Indebtedness is an internal discomfort experienced by an individual upon receiving help or gifts from others, accompanied by negative emotions driven by a perceived obligation to reciprocate [12,13]. It is noteworthy that, in addition to indebtedness, receiving favors can also elicit gratitude. However, research indicates that gratitude and indebtedness are distinct emotional responses. Gratitude is an other-focused emotion characterized by appreciation and thankfulness, which functions to foster and strengthen social bonds [14]. In contrast, indebtedness is an uncomfortable self-focused emotion, which is more likely to trigger or exacerbate social anxiety [10].

According to the regulatory focus theory [15], individuals who experience a strong sense of indebtedness tend to become self-focused and scrutinize the motives behind the benefactors’ help to assess the extent of their indebtedness. From the perspective of cognitive theories of social anxiety [8], this heightened self-monitoring centered on “repaying renqing”—a specific manifestation of debt within renqing culture—can lead individuals to develop a negative self-image characterized by the belief that they appear ungrateful or unable to reciprocate. Consequently, this negative self-perception may trigger avoidance and control behaviors as protective mechanisms, thereby maintaining and exacerbating social anxiety. Existing research has suggested that the social pressure associated with indebtedness hindered the development of effective interpersonal skills, further contributing to social anxiety [10,16].

Based on these findings, Hypothesis 1 is proposed: Indebtedness significantly predicts social anxiety among university students.

From the perspective of Acceptance and Commitment Therapy (ACT) [17,18], psychological inflexibility, as the opposing concept to psychological flexibility, encompasses two core processes: experiential avoidance and cognitive fusion. Experiential avoidance refers to the tendency of psychologically inflexible individuals to avoid or suppress distressing personal experiences [18]. Cognitive fusion is characterized by becoming so absorbed in one’s own thoughts and emotions that they are perceived as external realities [18].

As posited by the cognitive model of social anxiety [8], when individuals are driven by feelings of indebtedness and engage in continuous monitoring and calculation of “renqing,” they may develop a series of coping strategies that function similarly to safety behaviors. These may include excessive compensation towards the benefactor, avoidance of social interactions until the debt is repaid, or making commitments that exceed their capabilities. From the perspective of ACT [17], these behaviors essentially reflect a core process of psychological inflexibility: individuals become cognitively fused with the belief that “I must perfectly repay my debts,” solidifying this belief into an absolute fact. Consequently, they employ experiential avoidance strategies to escape the internal discomfort associated with their indebtedness and external social situations. Such rigid coping mechanisms hinder the individual’s ability to revise and empirically test the belief that “social interactions do not necessarily lead to negative evaluations,” thus perpetuating and exacerbating social anxiety.

Empirical research supports the significant role of psychological inflexibility in the formation of social anxiety [19-21]. For instance, a longitudinal study found that experiential avoidance among adolescents plays a substantial mediating role between empathy and social anxiety [19]. This indicates that psychological inflexibility is not merely a correlational factor of social anxiety but serves as a critical mechanism that transmits and amplifies anxiety within the cognitive-affective process.

Therefore, this study proposes Hypothesis 2: psychological inflexibility mediates the relationship between indebtedness and social anxiety among university students.

As discussed, in many East Asian societies, particularly China, the renqing—a culturally specific expression of reciprocity—serves as a foundational framework that governs and shapes interpersonal interactions [22]. Huang’s theory of renqing posits that the concept encompasses three key dimensions [22,23]: First, there exists a fundamental emotional connection among individuals, wherein each person has the ability to understand and empathize with the emotional struggles of others, encapsulated in the adage, “Everyone has a heart of compassion.” This aspect is referred to as renqing affection [22,23]. Second, renqing permeates the entire process of giving and receiving favors within interpersonal exchanges, thereby transforming these interactions into a form of social capital, as reflected in the saying, “Accumulating social capital in daily life enables its mobilization during crises.” This dimension is designated as renqing resource [22,23]. Lastly, when an individual receives assistance from others, there is an inherent obligation to acknowledge and reciprocate that kindness, exemplified by the saying, “A small favor should be repaid with a great kindness.” This aspect is identified as renqing norm [22,23].

However, significant differences exist in individuals’ interpretations of renqing [24,25]. According to the renqing theory [22], when individuals primarily perceive these renqing as rigid rules of norm that lack emotional depth (such as the strict principle of “tit-for-tat”), the severity of this negative interpretive bias enhances the transformation of feelings of indebtedness into psychological inflexibility, ultimately resulting in cognitive and behavioral inflexibility. The cognitive theory of social anxiety posits that this reinforced state of psychological inflexibility impedes individuals’ ability to respond flexibly to social situations, thereby making them more likely to become ensnared in an anxiety cycle maintained by self-focus and threat interpretation [8]. Consequently, the moderating role of renqing is primarily manifested in strengthening the association between feelings of indebtedness and psychological inflexibility, which indirectly exacerbates the trajectory of social anxiety development.

Empirical studies have demonstrated that individuals from East Asian cultures are more profoundly impacted by renqing norm than their counterparts from Western cultures, resulting in a heightened sense of indebtedness within social interactions [26]. Additionally, the pressure to repay indebtedness drove individuals to adopt an inflexible pattern of reciprocity in order to quickly restore equality in the relationship [27].

Thus, this study proposes Hypothesis 3: renqing moderates the relationship between indebtedness and psychological inflexibility among Chinese university students.

In summary, this study aims to explore the relationship between indebtedness and social anxiety, along with the underlying mechanisms. Notably, the study will specifically examine the moderating role of renqing, a concept deeply embedded in Chinese culture, in the functioning of indebtedness. The hypothesized model for this study is shown in Figure 1.

The study utilized a cluster sampling method, surveying students from two universities in the Inner Mongolia region, with classes serving as the sampling units. The sample size was determined using WebPower R [28], which indicated that a minimum of 520 participants was required to achieve a statistical power of 0.80. The study received approval from the Ethics Review Committee of the School of Psychology at Inner Mongolia Normal University (number of approval: 23060102). Informed consent was obtained from all participants, who were fully informed of their voluntary participation, confidentiality, and the right to withdraw at any time.

A total of 600 questionnaires were distributed. After excluding invalid responses, 547 valid questionnaires were retained, yielding an effective response rate of 91.17%. Participants’ ages ranged from 17 to 25 years (M=19.33, SD=1.95), with 167 males (30.53%) and 380 females (69.47%). Among the participants, 183 were freshmen (33.46%), 249 were sophomores (45.52%), 79 were juniors (14.44%), and 36 were seniors (6.58%).

The data were processed and analyzed utilizing SPSS 25.0, Mplus 8.3, and PROCESS 3.5. Initially, SPSS 25.0 was employed to perform descriptive statistics and conduct correlation analysis. Subsequently, Mplus 8.3 was used for confirmatory factor analysis. PROCESS 3.5 (model 14) was utilized to construct a moderated mediation model, investigating the role of psychological inflexibility as a mediator and the impact of renqing norm as a moderator. Given the influences of gender, age, and grade on social anxiety [36], this study controlled for these variables in the structural equation modeling analysis. Furthermore, 95% confidence intervals (CIs), derived from 5,000 bootstrap samples, were implemented to evaluate the moderated mediation effect. Prior to the analyses, all quantitative variables were standardized.

Harman’s single-factor test was conducted to assess potential common method bias [37,38]. The results indicated that 12 factors had eigenvalues greater than 1. The total variance explained by the first common factor was 19.22%, which is below the critical threshold of 40%, indicating no significant common method bias in this study.

The means, standard deviations, and correlations for all variables are presented in Table 1. The results indicated that there was no significant correlation between social anxiety and renqing (r=-0.06, p=0.15), as well as between social anxiety and the two dimensions of renqing, affection (r=0.05, p=0.22) and norm (r=-0.07, p=0.10). Furthermore, the norm dimension of renqing was not significantly correlated with psychological inflexibility (r=-0.002, p=0.96). All other variables exhibit significant positive correlations.

After the data were standardized, the mediation effect of psychological inflexibility was conducted following the mediation effect testing procedure outlined by Wen et al. [39]. First, a total effect model of indebtedness on social anxiety was constructed. The results indicated that indebtedness significantly predicted both social anxiety (β=0.30, standard error [SE]=0.04, p<0.001, 95% CI [0.22, 0.38]). Next, psychological inflexibility was incorporated as a mediator, and a simple mediation model was developed. The results indicated that indebtedness significantly predicted psychological inflexibility (β=0.39, SE=0.04, p<0.001, 95% CI [0.31, 0.47]). When both variables were included in the model, indebtedness (β=0.18, SE=0.04, p<0.001, 95% CI [0.10, 0.26]) and psychological inflexibility (β=0.32, SE=0.04, p<0.001, 95% CI [0.23, 0.40]) significantly predicted social anxiety. The bias-corrected bootstrap method revealed that psychological inflexibility significantly mediated the relationship between indebtedness and social anxiety, the effect was 0.12 (SE=0.02, 95% CI [0.08, 0.17]), with the confidence interval excluding zero. Therefore, psychological inflexibility mediates the relationship between indebtedness and social anxiety, accounting for 40% of the total effect.

The results presented in Table 2 indicated that the interaction between indebtedness and renqing affection did not significantly predict psychological inflexibility (β=-0.02, SE=0.03, t=-0.63, p=0.53), with a 95% CI [-0.08, 0.04]. Similarly, as shown in Table 3, the interaction between indebtedness and renqing resource did not significantly predict psychological inflexibility (β=0.09, SE=0.05, t=1.95, p=0.051, 95% CI [-0.002, 0.19]), with the confidence interval including zero.

The results in Table 4 indicated that the interaction between indebtedness and renqing norm significantly predicted psychological inflexibility (β=0.13, SE=0.04, t=3.69, p<0.001), with a 95% CI [0.06, 0.20]. At low levels of renqing norm (M-SD), the mediation effect of psychological inflexibility was 0.09 (SE=0.02, 95% CI [0.05, 0.14]). At the average level (M), the effect was 0.13 (SE=0.02, 95% CI [0.09, 0.18]). At high levels (M+SD), the effect was 0.17 (SE=0.03, 95% CI [0.11, 0.23]). Further analysis revealed a significant difference in the mediation effects between low and high renqing norm, with a difference of -0.08 (p<0.01, 95% CI [-0.03, -0.14]). These findings suggest that renqing norm moderate the mediation effect of psychological inflexibility on the relationship between indebtedness and social anxiety.

To further clarify the interaction effect between indebtedness and renqing norm, renqing norm were divided into high and low groups by adding or subtracting one standard deviation from the mean, and a simple slope test was performed. As shown in Figure 2, indebtedness significantly predicted psychological inflexibility when renqing norm were at a lower level (β_simple=0.28, t=5.16, p<0.001, 95% CI [0.17, 0.39]). When renqing norm were at a higher level, the positive predictive effect of indebtedness on psychological inflexibility was strengthened (β_simple=0.44, t=8.94, p<0.001, 95% CI [0.34, 0.54]). However, it is noteworthy that at lower levels of renqing norm, individuals with low indebtedness demonstrated higher psychological inflexibility, whereas those with high indebtedness exhibited decreased psychological inflexibility.

This study validated Hypothesis 1, showing that those with a high level of indebtedness was more likely to experience social anxiety. This finding not only aligns with previous research conclusions but also supports the explanatory framework of cognitive theories on social anxiety [10]. As a culturally contextualized form of self-focus, the sense of indebtedness stemming from receiving help heightens individuals’ concerns about interpersonal inequality and negative social evaluations. While fearing the possibility of leaving a negative impression on others, individuals are repeatedly compelled to adopt an “observer perspective,” monitoring whether they fulfill their obligations to reciprocate, leading to the development of social anxiety [8].

This study also validated Hypothesis 2, demonstrating that psychological inflexibility serves as a mediating factor between the sense of indebtedness and social anxiety. From the perspective of cognitive theories of social anxiety [8], the persistent self-focus induced by indebtedness first solidifies into a state of psychological inflexibility through two mechanisms: cognitive fusion (becoming overly entrenched in the identity of the “debtor” and associated negative thought patterns) and experiential avoidance (escaping emotions and social situations related to receiving help). This psychological inflexibility subsequently restricts the individual’s cognitive and behavioral flexibility in social contexts, making it difficult to break free from the cycle of negative self-representation and exacerbating fears and avoidance of social evaluation [19]. These findings corroborate the internal process proposed by cognitive theory wherein cognitive-emotional inflexibility sustains social anxiety [8], and further reveal that indebtedness systematically intensifies individuals’ anxiety experiences in interpersonal interactions by facilitating cognitive fusion and experiential avoidance.

Building on the validation of Hypothesis 3, this study reveals that only the moderating effect of renqing norm is significant in the relationship between indebtedness and psychological inflexibility. Overall, higher levels of renqing norm intensify the detrimental impact of indebtedness on psychological inflexibility. Furthermore, this moderating effect of renqing norm exhibits a degree of asymmetry among individuals, suggesting variations in its influence. This phenomenon can be coherently interpreted through the framework of cognitive models of social anxiety [8]. Specifically, for individuals with high sensitivity to renqing norm, these explicit social rules function as a protective “cognitive script” under conditions of low indebtedness, providing clear guidelines that reduce ambiguity and potential psychological distress. However, in situations of high indebtedness—characterized by heightened self-focused attention—the same norm is interpreted through a negative explanatory bias, morphing into “rigid constraints.” This bias amplifies the perceived obligation for strict reciprocity, intensifying cognitive fusion with obligatory thoughts and promoting behavioral avoidance. Consequently, this process accelerates psychological inflexibility and perpetuates social anxiety. Moreover, when individuals experience a high sense of indebtedness, even perceptions of low renqing norm are constrained by the intense self-focus associated with high indebtedness, thus failing to ameliorate resulting psychological rigidity and ultimately leading to the development of social anxiety.

This dynamic highlights that the sense of indebtedness has a stronger facilitating effect on psychological inflexibility and social anxiety compared to renqing norm. The sense of indebtedness reflects an individual’s intrinsic self-focus, whereas renqing norm signifies cognitive biases in one’s responses to the external world. Lin et al. [40] found that individuals with high social anxiety exhibit significantly greater attention towards self-relevant stimuli that represent their internal anxiety states, as opposed to focusing on positive, neutral, or negative feedback related to external evaluations. In light of our findings, it is highly probable that, within the context of social anxiety, self-focus (such as the “sense of indebtedness”) emerges as a more dominant and central characteristic than the attentional bias towards negative external information (such as the “negative interpretation of renqing norm”) [11].

This study investigates the mediating mechanism by which the sense of indebtedness influences social anxiety through psychological inflexibility. It further elucidates the boundary role of renqing as a moderating variable, thereby validating the cognitive model of social anxiety from the perspective of Chinese renqing culture. Building upon this foundation, the research reveals that Chinese university students tend to conceptualize renqing more as a tool or obligation-based “principle” rather than a form of emotional connection. This suggests that future research could explore how the connotation of renqing is reconstructed in cross-cultural contexts (e.g., among overseas Chinese or Asian immigrant communities) as a function of cultural adaptation and identity integration, and how these reconstructions differentially impact the relationship between feelings of indebtedness and anxiety [11].

Moreover, the conclusions of this study are rooted in the sociocultural context of China, prompting the potential for cross-cultural comparative research to systematically examine whether the relationships among feelings of indebtedness, perceptions of renqing, and social anxiety manifest differently in societies that share a similar collectivist orientation but have distinct interpersonal norms (such as certain regions in Africa) [41]. This could help clarify both cultural commonalities and specificities.

Finally, this study found that renqing is not directly related to social anxiety, and that the moderating effect of renqing interacts with feelings of indebtedness in an asymmetric manner, but only at the level of norm. Therefore, when designing interventions for renqing education [42], educators should carefully consider the cognitive differences individuals exhibit regarding renqing—particularly distinguishing between those with high and low levels of indebtedness. Implementing differentiated guidance strategies, such as employing gratitude interventions that enhance individuals’ awareness of relational development in reciprocal exchanges [27], can not only prevent individuals with high indebtedness from exacerbating psychological inflexibility and anxiety due to a rigid understanding of renqing, but also help those with low levels of indebtedness better leverage the adaptive functions of renqing. Consequently, this approach can lead to a more precise and effective reduction of social anxiety risks on a holistic level.

This study has several limitations. First, it has reaffirmed the negative impact of indebtedness on university students’ interpersonal adaptation. However, from the perspective of reciprocal exchange, indebtedness can also motivate individuals to take action to restore interpersonal fairness [43]. Therefore, under what circumstances does indebtedness exert a negative effect, and when does it have a positive impact? This remains a question to be explored further in future research. Second, due to the cross-sectional design of this study, it is unable to establish causal relationships. Future research could employ longitudinal network analysis to comprehensively examine the various factors contributing to social anxiety, uncovering the dynamic changes and interactions among variables [19]. This approach would offer a more nuanced understanding of the mechanisms through which indebtedness influences social anxiety. Third, this study has limitations in terms of demographic characteristics within the university student population. Future research should broaden the sampling range by selecting students from various regions and different types of higher education institutions to test the generalizability of the current model. Additionally, it is essential to enhance the statistical analysis of other demographic variables (such as ethnicity and residence) in order to control for their potential influences on the primary variables. Furthermore, the inclusion of a social desirability scale or the implementation of anonymous testing methods can help mitigate the effects of social desirability. Efforts should also be made to balance gender ratios and expand both the sample size and participant diversity to enhance the representativeness and ecological validity of the research findings.