Bianka Brezóczki^1,2,3, Teodóra Vékony⁴, Bence Csaba Farkas^5,6, Flóra Hann^1,2,3, Dezső Németh^4,7,8; ¹Brain, Memory and Language Research Group, Institute of Cognitive Neuroscience and Psychology, HUN-REN Research Centre for Natural Sciences, ²Doctoral School of Psychology, ELTE Eötvös Loránd University, Budapest, Hungary, ³Institute of Psychology, ELTE Eötvös Loránd University, Budapest, Hungary, ⁴Gran Canaria Cognitive Research Center, Department of Education and Psychology, Atlántico Medio University, Las Palmas de Gran Canaria, Spain, ⁵UVSQ, Inserm, Centre de Recherche en Epidémiologie et Santé des Populations, Université Paris-Saclay, Versailles, France, ⁶ LNC2, Département d’études Cognitives, École Normale Supérieure, INSERM, PSL Research University, Paris, France, ⁷BML-NAP Research Group, Institute of Psychology, Eötvös Loránd University and Institute of Cognitive Neuroscience and Psychology, HUN-REN Research Centre for Natural Sciences, Budapest, Hungary, ⁸Centre de Recherche en Neurosciences de Lyon CRNL U1028 UMR5292, INSERM, CRNS, Université Claude Bernard Lyon 1, 69500 Bron, France

Theoretical models of Obsessive-Compulsive Disorder (OCD) propose that its symptoms stem from an imbalance between habitual and goal-directed processes, marked by a shift toward habitual responding and reduced goal-directed control. Although prior research has largely focused on reward-based learning, the contribution of reward-independent learning mechanisms to this imbalance remains insufficiently understood. To address this gap, the present study investigated the antagonistic interplay between statistical learning (SL), a reward-free form of learning, and cognitive flexibility, a key dorsolateral prefrontal cortex function supporting goal-directed behavior, in a non-clinical population. Adopting a dimensional approach to obsessive-compulsive (OC) tendencies allowed us to move beyond categorical diagnoses and more precisely capture subtle, continuous variations in symptom expression, thereby clarifying how specific neurocognitive processes relate to OC tendencies. A total of 404 non-clinical participants completed the Alternating Serial Reaction Time (ASRT) task to assess SL and a Card Sorting Task to measure cognitive flexibility. Our findings revealed an antagonistic relationship between SL and cognitive flexibility. Crucially, this inverse association weakened as OC tendencies increased, suggesting that even at non-clinical levels, OC tendencies may attenuate the typical competitive balance between habitual and goal-directed processes. Importantly, SL performance itself remained intact, and the observed effects can not be attributed to reward sensitivity, as learning occurred without external reinforcement. Overall, these results underscore the value of studying OC tendencies dimensionally and highlight the importance of examining interactions among neurocognitive systems, rather than isolated functions, to advance our understanding of OCD.