Nouns before verbs in comprehension vs. production: the view from pragmatics.

This study examines pragmatic factors that bias English-speaking children to produce more of the nouns and fewer of the verbs that they know. If nouns are favoured for production, parents should elicit more nouns than verbs in child speech. If verb comprehension is favoured over verb production, parents should more often prompt children to produce an action than to produce a verb. Data from 44 parent-child (age 1;8) dyads in the New England directory of the CHILDES data base were analysed. Children produced more nouns than verbs but mothers produced more verbs than nouns. Speech act analyses indicate that mothers elicited noun production but rarely prompted children to produce verbs. Mothers more often prompted children to produce an action than to produce a verb, and verbs occurred most often in maternal speech acts used to elicit children's actions. Moreover, children comprehended many more verbs than they produced. These data suggest that production measures underestimate the frequency and significance of verb-learning in early lexical development.

Measuring the vocabulary spurt: a reply to Mervis & Bertrand.

We reply to Mervis & Bertrand's report of three children (aged 1;6-1;8 at the start of the study) who evidenced a 'late' vocabulary spurt. Differences in assessing productive vocabulary, and the questionable inference that size of the lexicon is a reliable indicator of the vocabulary spurt, make it inappropriate to compare these children to previous studies that directly measure change in rate of word learning. Further work using continuous records of lexical development and controls for repeated cognitive assessments is needed to test hypotheses about the spurt and related cognitive and linguistic achievements.

Diary vs. representative checklist assessment of productive vocabulary.

Twenty-four infants were followed longitudinally from 1.2 to 1.10. Parents maintained diaries of the child's spoken words and at two-month intervals completed a representative checklist of words produced. There was good agreement across the two instruments and robust month-to-month correlations for both. However, the overall pattern of results suggests that the diary method is more effective during the early emergence of language and the representative checklist method is more effective late in the second year when vocabulary size becomes relatively large. Accurate longitudinal assessment of vocabulary may require a combination of the diary and checklist approaches.

Noun bias in maternal speech to one-year-olds.

This study examines the distribution of nouns and verbs in maternal speech to one-year-olds. Mothers and children were videotaped during toy play and non-toy play. Nouns and verbs in maternal speech were coded for frequency, sentence position and occurrence with grammatical inflections. Maternal speech was also coded for utterances that prompted the child to produce a noun or a verb. Frequency of nouns and verbs varied with context. There were more noun types and tokens during toy play, and more verb types and tokens during non-toy play. Nouns occurred more often than verbs in shorter maternal sentences, in sentence-final position, and with fewer grammatical inflections. Mothers also more often prompted their children to produce nouns. There was a significant positive correlation between frequency of noun types and tokens during toy play, and the proportion of nouns in children's first 50 words.

Early lexical acquisition: rate, content, and the vocabulary spurt.

The transition from slow to rapid word-learning was examined in a longitudinal study of 18 children. Beginning at age 1.2, mothers kept a diary of children's words. Diary entries were discussed during phone calls to the home every 2 1/2 weeks. A chronological record of nouns and other word classes was coded from the diary records. Thirteen children evidenced a prolonged period of up to three months during which rate of acquisition markedly increased. Almost three-quarters of the words learned during this period were nouns. Five children evidenced more gradual word-learning, and acquired a balance of nouns and other word classes. These results suggest that the terms 'vocabulary spurt' and 'naming explosion' best describe children who focus their early linguistic efforts on a single strategy: learning names for things. Other children may attempt to encode a broad range of experience with a more varied lexicon, a strategy that results in more gradual lexical growth.