Aggression studies in laboratory animals have largely focused on natural species-specific forms of aggression that poorly reflect pathological types of aggression in humans. The primary goal of this dissertation was to identify and characterize a subtype of aggression in support for a congenital animal model of reactive/impulsive-aggression in humans. Experiments using novel second-by-second analyses to investigate for individual differences in aggression and impulsive choice showed detailed quantitative and qualitative differences, and identified a convergence of behaviors to one distinct impulsive-aggressive profile in high-attack frequency (HAF) hamsters. As aggression and impulsivity widely implicate the serotonin (5HT) system, and previous studies have similarly characterized the neural control of aggression in hamsters, it was hypothesized that impulsive-aggression in HAF individuals was associated to common neurobiology. While 5HT does play a role, immunocytochemical experiments and pharmacological manipulations showed a distinct neurobiological profile of decreased 5HT availability, increased densities of 5HT1A and 5HT3 receptor subtypes, and drastically differential and opposite phenotypic-dependent reactivity to 5HT3 receptor blockade. Moreover, the current studies also showed that while 5HT3 receptor activity has broad effects, attenuating all behavioral aspects of the impulsive-aggressive phenotype (i.e. aggression, repetitiveness, fragmentation, and impulsive choice), 5HT1A receptor activity seems to have more limited effects. Additional retrospective studies investigated developmental and etiological differences between the phenotypes. HAF adults were associated with low agonistic activity in early puberty and an early emergence of impulsivity-related characteristics. These data indicate a differential developmental trajectory of behavior and accelerated maturation, consisting of a lack of play fighting during early puberty. The HAF phenotype was additionally associated with paternal, but not maternal influence, suggesting male genetic contribution. Together, these data support a congenital animal model that better reflects reactive forms of aggression in humans through the behavioral, neurobiological, and developmental characterization of HAF hamsters described herein. These data have pre-clinical and clinical significance and can be applied to diagnostic and preventative measures, as they illustrate the importance of distinguishing predictions about extreme fringe populations from that of normal populations, point towards more specific pharmacological therapeutic applications, identify early predictive behaviors of impulsive-aggression, and suggest heritability. / text

The current study explored the nuanced associations between components of executive functioning (EF) and subtypes of aggression, using a latent variable approach. Participants were racially diverse undergraduate students who completed a self-report of reactive (RA) and proactive aggression (PA), and traditional neuropsychological tasks of EF. The appropriateness of using a nested bifactor model of EF was confirmed, and this bifactor model of EF was used to examine the specific associations between components of EF and RA and PA. Results revealed components of EF are differentially associated with RA and PA, such that impulsive, provoked aggression is associated with lower levels of goal-oriented inhibition and higher levels of flexibility, whereas planned, goal-oriented aggression is associated with higher levels of working memory. Findings from the current study underscore the importance of considering the multidimensional nature of EF as well as aggression when examining their associations with external constructs of interest.

Aggression has traditionally been subdivided into two correlated, but distinct, subtypes: reactive and instrumental. Reactive aggression (RA) is considered impulsive, emotionally driven behavior, whereas instrumental aggression (IA) is planned and incentive-motivated. This thesis examines the relationships between RA, IA, psychopathy, and antisocial personality disorder (APD) symptoms in male and female offenders recruited from a jail in north Texas. Contrary to predictions, psychopathic traits did not account for more variance in aggression than did APD symptoms. Impulsivity demonstrated slight incremental validity over psychopathy for RA, and to a lesser degree, IA. the continued utility of the reactive-instrumental distinction and implications for professional practice in relation to the current study are examined. Study limitations and directions for future research are discussed.

In the current study, we investigated the association between relational aggression and measures of delinquency and overt aggression in a sample of detained adolescent girls. We also tested the validity of the distinction between reactive and proactive subtypes of relational aggression by testing their independent associations with important emotional, behavioral, personality, social, and cognitive variables that have been studied in past research and found to be important for distinguishing between reactive and proactive overt aggression. Our sample consisted of 58 predominantly African-American (78%) adolescent girls recruited from three juvenile detention centers in the southeastern United States. Participants ranged in age from 12 to 18 (Mn = 14.98; SD = 1.30). Relational aggression was measured using both self-report and observation, while overt aggression, delinquency, and social-psychological variables were measured using self-report only. As predicted, both self-reported and observed relational aggression were associated with higher rates of self-reported delinquency. Self-reported relational aggression was also associated with self-reported overt aggression, while observed relational aggression was not. On a self-report rating scale, we found evidence for four subscales that were moderately correlated and had good internal consistency. These subscales corresponded to the four aggressive subtypes (i.e., reactive overt, reactive relational, proactive overt, proactive relational). Further, we found evidence for divergence between reactive and proactive relational aggression on emotional dysregulation, CU traits, and positive outcome expectations for aggression, supporting the hypothesis that these are important subtypes that could involve distinct developmental processes, similar to reactive and proactive subtypes of overt aggression. Finally, this study found that relational aggression accounted for unique variance in callous and unemotional (CU) traits among detained girls, even after controlling for levels of overt aggression. The current findings highlight the importance of assessing relational aggression in detained girls and could have implications for designing more successful interventions for girls in the juvenile justice system.

The purpose of the current study is to examine the association between self-esteem and the forms and functions of aggression. Research supports the existence of four aggressive subtypes (i.e., reactive overt, reactive relational, proactive overt, and proactive relational), and past research has found associations between aggression and self-esteem. However, past studies have not examined the relationships between all four subtypes of aggression and self-esteem together. 141 adolescents were recruited from the community with a mean age of 13.55. The sampled group was composed of 51% females and 52% Caucasians. Participants completed self-report questionnaires on self-esteem and aggression. The results provide support for an association between proactive aggression and self-esteem. Additionally, overt aggression was more associated with self-esteem than relational aggression. These findings will help fill the gap in literature on the forms and functions of aggression and will further define the relationship between aggression and self-esteem.

Previous research has demonstrated an association between violence exposure and aggression; however, research exploring the association between violence exposure and the forms and functions of aggression is scarce. The aim of this study was to explore the associations between trauma exposure with both reactive and proactive functions of aggression by examining two potential mediators (e.g., psychopathic traits and emotional dysregulation). Participants included 132 male juvenile offenders mandated to treatment in a residential facility (M = 16.78 years old; SD = 1.25). Results indicate emotional dysregulation partially mediated the association between trauma exposure and reactive aggression while controlling for proactive aggression. However, no evidence was found to support the hypothesis that psychopathic traits mediated the association between trauma exposure and proactive aggression. Results suggest trauma exposure is important in the development of reactive aggression. Thus, treatment approaches for aggressive youth should address issues of trauma exposure.

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While both social information processing and cortisol secretion in childhood aggression have generated a great deal of interest and research in the past few decades, these social-cognitive and physiological components of aggressive behavior have not been examined in the context of an integrative model. This lack of an integrative framework may underlie some of the inconsistencies that have plagued the literature in this area to date, especially with respect to hypothalamic-pituitary-adrenal (HPA) axis functioning in aggressive children. This investigation tested a mediational model of the relationship between social-information processing, cortisol secretion, and reactive and proactive aggression. Specifically, it was hypothesized that social-information processing variables would mediate the proposed relationship between reactive and proactive aggression and cortisol secretion. One hundred and twenty-six children between the ages of 13 and 18 were administered the Child Behavior Rating Form (CBR), the Home Interview with Child (HIC), the Response Decision and Social Goals Instrument (RDSGI), the Antisocial Processes Screening Device (APSD), the Buss-Durkee Hostility Inventory (BDHI), the Children's Depression Inventory (CDI), and the Revised Children's Manifest Anxiety Scale (RCMAS). Each child also contributed two samples of saliva for cortisol assay, and each child's teacher completed a teacher-version of the APSD and the CBR. Regression analyses revealed no significant associations between proactive or reactive aggression and cortisol secretion, or between any of the social-information processing variables and cortisol secretion. Predicted associations between proactive and reactive aggression and social-information processing variables were found. Overall, therefore, the mediational model was not supported. However, cortisol secretion was found to be associated with both anxiety and depression, and exploratory analyses revealed significant associations between cortisol secretion and Psychopathy as measured by the APSD. Taken together, the findings suggest that while the specific relationship proposed here among social-cognitive, psychophysiological, and behavioral variables was not found, an integrative model examining each of these components may be useful in further investigations of the complex phenomenon of childhood aggression. / Ph. D.

Doctor of Philosophy / School of Family Studies and Human Services / Amber Vennum / The literature suggests that aggressive behaviors occur in response to provocation (i.e., reactive aggression) or to achieve a goal (i.e., instrumental aggression). Relational aggression –when an individual harms another’s interpersonal relationships – has been studied from the reactive and instrumental framework in peer-directed contexts, usually with children. However, relational aggression in romantic relationships is yet to be studied from this framework. This dissertation includes a series of studies investigating whether two specific relationally aggressive behaviors found in romantic relationships (i.e., social sabotage and love withdrawal) are 1) motivated by instrumental and reactive aggression, 2) associated with differential characteristics, and 3) predictive of negative outcomes. The Romantic Relational Aggression Motivation (RRAM) scale, which included social sabotage and love withdrawal items with both instrumental and reactive motivations, was created to explore the above research questions. During Study 1a, an exploratory factor analysis using a sample of 170 emerging adults tested the factor structure of the RRAM. This resulted in love withdrawal, but not social sabotage, factoring into instrumental and reactive subscales. Using the same sample at a later wave, Study 1b refined the RRAM from Study 1a; the findings confirmed the results of Study 1a. In Study 2, using a sample of 118 emerging adults, the factor structure found in Study 1b was corroborated using a confirmatory factor analysis. Study 2 found that social sabotage was more closely related to instrumental than reactive love withdrawal. Reactive and instrumental love withdrawal were clearly differentiated based on their associations with constructs that were emotionally driven (e.g. neuroticism and hostile attribution bias) but not by their associations with constructs that dealt with power (e.g. self-relationship power and trait dominance). None of the romantic relational aggression scales were predictive of the negative outcomes in the study, possibly due to the small sample size (85 emerging adults) in the longitudinal portion of Study 2. As instrumental and reactive love withdrawal were associated with different constructs and combining the two together may cause substantial differences to be lost, the RRAM may be a useful tool for researchers of romantic relational aggression.

This study investigated the factorial validity, stability, and social, behavioral and emotional correlates of several different roles that students can play in the context of bullying. Data were collected from students at two time points across two school years, April and May of 2006 (n=284) and again in November and December of 2006 (n=185). A confirmatory factor analysis provided evidence for the validity of 4 participant roles (i.e. bully, reinforcer, assistant, and defender). However, further analysis revealed that there was a strong degree of intercorrelation between the three bully factors (i.e., bully, reinforcer, and assistant). Analyses found that participant roles are fairly stable across school years and that the greater the percentage of same raters across the time points, the greater the stability. All of the bullying roles (i.e., bully, reinforcer, and assistant) were significantly related to callous unemotional traits, emotional dysregulation, positive expectations for aggression, conduct problems, reactive relational aggression, proactive relational aggression, reactive overt aggression, and proactive overt aggression, but these relationships were stronger in boys. It was also found that the defender role was associated with less aggression and more prosocial behavior. These associations were stronger in girls. Finally, a linear regression analysis of the interaction between participant roles and victimization revealed that at T1, the association between bullying roles and aggression was moderated by victimization. Specifically, the association was stronger in those low on victimization. At T2, the association between defending and lower aggression and greater prosocial behavior was stronger in those low in victimization.