Throughout the history of psychology, researchers have always paid close attention to prosocial behavior in their exploration journey, as it highlights the brilliance of human nature when dealing with core psychological issues such as the relationship between oneself and others, oneself and groups, oneself and society in social life, as well as the interests of present and future, material and spiritual, individual and collective (Zhang and Kou 2019). It is crucial not only for maintaining positive interpersonal relationships but also for fostering a benevolent social mindset (Liu et al., 2022). Prosocial behavior encompasses actions by individuals in social interactions that adhere to social expectations and benefit others, groups, and society (Piff and Robinson, 2017). As the foundational element of moral behavior, it significantly impacts the occurrence of prosocial actions (Miles and Upenieks, 2021).

Moral sensitivity is the ability to recognize and interpret moral issues based on one’s experiences and understanding, specifically identifying when a situation presents a moral dilemma. It is a key component of moral cognition (Gao and Mao, 2024). This sensitivity involves perceiving the moral significance of various aspects of a situation, including interpreting others’ reactions and feelings, understanding causal chains and their impacts, and employing empathy and role-taking skills (Reynolds and Miller, 2015). Research shows that individuals with high moral sensitivity are more likely to engage in prosocial behaviors (French et al., 2018). Thus, moral sensitivity is crucial for the development of prosocial behavior, although the specific mechanisms through which it influences prosocial actions remain unclear. According to the four-component model of moral psychology, as individuals’ moral judgment, identity, and motivation evolve, the activation of moral sensitivity becomes increasingly indirect (Thoma and Bebeau, 2013). Moral disengagement and reciprocity norms are potential mediators in the relationship between moral sensitivity and moral behavior.

Moral disengagement refers to a cognitive mechanism that allows individuals to avoid self-sanction by disconnecting their actions from their internal moral standards (Schaefer and Bouwmeester, 2020). This process is crucial in both moral and immoral behavior (Jean et al., 2012). According to moral disengagement theory, while experiential self-regulation can typically suppress undesirable behavior, moral disengagement selectively renders self-regulation mechanisms ineffective, leading to a lack of guilt following moral transgressions (Gutzwiller-Helfenfinge, 2015). Empirical studies have shown that moral disengagement negatively predicts prosocial behavior; individuals with higher tendencies toward moral disengagement tend to exhibit lower prosocial tendencies (Killer et al., 2019). When individuals perceive that moral behavior involves personal costs or sacrifices, they may employ defensive strategies such as moral disengagement or reinterpretation of moral situations to justify alternative actions (Zhao and Kushnir, 2023). Thus, moral disengagement may mediate the effect of moral sensitivity on prosocial behavior. Reciprocity norms are prevalent in human societies and manifest across various social relationships, setting moral standards for giving and receiving help and forming fundamental principles in social exchanges (Guala, 2012).

Conversely, negative reciprocators are attuned to negative behaviors, remembering harm and retaliating with negative actions—returning resentment for resentment (Schug et al., 2016). Social exchange theory suggests that individuals internalize these norms to maintain balance in interpersonal relationships and psychological states, influencing whether they exhibit moral or immoral behavior (Jeung et al., 2017). Research shows that positive reciprocators are more likely to experience positive emotions like gratitude after receiving help, which fosters prosocial behavior (Leimgruber et al., 2014). In contrast, negative reciprocity is linked to negative emotions such as anger, which can reduce prosocial behavior (Wu et al., 2014). Given that moral sensitivity involves complex interactions between moral cognition and emotions (Zhou et al., 2024), individuals with high moral sensitivity are more likely to follow reciprocity norms, displaying corresponding positive or negative reciprocity behaviors (Van Baar et al., 2019). Thus, reciprocity norms may mediate the effect of moral sensitivity on prosocial behavior. Furthermore, moral disengagement may influence these norms. As a self-regulation process, individuals with high moral disengagement might adopt reciprocity norms such as “returning good for good and resentment for resentment” to alleviate the tension from not engaging in moral behavior, thus avoiding self-sanction (Jean et al., 2012). Consequently, moral disengagement might reduce positive reciprocity while increasing negative reciprocity. Therefore, it can be hypothesized that moral disengagement and reciprocity norms may serve as chain-mediators in the relationship between moral sensitivity and prosocial behavior.

In summary, this study aims to explore the impact of moral sensitivity on prosocial behavior and the multiple mediating effects of moral disengagement and reciprocity norms based on the four-component model theory of moral psychology. The following hypotheses are proposed: H1: Moral sensitivity is significantly positively correlated with prosocial behavior; H2: Moral disengagement mediates the relationship between moral sensitivity and prosocial behavior; H3: Reciprocity norms mediate the relationship between moral sensitivity and prosocial behavior; H4: Moral disengagement and reciprocity norms play a chain-mediating role in the relationship between moral sensitivity and prosocial behavior.

Through an investigation involving 567 college students, the study found that moral sensitivity positively predicted prosocial behavior both directly and through the mediating factor of positive reciprocity. Conversely, moral sensitivity negatively predicted prosocial behavior through moral disengagement and negative reciprocity, respectively. Additionally, significantly negative mediating effects were observed in the relationship between moral sensitivity and prosocial behavior, mediated by moral disengagement via positive or negative reciprocity.

Firstly, the study found a significant positive correlation between moral sensitivity and prosocial behavior, thereby confirming Hypothesis 1 (H1). This result is consistent with the four-component model of moral psychology and aligns with previous research (Xiang et al., 2022). Moral sensitivity, defined as a heightened awareness and interpretative tendency based on moral values (Zhao and Kushnir, 2023), leads individuals to perceive social information through a moral lens, eliciting stronger cognitive and emotional responses in moral situations (Gao and Mao, 2024). Moreover, moral sensitivity reflects an individual’s level of virtue. Those who perceive and are inspired by virtue are more likely to engage in and commit to prosocial behavior (Li and Hu, 2023).

Secondly, the study supports Hypothesis 2 (H2) by demonstrating that moral disengagement mediates the relationship between moral sensitivity and prosocial behavior. This finding aligns with moral disengagement theory, which suggests that self-regulation mechanisms can promote prosocial behavior. However, individuals with high moral sensitivity might experience impaired self-control, leading them to selectively disregard self-regulation processes. Consequently, they may avoid significant guilt or self-reproach for failing to engage in moral behavior (Gutzwiller-Helfenfinge, 2015). Zhou et al. (2024) further argue that individuals with high moral sensitivity might rationalize or deny responsibility for prosocial actions due to perceived costs, opting instead for alternative behaviors. This is consistent with previous research showing that lower levels of moral disengagement are linked to higher levels of prosocial behavior (Killer et al., 2019). Moral disengagement can be viewed as a cognitive bias that enables individuals to deny responsibility for immoral actions, thereby suppressing prosocial behavior. Lower moral disengagement facilitates self-reflection on attitudes and behaviors, encouraging prosocial actions. In contrast, higher levels of moral disengagement can obscure behavioral outcomes and lead to more immoral actions. Therefore, reducing moral disengagement is a crucial factor in fostering prosocial behavior among college students.

Additionally, the study confirms Hypothesis 3 (H3), demonstrating that moral sensitivity influences prosocial behavior through reciprocity norms. Moral sensitivity enhances individuals’ moral cognition and emotional responses, which in turn shape their reciprocity norms in social interactions. Individuals with high moral sensitivity are more perceptive of moral issues in social contexts and react accordingly (Sparks, 2015). When considering long-term exchanges and relationship balance in interpersonal interactions, people tend to reciprocate in kind, mirroring the behaviors others have shown toward them (Valle et al., 2018). The impact of reciprocity norms on prosocial behavior varies: individuals with positive reciprocity norms are more likely to engage in prosocial actions driven by feelings of gratitude, whereas those with negative reciprocity norms may focus on negative behaviors, leading to emotions such as anger that inhibit prosocial behavior. Thus, reciprocity norms are crucial in mediating the relationship between moral sensitivity and prosocial behavior.

The findings of the study also support Hypothesis 4 (H4), indicating that moral disengagement and reciprocity norms serve as chain mediators between moral sensitivity and prosocial behavior. When individuals with high moral sensitivity perceive the costs of engaging in prosocial behavior as significant, they may resort to moral disengagement to comply with reciprocity norms, which can lead to a focus on negative interpersonal behaviors. College students, who are in a crucial phase of developing stable values, may encounter social issues or exhibit immoral behaviors influenced by negative reciprocity norms (Stijnen and Dijker, 2011). In contrast, individuals with lower levels of moral disengagement are more likely to embrace positive reciprocity norms. This tendency enhances long-term social interactions, improves self-perceptions, and reduces mistaken beliefs about immoral behavior, thereby fostering prosocial actions. The emergence of prosocial behavior among college students is influenced by their moral cognition, emotions, and reciprocity tendencies in response to both cognitive and emotional factors.

The study still has limitations. First, the cross-sectional design of this study limits the ability to explore the dynamic interactions between moral sensitivity and prosocial behavior. An individual’s moral sensitivity can influence the development of prosocial behavior, which in turn can enhance moral sensitivity over time. Future research should employ longitudinal study designs to explore these dynamics in greater depth. Secondly, this study examined the impact of moral sensitivity on prosocial behavior from a single perspective. Moral sensitivity influences attentional biases, memory biases, and interpretative biases related to moral components, and may also interact with emotions such as empathy, guilt, and gratitude (Zhao and Kushnir, 2023). Future research could integrate cognitive variables (such as attention bias and memory bias) and emotional variables (such as empathy and gratitude) to further explore the mechanisms and boundary conditions of moral sensitivity’s influence on prosocial behavior, contributing to the development of interventions and educational strategies for enhancing moral sensitivity.

Despite its limitations, the study presents several advantages. Firstly, it reveals that moral sensitivity is significantly and positively correlated with moral disengagement, positive reciprocity, negative reciprocity, and prosocial behavior. Secondly, the study demonstrated that moral sensitivity influences prosocial behavior through the mediating roles of moral disengagement and reciprocity norms, as well as the chain-mediating role of both moral disengagement and reciprocity norms. This research underscores the intricate roles of moral disengagement and reciprocity norms in amplifying prosocial behavior through moral sensitivity. These insights are crucial for developing and promoting prosocial behavior norms among college students.

Moral sensitivity is significantly positively correlated with moral disengagement, positive reciprocity, negative reciprocity, and prosocial behavior. Moral disengagement is significantly negatively correlated with positive reciprocity and prosocial behavior, and significantly positively correlated with negative reciprocity; Prosocial behavior is significantly positively correlated with positive reciprocity and negatively correlated with negative reciprocity.

Moral disengagement and reciprocity norms played multiple mediating roles between moral sensitivity and prosocial behavior. Specifically, moral sensitivity affected prosocial behavior through the independent mediating effect of moral disengagement, reciprocity norms, as well as the chain mediating effect of moral disengagement and reciprocity norms.