Does it feel certain enough? Intolerance of uncertainty predicts checking behavior through ‘not just right’ experiences

Understanding the mechanisms underlying pathological safety behavior is crucial for the development of effective treatments for mental disorders. This study investigates the interplay between intolerance of uncertainty (IU), not just right experiences (NJREs), and safety behaviors using a behavior-based checking paradigm in individuals (<i>N</i> = 164) diagnosed with obsessive-compulsive disorder and/or anxiety disorders. Findings revealed that IU was related to more disturbance caused by experimentally induced NJREs. In addition, IU was linked to more NJREs on a trait level. Regarding safety behavior in the form of checking, IU was also indirectly associated with longer checking via NJRE-related disturbance. This indirect effect is in line with a conceptual pathway where IU promotes NJRE-related disturbance, thus contributing to excessive uncertainty-reducing safety behaviors. These results add evidence regarding IU as a factor driving safety behaviors, which can contribute to maintaining pathology. Furthermore, the findings demonstrate a mediating role of NJREs in this relationship. Implications include considering IU and NJREs in therapies across anxiety-related diagnoses for addressing pathological safety behaviors.