Piagetian measures of cognitive development for children up to age two.

This paper proposes a measure of cognitive development which is based primarily on Piaget's concepts. The choice of the particular items was determined by their assumed relation to general representational ability, including linguistic and nonverbal communication abilities. The present approach is distinguished from those of some linguists who suggest that a child's early linguistic development is not compatible with his cognitive skills and, thus, that a child's grammatical competence implies the existence of some innate set of principles for the generation of language. In contrast, the present approach hypothesizes that a child's cognitive skills during the first 2 years, particularly nonverbal representational abilities, not only precede but enhance his subsequent acquisition of language. The assumption that the items of the proposed scale together test a common ability was supported by a multidimensional homogeneity analysis of the scale, which indicated that it defines an essentially unitary ability dimension and also has strong ordinal characteristics.