Cross-linguistic effects on syntactic complexity in Japanese L2 writing

This study explores the role of first language (L1) typological distance and proficiency in shaping the syntactic complexity of second language (L2) Japanese writing. Using a dependency-based framework and Lang2Vec to quantify the typological distance between Japanese and twelve learners’ L1s, this research examines how these factors interact to influence syntactic organization. The study addresses three questions: (a) the independent and interactive effects of L1 distance and proficiency on syntactic complexity, (b) the reflection of these effects in dependency relations, and (c) the extent to which L1 distance, proficiency level, and dependency type explain structural variation in learners’ writing. The results suggest that L1 typological distance has minimal impact during the early stages of L2 acquisition, where proficiency is the primary driver of syntactic complexity. As learners progress, however, more advanced learners from closely related L1 backgrounds tend to produce more complex dependency structures, particularly in oblique nominal relations. The study also highlights the distinction between the frequency of syntactic structures and their internal complexity, showing that learners’ proficiency influences the internal length of dependencies rather than their frequency.