Research pertaining to personality traits has largely focused on broad dimensions that define personality configurations, rather than on specific actions and behaviours that people engage in every day. While trait theorists hold the belief that individuals' personality traits predict their behaviours, there is no thorough conceptualization of behavioural manifestations of personality traits in the existing literature. The first goal of the present dissertation was therefore to conceptualize a model of behavioural manifestations of the Five Factor Model (FFM) traits. To achieve this goal, in the first article, a taxonomy of behavioural expressions of FFM traits was operationalized through the development of an instrument: the Behavioural Expressions of Traits Inventory (BETI). Results from Study 1 (N = 454) and Study 2 (N = 297) validated the proposed taxonomy by means of both exploratory and confirmatory factor analyses. The final version of the BETI comprised 30 items (6 items/subscale) that presented a clean factor structure. Concurrent validity results revealed that the taxonomy of behavioural expressions could be distinguished from FFM traits. The BETI also displayed good construct validity, satisfactory internal consistency values of all subscales, and no issues with social desirability. The second goal of this dissertation was to use this conceptualization of behavioural expressions of traits advantageously to examine an important fundamental topic: the processes at play in the associations between FFM personality traits and motivation through the lens of Self-Determination Theory (SDT). Results from emerging studies consistently revealed positive associations between beneficial FFM traits (openness to experience, conscientiousness, extraversion, and agreeableness) and autonomous motivation. Conversely, negative associations were obtained for neuroticism, a detrimental trait. The second article of this dissertation aimed to further our understanding of the associations between FFM traits and autonomous motivation by examining two potential mediators of this relationship: behavioural expressions of FFM traits and basic psychological need (BPN) satisfaction, a well-known antecedent of autonomous motivation. Two motivation domains central to the lives of undergraduate students were examined: academics and friendship. In Study 3 (N=635), undergraduate students completed online questionnaires. Structural equation modelling revealed a series of direct and indirect effects, as evaluated by Sobel's test of indirect effects: (1) FFM personality traits were positively associated with their corresponding behavioural expressions; (2) behavioural expressions of beneficial personality traits (openness to experience, conscientiousness, extraversion, and agreeableness) were positively associated with BPN satisfaction (autonomy, competence, and relatedness), while neuroticism was negatively associated with BPN satisfaction; (3) BPN satisfaction was positively associated with (a) autonomous academic motivation and (b) autonomous friendship motivation; (4) behavioural expressions of personality traits mediated the relationships between their corresponding trait and BPN satisfaction; (5) BPN satisfaction mediated the relationships between behavioural expressions of personality traits and (a) autonomous academic, and (b) friendship motivation and (6) behavioural expressions of personality traits and BPN satisfaction acted as sequential mediators of the associations between personality traits and (a) autonomous academic, and (b) friendship motivation. The sequential action of behavioural expressions of traits and BPN satisfaction as processes that explain the relationship between FFM personality dimensions and autonomous motivation is a novel idea that was put to a successful empirical test herein. Taken together, this research contributes to further our understanding of the intricacies involved in the joint study of the FFM model of personality traits and motivation as conceived by SDT.

Research question: How does hybrid work, regulated and unregulated, influence the intrinsic motivation of employees within knowledge-intensive organizations in Sweden? Purpose: The purpose of this paper is to explore employees experiences and perceptions of intrinsic workplace motivation with implemented hybrid work arrangements. Additionally, it seeks to compare two groups of workers: with mandatory work regulations and without.  Method: The thesis was formed by a qualitative research method where the empirical data was collected through semi-structured interviews with knowledge-intensive employees from different companies. This paper also discusses the prevalent theoretical frameworks in motivation. Conclusion: In both sample groups, fulfillment of autonomy as a psychological need is a prerequisite for relatedness and self-perceived competence. Relatedness is better met in the group with mandatory days at the office, whilst in the unregulated group this need was not fully satisfied. No major differences between the groups were noted in terms of self-perceived competence. Both groups expressed satisfaction of this need, and there was no strong indication saying it was influenced by hybrid work arrangements. Overall, regulated hybrid work settings were found to have a positive influence on intrinsic motivation.

Spending your time „nurturing what is right‟ enables people to grow and negotiate the problems of life which is more than only fixing what is wrong. The World Health Organisation also defined well-being as more than not ill-being. Flourishing is an optimal state of well-being. The question is, „what is it that flourishers do different from non-flourishers?‟ Pharmacy students prepare themselves for a profession which is being bombarded with change; they are the pharmacists of tomorrow. Among them some students flourish and the others do not. This study aimed to look at possible pathways to flourishing that flourishers utilise. In this way the study addressed several gaps in the knowledge regarding flourishing: 1) The prevalence of flourishing among pharmacy students, 2) The role of demands and resources in flourishing of students, 3) The role of antecedent factors of basic psychological need satisfaction on the basic psychological need satisfaction of students and therefore in their flourishing, and 4) The use of positive affect regulation (an internal strategy) as a pathway to flourishing. A cross-sectional design was utilised. The study population was all the enrolled pharmacy students at the North West University during 2014. A convenience sample of 779 students participated. The measuring battery consisted of the Mental Health Continuum-Short Form (MHC-SF; Keyes, 2009), the Emotional Regulation Profile-Revised (ERP-R; Nelis, Quoidbach, Hansenne, & Mikolajczak, 2011), the Balanced Measure of Psychological Needs (BMPN; Sheldon & Hilpert, 2012), statements about the antecedents of basic psychological need satisfaction and statements about demands and resources, developed for the purpose of this study, and a demographic questionnaire. Structural equation modelling, invariance testing and latent class analysis were some of the statistical techniques used to analyse the cross-sectional data. Manuscript one addressed the prevalence of flourishing among pharmacy students as well as possible differences between the year groups. The manuscript also investigated the role of workload as a study demand and the lecturer as a study resource and the possible interaction between them in the flourishing of students. Year group as a possible moderator in the respective relationships between demands, resources, the interaction between them on the one hand and flourishing on the other, were also assessed. 40% of the group flourished whilst 57% was moderately healthy and 3% languished. The different year groups negotiated the demands and resources in their study environment differently in their path to flourishing. The possible pathways to flourishing in this context were identified as the use of lecturer support (a resource), especially when the workload (a demand) is high and the successful negotiation of workload over their four years of study. Manuscript two dealt with the impact of antecedent factors of basic psychological need satisfaction of pharmacy students on their basic psychological need satisfaction and therefore ultimately the influence of these contextual factors on their flourishing. The researcher wanted to determine whether there is a difference in the role(s) that family, peers, lecturers and workload play in the satisfaction of the students‟ basic psychological needs (relatedness, competence and autonomy). Year group as a moderator in these respective relationships was also investigated. Family and peers played the most important role in need satisfaction of students. However, lecturers can actively engage in supporting the need satisfaction of students, which would increase their levels of autonomous motivation and thereby their levels of flourishing. In manuscript three the use of internal strategies as pathways to flourishing were explored. Positive emotion regulation strategies have a positive relationship with well-being. However, a person can dampen or savour his or her positive emotions. The students were clustered into distinctive groups by means of a latent class analysis. Three distinctive groups were posterior identified based on the characteristics of group members, namely flourishers, languishers and moderately healthy students. Regression analyses of the three groups revealed that flourishers are the only group that most likely will utilise savouring positive emotion regulation strategies and refrain from utilising dampening positive emotion regulation strategies. Pathways to flourishing that flourishing pharmacy students utilise are therefore the use of savouring positive emotion regulation strategies and the non-use of dampening positive emotion regulation strategies.

Spending your time „nurturing what is right‟ enables people to grow and negotiate the problems of life which is more than only fixing what is wrong. The World Health Organisation also defined well-being as more than not ill-being. Flourishing is an optimal state of well-being. The question is, „what is it that flourishers do different from non-flourishers?‟ Pharmacy students prepare themselves for a profession which is being bombarded with change; they are the pharmacists of tomorrow. Among them some students flourish and the others do not. This study aimed to look at possible pathways to flourishing that flourishers utilise. In this way the study addressed several gaps in the knowledge regarding flourishing: 1) The prevalence of flourishing among pharmacy students, 2) The role of demands and resources in flourishing of students, 3) The role of antecedent factors of basic psychological need satisfaction on the basic psychological need satisfaction of students and therefore in their flourishing, and 4) The use of positive affect regulation (an internal strategy) as a pathway to flourishing. A cross-sectional design was utilised. The study population was all the enrolled pharmacy students at the North West University during 2014. A convenience sample of 779 students participated. The measuring battery consisted of the Mental Health Continuum-Short Form (MHC-SF; Keyes, 2009), the Emotional Regulation Profile-Revised (ERP-R; Nelis, Quoidbach, Hansenne, & Mikolajczak, 2011), the Balanced Measure of Psychological Needs (BMPN; Sheldon & Hilpert, 2012), statements about the antecedents of basic psychological need satisfaction and statements about demands and resources, developed for the purpose of this study, and a demographic questionnaire. Structural equation modelling, invariance testing and latent class analysis were some of the statistical techniques used to analyse the cross-sectional data. Manuscript one addressed the prevalence of flourishing among pharmacy students as well as possible differences between the year groups. The manuscript also investigated the role of workload as a study demand and the lecturer as a study resource and the possible interaction between them in the flourishing of students. Year group as a possible moderator in the respective relationships between demands, resources, the interaction between them on the one hand and flourishing on the other, were also assessed. 40% of the group flourished whilst 57% was moderately healthy and 3% languished. The different year groups negotiated the demands and resources in their study environment differently in their path to flourishing. The possible pathways to flourishing in this context were identified as the use of lecturer support (a resource), especially when the workload (a demand) is high and the successful negotiation of workload over their four years of study. Manuscript two dealt with the impact of antecedent factors of basic psychological need satisfaction of pharmacy students on their basic psychological need satisfaction and therefore ultimately the influence of these contextual factors on their flourishing. The researcher wanted to determine whether there is a difference in the role(s) that family, peers, lecturers and workload play in the satisfaction of the students‟ basic psychological needs (relatedness, competence and autonomy). Year group as a moderator in these respective relationships was also investigated. Family and peers played the most important role in need satisfaction of students. However, lecturers can actively engage in supporting the need satisfaction of students, which would increase their levels of autonomous motivation and thereby their levels of flourishing. In manuscript three the use of internal strategies as pathways to flourishing were explored. Positive emotion regulation strategies have a positive relationship with well-being. However, a person can dampen or savour his or her positive emotions. The students were clustered into distinctive groups by means of a latent class analysis. Three distinctive groups were posterior identified based on the characteristics of group members, namely flourishers, languishers and moderately healthy students. Regression analyses of the three groups revealed that flourishers are the only group that most likely will utilise savouring positive emotion regulation strategies and refrain from utilising dampening positive emotion regulation strategies. Pathways to flourishing that flourishing pharmacy students utilise are therefore the use of savouring positive emotion regulation strategies and the non-use of dampening positive emotion regulation strategies.

L’objectif principal de cette thèse était de mettre en évidence l’évolution et l’orientation de la motivation intrinsèque et extrinsèque des élèves roumains tout au long du second cycle d’enseignement secondaire général. Depuis plusieurs années la théorie de l’autodétermination (Deci et Ryan, 1985b, 2000) a été utilisée afin de mieux comprendre le comportement des élèves en milieux scolaire. Ryan et Deci distinguent la motivation intrinsèque et la motivation extrinsèque qui diffèrent selon le type de récompense rattachée à l’activité. La théorie de l’autodétermination repose sur trois besoins psychologiques fondamentaux : l’autonomie, la compétence et la relation à autrui. Les déterminants psychologiques familiaux (parents), institutionnels (professeurs) et écologiques (système scolaire compétitif et évaluatif) sont aussi susceptibles d’influencer l’orientation motivationnelle de l’élève. Une première étude s’est attachée à analyser l’orientation et l’évolution de la motivation intrinsèque et extrinsèque. Les résultats présentent les élèves comme plus motivés extrinsèquement plutôt qu’intrinsèquement. De plus les deux formes de motivation diminuent tout au long de leur cursus scolaire. Une seconde étude s’est employée à mesurer le degré d’influence des trois besoins psychologiques sur la motivation intrinsèque des élèves. Les résultats ont montré que le besoin d’affiliation était le plus fortement corrélé positivement à la motivation intrinsèque. Les deux dernières études ont visé à mettre en évidence la relation entre le sentiment d’autonomie des élèves exercé par les parents et les professeurs et leur motivation intrinsèque. Les résultats confirment l’influence positive de ces deux déterminants sur la motivation intrinsèque des élèves. Enfin ces résultats seront discutés notamment sur le rôle des déterminants psychologiques dans cette recherche et dans le cadre des travaux sur la normativité de la motivation intrinsèque. / The main objective of this thesis was to highlight the evolution and direction of the intrinsic and extrinsic motivation of Romanian pupils throughout the second cycle of general secondary education. For several years the self-determination theory (Deci and Ryan, 1985b, 2000) was used to better understand the behavior of students in the school. Ryan and Deci distinguish intrinsic motivation and extrinsic motivation that vary by type of reward attached to the activity. Self-determination theory is based on three basic psychological needs: autonomy, competence and relatedness. The psychological determinants family (parents), institutional (college), and environmental (school system competitive and evaluative) are also likely to influence motivational orientation of students. A first study has sought to analyze the direction and evolution of the intrinsic and extrinsic motivation. The results show the students as more extrinsically motivated rather than intrinsically. In addition, both forms of motivation decrease throughout their school career. A second study aimed to measure the influence of the three basic psychological needs on the intrinsic motivation of students. The results showed that the need for affiliation was most strongly correlated positively to intrinsic motivation. Two recent studies have sought to highlight the relationship between perceived autonomy of students by parents and teachers and their intrinsic motivation. The results confirm the positive influence of these two determinants on the intrinsic motivation of students. Finally, these results will be discussed including the role of psychological determinants in this research and the work on the normativity of intrinsic motivation.

Le rôle des parents est essentiel dans les expériences sportives de leur enfant. Cependant, de nombreux exemples relatés par les médias ont montré que le soutien qu’ils apportent n’est pas toujours adapté. Face à ce constat, de plus en plus d’études se sont intéressées à l’influence des parents dans le sport. Leur investissement pourrait aider leur enfant à faire face aux exigences qui découlent de leur double projet sportif et scolaire. Ainsi, l’objectif de cette thèse était de comprendre et d’accompagner les parents d’adolescents sportifs de haut niveau. Un premier chapitre présente une revue de littérature sur le sujet. Ensuite trois chapitres détaillent le travail réalisé afin de répondre à l’objectif.Le deuxième chapitre a exploré quantitativement les comportements parentaux et leur influence sur certaines variables psychologiques des sportifs. Il a montré que l’investissement parental le plus adapté au développement du sportif correspond à un investissement modéré incluant des encouragements, et une pression et des comportements directifs peu fréquents de la part des deux parents. Le troisième chapitre a étudié qualitativement les antécédents de l’investissement parental. Les analyses ont révélé que les parents vivent différents facteurs de stress organisationnels, développementaux, compétitifs et personnels qu’ils perçoivent comme étant, pour la plupart, difficiles à gérer. Afin de faire face à ces inquiétudes, les parents s’appuient sur différentes stratégies qu’ils mettent eux-mêmes en place et sur des stratégies réalisées par la famille et la structure sportive. Cependant, selon eux, ces dernières ne sont pas toujours efficaces. Le quatrième chapitre présente une étude interventionnelle qui a évalué l’efficacité d’un programme d’accompagnement. Les résultats ont montré que le programme influence positivement les expériences des parents. Ils ont également mis en avant les difficultés rencontrées pour engendrer des modifications comportementales perceptibles par les sportifs.Au regard des résultats des six études réalisées auprès de 1595 parents et 919 sportifs, des perspectives de recherches sont discutées. Des recommandations pratiques permettant de favoriser un investissement parental adapté au développement du sportif sont également exposées / Parents play a crucial role in their child’s sporting experiences. However, many examples outlined from the media have shown that parental support is not always appropriate. Besides, researchers have currently focused on the influence of parents in sport. Their involvement could sustain their child to cope with the demands of their dual careers in sport and education. Thus, the objective of this thesis was to understand and support parents of elite adolescent athletes. The first chapter presents a literature review on the topic. Then, three chapters detail the studies completed to meet the objective.The second chapter quantitatively explored parents’ behaviors and their influence on specific psychological variables of athletes. It showed that the most appropriate parental involvement to the athlete’s development corresponds to a moderate involvement from both parents: encouragements, and few pressure and directive behaviors. The third chapter qualitatively examined factors inducing parental involvement. Analysis revealed that parents feel different organizational, developmental, competitive and personal stressors mainly perceived as being difficult to manage. In order to cope with these concerns, parents rely on various strategies that they themselves implement but also on strategies carried out by family and sport center. However, according to them, the latter are not always effective. The fourth chapter presents an intervention study that evaluated the effectiveness of a support program. The results showed that the program positively influences parents’ experiences. They also highlighted the difficulties to create parental behavioral changes perceptible by athletes.Based on results of the six studies conducted with 1595 parents and 919 athletes, new directions of research are discussed. Practical recommendations to foster an appropriate parental involvement to the athlete’s development are also shared

This research assessed psychosocial and cognitive factors influencing well-being, utilising a positive psychological perspective. The theoretical framework of this research was provided by two of the sub-theories of Self-Determination Theory – Basic Needs Theory and Organismic Integration Theory – along with Gender Role Theory, and Beck’s Cognitive Triad, with each of these theories relating differentially to the concept of control or self-determination. More specifically, the current research examined the relationship between gender role schema and the experience of childhood trauma with psychological, physical, and social well-being in adults. Two studies were conducted. Study 1 employed a random sample of 410 participants from Central Queensland, Australia, to develop the World Beliefs Inventory (WBI). This 21-item inventory was developed to assess world beliefs, based on a translation of Aerts et al.’s (1994) philosophical conceptualisation of world beliefs into common terminology. Developing the WBI enabled the assessment of world beliefs, which along with beliefs about oneself (operationalised as perceived control), and the future (dispositional optimism) constitute Beck’s (1976) cognitive triad. Statistical analyses indicated that the inventory provided a good representation of the world beliefs construct, as well as possessing favourable concurrent validity (e.g., positive views regarding the nature of the world were associated with decreased frequency of depressive symptoms experienced, and greater general psychological health and self-esteem). Study 2 was designed to investigate the direct and indirect relationships between gender role schema (masculinity and femininity) and the experience of childhood trauma with psychological, physical, and social well-being, being mediated by (a) the satisfaction of the basic psychological needs for autonomy, competence, and relatedness, (b) beliefs about the world, oneself, and the future, (c) the self-regulation of withholding negative emotion (SRWNE), and (d) somatic amplification. Study 2 employed a separate random sample of 605 participants from Central Queensland. Psychological, physical, and social well-being were each assessed independently to determine whether patterns of significant relationships were similar or different across the different types of well-being. In order to test the theories underlying the structural models of well-being, five hierarchical models of each type of well-being were analysed and compared. Satisfaction of the basic psychological needs for autonomy, competence, and relatedness, and beliefs about the future (dispositional optimism) were found to play a role in the process via which masculinity, femininity, and the experience of childhood trauma influenced all three forms of well-being, while world beliefs were additionally found to influence social well-being, and the SRWNE additionally influenced physical well-being. Results therefore support Basic Needs Theory and provide partial support for Beck’s cognitive triad. They also provide evidence of the utility of the concept of the SRWNE, which was developed in accordance with Organismic Integration Theory.

How does the satisfaction (or the lack of satisfaction) of the innate need to have meaningful interpersonal relationships affects behavioural self-regulation? How does having/lacking interpersonal relatedness impact one’s perception of future interpersonal relationships? This doctoral dissertation aimed to answer these two fundamental questions by integrating the views of two complementary theories, need to belong theory (NBT; Baumeister & Leary, 1995) and self-determination theory (SDT; Deci & Ryan, 1985, 2000). Using a series of two laboratory experiments and one longitudinal study, this thesis examined the effects of social exclusion and inclusion on satisfaction of basic psychological needs, self-determined motivation, and self-regulation of behaviours. In Study 1 (N=72), social exclusion and inclusion were manipulated in order to examine their effects on the satisfaction of the three basic psychological needs proposed by SDT, that is the needs for autonomy, competence, and relatedness. Findings from this first experiment revealed that social exclusion decreases satisfaction of the three needs, whereas social inclusion increases satisfaction of these needs when compared to the control condition. Furthermore, significant differences were found between the exclusion condition and the inclusion condition for the reported levels of satisfaction of the needs for competence and relatedness. The effects of social exclusion and inclusion on basic needs satisfaction were further investigated in Study 2 (N=70); also, the second study examined how self-determined motivation and behavioural self-regulation are affected. More specifically, it tested whether participants’ persistence at a laboratory task, as well as their intentions for a future peer interaction (intentions to compete against a peer participant and intentions to collaborate with a peer participant) are influenced by social exclusion and inclusion, through the meditating effects of basic needs satisfaction and self-determined motivation. The results suggested that social exclusion, via the effects of basic needs and motivation decreases peer collaboration, whereas social inclusion was shown to have an opposite effect on peer collaboration. The effect of condition via the mediating effects of basic needs satisfaction and motivation failed to predict persistence at the task and peer competition. Lastly, Study 3 (N=624) assessed naturally occurring social exclusion and inclusion in a population of junior high school students. This third study investigated the independent contributions of SDT and NBT in the prediction of academic motivation and high school dropout. Peer relatedness, perceived needs support from parents, and perceived needs support from teachers were examined as potential predictors of academic motivation and high school dropout. Findings suggested that peer relatedness plays an important role in the prediction of academic motivation, but, that perceived needs support from parents and perceived needs support from teachers are stronger predictors of that outcome. Results from this study also revealed that peer relatedness contributes to the prediction of high school dropout, beyond what can be explained by academic motivation, perceived needs support from parents, and perceived needs support from teachers. However, perceived needs support from parents was shown to be the most essential predictor of high school dropout. In sum, findings from this doctoral dissertation suggested that social exclusion has detrimental effects on one’s motivation and behavioural self-regulation. In contrast, social inclusion fosters social support which promotes satisfaction of the basic psychological needs, self-determined motivation, and successful self-regulation. This doctoral thesis contributed to the application of SDT and NBT by comparing elements of the two complementary frameworks. It also offered an original contribution to research on social exclusion and inclusion by examining their impacts on self-determined motivation, and basic needs satisfaction, as well as testing them in both the laboratory setting and the natural setting.

How does the satisfaction (or the lack of satisfaction) of the innate need to have meaningful interpersonal relationships affects behavioural self-regulation? How does having/lacking interpersonal relatedness impact one’s perception of future interpersonal relationships? This doctoral dissertation aimed to answer these two fundamental questions by integrating the views of two complementary theories, need to belong theory (NBT; Baumeister & Leary, 1995) and self-determination theory (SDT; Deci & Ryan, 1985, 2000). Using a series of two laboratory experiments and one longitudinal study, this thesis examined the effects of social exclusion and inclusion on satisfaction of basic psychological needs, self-determined motivation, and self-regulation of behaviours. In Study 1 (N=72), social exclusion and inclusion were manipulated in order to examine their effects on the satisfaction of the three basic psychological needs proposed by SDT, that is the needs for autonomy, competence, and relatedness. Findings from this first experiment revealed that social exclusion decreases satisfaction of the three needs, whereas social inclusion increases satisfaction of these needs when compared to the control condition. Furthermore, significant differences were found between the exclusion condition and the inclusion condition for the reported levels of satisfaction of the needs for competence and relatedness. The effects of social exclusion and inclusion on basic needs satisfaction were further investigated in Study 2 (N=70); also, the second study examined how self-determined motivation and behavioural self-regulation are affected. More specifically, it tested whether participants’ persistence at a laboratory task, as well as their intentions for a future peer interaction (intentions to compete against a peer participant and intentions to collaborate with a peer participant) are influenced by social exclusion and inclusion, through the meditating effects of basic needs satisfaction and self-determined motivation. The results suggested that social exclusion, via the effects of basic needs and motivation decreases peer collaboration, whereas social inclusion was shown to have an opposite effect on peer collaboration. The effect of condition via the mediating effects of basic needs satisfaction and motivation failed to predict persistence at the task and peer competition. Lastly, Study 3 (N=624) assessed naturally occurring social exclusion and inclusion in a population of junior high school students. This third study investigated the independent contributions of SDT and NBT in the prediction of academic motivation and high school dropout. Peer relatedness, perceived needs support from parents, and perceived needs support from teachers were examined as potential predictors of academic motivation and high school dropout. Findings suggested that peer relatedness plays an important role in the prediction of academic motivation, but, that perceived needs support from parents and perceived needs support from teachers are stronger predictors of that outcome. Results from this study also revealed that peer relatedness contributes to the prediction of high school dropout, beyond what can be explained by academic motivation, perceived needs support from parents, and perceived needs support from teachers. However, perceived needs support from parents was shown to be the most essential predictor of high school dropout. In sum, findings from this doctoral dissertation suggested that social exclusion has detrimental effects on one’s motivation and behavioural self-regulation. In contrast, social inclusion fosters social support which promotes satisfaction of the basic psychological needs, self-determined motivation, and successful self-regulation. This doctoral thesis contributed to the application of SDT and NBT by comparing elements of the two complementary frameworks. It also offered an original contribution to research on social exclusion and inclusion by examining their impacts on self-determined motivation, and basic needs satisfaction, as well as testing them in both the laboratory setting and the natural setting.

How does the satisfaction (or the lack of satisfaction) of the innate need to have meaningful interpersonal relationships affects behavioural self-regulation? How does having/lacking interpersonal relatedness impact one’s perception of future interpersonal relationships? This doctoral dissertation aimed to answer these two fundamental questions by integrating the views of two complementary theories, need to belong theory (NBT; Baumeister & Leary, 1995) and self-determination theory (SDT; Deci & Ryan, 1985, 2000). Using a series of two laboratory experiments and one longitudinal study, this thesis examined the effects of social exclusion and inclusion on satisfaction of basic psychological needs, self-determined motivation, and self-regulation of behaviours. In Study 1 (N=72), social exclusion and inclusion were manipulated in order to examine their effects on the satisfaction of the three basic psychological needs proposed by SDT, that is the needs for autonomy, competence, and relatedness. Findings from this first experiment revealed that social exclusion decreases satisfaction of the three needs, whereas social inclusion increases satisfaction of these needs when compared to the control condition. Furthermore, significant differences were found between the exclusion condition and the inclusion condition for the reported levels of satisfaction of the needs for competence and relatedness. The effects of social exclusion and inclusion on basic needs satisfaction were further investigated in Study 2 (N=70); also, the second study examined how self-determined motivation and behavioural self-regulation are affected. More specifically, it tested whether participants’ persistence at a laboratory task, as well as their intentions for a future peer interaction (intentions to compete against a peer participant and intentions to collaborate with a peer participant) are influenced by social exclusion and inclusion, through the meditating effects of basic needs satisfaction and self-determined motivation. The results suggested that social exclusion, via the effects of basic needs and motivation decreases peer collaboration, whereas social inclusion was shown to have an opposite effect on peer collaboration. The effect of condition via the mediating effects of basic needs satisfaction and motivation failed to predict persistence at the task and peer competition. Lastly, Study 3 (N=624) assessed naturally occurring social exclusion and inclusion in a population of junior high school students. This third study investigated the independent contributions of SDT and NBT in the prediction of academic motivation and high school dropout. Peer relatedness, perceived needs support from parents, and perceived needs support from teachers were examined as potential predictors of academic motivation and high school dropout. Findings suggested that peer relatedness plays an important role in the prediction of academic motivation, but, that perceived needs support from parents and perceived needs support from teachers are stronger predictors of that outcome. Results from this study also revealed that peer relatedness contributes to the prediction of high school dropout, beyond what can be explained by academic motivation, perceived needs support from parents, and perceived needs support from teachers. However, perceived needs support from parents was shown to be the most essential predictor of high school dropout. In sum, findings from this doctoral dissertation suggested that social exclusion has detrimental effects on one’s motivation and behavioural self-regulation. In contrast, social inclusion fosters social support which promotes satisfaction of the basic psychological needs, self-determined motivation, and successful self-regulation. This doctoral thesis contributed to the application of SDT and NBT by comparing elements of the two complementary frameworks. It also offered an original contribution to research on social exclusion and inclusion by examining their impacts on self-determined motivation, and basic needs satisfaction, as well as testing them in both the laboratory setting and the natural setting.