Intolerance of Uncertainty (IU) is marked discomfort when faced with situations that are ambiguous, unpredictable, or lack clear outcomes. People with high IU often struggle with intrusive doubt and the need for certainty, which can lead to excessive worry, checking, or avoidance. IU plays a central role in anxiety disorders, where fear of the unknown fuels persistent worry and hypervigilance, and in obsessive-compulsive disorder (OCD), where it contributes to repetitive behaviors and mental rituals aimed at reducing uncertainty. In both cases, there is no true test of what will happen if they accept ambiguity, which leads to a vicious cycle of more repetitive behavior and avoidance, and ultimately more distress.
