Contextual Effects in the Interpretations of Probability Words : Perceived Base Rate and Severity of Events

Previous research has demonstrated substantial effects of context on the numerical interpretation of verbal probability statements and has attributed these effects to the perceived base-rate probability of the predicted events. These context effects are shown to be attributable to the perceived severity of the predicted event as well as to the perceived base rate. Furthermore, there is evidence for strong context effects that are not explained by either of these 2 variables. The implications of these results for the use of probability statements in the communication of verbal probability information are discussed