Abstract
Research suggests that English-derived loanwords in Japanese can affect Japanese learners' acquisition and receptive knowledge of their English words of origin (‘basewords'). This study adopts a corpus-based approach to expand on this research by exploring the effects of loanwords on learners' productive knowledge. It primarily uses a corpus of written English produced by Japanese learners of English, a corpus of written English produced by native English speakers, and samples from a corpus of written Japanese to compare quantitatively how basewords and loanwords are used in each. The results provide statistically non-significant evidence that basewords are used relatively more frequently by learners than by native speakers, and some significant evidence that learners' baseword usage exhibits features of loanword usage where loanwords have changed in meaning or part of speech from their words of origin. The corpora also provide weak evidence that loanwords' effects on baseword usage increase with length of study of English. The findings point the way to more targeted use of loanwords in the classroom, including through the exploration of corpora by learners themselves.