Gavin BROOKS    Department   Kyoto University of Foreign Studies  Department of British and American Studies, Faculty of Foreign Studies    Position   Associate Professor
Date	2025/11/01
Presentation Theme	Vocabulary usage across L2 spoken and written production
Conference	51st Annual JALT International Conference
Promoters	JALT (Japan Association for Language Teaching)
Conference Type	International
Presentation Type	Speech (General)
Contribution Type	Collaborative
Country	Japan
Venue	National Youth Olympic Center, Yoyogi
Holding period	2025/10/31～2025/11/02
Publisher and common publisher	Gavin Brooks, Jen Jordan
Details	This study analyzed a longitudinal learner corpus of 500 Japanese first-year university English learners collected over a year across three modes: discussions, presentations, and essays, measuring lexical diversity using MTLD and Guiraud's index and lexical sophistication using word frequency bands and cross-corpus frequency measures. Regression analysis showed significant correlations between proficiency and lexical diversity (p = 0.046) and sophistication (p = 0.014) in spoken texts. More proficient learners used lower-frequency words appropriately in written texts, and mixed-effects regression identified key lexical diversity and sophistication measures influencing proficiency across production modes.