Children's simultaneous or successive acquisition of vocabulary and grammar: Evidence from cross-situational learning.

Recent evidence from cross-situational learning (CSL) studies have shown that adult learners can acquire words and grammar simultaneously when sentences of the novel language co-occur with dynamic scenes to which they refer. Syntactic bootstrapping accounts suggest that grammatical knowledge may help scaffold vocabulary acquisition by constraining possible meanings, thus, for children, words and grammar may be acquired at different rates. Twenty children (ages 8 to 9) were exposed in a CSSL study to an artificial language comprising nouns, verbs, and case markers occurring within a verb-final grammatical structure. Children acquired syntax (i.e., word order) effectively, but we found no evidence of vocabulary learning, whereas previous adult studies showed learning of both from similar input. Grammatical information may thus be available early for children, to help constrain and support later vocabulary learning. We propose that gradual maturation of declarative memory systems may result in more effective vocabulary learning in adults.