Strategies and classification learning

How do strategies affect the learning of categories that lack necessary and sufficient attributes? The usual answer is that different strategies correspond to different models. In this article we provide evidence for an alternative view— Strategy variations induced by instructions affect only the amount of information represented about attributes, not the process operating on these representations. The experiment required subjects to classify schematic faces into two categories. Three groups of subjects worked with different sets of instructions: roughly, form a prototype of each category, learn each category as a rule-plus-exception, or standard neutral instructions. In addition to learning the faces (Phase 1), subjects were given transfer tests on learned and novel faces (Phase 2) and speeded categorization tests on learned faces (Phase 3). There were performance differences in all three phases due to instructions, but these results were readily accounted for by specific changes in the representations posited by the context model of Medin and Schaffer; that is, strategies seemed to affect only the amount of information stored about each exemplar's attributes.