Influence of consistency, type frequency, and semantics on Japanese verb inflection

2022 Fiscal Year Final Research Report

• Project/Area Number: 17K02737
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Linguistics
• Research Institution: Prefectural University of Hiroshima
• Principal Investigator: Watanabe Masumi 県立広島大学, 保健福祉学部(三原キャンパス), 教授 (60285971)
• Project Period (FY): 2017-04-01 – 2023-03-31
• Keywords: 動詞 / 活用 / 一貫性 / type frequency / 音韻 / 意味 / 失語症 / 失文法

Outline of Final Research Achievements

In Japanese, the inflectional paradigm of generating the past tense form of a verb is determined by its final mora. Amongst nine such morae, whereas eight specify their respective consistent inflectional paradigms, mora /-ru/ specifies two alternatives i.e. inconsistent inflection. As such, verbs are classified as consistent and inconsistent. We figured out type frequency (the number of verbs with the same inflectional paradigm) and consistency index. Results of past tense generation tasks revealed that (1) consistent verbs are significantly easier to inflect than inconsistent verbs, (2) for consistent verbs, the higher the type frequency, the easier to inflect, (3) error rates of nonce verbs are larger than those of real verbs, (4) nonce verbs closely associated with real verbs are inflected more accurately than those having less association, indicating the involvement of semantic/lexical, rather than grammatical information in Japanese verb inflection.

Free Research Field

言語障害学、失語症、認知神経心理学

Academic Significance and Societal Importance of the Research Achievements

失語症では,従来から知られている格助詞の誤りだけでなく、動詞の活用障害もみられるが、ほとんど検討されて来なかった。文の要である動詞に関して検討を行い、動詞処理プロセスを明らかにすることは、失語症の障害機能の特定、さらに適切な言語治療法の開発のためには避けて通ることはできない。本研究では、英語などの他言語と異なる特徴をもった日本語の動詞活用に関し、先行研究の詳細な分析と新たな視点による健常者対象の実験により、今後の研究の礎を築くことができた。