The ‘Base-Rate Fallacy’ — Heuristics and/or the Modeling of Judgmental Biases by Information Weights

Abstract

For more than a decade now, the ‘base—rate fallacy’ has been treated as a theoretical puzzle in both psychology and branches of other sciences concerned with human decision behavior and probability judgments. Generally, the term ‘base—rate fallacy’ denotes the phenomenon that when people are exposed to additional or diagnostic information about the probability of an event, they often show insufficient consideration of prior actuarial knowledge, hypotheses, or base —rates. The extent of interest in the ‘base —rate fallacy’ and of research running under this title can be seen from the list of papers which contain extended reviews or the many chapters in books in which the discussion about base — rates is predominant (e.g., AJZEN, 1977; BAR — HILLEL, 1980, 1983; BORGIDA & BREKKE, 1981; GINOSAR & TROPE, 1980; LYON & SLOVIC, 1976; KASSIN, 1979; SCHOLZ, 1981, 1983b; WALLSTEN, 1983; NISBETT & ROSS, 1980).