Acquisition of the lexicon: Limits of word to world pairing procedures

The work presented here investigates the question of how well nonlinguistic information supports a model of lexical acquisition that relies solely on a word to world pairing procedure. We explored the hypothesis that nonlinguistic context is sufficient to enable the learner to infer the meaning of some words but insufficient for others. The child language acquisition literature documents that children\u27s early vocabularies are heavily dominated by nouns and contain fewer verbs. Therefore, we first investigated the identification of common nouns and verbs when information about word meaning was restricted to observation of the extralinguistic context in which the word was used. The noun-verb difference is often attributed to the conceptual maturity of the learner since verbs have been described as conceptually more difficult. To focus on the information available rather than the conceptual abilities of the learner, we simulated the language acquisition performance of young children with conceptually mature subjects. Adults were given a task in which they had to identify word meaning for the 24 most frequent nouns and 24 most frequent verbs in a sample of maternal speech to young language learners. We found significant differences in the ability to correctly identify nouns and verbs that paralleled the noun advantage found in the child literature. The nonlinguistic context supported noun learning significantly better than verb learning; however, there was significant variation among items that was strongly correlated with measures of abstractness for the items. Demonstrating that nonlinguistic information is insufficient to account for all word learning has theoretical implications for a word to world pairing model of lexical acquisition. We present an alternative model of lexical acquisition that explores the interface between the acquisition of lexical items and the acquisition of syntax. A word to world pairing procedure can account for a set of concrete terms, primarily nouns. This set of words then provides cues to clause-level syntax. Once the learner has acquired syntactic knowledge, the available sources of information about word meaning become linguistic and nonlinguistic. Such a proposal includes both sentence to world pairing procedures and word to world pairing procedures to account for lexical acquisition