Vocabulary Size and Kanji Knowledge of Japanese as a Second Language

Effects of the First Language and Learning Period

Abstract

　In this study, a Kanji Conversion Test（KCT） was developed and implemented together with the Vocabulary Size Test for Reading Japanese（VSTRJ-50K）（Tajima et al., 2015; Sato et al., 2017） for university students who learn Japanese as a second language（JSL）. Among JSL students at three universities in Japan, the estimated vocabulary size of Chinese-background students was 30,000 or more on average, while that of non-Kanji-background students was less than 20,000. Although the correlation between the two tests was high, the unidimensionality of VSTRJ-50K was low in the Rasch analysis. Accordingly, when DIF analysis was performed for each L1 group, the goodness of fit to the model increased within each group, and there were many words with different difficulty levels depending on L1. In particular, the differences depending on word origin were remarkable. Examining the average learning time per word/kanji revealed that it declined as learners progressed from beginner to intermediate and advanced, and then increased from advanced to highly advanced. Therefore, a comprehensive consideration of L1/L2 learnersʼ vocabulary and kanji knowledge is necessary for curriculum development.