Pseudodiagnosticity in judgment under uncertainty

The study investigates the extent to which the false alarm (i.e., P( D H ̄)) is utilized in judgment under uncertainty. The main findings are (1) this cue is utilized by subjects when provided with a numerically low base-rate (i.e., P(H)) and a high hit-rate (i.e., P( D H)). Under these conditions the false alarm helps resolve the inconsistency between the implications of these probabilistic cues. (2) The false alarm is ignored by subjects when provided with a numerically high base-rate and a high hit-rate. Under these conditions both latter probabilities are consistent and imply strong support for the focal hypothesis. The false alarm is either not consistent with these cues or redundant and ignored. In addition, three experiments provided evidence regarding base-rate utilization. When comparing conditions (1) and (2) it is demonstrated that the base-rate has a significant effect on judgments. Finally, the experiments provided evidence suggesting that the base-rate is not ignored when the datum is not diagnostic. The results are discussed in relation to the base-rate fallacy, pseudodiagnosticity, and cue consistency.