Minami, Y. , Kobayashi, T. & Sugiyama, H.
NTT
Gentner (1982) analyzed the contents of children?s productive vocabularies in six languages, providing the pioneering work in cross-linguistic child development. Since then, many studies of linguistic universality have been investigated in this field (Bornstein et al. 2004). However, no study has investigated cross-linguistic universality in word-comprehension and -production days calculated directly from a CDI database. Therefore, this study investigates cross-linguistic universality using English and Spanish Lex2005 CDI database (Dale et al., 1996) along with our Japanese CDI database (from 1,699 toddlers). We defined the word-comprehension and -production days as the days when 50% of the children comprehend and produce a word, respectively. We determined these days by approximating rate curves of the children who comprehend and produce the word with two logistic functions, setting these functions to 0.5 and solving them by the Newton method. The correlations of comprehension and production days between two languages were calculated category on category and word on word. Casselli?s criterion (1999) was used to set the categories. We determined word-on-word correspondences only for verbs common to both CDI databases, looking them up in ordinary dictionaries. For category-on-category comparison of the comprehension days, English-Japanese, English-Spanish, and Japanese-Spanish correlation coefficients were 0.77, 0.80 and 0.64, respectively (p<0.01). For category-on-category comparison of the production days, English-Japanese, English-Spanish, and Japanese-Spanish correlation coefficients were 0.73, 0.76 and 0.73, respectively (p < 0.01). For word-on-word comparison of the comprehension days, English-Japanese, English-Spanish, and Japanese-Spanish correlation coefficients were 0.73, 0.71 and 0.62, respectively (p<0.01). For word-on-word comparison of the production days, English-Japanese, English-Spanish, and Japanese-Spanish correlation coefficients were 0.57, 0.61 and 0.63 (p < 0.01). These results confirmed there are strong correlations in word-comprehension days and word-production days as seen through both category-on-category and word-on-word comparisons. This suggests that there is cross-linguistic universality of word acquisition ages in comprehension and production.