IntroductionStudent Evaluation of Teaching (SET) is essential for educational development; however, it increasingly suffers from survey fatigue and perfunctory responses, particularly among medical students facing high academic stress and cognitive loads. Traditional behavioral theories often overlook the psychological appraisal of “cost–benefit” in students’ decision-making processes. To address this gap, this study constructed an Extended Theory of Planned Behavior incorporating Perceived Value (Extended TPB) model, introducing “Perceived Value” as a central psychological mediator to explore the cognitive and motivational mechanisms driving students’ intentions to participate in SET.MethodsA cross-sectional survey was conducted among 3,365 undergraduate medical students at a medical university in China. Data were collected using validated scales measuring attitude, subjective norm, perceived behavioral control, perceived value, and behavioral intention. Structural Equation Modeling (SEM) was utilized to test the theoretical model, and a Bootstrapping approach with 5,000 resamples was applied to examine mediating effects.ResultsThe Extended TPB model demonstrated an excellent fit and high explanatory power, accounting for 95.9% of the variance in SET behavioral intention. Perceived value exerted a strong positive predictive effect on behavioral intention (β = 0.979, p < 0.001). Attitude (β = 0.498), perceived behavioral control (β = 0.333), and subjective norm (β = 0.141) significantly and positively influenced perceived value. Furthermore, perceived value served as a crucial partial mediator between the three TPB antecedents and behavioral intention. Notably, senior students facing clinical rotations exhibited the lowest intention to evaluate.DiscussionPerceived value acts as a critical psychological “gatekeeper” in behavioral decision-making. Stimulating intrinsic motivation (attitude) and reducing cognitive load (perceived behavioral control) are far more effective than imposing external Controlled motivation (subjective norm). To mitigate survey fatigue, educational institutions must foster “student agency” by establishing transparent closed-loop feedback systems, thereby rebuilding the perceived psychological utility of evaluations.