Surface features and feedback type affect formation of prototype or exemplar representations in the 5/5 category learning task

Abstract

Abstract Theories of category learning have typically focused on how the underlying category structure affects the category representations acquired by learners. However, there is limited research as to how other factors such as how the category structure is instantiated as stimulus features and how feedback is structured affect what representations are learned and utilized. Across three experiments we varied the surface appearance and type of feedback while holding category structure consistent. We used a novel “5/5” categorization task developed from the well-studied 5/4 task with the addition of one more stimulus to clarify an ambiguity in the 5/4 prototypes. We used multiple methods including computational modeling to identify whether participants categorized on the basis of exemplar or prototype representations. We found substantial differences when the same structure was instantiated as schematic robot-like stimuli and richer bee-like images, in that the former was characterized by use of prototypes and the latter by use of exemplars. We also compared standard correct/incorrect feedback with point-valued feedback for the bee stimulus set and found exemplar use in the former but greater prototype use in the latter. These results indicated that in addition to the underlying structure of categories, the appearance of the stimuli, and form of feedback may affect the strategies utilized and resulting representations during category learning.