The purpose of this paper is to clarify which early language behaviors correlate with which cognitive behaviors.
The subjects were 35 nursery school children from 10 to 21 months old. The language measure was the stage of single word utterances. The developmental process of single word utterances was divided into four stages - the preverbal stage, the emergence stage in which the number of semi-referential and referential words are below 4, the growth stage in which referential words are from 5 to 10, the fixation stage in which referential words are above 11 but without two-word utterances. For each stage one point was scored when the child had already passed the stage or was now at that stage. Otherwise zero was scored. Cognitive tasks were means-ends and causality which Miller et al (1980) used, some combination tasks, some memory tasks, drawing, manipulation of objects and play. The scoring of cognitive tasks was as follows : when each item of the cognitive tasks was achieved, one point was scored. Otherwise zero was scored. As to manipulation of objects and play, the percentage of occurence of behavior in each category, for example symbolic play, was calculated.
The partial correlations between language measures and cognitive measures were computed. The results were as stage V of means-ends, the memory task in which children find a toy wrapped in a cloth, combination tasks in which children recognize the relation of objects and combine two paired pieces, and manipulation of objects with sensorimotor schemes already acquired, consequently the manuplation is suitable to their usage.
The cognitive correlates for the growth of single word utterances were the detailed and the differentiated recogntion of the environment and the increase of the appropriate manipulation of the obiects according to their conventional usage with new schemes. At the growth stage, children began to know the meanings of the sounds and the identification of the objects, and to acquire vocal and gestural symbols.
The cognitive correlates for the fixation of single word utterances were symbolic play, building a tower with blocks, scribbling and drawing a circle, and the memory task in which children find a toy hidden under one of three cups after the situation was screened for five seconds. To perform these tasks and produce referential words require the capacity for mental representation.
The results suggested that several functions and structures were shared by early language and cognition, and that the shared functions and structures varied at each stage of single word utterances.
The hypothesis of local homology proposed by Bates et al (1979), namely that specific tasks are correlated at specific moments in development on the basis of a more limited set of shared structures, may be supported by this study.