Great expectations: inhibitory learning and change processes in exposure therapy for PTSD

Kooistra, M.J. (2026)

Doctoral Thesis

This dissertation examines mechanisms of change in exposure therapy for posttraumatic stress disorder (PTSD) and translates principles from the inhibitory learning and retrieval (ILR) model to clinical practice. The ILR model proposes strategies to refine exposure therapy, such as maximizing expectancy violation and increasing variability, with the aim of enhancing treatment efficacy. Across the studies included in this dissertation, exposure therapy was found to effectively reduce PTSD symptoms and trauma-related negative cognitions, including threat expectancies. However, we did not find evidence that the application of ILR-based principles was associated with superior treatment outcomes in patients with PTSD. These findings underscore the importance of empirically testing theoretical assumptions about the mechanisms of exposure therapy in order to further refine and optimize clinical practice.

• Posttraumatic stress disorder
• exposure therapy
• inhibitory learning and retrieval model
• mechanisms of change

• All authors: Kooistra, M.J.
• Supervisor: Does, A.J.W. van der; Schoorl, S.M.D.
• Co-supervisor: Kleine, R.A. de
• Committee: Hulst, H.E.; Elzinga, B.M.; Nauta, M.H.; Verkuil, B.; Meyerbröker, K.
• Qualification: Doctor (dr.)
• Awarding Institution: Institute of Psychology, Faculty of Social and Behavioural Sciences, Leiden University
• Date: 2026-03-12
• DOI: doi:10.60602/1887-4297183