When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.
Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.
Dispositional optimism is a personality trait that reflects the generalized expectancy that positive, as opposed to negative, outcomes will occur in the future across a variety of domains (Carver & Scheier, 1985). Although numerous studies have demonstrated that dispositional optimism predicts greater well-being across the lifespan (Mens, Scheier, & Carver, 2016; Scheier, & Carver, 2018), a paucity of research has examined whether individuals’ levels of optimism fluctuate over time or the psychological factors that contribute to its development. Therefore, the aims of the research presented herein are to identify the developmental antecedents of dispositional optimism, whether levels of dispositional optimism change over time, and predictors of those fluctuations during periods of transition. This dissertation was conducted to address these gaps in the empirical literature on dispositional optimism. To examine these research questions, the results from two longitudinal prospective studies will be presented. Study 1 examines the role of early environmental experiences in childhood for predicting the development of optimism during the transition to early adulthood. The results from Study 1 show that greater maternal attachment security in childhood promoted greater optimism during the transition from late adolescence into early adulthood via higher levels of perceived internal locus of control. In addition, greater optimism contributed to higher levels of psychological well-being. Study 2 explores the extent to which dispositional optimism and its two subscales (optimism and pessimism) fluctuate over time in early adulthood, and whether individual differences in coping may predict those fluctuations. The results from Study 2 document that dispositional optimism and pessimism continue to undergo both short and long-term fluctuations during early adulthood. Moreover, these changes in optimism and pessimism are promoted by individual differences in the engagement in adaptive and maladaptive coping with contextual demands. Together, the findings from this research have important implications for enhancing our understanding of the precursors to the development of, and predictors of fluctuations in, dispositional optimism and psychological well-being. This knowledge provides a novel contribution to the specific literature on dispositional optimism, as well as the broader literature on predictors of personality development. Furthermore, this research demonstrates the importance of examining the development of personality traits, and optimism in particular, using a lifespan perspective.