Ties between lexical and grammatical development: evidence from early-talkers.

Case studies are presented for two linguistically precious children (early-talkers) aged 1;9 and 1;5, one of whom represents a striking dissociation between vocabulary size and mean length of utterance. Each early-talker is compared to controls in the same language stage; 10 in Early State I (mean age 1;7) and 10 in Stage II (mean age 2;3). Data are explored to determine if the dissociation is best characterized as one between grammar and semantics, or a difference in cognitive style. Results showed that the child who used mostly single words produced high proportions of predicates and bound and closed class grammatical morphemes, providing no evidence of a dissociation between grammar and semantics. Results also failed to support a clear contrast between analytic and holistic processing, although partial support was found for some predictions based on cognitive style. A unifying account is proposed that considers differences in auditory short term memory, a factor which could affect the size of the linguistic unit that children can store, manipulate, and/or retrieve at a particular point in development.