The Precision Effect: How Numerical Precision Influences Everyday Judgments

Numerical judgments are not always based on the rules of arithmetic and logic; people often rely on heuristic inferences to make sense of numbers. In this chapter, we argue that unusually precise or sharp numbers can trigger heuristic processing and propose a model—the discrepancy attribution model—to characterize the nature of this heuristic processing. The discrepancy attribution process entails three postulates. First, we posit that atypical numbers cause processing discrepancy. Individuals have certain expectations as to how easy or difficult it will be to process numbers, and unusually round or precise numbers can render the processing easier or more difficult than expected. Second, we posit that when the processing discrepancy arises, individuals (mis)attribute this discrepancy to a salient factor. Finally, we posit that the (mis)attribution process is guided by the naive theories people have and by the contextual cues surrounding the judgment. We review several empirical studies on numerical precision that support the proposed discrepancy attribution model.