Gehechtheidsontwikkeling als een Leerproces: Van Theorie naar Interventie

Attachment theory proposes that children possess an innate tendency to seek proximity to caregivers during distress. Although attachment has traditionally been considered largely stable after early childhood, accumulating evidence suggests that attachment development remains dynamic and sensitive to caregiving experiences across development. However, the mechanisms underlying attachment development remain insufficiently understood. This doctoral project addressed this gap by adopting the Learning Theory of Attachment, which conceptualizes attachment development as a safety-learning process in which repeated caregiver-support experiences shape children's expectations and behavior. The overarching aims of this dissertation were twofold: (1) to advance fundamental understanding of attachment-related learning mechanisms, and (2) to examine whether these mechanisms can be translated into an attachment-based blended care intervention. Across two fundamental studies, mechanisms underlying attachment development were examined. First (Chapter 2), associations between attachment development and cumulative cortisol release were investigated in the context of the COVID-19 pandemic. Higher chronic stress, indexed by hair cortisol concentration, was associated with decreases in children's trust in caregiver support, whereas Secure Base Script knowledge increased across children, suggesting partly distinct developmental pathways for affective and cognitive attachment dimensions. Second (Chapter 3), experimental manipulating of caregiver-support contingencies demonstrated that trust declined when previously reliable support was withdrawn and that support-seeking behavior flexibly adjusted to perceived caregiver availability, supporting the LTA assumption that attachment expectations are continuously updated through learning. The applied research objective focused on translating these learning principles into clinical practice through the development and evaluation of FamilieLink, an attachment-based blended care intervention. An in-depth case study (Chapter 4) illustrated how attachment-related learning strategies can be implemented within a therapeutic trajectory, showing subjective benefits despite limited change on standardized outcome measures. A broader implementation study (Chapter 5) demonstrated high user satisfaction among caregivers and professionals, alongside substantial dropout rates, particularly among caregivers with elevated depressive symptoms and avoidant attachment styles. Taken together, this dissertation advances attachment research by integrating learning theory, psychobiological processes, and clinical innovation. The findings support the conceptualization of attachment development as a dynamic learning process, demonstrate that affective and cognitive attachment dimensions may not develop synchronously under chronic stress, and provide a foundation for embedding attachment-based blended care within a stepped care model.