Medical expertise asa function of task difficulty

Abstract

This paper is concerned with factors that disrupt the pattern of forward reasoning characteristic of experts with accurate performance. Two experiments are described. In the first, the performances of cardiologists, psychiatrists, and surgeons in diagnostic explanation of a clinical problem in cardiology were examined. In the second, the performances of cardiologists and endocrinologists in diagnostic explanation of clinical problems within and outside their domains of expertise were examined. The performances of researchers and practicing physicians are also compared. The results of Experiment 1 replicated earlier results regarding the relationship between forward reasoning and accurate diagnosis. There were no differences in recall as a function of expertise. Experts did not show any bias toward using specific knowledge from their own areas of expertise. The results of Experiment 2 showed that the breakdown of forward reasoning was related to the structure of the task. In particular, nonsalient cues induced some backward reasoning even in subjects with accurate diagnoses. Some differences were also found between the types of explanation used by researchers and practitioners. The practitioners referred more to clinical components in their explanations, whereas the researchers focused more on the biomedical components.An important distinction made in rule-based models of problem solving involves the directionality of inferences.Forward reasoning (or forward chaining) involves the generation of a hypothesis on the basis of data given in the problem. Backward reasoning involves the generation of data on the basis of a hypothesis. The distinction between forward and backward reasoning originated not in psychology but in artificial intelligence, where early expert systems tended to use one of these two kinds of inference mechanisms exclusively. However, this distinction motivated two empirical studies (Larkin, McDermott, Simon, & Simon, 1980;Simon & Simon, 1978) that were interpreted as showing that directionality is directly related to expertise. At least on routine problems, experts used forward reasoning, whereas novices used backward reasoning.It is important to note that this interpretation was based more on theory than on data. The data, which were based on only 3 subjects, simply demonstrated the existence of the two methods of reasoning and suggested a correlation with level of expertise. The interpretation of this correlation was derived from the well-established finding in artificial intelligence that forward reasoning is an optimal inference mechanism for solving well-structured problems in the presence of a large base of relevant knowledge, whereas backward reasoning is effective when a problem is ill-structured or relevant knowledge is absent. The obvious question of the generalizability of the results exists, and the experimenters made no attempt to manipulate the conditions under which the directionality of reasoning might change. There was also a confounding between accuracy and expertise, since no a...

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