Further clarifying prospective and inhibitory intolerance of uncertainty: Factorial and construct validity of test scores from the Intolerance of Uncertainty Scale.

The Intolerance to Uncertainty Scale (IUS) was developed to measure a dispositional tendency to react negatively to uncertain events, regardless of the occurrence probability of those events. Recent evidence suggests a 2-factor structure underlying the IUS; 1 factor measuring a prospective aspect (i.e., desire for predictability) and the other assessing an inhibitory aspect (i.e., uncertainty paralysis). The factorial and construct validity of the IUS test scores among undergraduate students in Singapore were examined in the present research using exploratory (n = 565) and confirmatory (n = 898) factor analyses. Results indicated that a 2-factor model was preferred over a unitary-factor model. The construct validity of the IUS (and subscale) scores was examined using a comprehensive nomological network of psychopathology and personality/affectivity variables. Differential relations were observed for the prospective and inhibitory components, providing support that the 2 subscales assessed unique aspects of the intolerance of uncertainty construct. An 18-item modified version of IUS was also proposed and its test scores had stronger validity evidence than scores from the widely used 12-item version.