3-1. People hold stored prototypes of many categories . They also form prototypes or representative exemplars of new categories and sets that they encounter . The prototypes of tables, of birds and of Harvard MBA’s are widely shared among members of the relevant culture. People also form ad hoc representations of a typical day of a seaside vacation, or of a typical resident of a city they visit. These representations of prototypes are evoked in the service of thinking about concepts and classes (Barsalou, 1992).