[The effects of judge's roles on probability judgment]

A number of studies on probability judgment have reported that people often tend to neglect the base-rate in the Cab Problem (Bar-Hillel, 1980). To explain the base-rate neglect, the present research hypothesized that subjects presented with the Cab Problem focused on the case information in the problem, because the subjects were asked to estimate probability based on that particular case. In 'two experiments, subjects' individuated or general interpretation of the Cab Problem was manipulated by instructing the subjects to play either responsible or neutral judge's role, respectively. The results suggested that in the responsible judge condition the case information had large impact on subjects' judgment, whereas in the neutral judge condition it did not. These results implied that the subject's base-rate neglect arose from taking the individuated interpretation.