Ideals, central tendency, and frequency of instantiation as determinants of graded structure in categories.

Abstract

Two experiments examined 3 possible determinants of graded structure (central tendency, ideals, and frequency of instantiation). Ss were 74 and 54 university students in Exps I and II, respectively. Exp I found that central tendency did not predict graded structure in goal-derived categories, although it did predict graded structure in common taxonomic categories. Ideals and frequency of instantiation predicted graded structure in both category types to sizable and equal extents. A 4th possible determinant—familiarity—did not predict typicality in either common taxonomic or goal-derived categories. Exp II demonstrated that both central tendency and ideals causally determined graded structure and that the determinants of a particular category's graded structure could change with context. It is suggested that ideals may determine a category's graded structure in one context, whereas central tendency may determine a different graded structure in another. It is proposed that graded structures do not reflect invariant structures associated with categories but instead reflect people's dynamic ability to construct concepts.