Fearing the unknown: a short version of the Intolerance of Uncertainty Scale.

Intolerance of uncertainty is the tendency of an individual to consider the possibility of a negative event occurring unacceptable, irrespective of the probability of occurrence. It is a key component of worry, state anxiety, and related anxiety pathologies. The 27-item Intolerance of Uncertainty Scale (IUS) was developed to measure intolerance of uncertainty. Previous psychometric analyses of the IUS have suggested both four- and five-factor models. High inter-item correlations, factor instability, and previous theoretical research support the development of a reduced measure. The present study used two undergraduate samples and evaluated a psychometrically stable 12-item two-factor version of the IUS. The reduced measure (IUS-12) retained exemplary internal consistency, while correlating extremely well with the original IUS and related measures of anxiety and worry. The IUS-12 also demonstrated a stable two-factor structure, representing both anxious and avoidance components of intolerance of uncertainty. Directions for future research and potential applications for assessment are discussed.