Causes of the noun bias in early vocabulary development

Abstract

Children typically learn many more nouns than verbs early in vocabulary development. The cause of this "noun-bias" is unclear. One possibility is that caregivers use more nouns and prompt for nouns more often. That is, the noun-bias may be the result of input frequency. To evaluate the role of frequency, 26 English-speaking toddlers from 12- to 30-months of age were presented novel nouns and verbs with equal frequencies. Six unfamiliar objects were paired with novel words used in noun syntax. Six actions, one with each object, were paired with novel words used in verb syntax. Each object and action with their corresponding words was presented six times in each of ten bimonthly sessions. Vocabulary acquisition was examined with production and comprehension tasks. When input frequency of novel words was controlled in this longitudinal study, children did not produce a noun-bias in baseline, imitation, spontaneous production, or prompted production. Likewise, there was not evidence of a noun-bias in comprehension. Instead, children produced the verbs more often in all production contexts. The noun and verb comprehension tasks were not directly comparable, but children did not appear to comprehend words from one syntactic category earlier than the other. Thus, contrary to prior studies of word learning in English-speaking children, we did not find a noun-bias when input word frequency was controlled. Alternative explanations for the noun-bias are considered.