Challenging the golden mean: Testing the inverted U-shaped relationship between trait self-control and subjective well-being among Chinese adolescents.

Self-control (SC) is a robust predictor of subjective well-being (SWB), and a positive linear relationship between them is often taken as the default assumption. However, some perspectives suggest that excessive SC may diminish SWB, implying an inverted U-shaped relationship. This study examined this inverted U-shaped hypothesis among Chinese adolescents, who are raised in a culture emphasizing moderation. We analyzed five samples (total N = 25,936), including four cross-sectional samples, two of which were nationally representative, and a three-wave longitudinal sample collected over two years. Participants ranged from middle school to university students, with SC assessed via self- and parent-report, and SWB through multiple indicators including positive and negative affect, life satisfaction, and one-item happiness assessment. Quadratic regression analyses and Simonsohn's two-lines test found no inverted U-shaped relationship between SC and SWB in five samples. Instead, SC consistently correlated positively with SWB across samples, regardless of measurement methods or whether data were cross-sectional or longitudinal. These findings reinforce the notion that higher SC contributes to greater SWB, with no indication of an inverted U-shape in Chinese culture. Encouraging the development of SC in adolescents might be a beneficial approach to enhancing long-term well-being, without concerns about unintended negative consequences.