J. Neil Bearden
Associate Professor of Decision Sciences
There is considerable evidence that frequency (and probability) judgments are often subadditive. That is, the frequency judgment assigned to an event is often less than the sum of the frequency judgments assigned to the mutually exclusive component events that together form it.Explanations for subadditive judgments have typically relied on relatively high-level cognitive constructs such as the availability and representativeness heuristics. A lower-level explanation of subadditivity is presented in this paper through a model of memory and judgment processes, MINERVA-DM. Under MINERVA-DM, subadditivity is influenced by the similarity of the representations of the judged component events in memory to one another and by the placement of decision criteria. Results from two experiments support the model predictions.The first examines the effects of component event similarity on subadditivity. The second replicates the first and also provides support for the model's prediction of the effects of payoffs on similarity criteria.