Domain knowledge and hypothesis generation in diagnostic reasoning.

The role of domain knowledge in the process of hypothesis generation during diagnostic reasoning was examined. Subjects were given a clinical case presented one segment at a time on a microcomputer. They were prompted to think aloud after presentation of each segment of the clinical case. A combination of discourse and protocol analysis techniques was used to investigate the problem solving process in two groups of experts working on an endocrine problem. The groups consisted of high-domain-knowledge subjects (HDK), endocrinologists, and low-domain-knowledge subjects (LDK), cardiologists. The results showed no significant differences between the groups in terms of selection of relevant and critical cues from the case. However, specific differences were found in the links or relations between the cues, with the HDK subjects using more relations to connect important information. The HDK subjects generated accurate diagnostic hypotheses early in the problem encounter and spent the rest of the time confirming the hypotheses by explaining the given cues. The LDK subjects also generated accurate diagnostic hypotheses but were unable to discriminate between and eliminate alternative hypotheses. A two-stage problem solving process and its relationship to domain specific knowledge are proposed.