirty males completed an abbreviated version of the Wechsler Adult Intelligence Scale—Revised. Aggression was measured using a modified version of the Taylor reaction-time (RT) aggression paradigm in which subjects competed on a RT task and both received and delivered shocks to a fictitious opponent in provoking and nonprovoking conditions. Provocation conditions (High and Low) were defined by the intensity of shocks the subjects received. Results demonstrated strong inverse correlations between IQ and aggressive behavior under both High and Low Provocation conditions.     

Generalization of aggressive behavior in adolescent delinquent boys

The generalization of conditioned aggressive and nonaggressive responses in a group of six adolescent delinquent boys was investigated. Responses were reinforced in card games where a token reinforcement system with money as a back-up rinforcer was used. Conditioning of responses was rapid. Generalization, measured in terms of frequency of physical contact, was tested in a group game for which no reinforcement was given. Generalization occurred during aggressive contingencies. During nonaggressive contingencies, responses did not return completely to the baseline level.     

Midbrain-hypothalamic interrelationships in the control of aggressive behavior

Previous studies have suggested an involvement of the midbrain ventral tegmental area in the biting attack upon a rat elicited by electrical stimulation of the lateral hypothalamus in cats. In order assess further the relationship between these two regions, 12 cats were implanted with attack-eliciting electrodes in both the lateral hypothalamus and the midbrain ventral tegmental area. Following a lesion of the midbrain attack site, attack previously elicited from hypothalamic electrodes ipsilateral to the lesion was eliminated or significantly reduced in frequency. The attack elicited from electrodes in the hypothalamus contralateral to the lesion was unaffected. Midbrain lesions made at sites from which attack was never elicited had no effect on hypothalamically elicited attack. The midbrain lesion in some cases eliminated only certain components of the total attack pattern; for example, the approach of a cat to the rat frequently remained present while the bite was absent. Additionally, it was found that the attack elicited from rostral hypothalamic electrodes was disrupted to a greater degree by a single midbrain lesion than the attack elicited from more caudal hypothalamic electrodes. These finding are discussed in terms of the neural system mediating this form of aggressive behavior in cats.     

Emotional competence and aggressive behavior in school-age children

Examined emotional competence in 87 children, aged 7–10 years, who varied with respect to reports of aggressive behavior to determine whether individual differences in emotional competence characterize children with higher levels of aggressive behavior. Emotional competence was assessed during a 1-hr lab visit that included (a) an observational period consisting of a modified disappointment paradigm, (b) assessment of cognitive and language abilities, and (c) 2 structured emotion interviews. Children with higher levels of aggressive behavior exhibited more intense and frequent expressions of anger, both as reported by mothers and as observed during the disappointment paradigm. Less sophisticated ability to identify the causes of emotion also characterized children with higher levels of aggressive behavior. Gender moderated the relation between aggressive behavior and type of emotion identified such that reports of happiness (in response to receiving a disappointing prize) were associated with lower levels of reported aggressive behavior for boys. The value of assessing children's emotional competence in the context of an emotionally arousing situation is suggested by these findings.     

Neural correlates of intertemporal choice in aggressive behavior

People often have to make decisions between immediate rewards and more long-term goals. Such intertemporal judgments are often investigated in the context of monetary choice or drug use, yet not in regard to aggressive behavior. We combined a novel intertemporal aggression paradigm with functional neuroimaging to examine the role of temporal delay in aggressive behavior and the neural correlates thereof. Sixty-one participants (aged 18–22 years; 37 females) exhibited substantial variability in the extent to which they selected immediate acts of lesser aggression versus delayed acts of greater aggression against a same-sex opponent. Choosing delayed-yet-more-severe aggression was increased by provocation and associated with greater self-control. Preferences for delayed aggression were associated with greater activity in the ventromedial prefrontal cortex (VMPFC) during such choices, and reduced functional connectivity between the VMPFC and brain regions implicated in motor impulsivity. Preferences for immediate aggression were associated with reduced functional connectivity between the VMPFC and the frontoparietal control network. Dispositionally aggressive participants exhibited reduced VMPFC activity, which partially explained and suppressed their preferences for delayed aggression. Blunted VMPFC activity may thus be a neural mechanism that promotes reactive aggression towards provocateurs among dispositionally aggressive individuals. These findings demonstrate the utility of an intertemporal framework for investigating aggression and provide further evidence for the similar underlying neurobiology between aggression and other rewarding behaviors.     

Attribution of apparent arousal and proficiency of recovery from sympathetic activation affecting excitation transfer to aggressive behavior

In a pretest, subjects' proficiency to recover from sympathetic arousal induced by strenuous exercise was assessed. The results were used to determine conditions of high, intermediate, and low recovery proficiency (fitness). After an assessment of subjects' unprovoked aggressiveness, subjects were aggressively provoked. Within proficiency blocks, they were then given one of two treatments, (a) sitting followed by exercising (no decay) or (b) exercising followed by sitting (partial decay), and were there-after provided with an opportunity to retaliate against their tormentor. Under conditions of no decay, in which the high levels of arousal experienced were attributable to exertion, the provocation treatment failed to increase aggressiveness significantly, and there were no differences in aggressiveness in the various proficiency conditions in spite of differentiations in the magnitude of prevailing excitatory residues. Under partial decay, in the absence of cues linking arousal to exertion, the magnitude of residual arousal did affect aggressive behavior: In the conditions of intermediate and low recovery proficiency, aggressiveness increased significantly with provocation and was more pronounced than in the condition of high proficiency (best fitness); in the condition of low proficiency (least fitness) aggressiveness was higher than in the condition of intermediate proficiency, but not reliably so.     

Characterization of aggressive behavior and phenytoin response

Recent work has suggested that the success of pharmacological treatment for chronic aggressive behavior may depend, in part, on the subtype of aggressive behavior displayed (e.g. reactive, impulsive aggression vs. predatory, premeditated aggression). The present study examined the usefulness of characterizing aggressive behavior during a 16‐week double‐blind crossover study of phenytoin (PHT) treatment in 41 aggressive adult males. The Impulsive/Premeditated Aggression Scales (IPAS) were used to characterize aggressive behavior as predominantly impulsive or predominantly premeditated in nature. Analyses indicated that participants who did not respond to PHT treatment endorsed significantly more premeditated characteristics on the IPAS than those who responded to PHT treatment. Non‐responders also exhibited fewer aggressive outbursts during placebo treatment, suggesting a greater level of behavior control. Participants who did not complete the study were younger, endorsed significantly more premeditated aggression characteristics and reported more lifetime antisocial behaviors than those who completed the study. Taken together, these data emphasize several factors that may influence the success of pharmacological treatment in aggressive individuals, namely the importance of characterizing the predominant type of problem aggressive behavior. Aggr. Behav. 00:1–6, 2005. © 2005 Wiley‐Liss, Inc.     

Androgens and aggressive behavior in primates: A review

This review deals with possible central and peripheral effects of androgens upon primate aggressive behavior. One problem that clouds interpretation of experimental work is that measurements of dominance have often been employed, such as competition tests for food and water. Such measures often do not correlate with those obtained by quantifying aggressive interactions. It should be remembered that very few of the 188 primate species have been studied experimentally and that great behavioral and physiological diversity occurs within the order. Therefore, generalizations about the effects of androgens upon aggressive behavior in primates (including man) should be made with caution. Testosterone has an organizing influence upon the foetal brain of rhesus monkeys and may affect the development of neural mechanisms which govern aggression in males. More data are required on primates, however, since rhesus monkeys show some important differences from rodents as regards the effects of androgen upon sexual differentiation of the hypothalamus. In future, marmosets may provide a suitable model for such studies, because there is evidence that sexual differentiation of brain by androgen occurs postnatally in these monkeys. At puberty, male primates show a variety of behavioral changes and, during adulthood, males of seasonally breeding species may be more aggressive during the mating season, when testosterone levels are maximal. This does not indicate a causative relationship between testosterone and aggressive responses, because castration and androgen treatments have little effect upon aggression in prepubertal or adult males of several primate species. Androgens have pronounced effects on sexual responses in adult male monkeys, but their central effects upon aggression are much less important than among rodents. Elec trical stimulation of hypothalamic pathways has been employed to evoke aggressive behavior in marmosets and rhesus monkeys. In the rhesus, preliminary evidence indicates that such pathways show some sensitivity to androgens. In rodents it is known that these areas are richly supplied with monoaminergic neurons, which play an important role in aggressive behavior. There is little evidence on primates, however, and this remains a crucial topic for future research. Peripheral effects of androgens should also be considered. Many prosimians and New World monkeys use scent-marking behaviors and, in males, androgen-dependent chemical cues may be involved in sexual recognition and territorial behavior. This possibility awaits investigation. Finally, plasma testosterone levels may alter as a function of aggression itself; thus levels decrease if male rhesus monkeys are defeated by conspecifics. This might occur because neural events associated with giving (or receiving) aggression also influence pituitary function and hence alter gonadal testosterone secretion. Theoretically, it is possible that such changes in circulating testosterone might affect aggressive behavior via a feedback action on the brain, but the experimental evidence does not support such a view.