A Study of the Development of Productive Vocabulary : Research on Written Production of University Students

抄録

This study describes the development of productive vocabulary used in English essay writings of university students in Japan. Estimated vocabulary size is chosen as an index to describe the development. The results indicate that learners whose vocabulary size exceed 3000 significantly improve in their writing in quantity. Learners whose vocabulary size exceed 4500 also write significantly longer in 20 minutes compared to those with less vocabulary size. The results also indicate that it seems difficult to estimate the quantity of writing from vocabulary size, but there is a necessary condition, though insufficient, between them. That is, no learners below 3500 vocabulary size write more than 200 words, and no learners below 4500 vocabulary size write more than 350 words within 20 minutes. On the other hand, the results indicate that it is partially possible to estimate the quality of writing from vocabulary size -- a significant relationship is found between vocabulary size and part-of-speech used in writing. Learners use significantly less nouns while they use more pronouns, conjunctions, and articles when their vocabulary size exceed 3000 and 4500. In sum, the study implies that 3000 and 4500 vocabulary size are threshold levels in the process of the development of productive vocabulary.