Background: While the physical and mental health advantages of regular physical activity are evident, 68% of adult Canadians are not meeting PA guidelines. Over the last thirty years, exercise behaviour has been mostly studied under the guise of the social cognitive framework, but emerging findings have shown identity to demonstrate predictive validity with physical activity independent of social cognitions. Exercise identity has been associated with increased frequency, duration, and intensity of exercise behaviour. Despite the bivariate correlation between identity and PA, the literature currently lacks longitudinal research to enhance the understanding of identity formation in new exercisers. Objective: The purpose of this study was to understand changes in identity among new exercisers based on the Physical Activity Self-Definition model and investigate whether exercise identity can predict exercise behaviour variations over nine weeks. Methods: Participants for this study were healthy adults (18-65) who were recruited from local gyms and recreation centres in Victoria, BC. The inclusion criteria were that participants must be new exercisers (new exercisers are those who just decided to exercise regularly or started exercising for less than 2 weeks, before baseline measurement) who were not meeting the Canadian Physical Activity guidelines upon recruitment. The study used a prospective, observational design with four measurement periods across nine weeks. Demographics were collected and exercise identity, affective attitude, commitment, capability and exercise behaviour were measured using questionnaires. The exercise Identity questionnaire was administered at 1 week, 3 weeks, 6 weeks and 9 weeks. Data analysis and longitudinal models used HLM and descriptive were generated with SPSS. Results: Affective attitude and commitment had significant correlations with identity, and identity had a significant correlation with exercise behaviour across all measurement times. Affective attitude, however, was the only significant predictor of exercise identity change over time. Capability was not associated with exercise identity. Furthermore, identity did not predict change in exercise over time. Discussion: This study provided insight into some of the factors that influence shifting exercise identity of new exercisers by testing the physical activity self-definition model (Kendzierski & Morganstein, 2009a) with longitudinal modelling. Based on the present results, it is recommended that health promoters focus on designing enjoyable programs for their novice clients, and provide a positive affective attitude toward exercising during each session. Although, exercise behaviours of the participants improved significantly during the course of this study, exercise identity was not able to predict the variation in exercise behaviour over 9 weeks. Overall, exercise identity formation can be a time-consuming process in adults, however, engaging in identity-related behaviours that are enjoyable can accelerate this process. / Graduate

This is a longitudinal cross-lagged panel model examining the bi-directional association of attachment styles and relationship quality in a community sample of 355 married couples, with at least one child between 10-14 years of age at the beginning of the study and 17-21 years of age at the end of the study. An Actor-Partner Interdependence Model (APIM), was used to test for actor and partner effects, thereby accounting for the non-independent nature of the data. Two separate APIM models were tested with Male Attachment predicting Female Relationship Quality and Female Attachment predicting Male Relationship Quality. Results indicate that own attachment was a stronger predictor of partner relationship quality over time than was own relationship quality to partner attachment; although male relationship quality did predict female attachment from T1 to T3, it was not significant at all other time points. Clinical implications and future research are discussed.

Introduction: Executive functions (EFs) are a set of inter-related neurocognitive abilities, recruited for top-down, conscious control of thoughts, actions and emotions. EFs develop rapidly during the preschool period (age 3 to 6 years), which is the same time, during which the symptoms of Attention Deficit/Hyperactivity Disorder (ADHD), namely hyperactivity, impulsivity, and inattention, become evident. Furthermore, hyperactivity, inattention, and the EFs contribute to academic performance once children begin formal schooling. To clarify the interplay of these processes, this dissertation conducted 3 studies that used a longitudinal design (4 time-points) to investigate the development of EFs from age 3 to 6 years, the relations between EFs and hyperactivity across this same period of time, and their relative contributions to inattention and academic performance at 6 years of age. Study One: Children’s performance on EF tasks was examined across 4 time points, beginning at 36-48 months of age. Results indicated significant between-child variability for all EF component processes at 3 years of age, significant growth over time, and preliminary support for the theory that, among EFs, working memory may develop first. Furthermore, EF performance at 3 years of age made significant contributions to performance on complex tasks of problem solving and planning at 6 years of age. Study Two: The aim of study two was to evaluate the relations between EF, hyperactivity, and inattention. Results indicated significant between-child variability in EF task performance, with a decrease in variability from age 3 to 4.5 years. Hyperactivity at age 3 years reliably predicted hyperactivity at 6 years of age for females, who also had lower hyperactivity scores. In contrast, for males, child EF performance and parent-report of EF at age 3 years were the best predictors of hyperactivity at 6 years of age. Study Three: The aim of study three was to expand upon the relations between EF, hyperactivity, and inattention by evaluating their relative contributions to academic performance. There were limited relations between academic performance, hyperactivity, and inattention. However, EF performance at 3 years of age predicted age 6 reading and math, whereas parent-report EF only predicted reading. Furthermore, hyperactivity at 4.5 years of age moderated the relation between age 3 performance EF and age 6 academic performance, with this relation becoming stronger as hyperactivity increased. Conclusion: Together, these studies make several notable contributions to the field: (a) that initial EF abilities at 3 years of age are highly variable between children, but improve consistently over time, (b) that the relations between hyperactivity and EF appear to be different for males and females (or higher/lower levels of hyperactivity), and (c) that even in a community sample, hyperactivity moderates the EF-academic performance relation. These findings contribute to the early identification of hyperactivity and interindividual differences in EF abilities, in very young pre-schoolers, who may go on to have more difficulty in a formal schooling setting. / Graduate / 2023-08-09

Objectives The development of aggression from childhood to adulthood is well-researched, and extant work has identified a large number of developmental risk factors within the individual, family, and social domains. Among them, poor parenting, including harsh practices like corporal punishment, have repeatedly been found to predict adolescent behavioural problems, that may then negatively affect adult behaviours such as violence and offending. An area of research that is becoming increasingly important is one that seeks to identify the reasons why some people do not become aggressive, even when they have been exposed to well established risk factors. What is it that has protected them from becoming aggressive later in life? The current study examined whether self-control and having a positive teacher-child relationship acted as protective factors between corporal punishment and adolescent aggression. Methods An autoregressive cross-lagged panel model was used to examine self-control and teacher-child relationships as both direct and interactive protective factors between corporal punishment and adolescent aggression. Teacher and self-reported data was used from three waves (waves 4-6) of the Zurich Project on the Social Development of Children and Youths (Z-proso), a prospective longitudinal study of adolescents in Switzerland. Results The results show that both self-control and having a positive teacher-child relationship were direct protective factors against concurrent aggression. However, the interactive protective effect of these factors differed depending on the stage of adolescence and level of exposure to risk. Furthermore, differences were found when considering males and females separately.

L'adolescence est une période importante de la vie caractérisée par des changements majeurs psychologiques et comportementaux qui ont été théoriquement et empiriquement reliés aux changements dans l'environnement social. Les différents milieux de vie des adolescents leur offrent un «terrain de jeu» pour explorer, tester, développer et intégrer des compétences cruciales nécessaires à l’interaction sociale, comme les comportements prosociaux. À l'adolescence, les relations entre pairs deviennent plus saillantes et plus importantes qu’a toute autre période de la vie. Au-delà des contextes familial et scolaire, les adolescents consacrent beaucoup de temps à différentes activités avec des pairs. Parmi ces activités, nous nous sommes focalisées sur la participation à des activités extrascolaires qui sont considérés comme un milieu de vie important dans le développement positif des adolescents.Le premier objectif de cette thèse était de mieux comprendre le rôle des milieux de vie dans l'empathie et les comportements prosociaux à l'adolescence. Nous avons développé et examiné un modèle théorique intégratif des relations entre les caractéristiques positives et négatives des milieux de vie (famille, classe et groupe de pairs extrascolaire), la perception par les adolescents des comportements prosociaux dans chacun de ces milieux de vie et de leurs propres comportements prosociaux, en tenant compte du rôle médiateur de l'empathie.Le deuxième objectif était de mieux comprendre les relations longitudinales bidirectionnelles entre l'empathie et les comportements prosociaux à l'adolescence, en mettant un accent particulier sur les processus internes à la personne.Enfin, le troisième objectif était de mieux comprendre les trajectoires de développement de l’empathie et des comportements prosociaux des adolescents en prenant en compte leur participation à des activités extrascolaires.Nous avons conduit un recueil de données longitudinales à 3 vagues avec un intervalle d’un an. Les adolescents ont répondu à des questions concernant les caractéristiques des trois milieux de vie, les comportements prosociaux dans chacun d’eux, leur participation extrascolaire, ainsi que leur empathie et leurs comportements prosociaux.Nos résultats suggèrent que les caractéristiques des groupes de pairs extrascolaires et de la famille (en particulier les plus négatives) et la perception de leurs comportements prosociaux jouent un rôle majeur dans les comportements prosociaux des adolescents via l'empathie à l'adolescence. Ils montrent également que l’empathie est un prédicteur des comportements prosociaux et que les trajectoires de développement de l’empathie et des comportements prosociaux à l’adolescence sont différentes chez ceux qui participent à des activités extrascolaires où on n’observe pas de trajectoire développementale décroissante comparé à ceux qui n’y participent pas.En utilisant une seule approche théorique dans trois milieux de vie différents, nous avons pu saisir les caractéristiques communes et spécifiques de la famille, du groupe-classe et des groupes de pairs extrascolaires, qui ont une influence sur les comportements prosociaux des adolescents. De plus, prendre en compte les différences entre les individus et les processus de développement intra-individuels, l’hétérogénéité des trajectoires développementales concernant l’empathie et les comportements prosociaux à l’adolescence est essentiel pour saisir l’interaction complexe entre la famille, la classe, le groupe de pairs extrascolaire, l’empathie et le développement prosocial / Adolescence is a significant period in life that is characterized by major changes that have been theoretically and empirically related to changes in social environments. Adolescents different living environments offer the “playground” to explore, to test, to develop and integrate social cues and crucial abilities that are necessary for social interaction, such as prosocial behaviours. During adolescence, peer relationships become more salient and prominent than in any other period in life. Away from the family and the school context, adolescents spend a large amount of time in activities with peers. Among these activities we focused on extracurricular activity participation, that have been conceptualised as an important developmental context of adolescents’ livesThe first aim of this dissertation was to provide more insight into the role of living environments in relation to empathy and prosocial behaviours in adolescence. We developed and examined an integrative model of the relations between positive and negative living environment features, adolescents’ perceptions of prosocial behaviours across the three contexts (family, class and extracurricular peer group) and their own prosocial behaviours, taking into account the potential mediating role of empathy.The second aim was to provide more insight into the bidirectional longitudinal relations between empathy and prosocial behaviours during adolescence, with a special focus on the within-person processes.Finally, the third aim of this dissertation was to provide more insight into adolescents’ prosocial behaviours and empathy developmental trajectories considering extracurricular activity participation.This dissertation used data from a 3-Wave longitudinal study gathered during the three years of the PhD with data collected at one-year intervals. Adolescents answered questions concerning the features of the living environment, their peer group’s and parents’ prosocial behaviours, extracurricular activity participation, and their own empathy and prosocial behaviour.Our findings suggest that extracurricular peer group features, family features (particularly the negative ones) and extracurricular peer group and parents’ prosocial behaviours play a major role in adolescents’ prosocial behaviours via empathy in adolescence.Therefore, we found that empathy is a driver of prosocial behaviours. We also identified that latent class growth for empathy and prosocial behaviour were different in the extracurricular activity group for which there was no downward trend trajectory over time compared to the non-extracurricular group.Using one approach across three living environments allowed us to capture the common and specific features of the family, school and extracurricular peer group contexts that influence adolescents’ prosocial behaviours. Furthermore, our results highlighted the need to acknowledge the between person differences and the within-person processes of development. Moreover, it is important to consider the heterogeneity of developmental trajectories concerning empathy and prosocial behaviours during adolescence if we want to capture the complex interplay between family, class, extracurricular peer group, empathy and prosocial development.

<p>The aims of the present thesis were to study: 1. reported eating attitudes, dieting behavior and body image over a 1-year period among preadolescent girls (age 7-8); 2. differences in eating attitudes and coping between groups of teenage girls differing in dieting frequency, and to assess changes with increasing age (age 13-17); and 3. to what extent eating attitudes, self-esteem and coping predict disturbed eating attitudes. A final aim was to explore differences in the reported wish to be thinner, dieting, and eating attitudes between two age-matched cohorts of girls in 1995 and 1999 (7-15 years).</p><p>The project is designed as a longitudinal prospective study, spanning seven years. 1300 girls in the ages (1995) 7, 9, 11, 13 and 15 years have been assessed annually for three consecutive years (1995-1997) (Main Cohort). An additional group matched for age with the original group was recruited in 1999 (Societal Cohort). The results suggest that dieting and the wish to be thinner starts as early as at 7 years of age, and that repeated dieting attempts correlate with disturbed eating attitudes. A marked increase of the wish to be thinner was evident in the 10- to 14-year age range, and significant increases in dieting attempts occurred mainly between ages 9 and 13. There were no differences between 1995 (Main Cohort) and 1999 (Societal Cohort) (except among 7 and 11-year-olds) with regard to dieting, the wish to be thinner and disturbed eating attitudes. Eating patterns and attitudes were shown to be the strongest predictors of disturbed eating attitudes three years later. Assessment of dieting, the wish to be thinner and eating attitudes is suggested BS a component in school health care.</p>

The aims of the present thesis were to study: 1. reported eating attitudes, dieting behavior and body image over a 1-year period among preadolescent girls (age 7-8); 2. differences in eating attitudes and coping between groups of teenage girls differing in dieting frequency, and to assess changes with increasing age (age 13-17); and 3. to what extent eating attitudes, self-esteem and coping predict disturbed eating attitudes. A final aim was to explore differences in the reported wish to be thinner, dieting, and eating attitudes between two age-matched cohorts of girls in 1995 and 1999 (7-15 years). The project is designed as a longitudinal prospective study, spanning seven years. 1300 girls in the ages (1995) 7, 9, 11, 13 and 15 years have been assessed annually for three consecutive years (1995-1997) (Main Cohort). An additional group matched for age with the original group was recruited in 1999 (Societal Cohort). The results suggest that dieting and the wish to be thinner starts as early as at 7 years of age, and that repeated dieting attempts correlate with disturbed eating attitudes. A marked increase of the wish to be thinner was evident in the 10- to 14-year age range, and significant increases in dieting attempts occurred mainly between ages 9 and 13. There were no differences between 1995 (Main Cohort) and 1999 (Societal Cohort) (except among 7 and 11-year-olds) with regard to dieting, the wish to be thinner and disturbed eating attitudes. Eating patterns and attitudes were shown to be the strongest predictors of disturbed eating attitudes three years later. Assessment of dieting, the wish to be thinner and eating attitudes is suggested BS a component in school health care.

Prior research suggests aggressive cancer treatments contribute to cognitive impairments in children diagnosed with pediatric brain tumors. The literature also suggests that younger age at diagnosis (AAD) and treatment may result in disrupted cognitive trajectories due to limited brain plasticity. In line with this research, we hypothesized an interaction between radiation therapy (RT) and young AAD of brain tumors, where young AAD and RT results in lower standard scores on the WRAT-R Reading Comprehension Subtest. Analyses included archival data; the sample consists of 134 children diagnosed with pediatric brain tumors with multiple assessments resulting in 487 cases for analysis. Participants were diagnosed with mixed tumor types and locations. A two level multilevel model was used to analyze reading trajectories while taking into account AAD, time since diagnosis, socioeconomic status (SES), and RT. Results detected a positive interaction between AAD and RT (γ =2.08, p=.02). For participants with RT, younger AAD was associated with lower reading scores, whereas AAD had no effect for participants without RT. Results also detected a negative interaction between radiation and time (γ =-2.29, p=.00) indicating that children treated with RT have reading scores that decrease over time. These data suggested that children diagnosed with pediatric brain tumors treated with RT are at higher risk of reading impairment as reflected in their reading scores.

Prior research suggests aggressive cancer treatments contribute to cognitive impairments in children diagnosed with pediatric brain tumors. The literature also suggests that younger age at diagnosis (AAD) and treatment may result in disrupted cognitive trajectories due to limited brain plasticity. In line with this research, we hypothesized an interaction between radiation therapy (RT) and young AAD of brain tumors, where young AAD and RT results in lower standard scores on the WRAT-R Reading Comprehension Subtest. Analyses included archival data; the sample consists of 134 children diagnosed with pediatric brain tumors with multiple assessments resulting in 487 cases for analysis. Participants were diagnosed with mixed tumor types and locations. A two level multilevel model was used to analyze reading trajectories while taking into account AAD, time since diagnosis, socioeconomic status (SES), and RT. Results detected a positive interaction between AAD and RT (γ =2.08, p=.02). For participants with RT, younger AAD was associated with lower reading scores, whereas AAD had no effect for participants without RT. Results also detected a negative interaction between radiation and time (γ =-2.29, p=.00) indicating that children treated with RT have reading scores that decrease over time. These data suggested that children diagnosed with pediatric brain tumors treated with RT are at higher risk of reading impairment as reflected in their reading scores.

In research, it is typical to analyse and discuss the utility of education in economic terms—specifically the market value of a particular degree or the financial returns associated with additional years in higher education. However, education may also generate outcomes that belong to the non-market sphere, such as open-mindedness, societal cohesion, community involvement, better health, and gender equality; yet these outcomes have received little scholarly attention. The main objective of this thesis, therefore, is to investigate the relationship between education and four non-market outcomes: agency, voice, health behaviour and psychological distress. By utilizing two longitudinal data sets, the Swedish Survey of Living Conditions and the Northern Swedish Cohort, it is possible to assess the long-term effects of education on each of these four non-market outcomes. Results clearly demonstrate that education has a critical impact on each of the outcomes of interest. Having a higher education—and in particular a university degree–enhances individuals’ agency and voice, reduces psychological distress, and improves individuals’ health behaviour. Further, results show that different academic subjects generate field-specific resources. In contrast to a market perspective, where the value of the specific field of study is assessed only in economic terms, results indicate that fields that are commonly viewed as having low market value may actually yield non-economic rewards that benefit individuals in critically important ways. Analyses also show that individual and social factors shape the extent to which education leads to positive outcomes. In terms of agency and voice, results indicate that education can compensate for social differences. Among those with a working class background, earning a university degree contributes to increasing levels of agency and voice, while no significant effects of education exist for those with a white-collar background. Results also demonstrate that the impact of education on psychological well-being differs for men and women. For men, labour market resources (i.e., being employed) was important for reducing psychological distress, while for women social resources (i.e., having a partner) was more important. Due to its use of high quality, longitudinal data, this thesis makes a significant contribution to the scholarly literature and to what we know about the impact of education attainment. A limitation of cross-sectional analyses is that it is difficult to separate causal effects from selection effects. By adopting a longitudinal approach, it is possible to control for earlier (baseline) circumstances and therefore assess the causal impact of education on individual outcomes. This strategy yields robust results that make clear the long-term effects of educational attainment on individuals.