What factors drive adult personality development? Several theoretical perspectives have been offered that propose different sources of influence on personality development, such as genetic and environmental factors, developmental tasks, life events, and peers. From a systems perspective, developmental tasks, life events, and peers constitute more or less external factors of influence on personality development. However, at some point, many of these external influences will be translated by the individual into the form of a deliberate goal to change the self. Exploring this idea, researchers have by now become increasingly interested in the roles of motivation and self-regulation for personality development. Research findings support the assumption that goals to change one’s personality traits play an important role in shaping current thoughts, feelings, and behaviors, and thus potentially influence even the developmental pattern of personality traits over time. The overall aim of this dissertation is to investigate processes of personality trait development from a micro- and a macro-perspective while focusing on goals as driving mechanisms in intentional personality development. This overall aim was accomplished by implementing an experience-sampling design within the broader timeframe of longitudinal data collection as well as capturing personality and goal characteristics at multiple time-points.
After a general theoretical introduction (chapter 1), the second chapter presents macro-perspective findings on motivational determinants of personality trait development with respect to mean-level changes as well as inter-individual differences in change. The analyses carried out in this dissertation yielded support for the effect on personality trait change both of goals to change oneself and of broader major life goals. These results establish investment in goals at different levels of the definitional hierarchy as underlying processes of personality development. While short-term goals to change oneself exerted influence on short-term changes, major life goals were predictive of more long-term trait changes.
The experience-sampling study presented in the third chapter addresses developmental processes at the micro-level and examines both unique and interaction effects of change goal characteristics on trait-related behavior. It builds on previous research that identified different social role contexts as relevant predictors of trait-related behavior. My results indicate that the importance and perceived feasibility of personal goals functioned as underlying micro-processes that may explain the effects of social roles on trait-related behavior. Findings that close the gap between analyses from the micro- and macro-perspective seem to suggest that there are behavioral investment effects on mean-level changes in corresponding personality traits.
In sum, the research findings from this multiple-time-scale design confirm the meaningful influence of deliberate goals on both variability in personality-related behavior and development of personality traits. Thus, the results point to the relevance of the recently suggested perspective on personality development that highlights self-regulation and motivational factors as important driving forces of personality development.
The fourth chapter will give a critical reflection and theoretical integration of my overall results and indicate profitable areas for future research. The dissertation is rounded off by a general conclusion in the fifth chapter.