When less is more: representation and selective memory in expert problem solving.

Few studies of problem-solving expertise in professional domains have undertaken independent assessments of how domain-specific knowledge contributes to the development of problem representations as well as subsequent memory for task information. These issues were investigated in the present study by asking participants at three levels of training and experience (novice, trainee, and expert) in a medical specialty to solve two complex diagnostic problems (patient cases) selected from medical records of a university hospital. The subjects were also asked to provide an incidental free recall of the patient information contained in each case immediately after problem solving and one week later. Problem representations (identified as "lines of reasoning") used by each subject in each case were determined from an analysis of thinking-aloud protocols generated during problem solving. The three groups did not differ on the overall amount of case information recalled at the immediate retention test and did not show selective recall for information statements that were directly relevant to the lines of reasoning used during problem solving. After one week, however, the expert physicians remembered fewer information units than novices but showed selective retention for case information contained in the lines of reasoning used to reach a diagnosis. Experts also increased their recall of specific diagnostic interpretations contained in their initial problem-solving experience while novices did not demonstrate evidence of their problem representations in recalling case information.

On the development of procedural knowledge.

Amnesic patients demonstrate by their performance on a serial reaction time task that they learned a repeating spatial sequence despite their lack of awareness of the repetition (Nissen & Bullemer, 1987). In the experiments reported here, we investigated this form of procedural learning in normal subjects. A subgroup of subjects showed substantial procedural learning of the sequence in the absence of explicit declarative knowledge of it. Their ability to generate the sequence was effectively at chance and showed no savings in learning. Additional amounts of training increased both procedural and declarative knowledge of the sequence. Development of knowledge in one system seems not to depend on knowledge in the other. Procedural learning in this situation is neither solely perceptual nor solely motor. The learning shows minimal transfer to a situation employing the same motor sequence.