手指の構造と機能にもとづく日本語動詞活用の機能的 モデル化- 動詞文法と解剖学に関する形態論的・認知的考察 -

This paper examines the semantic functions of Japanese verb conjugations by drawing analogies with the anatomical and functional characteristics of human fingers. A multilayered correspondence between each verb conjugation form and the functions of individual fingers was identified. The thumb corresponds to the irrealis form (such as the nai-form, passive, causative, and volitional forms), as both are associated with directional shifts. While the thumb handles physical redirection, the irrealis form functions as a semantic pivot, marking changes from the default state or flow. The index finger, which specializes in precise manipulation, corresponds to the continuative form (ren’yōkei), including the masu-form, te-form, ta-form, tari-form, and tara-form, expressing fine-grained aspects of actions and states such as initiation, repetition, and emphasis. The middle finger serves as the central axis of grip and coordinates with other fingers for stable force transmission. It parallels the terminal form (shūshikei), which appears at the end of sentences and carries the central meaning, completing the utterance. The ring finger harmonizes through complementary interaction with other fingers, corresponding to the attributive form (rentaikei), which functions when combined with nouns to establish semantic identity. The little finger contributes to grip stability and fine control, aligning with the conditional and imperative forms, which act as foundational “levers” enabling nuanced expression of the speaker’s mental attitude in relation to subsequent expressions.