Hypothesis generation and the coordination of theory and evidence in novice diagnostic reasoning.

This study investigates hypothesis generation and evaluation in clinical problem solving by medical trainees. The study focuses on 1) directionality of reasoning and 2) use of confirmation and disconfirmation strategies in generating and evaluating hypotheses. Two clinical problems were divided into segments of information containing presenting complaint, past history, and physical examination. The initial information indicated a typical myocardial infarct but subsequent information contradicted it. The results showed that the participating students predominantly used forward reasoning and confirmation strategies. When faced with contradictory evidence: 1) second-year students ignored cues in the problem or reinterpreted them to fit the hypothesis; 2) third-year students generated concurrent hypotheses to account for different sets of data; and 3) fourth-year students generated several initial hypotheses and subsequently narrowed the hypothesis space by generating a single coherent diagnostic explanation. The results are discussed in terms of coordination of clinical evidence and its relationship to scientific reasoning.