Influence of predominance in noun learning examined by period from comprehending to producing words: A cross-linguistic statistical investigation using CDI

Minami, Y. & Kobayashi, T.

NTT

Previous studies have found that children?s noun learning predominates over their verb learning (Gentner et al. 1982, 1988, 2002; Maguire et al., 2006), since across several languages, children?s early productive nouns appear earlier than do verbs. However, no study has statistically investigated which learning process significantly contributes to this noun-learning predomination. Focusing on the process between comprehending and producing a word, this study investigates how this process cross-linguistically affects learning-speed differences between verbs and nouns using English and Spanish Lex2005 CDI database (Dale et al., 1996) with our Japanese CDI database (1,699 toddlers from 10 to 32 months). We defined the word-comprehension and -production days as the days when 50% of the children comprehend and produce the word, respectively. These days were determined by approximating the word comprehension and production rate curves by two logistic functions, setting the functions to 0.5 and solving them by the Newton method. The differences in word-comprehension day between verbs and nouns (verb-comprehension day - noun-comprehension day) were -24 days (English), -27 days (Japanese) and -63 days (Spanish) (p<0.05). The word-production day differences between verbs and nouns (verb-production day - noun-production day) were 58 days, 33 days and 55 days, respectively (p<0.01).Since these absolute values are strongly affected by word selection in CDI, we investigated relative differences between comprehension and production days. We found that the differences drastically increase from comprehension to production. This result shows that the process occurring between word comprehension and production affects the increases. Therefore, we directly calculated the period between comprehension and production, finding that these periods for English, Japanese and Spanish were 82 days, 60 days and 118 days, respectively. This shows that the process between comprehension and production of a word is a significant factor of predominance in noun learning by children.