Relationship among motivation, vocabulary learning strategies and the breadth of vocabulary knowledge: A structural equation modeling study on second language learning

This study investigated Chinese second language learners’ learning motivation, second language learning (SLL) vocabulary learning strategies (VLSs), and their relationships with vocabulary knowledge (VK), especially with vocabulary size. Data were collected from 275 non-English major students at a university in Wuhan (230 valid responses, effective rate 83.63%), spanning from freshmen to seniors, predominantly composed of first-year and second-year students (90.9%), with limited representation from third- and fourth-year students across three semesters (2024 spring, 2024 autumn, and 2025 autumn). Questionnaires were used to gather demographic information, motivation, and VLSs for English learning. Vocabulary breadth was measured using the Vocabulary Size Test (VST). The VLSs questionnaire comprised three constructs: memory strategies, cognitive strategies, and metacognitive strategies. Structural equation modelling (SEM) was adopted to test the measurement model and the hypothesized structural model. Results demonstrated that (1) the sampled Chinese college students reported a moderate, slightly below average motivation level to study English vocabulary; (2) the sampled Chinese college students exhibited a preference for cognitive strategies in their English vocabulary learning; (3) a. EFL learners’ level of L2 motivation exerted a significant, positive direct effect on their use of VLSs (β = 0.796, p < 0.001); b. EFL learners’ level of L2 motivation exerted a moderate, positive direct effect on VK breadth (β = 0.294, p = 0.031); c. VLSs did not serve as a significant positive predictor of VK breadth (β = −0.097, p = 0.468); d. After controlling for VLSs, motivation had no significant indirect effect on VK breadth (Estimate = −2.692, 95% CI [−13.901, 6.863], p = 0.554), indicating the absence of mediation. These findings carry significant implications for both theory and practice. Theoretically, they enhance our understanding of the complex interplay among EFL learners’ motivation, VLSs, and VK. Practically, the insights can assist educators in integrating these constructs into instructional design to foster more efficient vocabulary acquisition and improve the effectiveness of college English teaching.