抄録
This paper reviews studies on informal learning inside and outside of Japan. In the review process, we analyzed a total
of 194 Japanese language articles and 3,000 English language articles from Web of Science, CiNii and J-STAGE during
the period from 1970 to 2025. Initially, we identified the 150 most frequent words by applying word segmentation
(tokenization) to English titles and abstracts and morphological analysis to their Japanese counterparts. We then
employed co-occurrence network analysis using KH Coder to capture the overall thematic landscape of the literature.
By further integrating five-year periods as exogenous variables, we delineated chronological shifts in research trends of
informal language learning research in Japan and international journals. As a result, we found that “learn,” “student,”
“teacher” and “science” are some of the common words. While the international literature focuses on workplace,
corporate and organizational themes, Japanese research appears to concentrate on how learners utilize various resources, such as social media and online communities, to supplement formal language education. This study concludes insights into the evolving trends of informal learning studies.
https://ror.org/03ynn1n59 
