Abstract:

This meta-analysis resolves a longstanding debate about sadness's impact on prosocial behavior through an innovative three-level modeling approach, systematically integrating 41 studies (70 effect sizes, N = 10,173) spanning nearly 50 years. Challenging conventional views that predominantly emphasize sadness's negative effects, we found a weak but significant positive correlation between sadness and prosocial behavior. This finding provides robust empirical support for the perspective that sadness can indeed promote prosocial actions, moving beyond the traditional notion that it necessarily inhibits such behaviors. Our methodological innovations are crucial for the robustness of these findings: (1) We employed a three-level meta-analysis framework, which effectively addresses the limitations of traditional meta-analyses' effect size independence assumption by decomposing variance into sampling error, within-study, and between-study components. This allows for a more precise parsing of different-level variables' contributions and a systematic examination of individual and contextual moderating factors. (2) Comprehensive bias controls, including p-curve analysis (confirming the effect's authenticity and ruling out publication bias or p-hacking), funnel plots, and Egger's regression, were rigorously applied to ensure the reliability of our results. (3) Rigorous sensitivity analyses, using a leave-one-out method, further demonstrated the stability and robustness of our findings, indicating that the overall effect was not driven by any single study or outlier.
Moderation effect analysis revealed that age stage is a crucial moderator of the relationship between sadness and prosocial behavior, with correlations peaking during young adulthood and exhibiting a nonlinear trend. This suggests that sadness's prosocial effects dynamically change with individual development, closely associated with emotional cognitive maturation and moral development. In contrast, factors such as gender, sadness induction methods, sadness assessment approaches, prosocial behavior classification, and sadness types showed no significant moderating effects. This indicates a high cross-contextual consistency in sadness's impact on prosocial behavior, suggesting that the underlying mechanisms are broadly applicable across various contexts and forms of sadness.
Theoretically, by integrating emotion regulation theory, the negative state relief model, and the appraisal tendency framework, this study elucidates two primary pathways through which sadness promotes prosocial behavior: self-focused helping motivation driven by emotional repair and compensatory social connection needs triggered by a low sense of control. These mechanisms work together, enabling sadness to stimulate prosocial behavior. The research results offer a new perspective on the prosocial transformative potential inherent in sadness, suggesting that sadness, often perceived negatively, can serve an adaptive function in fostering social connection and altruism. These advances provide robust evidence that sadness can motivate prosocial actions, suggesting new intervention approaches that harness this adaptive potential. For instance, emotional interventions could focus on creating favorable conditions to guide sadness experiences toward promoting social connection, rather than solely aiming to alleviate the emotion.
Despite these significant contributions, the study has limitations. There was a low proportion of longitudinal research and trait sadness studies, which limits the understanding of long-term effects and the distinction between state and trait sadness. Additionally, the cross-cultural sample was imbalanced, with a predominance of Western samples, which may limit the generalizability of the findings. Future research should examine underlying mechanisms more deeply, explore sadness subtypes with more balanced samples, and investigate cross-cultural and developmental variations across the entire life cycle to further clarify this complex relationship. This work redefines sadness as a nuanced social emotion with important implications for psychological theory and practice, providing a more comprehensive understanding of its role in human social behavior.

Key words: sadness, prosocial behavior, three-level meta-analysis, moderating effect