Systematic errors in medical decision making: judgment limitations.

Much of medical practice involves the exercise of such basic cognitive tasks as estimating probabilities and synthesizing information. Scientists studying cognitive processes have identified impediments to accurate performance on these tasks. Together the impediments foster "cognitive bias." Five factors that can detract from accurate probability estimation and three that impair accurate information synthesis are discussed. Examples of all eight factors are illustrated by reference to published articles. The authors suggest ways to minimize the negative influences of these factors.