The Effect of Intolerance of Uncertainty on Indecisiveness in Anxiety and Obsessive-Compulsive Disorders

Objectives: Intolerance of uncertainty (IU) describes a dispositional aversion to uncertainty. Recent research has identified IU as a causal contributor to pervasive decision difficulties (indecisiveness). Given that IU and indecisiveness occur across mental disorders, understanding whether IU's causal role in indecisiveness extends to clinical populations is critical. This study therefore tested the effect of IU on indecisiveness in a clinical sample.Methods: In this pre-registered experiment, N = 154 individuals with formally diagnosed obsessive-compulsive and/or anxiety disorders were randomly assigned to a condition aimed at either increasing or decreasing IU. Subsequently, participants reported their current levels of (situational) IU and, critically, their indecisiveness regarding two personally relevant decisions.Results: The experimental manipulation successfully altered IU levels. Participants with heightened IU exhibited more indecisiveness compared to those with reduced IU, but this effect occurred only indirectly through situational IU. The observed effect sizes were small.Limitations: Compared to preceding research, effect sizes were small and the effect of IU on indecisiveness only manifested itself indirectly. More robust interventions may be necessary to induce more pronounced changes in IU within clinical populations. The reliance on a heterogeneous sample with various diagnoses limits the disorder-specificity of the findings.Conclusions: These results extend the causal role of IU in indecisiveness to mental disorders. The findings suggest IU as a potential approach for addressing problematic indecisiveness.