Proceedings of the Annual Meeting of the Cognitive Science Society

We adopt the interpretation of rationality according to which an organism's behavior is rational if it is optimally adapted to its environment (Anderson, 1990, 1991a, 1991b). Rationality, according to this view, often implies mechanisms that are as informationally efficient as possible. We interpret the problem of basic-level categorization (Rosch & Mervis, 1975) as one of data compression within an information theory framework, to define a framework whereby the best classification on a set of items is the one that maximally compresses the description of the similarity structure of these items. This framework is then used to examine whether participants in two experiments classified meaningless items in a way that reflected such a compression bias. In addition to the implications for human basic-level categorization, an objective criterion is established for assessing the relative merits of alternative clustering solutions on the same domain.