Drifting thoughts in an uncertain world: experiencing uncertainty and being intolerant of uncertainty is associated with increased mind-wandering

People's knowledge of the world is limited, and both being intolerant of uncertainty and experiencing uncertainty may be related to impaired focus on a current task. Across two pre-registered studies (Total <i>N</i> = 435) we found that intolerance of uncertainty was related to self-reported trait mind-wandering (Study 1) and probe-caught mind-wandering (Study 2). We also tested the exploratory hypothesis that uncertainty would be positively related to mind wandering, and found that both trait (Study 1) and state (Study 2) uncertainty were related to mind-wandering. Both spontaneous and deliberate mind-wandering were positively related to intolerance of uncertainty and uncertainty. In Study 2, participants were randomly assigned to write about a time when they were either uncertain or certain. Exploratory analyses indicated that participants assigned to the uncertain condition reported greater intolerance of uncertainty, than participants in the certain condition. There was an indirect effect of condition through intolerance of uncertainty on deliberate mind-wandering, but not spontaneous mind-wandering. Both studies found that intolerance of uncertainty and uncertainty were strongly related. These results indicate that concerns about the unknown are associated with decreased focus on the task at hand.