The current study was designed to explore profiles of reactive and proactive aggression in two distinct juvenile offender populations, in a group of juvenile offenders who have been adjudicated for illegal sexual behavior (n = 138) and in a group of juvenile offenders adjudicated for general delinquent behavior (n = 243). This is the first study of its kind to investigate profiles of aggression in a population of juveniles adjudicated for illegal sexual behavior. Preliminary profile analyses indicated that the two juvenile offender populations had similar profiles of aggression overall. Two step cluster analysis results were generally consistent with previous research (Crapanzano, Frick, & Terranova, 2010; Marsee et al., 2014) with 3 groups emerging for both overt and relational aggression: a combined group high on both reactive and proactive aggression, a group high in reactive aggression alone, and a low overall group. Post hoc comparisons of the clusters revealed that the high combined group consistently demonstrated higher reports of emotional and behavioral dysfunction supporting the hypothesis that the presence of proactive aggression serves more as an indicator of severity rather than as representing a qualitatively distinct group in and of itself. Policy implications regarding sex offender registration and notification laws extended to juveniles are discussed.

Family-of-origin aggression (FOOA) is an established risk factor for adult partner aggression. The research presented in this thesis tested a model proposing that (FOOA) is mediated through attachment and attributions to influence male and female partner aggression and withdrawal in early stage couple relationships. Study 1 tested the influence of FOOA, attachment, and attributions on partner aggression in a sample of 73 newlywed couples. FOOA was associated with male-to-female aggression, but not female-to-male aggression. Therefore the hypothesis that the influence of FOOA on partner aggression was mediated through attachment and attributions was tested only for men. Attachment was significantly associated with attributions, but there was no association between FOOA and attachment or between attributions and male partner aggression. Study 2 tested the influence of FOOA, attachment, and attributions on partner aggression and withdrawal in a sample of 101 dating couples. Structural equation model analyses found different results for men and women. For male partner aggression, the influence of FOOA was partially mediated through attachment and attributions. For male withdrawal, the influence of FOOA on withdrawal was fully mediated through attachment and attributions. The association between FOOA and withdrawal was also mediated through attachment independent of attributions, and through attributions independent of attachment. For female partner aggression and female withdrawal, the predicted associations were found for the attachment anxiety models but not for the attachment avoidance models. The current findings suggest that attachment and attributions should be intervention targets for improving relationship outcomes. The gender differences in model fit emphasise the importance of investigating risk factors for partner aggression and withdrawal separately for men and women.

Social aggression has been widely studied; however, findings have been inconsistent leading to confusion within the current literature. Previous research has linked social aggression to negative outcomes; including poor peer relations, internalizing symptoms, and low levels of empathy; as well as positive attributes, including prosocial behaviors, high social status, and social intelligence. This meta-analysis examined the relationship between social aggression and various correlates, both positive and negative, as well as how age and gender moderate these relationships. With 896 correlations derived from 108 studies (of a total of 107 published articles), the results using the random-effects model for computing overall effect sizes indicated that social aggression is related with maladaptive correlates, such as externalization (r= 0.46), internalization (r = 0.16), negative individual traits (r = 0.32), as well as negative peer relations (r = 0.28). However, findings also suggest that social aggression is associated with popularity (r = 0.22) and social skillfulness (r = 0.16). Implications, limitations, and future directions are discussed.

A large body of research exists relative to male aggression. Studies over the past 30 years, especially as related to male-to-female intimacy violence in a domestic context, have contributed greatly to a better understanding of aggressive male behavior. However, it is suggested that a more balanced approach to research on aggression should include studies related to female aggression. A search of the current literature indicates that this process has begun; however, studies tend to report a different dynamic at work in aggressive women versus aggressive men. It appears that overall, female aggression more than male aggression, has a stronger relational component. It is the case that females can be aggressive and place substantial importance on the relationships in their lives. Attachment theory addresses the salient issue of relationships and is such a broad and complete theory that it incorporates aggressive behaviors as well. Therefore, this study seeks to expand the research related to attachment styles and associated behaviors, in particular as they pertain to the influences upon female aggressive behavior. A study of the relationship between the independent variables of gender, psychopathology/personality, and attachment style and the dependent variable of aggression was conducted. It was hypothesized that attachment style would be a better predictor of female aggression as compared to psychopathology. Additionally, it was hypothesized that psychopathology would be a better predictor of male aggression as compared to attachment style. Significant results were obtained suggesting that attachment is a better predictor of female aggression than psychopathology, with a non-significant observation indicating the reverse being true of males. Specific gender differences related to aggression and violent behavior are presented. Current trends applicable to theories of aggression are discussed, as well as suggestions for future research.

This study examined a measure of children's memory for information from a story about a hypothetical mother and child, the Story Task, as a potential tool to delineate subtypes of aggressive children based on the pattern of information processing revealed through their Story Task performance. The Story Task scores of 263 second and third grade aggressive children were subjected to a cluster analytic procedure. Although four apparently distinct subgroups emerged from the cluster analysis (negative recall, low recall, defensive processing, and positive projection), validation analyses of these clusters against external variables failed to reveal significant group differences. Potential exaplanations for the failure to find meaningful subgroups of aggressive children and general limitations of the study are discussed.

This thesis will focus on the use of agonistic behaviour in both direct and indirect competition in two arboreal species: the eastern chipmunk (Tamias striatus) and Cyphoderris monstrosa, a primitive orthopteran insect. Chipmunks are an example of indirect competitors as they are competing for finite resources for dealing with abiotic stresses to ensure their survival. Chapter 2 of this project investigates the behavioural time budget for above ground activity at a time of critical importance for overwinter survival. The chipmunks in this study displayed a focus of their time budget on eating and collecting food in preparation of winter survival while they were above ground. Chapter 3 of this research project studies the physiological differences between males of Cyphoderris monstrosa which engage in aggressive territorial contests. The data suggest that metabolic scope is correlated with RHP. Males’ ability to mobilize energy reserves may be an important factor in contest outcomes.

Background: Antisocial behaviours in adolescents are costly in social and financial terms. These behaviours are heritable and genetic variants may be contributing factors. The purpose of this study was to determine whether genetic variants regulating the oxytocin-vasopressin (OXT-AVP) system were associated with aggressive behaviours. Methods: A sample of children displaying extreme, persistent and pervasive aggressive behaviours was first compared to adult controls (160 cases-160 controls) and then to child controls (182 cases-182 controls). We also tested for interactions between oxytocin receptor (OXTR) single nucleotide polymorphisms (SNPs) and serotoninergic polymorphism, 5-HTTLPR. Results: Using adult controls, OXTR SNPs rs6770632 and rs1042778 were associated with aggressive behaviours in females and males, respectively. However, using child controls revealed significant effects of AVPR1A rs11174811 in females; OXTR rs237898, rs237902 and AVP rs3761249 in males. There were no significant interactions between 5-HTTLPR and OXTR SNPs to predict aggression. Conclusion: OXT-AVP SNPs may be associated with aggressive behaviours.

This thesis will focus on the use of agonistic behaviour in both direct and indirect competition in two arboreal species: the eastern chipmunk (Tamias striatus) and Cyphoderris monstrosa, a primitive orthopteran insect. Chipmunks are an example of indirect competitors as they are competing for finite resources for dealing with abiotic stresses to ensure their survival. Chapter 2 of this project investigates the behavioural time budget for above ground activity at a time of critical importance for overwinter survival. The chipmunks in this study displayed a focus of their time budget on eating and collecting food in preparation of winter survival while they were above ground. Chapter 3 of this research project studies the physiological differences between males of Cyphoderris monstrosa which engage in aggressive territorial contests. The data suggest that metabolic scope is correlated with RHP. Males’ ability to mobilize energy reserves may be an important factor in contest outcomes.

Background: Antisocial behaviours in adolescents are costly in social and financial terms. These behaviours are heritable and genetic variants may be contributing factors. The purpose of this study was to determine whether genetic variants regulating the oxytocin-vasopressin (OXT-AVP) system were associated with aggressive behaviours. Methods: A sample of children displaying extreme, persistent and pervasive aggressive behaviours was first compared to adult controls (160 cases-160 controls) and then to child controls (182 cases-182 controls). We also tested for interactions between oxytocin receptor (OXTR) single nucleotide polymorphisms (SNPs) and serotoninergic polymorphism, 5-HTTLPR. Results: Using adult controls, OXTR SNPs rs6770632 and rs1042778 were associated with aggressive behaviours in females and males, respectively. However, using child controls revealed significant effects of AVPR1A rs11174811 in females; OXTR rs237898, rs237902 and AVP rs3761249 in males. There were no significant interactions between 5-HTTLPR and OXTR SNPs to predict aggression. Conclusion: OXT-AVP SNPs may be associated with aggressive behaviours.

This study examined a measure of children's memory for information from a story about a hypothetical mother and child, the Story Task, as a potential tool to delineate subtypes of aggressive children based on the pattern of information processing revealed through their Story Task performance. The Story Task scores of 263 second and third grade aggressive children were subjected to a cluster analytic procedure. Although four apparently distinct subgroups emerged from the cluster analysis (negative recall, low recall, defensive processing, and positive projection), validation analyses of these clusters against external variables failed to reveal significant group differences. Potential exaplanations for the failure to find meaningful subgroups of aggressive children and general limitations of the study are discussed.