Category representations and the effects of interacting with instances

People often classify new instances and then interact with or use them. Seven experiments showed that such interactions can affect the representation of the category. Equation categories, determined by both surface and mathematical properties, were used. In Experiments 1A and 1B, subjects solving the equations after classifying them were more likely to use the mathematical properties in later classifications than were subjects who had simply learned to classify. In Experiments 2A and 2B, different interactions led to very different classifications at test. Experiments 3-5 showed that such interactions affect category formation and graded structure, but do not lead to the solution group having worse memory for the surface contents. The discussion focuses on how these interactions may affect category representations and on the implications of this work for classification theories.