The relationship between instrumental motivation and English communication behavior through learning perseverance and self efficacy among Vietnamese undergraduates

This study investigated the structural relationships linking instrumental motivation (IM), learning perseverance (LP), English self-efficacy (ESE), and self-reported English communication behavior (self-reported ECB). Utilizing an explanatory sequential mixed-methods design, quantitative data were collected from undergraduate English majors in public universities across Southern Vietnam ( N = 382) and analyzed via Partial Least Squares Structural Equation Modeling (PLS-SEM). Qualitative data from semi-structured interviews ( n = 30) were analyzed through reflexive thematic analysis to contextualize the statistical associations. The structural model accounted for 58.9% of the variance in self-reported English communication behavior (R 2 = 0.589). Empirical testing provided support for the direct associations and the specified sequential mediation pathway (IM → LP → ESE → ECB). Effect size (f 2 ) analyses indicated that English self-efficacy functions as a primary proximal correlate of reported communication behavior (f 2 = 0.161), whereas instrumental motivation shares a strong direct variance with learning perseverance (f 2 = 0.284). Qualitative findings supported these quantitative pathways, illustrating how professional aspirations are associated with active self-reported communicative engagement—encompassing both oral interaction and digital communication—when accompanied by persistent effort and self-belief, while also highlighting context-specific barriers such as fear of negative evaluation. Pedagogically, the results emphasize the need to cultivate behavioral persistence, build task-specific efficacy, and create supportive learning environments that mitigate evaluative anxiety. Ultimately, this study demonstrates that extrinsic economic incentives are associated with self-reported communication practice primarily when aligned with internal behavioral persistence and cognitive self-belief.