Measuring the relative contributions of rule-based and exemplar-based processes in judgment: Validation of a simple model

Judgments and decisions can rely on rules to integrate cue information or on the retrieval of similar exemplars from memory. Research on exemplar-based processes in judgment has discovered several task variables influencing the dominant mode of processing. This research often aggregates data across participants or classifies them as using either exemplar-based or cue-based processing. It has been argued for theoretical and empirical reasons that both kinds of processes might operate together or in parallel. Hence, a classification of strategies may be a severe oversimplification that also sacrifices statistical power to detect task effects. We present a simple measurement tool combining both processing modes. The simple model contains a mixture parameter quantifying the relative contribution of both kinds of processes in a judgment and decision task. In three experiments, we validate the measurement model by demonstrating that instructions and task variables affect the mixture parameter in predictable ways, both in memory-based and screen-based judgments.