Windschitl, P. D., & Weber, E. U. (1999). The interpretation of "likely" depends on the context, but "70%" is 70%--right?: The influence of associative processes on perceived certainty. Journal of Experimental Psychology: Learning, Memory, and Cognition.

Past research has demonstrated that interpretations of verbal certainty forecasts (e.g., "likely") differ as a function of the context to which they refer. The vague meaning of verbal expressions has been assumed to play a key role in such context effects. Experiments 1 and 2 demonstrated that precise numeric forecasts (e.g., "70%") are also susceptible to context effects. Participants read descriptions of target events and experts’ numeric forecasts for the events. Perceptions of certainty, expressed on nonnumeric scales, differed as a function of context manipulations. Experiments 3a, 3b, and 4 tested whether such effects are mediated by a utilization of subjective base-rates or by processes that are sensitive to the perceived representativeness of an event. The results support the latter account. More generally, the results are consistent with the idea that two types of semi-independent processing—associative and rule based—have important influences on perceptions of certainty. We discuss how this distinction can be helpful regarding issues related to uncertainty in judgment and decision making.