Decision making and professional experience: an experimental study of generating, evaluating and modifying diagnostic hypotheses

Experimental investigations on generation, evaluation, and modification of diagnostic hypotheses in symptom pattern classification revealed in different domains (e.g. clinical decision making) that reasoning in non-experts and experts differ in the 'content' (e.g. issue-directed substance of concepts) rather than in the 'form' of reasoning (e.g. number, specificity of hypotheses). These results are essentially accounted for by the experts' upper-level flexibility in the interpretation of data. In a two-factorial design (competence x predictive value of data), patients' clinical data with varying predictive value were given singularly in succession to two groups (experts and novices; n = 20) of subjects. The task of the subjects was (a) to name their assumptions and (b) give a summarizing decision on the--probable--diagnostic category of hypothetical cases. Results: Between experts and novices no difference was found in the number and degree of specification of hypotheses; in summarizing decisions, experts considered more categories as plausible than novices; on patient data with low predictive value, experts considered more specific categories. The moment of hypothesis formation depends not on the competence level but on the predictive value of the patient's clinical data.