Natural sampling and base-rate neglect

Using an analogue of the lawyer-and-engineer item (Kahneman & Tversky, 1973), we compared conditions in which base rates were either presented as percentages (A), or frequencies (B), to conditions in which the natural sampling process was described additionally (C) or was directly experienced (D). We expected the likelihood of base-rate utilization to increase as the presentation approaches the process of natural sampling. Accordingly, results showed that the contingency of judgments on base rates systematically increased across conditions A to D. © 1998 John Wiley & Sons, Ltd.