Combining Prototypes: A Selective Modification Model

We propose a model that accounts for how people construct prototypes for composite concepts out of prototypes for simple concepts. The first component of the model is a prototype representation for simple, noun concepts, such as fruit, which specifies: (1) the relevant attributes of the concepts, (2) the possible values of each attribute, (3) the salience of each value, and (4) the diagnosticity of each attribute. The second component of the model specifies procedures for modifying simple prototypes so that they represent new, composite concepts. The procedure for adjectival modification, as when red modifies fruit, consists of selecting the relevant attribute(s) in the noun concept (color), boosting the diagnosticity of that attribute, and increasing the salience of the value named by the adjective (red). The procedure for adverbial modification, as in very red fruit, consists of multiplication-by-o-scalar of the salience of the relevant value (red). The outcome of these procedures is a new prototype representation. The third component of the model is tversky's (1977) contrast rule for determining the similarity between a representation for a prototype and one for an instance. The model is shown to be consistent with previous findings about prototypes in general, as well as with specific findings about typicality judgments for adjective-noun conjunctions. Four new experiments provide further detailed support for the model.