Complexity trade-off in morphosyntactic module: suggestions from Japanese dialects

Abstract Using the GiNZA v4 natural language processing library, this study examines the case marking richness and word order flexibility in Japanese dialects across 47 regions to investigate the dynamic self-adaptation within the language subsystem, specifically morphology and syntax. Case marking richness is evaluated using the moving-average mean size of paradigm, while word order flexibility is assessed through entropy. The findings reveal a positive correlation between case marking richness and word order flexibility, providing empirical support for the “complexity trade-off hypothesis”. Leveraging the distinct morphosyntactic features inherent in dialects, this study proposes a hypothesis for categorizing Japanese dialects.