What some concepts might not be

A discussion of the difficulties of prototype theories for describing composi-tional meaning motivates three experiments that inquire how well-defined concepts fare under paradigms that are commonly interpreted to support the prototype view. The stimulus materials include exemplars of prototype categories (sport, vehicle, fruit, vegetable) previously studied by others, and also exemplars of supposedly well-defined categories (odd number, even number, female, and plane geometry figure) Experiment I, using these materials, replicated the exemplar rating experiment of Rosch (1973). It showed that both the well-defined and prototypic categories yield graded responses, the supposed hall-mark of a family resemblance structure. Experi-ment II, using the same sorts of stimulus materials, replicated a verification-time paradigm, also from Rosch (1973). Again, the finding was that both well-defined and prototypic categories yielded results previously interpreted to support a family-resemblance description of those categories, with faster verification times for prototypical exemplars of each category In Experiment *We are indebted to quite a large number of colleagues for discussion of the issues addressed in this paper, and for reading and commenting on prior drafts of this manuscript. Particularly, we wish t