Categorization

Mathematically, categorization is the process of grouping objects, entities, or situations into classes on the basis of shared properties or equivalence relations. It is therefore closely linked to the notion of an equivalence relation, which partitions a set into disjoint classes whose elements share a given property. In cognitive and linguistic contexts, however, categorization extends far beyond the formal framework of mathematics: it is a fundamental mechanism of conceptualization, enabling people to reduce the world's complexity by organizing their knowledge into structured categories. Three types of categorical organization are traditionally recognized. Taxonomic categories, or families, bring together items that resemble one another and share intrinsic properties—animals, plants, and foods—and tend to be relatively stable across individuals. Schematic or thematic categories are based not on similarities among their items but on their co-occurrence in the same scene or everyday event; they may also encompass sequences of actions or events, and their contents vary with individual experience. Finally, perceptual categories group objects according to observable physical properties—size, shape, and color—and are among the first to develop in young children, who naturally use them to organize their environment.