Accommodating surprise in taxonomic tasks: The role of expertise

This paper reports a psychological study of human categorization that looke d at the procedures used by expert scientists when dealing with puzzling it ems. Five professional botanists were asked to specify a category from a se t of positive and negative instances. The target category in the study was defined by a feature that was unusual, hence situations of uncertainty and puzzlement were generated. Subjects were asked to think aloud while solving the tasks, and their verbal reports were analyzed. A number of problem sol ving strategies were identified, and subsequently integrated in a model of knowledge-guided inductive categorization. Our model proposes that expert k nowledge influences the subjects' reasoning in more complex ways than sugge sted by earlier investigations of scientific reasoning. As in previous stud ies, domain knowledge influenced our subjects' hypothesis generation and te sting; but, additionally, it played a central role when subjects revised th eir hypotheses.