One of the major themes in categorization research during the past two decades
has involved comparisons and contrasts between prototype and exemplar models
(e.g., Estes, 1986a; Hintzman, 1986; Homa & Chambliss, 1975; Medin &
Schaffer, 1978; Nosofsky, 1987; Posner & Keele, 1970; Reed, 1972). According
to prototype models, the observer forms an abstract summary representation of a
category, usually assumed to be the central tendency of the category
distribution. According to exemplar models, the observer
stores the individual training exemplars of a category in memory.
In both prototype and exemplar models, classification decisions
are based on the similarity of an item to the underlying category
representation .
Nosofsky, R.M. (1992). Exemplars, prototypes, and similarity rules. In A. Healy, S. Kosslyn, and R. Shiffrin (Eds.), From learning theory to connectionist theory: Essays in honor of William K. Estes, Volume 1 (pp. 149-168). Hillsdale, NJ: Erlbaum.