par Kassas, Sara 
Président du jury Van Assche, Jasper
Promoteur DeSmet, Ann
Co-Promoteur Culot, Catherine
Publication Non publié, 2026-09-08
Président du jury Van Assche, Jasper
Promoteur DeSmet, Ann
Co-Promoteur Culot, Catherine
Publication Non publié, 2026-09-08
Thèse de doctorat
| Résumé : | This thesis investigates how conflict and facilitation among personal goals, and between personal goals and values influence engagement in physical activity (PA) and healthy diet (HD) goals with a focus on methodological challenges in measuring these processes. Based on goal systems theory (GST) and the Schwartz value theory, the thesis distinguishes between horizontal goal relations; relations between lower-level goals that can be conflicting and facilitating, and vertical goal relations; relations between lower-level goals and personal values that can also be conflicting and facilitating. The first part of the thesis introduces and provides preliminary validation of an adapted version of the Personal Project Analysis (PPA) that assesses conflict and facilitation between the Schwartz personal values and health goals related to PA and HD. Findings from a cross-sectional mixed-methods study in the emerging adult population showed that PA and HD goals were more frequently perceived as facilitating than conflicting with personal values, although HD also conflicted with values in the Openness to Change domain. The findings suggest that health promotion interventions for emerging adults should not only focus on long-term health benefits, but also ways in which healthy behaviors are relevant to emerging adult population’s personal values, such as strengthening links with enjoyment, autonomy, novelty, achievement, and cultural relevance, while reducing the extent to which these healthy behaviors are perceived as barriers for personal enjoyment, compatibility with social settings, and conforming to cultural practices. The second part of the thesis addresses limitations of self-reports that examine goal relations by developing the PEP-Goal, the first implicit measure that assesses conflict and facilitation at the horizontal and vertical level, based on the Propositional Evaluation Paradigm (PEP). The study specifically assessed conflict and facilitation between life goals and health goals of PA and HD, as well as between these health goals and the Schwartz personal values. The PEP was also validated against the explicit self-report measure of goal relations, the PPA. Results showed dissociations between implicit and explicit measures of goal relations, suggesting that these measures may be measuring distinct aspects of goal relations. Implicit horizontal conflict and facilitation scores were associated with objectively measured PA behavior, demonstrating the predictive validity of indirect assessments of goal relations. The third part of the thesis extends the study of goal relations into daily life using ecological momentary assessment (EMA) methods. Cross-sectional methods do not provide insights into momentary changes in conflict and facilitation at the horizontal or vertical level, and their subsequent influence on short term changes in behavior. EMA-based approaches to measure momentary horizontal goal conflict and facilitation were developed by adapting existing measures for use in EMA studies, and refining them through cognitive interviews. The thesis further examines methodological considerations relevant to EMA research, specifically how reactivity to the measurement of PA in EMA influences participant compliance with EMA study questionnaires. Findings indicate that although reactivity to the continued monitoring of PA may positively influence study compliance, it may also compromise the study’s ecological validity by altering the behaviors under investigation. Overall, this thesis contributes theoretically and methodologically to the field of health psychology by informing our understanding of how goal relations influence health goal engagement, and exploring various methodologies for the measurement of goal relations. The thesis highlights the importance of integrating explicit self-report methods, implicit indirect methods, and intensive longitudinal methods with the aim of advancing our understanding of goal relations and their role in health goal engagement. |
