Effects of preferred and imposed number of categories on recall

Investigated the effect of individual differences in habitually preferred number of categories (PNC) on the form and interpretation of the category-recall function. 92 female undergraduates were divided into 3 groups (low, intermediate, and high) according to their PNC values, as measured in a free sorting of a 50-word list. In each of these groups, recall subsequently was studied as a function of experimentally imposed number of categories (INC) ranging from 4 to 20. Results show (a) a concave function relating recall to INC, (b) a monotonically increasing function relating PNC to recall, and (c) a relationship such that the higher the correspondence between PNC and INC, the higher the recall score. An interpretation of individual differences in PNC is offered, and the implications of these differences for the shape and meaning of the category-recall function are discussed. (PsycINFO Database Record (c) 2006 APA, all rights reserved).