Prosocial risky behavior refers to voluntary actions undertaken to benefit others or collective welfare, while knowingly bearing potential risks of personal loss, including physical harm, economic cost, foregone developmental opportunities, or social interpersonal penalties. As a unique prosocial construct that integrates altruistic motivation and voluntary risk-taking, it is a cornerstone of social cohesion, emergency mutual aid, and collective well-being in both daily risky scenarios and large-scale public crises. However, existing research has predominantly focused on the predictors of low-risk, cost-free conventional prosocial behaviors (e.g., charitable donation, informal helping) or separately explored the determinants of individual self-interested risk-taking. Few studies have examined the socio-cognitive drivers of prosocial risky behavior, which requires the simultaneous activation of altruistic motivation and a willingness to bear personal costs, leaving a critical gap in both theoretical explanations and empirical evidence. In particular, no systematic research has investigated how social mobility beliefs shape individuals’ subjective positive expectations of upward socioeconomic mobility through personal effort and hard work, influencing their willingness to engage in altruistic acts that involve risk. To address this gap, an integrated theoretical framework synthesizing the social comparison theory, conservation of resources theory, and social identity theory is constructed. Two hypotheses were tested: (1) social mobility belief significantly and positively predicts prosocial risky behavior; and (2) personal relative deprivation, the negative cognitive-affective experience arising from unfavorable upward social comparisons, mediates the positive association between social mobility belief and prosocial risky behavior.

A sequential multi-study design with multi-method triangulation was adopted to establish a rigorous evidence chain from macro correlational association to causal effect identification, and finally to underlying psychological mechanism verification. For Study 1, data were extracted from the 2013 Chinese General Social Survey (CGSS), a nationally representative large-scale dataset, with a final valid sample of 3800 community-dwelling adults across China. Social mobility belief was measured via items capturing its two core dimensions (perceived opportunity fairness and social class boundary permeability); prosocial risky behavior was assessed through a validated high-stakes situational indicator; and the predictive effect was tested via binary logistic regression, with key demographic and socioeconomic covariates controlled. Study 2 adopted a between-subjects experimental design (n = 260) to verify the causal effect of social mobility belief, where belief was manipulated via a well-validated self-persuasion writing task, and prosocial risky behavior was measured by a computerized 20-scenario daily-life prosocial risk dilemma task. Study 3 was a cross-sectional questionnaire survey (n = 600), where standardized and well-validated scales were used to measure all core variables, and bootstrap mediation analysis was performed to preliminarily test the hypothesized mediating role of relative deprivation. Study 4 used an experimental causal chain design (n = 260) with an alternative text-comic reading manipulation paradigm to validate the full causal mediation pathway by sequential measurement of the mediator and outcome variable after experimental manipulation.

The results from the four studies were highly consistent and robust. Study 1 showed that social mobility belief significantly and positively predicted prosocial risky behavior after controlling for all covariates. Study 2 confirmed the causal effect: participants in the high social mobility belief condition exhibited a significantly higher rate of helping choices than those in the low belief condition. Study 3 revealed a significant partial mediating effect of relative deprivation, accounting for 9% of the total effect. Most critically, Study 4 validated the full causal mediation chain: experimentally induced high social mobility belief significantly reduced participants’ relative deprivation, and lower relative deprivation in turn significantly increased prosocial risky behavior. The indirect effect via relative deprivation was robustly significant, explaining 69% of the total effect, and the direct effect of social mobility belief became non-significant after including the mediator.

In conclusion, social mobility beliefs can effectively promote prosocial risky behavior, with the positive effect primarily channeled through reducing individual relative deprivation. The findings yield key theoretical contributions: the explanatory scope of social mobility belief is extended from conventional low-cost prosocial behavior to the domain of risky altruism; the affective psychological mechanism linking macro-societal structural belief to micro individual prosocial action is clarified; and an integrated theoretical explanation is provided for the dual requirements of altruism and risk-taking in prosocial risky behavior. The findings also offer evidence-based practical insights for social governance, especially in the context of China’s common prosperity initiative, indicating that fostering positive social mobility beliefs via equal opportunity policies can help mitigate relative deprivation, enhance social cohesion, and encourage courageous mutual aid in risk situations.