A Theory-Based Meta-Analysis of Research on Instruction.

concepts, then, are the basic components of propositions that are themselves the basic units of deep-structure, linguistic thought. Given the importance of abstract concepts to linguistic thought, it is useful to consider these in some depth. The Nature of Abstract Concepts There has been a great deal of research and theory on the nature of abstract concepts (Klausmeier, 1980; Smith and Medin, 1981; Tennyson, 1975). Virtually all of the major discussions of the nature and format of abstract concepts acknowledge the role of semantic features. It was Katz and Fodor (1963) who first popularized the notion that abstract concepts can be defined as sets of semantic features. Unfortunately, to exemplify semantic features as they relate to abstract concepts, one must use words that are not the concepts themselves, only "tokens" for the abstract concepts. With this in mind, consider Figure 2.4 which illustrates the role of semantic features in defining abstract concepts. The words in set A all represent abstract concepts with the semantic features human, animal, and two-legged. The words in B1 and B2 represent abstract concepts that are differentiated by the fact that all B1 abstract concepts contain the added semantic feature of male, all B2 words represent abstract concepts with the added semantic feature of female. The abstract concepts represented by words in set C do not share a male-female distinction, but they do share a semantic feature that might be called siblings. Semantic feature theory, then, asserts that abstract concepts are defined by sets of semantic features. The abstract concept represented by the word cow is defined by semantic features such as animate, concrete, four-legged, milk-producing, and so on. The abstract concept represented by the word desk is defined by semantic features such as inanimate, concrete, four-legged, used for paper work, and so on.