Taking into account the strength of an alternative hypothesis

A common phenomenon in judgment under uncertainty is that alternative hypotheses are underweighted or ignored. This article addresses when and how the strength of the alternative is taken into account when there are 2 hypotheses. A learning manipulation was used to invoke 2 representations of 2 illnesses in a medical diagnosis task. One representation tended to lead to consideration of the alternative when, for example, requesting new information, reporting confidence, and making diagnoses. The other representation tended to result in ignoring or underweighting the alternative, but a simple change in how confidence was probed increased consideration of the alternative. Costs and benefits of each representation are discussed.