Changes in conceptual structure with expertise: Differences between real-world experts and novices

Four groups of Ss who varied in clinical expertise (12 practicing clinical psychologists, 21 experienced and 24 beginning child counselors, and 20 novice undergraduates) listed the typical features of 3 diagnostic categories. Both the richness of the categories, as measured by the number of attributes listed, and the level of interrater agreement increased systematically with expertise. Surprisingly, however, category distinctiveness decreased as expertise increased--experts' categories contained many features shared by 2 or more categories, whereas novices' categories contained virtually no overlapping attributes. In a 2nd study with 45 novices and 15 experienced counselors, independent ratings of feature distinctiveness revealed that the attributes that experts added to their categories were relatively nondistinctive. The authors examine possible reasons for the discrepancy between these findings and those obtained in laboratory concept-learning tasks and discuss the conditions under which increasing expertise may lead one to focus on the shared, rather than on the distinctive, features of objects in a given domain. (28 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).