Bullying involves repeated aggressive behavior mounted by a relatively stronger party against a weaker individual who is unable to protect themself (Salmivalli, 2010). Bullying among students in schools has become a significant social issue encountered in countries worldwide (Due et al., 2005) that can greatly undermine the mental and academic adaptation of both the bully and the victim (Hawker & Boulton, 2000; Troop-Gordon, 2017), resulting in severe anxiety (Nishina & Juvonen, 2005) and mental health problems (Rivers et al., 2009). Bystanders witnessing the bullying may also have negative effects: Nishina and Juvonen (2005) found that witnessed peer harassment was associated with increases in daily anxiety, and Rivers et al. (2009) found that observing bullying at school predicted risks to mental health.

Many researchers have confirmed that most bullying is witnessed by bystanders (Andreou & Metallidou, 2004; Chen et al., 2020; Goossens et al., 2006; Pouwels et al., 2016; Salmivalli et al., 1996; Sutton & Smith, 1999). In the mid-1990s, school bullying researchers gradually shifted from the dyadic approach to group process by moving their focus from the bully and the victim to the different behavior patterns of bystanders who affect the bullying (Yun, 2020). Salmivalli and colleagues (1996) proposed four roles that bystanders can play in school bullying: (a) assistants who actively join the bullying, (b) reinforcers who usually laugh or provide an audience for the bullying, (c) outsiders who do nothing or stay outside the bullying situation, and (d) defenders who demonstrate supportive behavior and attempt to stop the bullying. Although the majority of bystanders do not intervene in the bullying, defenders are effective in stopping bullying within 10 seconds in most cases (Hawkins et al., 2001). Victimized students who have benefited directly from bystander defending report higher self-esteem, peer acceptance, and popularity than their undefended peers do (Sainio et al., 2011). In contrast, reinforcer and assistant bystanders show support for the bully, and outsider bystanders indicate acquiescence and tolerance of the bullying. Such bystander behavior serves to reinforce the bully’s aggressive behavior and leads to continued bullying (O’Connell et al., 1999; Salmivalli et al., 1996).

In the context of bullying at school, the more that students are indifferent to bullying, the fewer defenders there are, and the more bullying incidents occur (Salmivalli, 2014; Salmivalli et al., 2011). According to related findings, in school bullying incidents outsiders account for the highest proportion of bystanders (Goossens et al., 2006; Pouwels et al., 2016), and defenders for the lowest (Fluke, 2016; Hymel et al., 2015). Therefore, it is essential to understand the contextual and psychological antecedents of bullying that will enable change in the silence of outsiders, elimination of the distraction from reinforcers, and prevention of help from assistants. We examined whether and how the family functioning (contextual variable) and moral disengagement (social cognitive variable) influence Chinese adolescents’ bystander behavior in bullying incidents.

Literature Review and Hypothesis Development

Family Functioning and Adolescent Bystander Behavior

From an ecological perspective (Bronfenbrenner, 1979), the family has an enduring effect on adolescents’ psychological development. Family factors may contribute to bullying involvement; for example, in a study conducted with children and their mothers, Georgiou (2008) found that having a responsive mother negatively predicts children’s bullying behavior, and having a demanding mother negatively predicts their victimization. Similarly, researchers have found that when parental attachment security is stronger (Murphy et al., 2017) and family members communicate more easily with one another (Spriggs et al., 2007), there is less child involvement in bullying. These results imply that positive family factors, such as secure parental attachment and parental responsiveness, decrease the likelihood of children in those families bullying others.

Some scholars have looked more closely at the relationship between family factors and bullying bystander behavior. Stronger parental attachment security has been found to be associated with a greater likelihood of defending (Murphy et al., 2017; Nickerson et al., 2008), but not with being an outsider (Murphy et al., 2017). Other researchers have shown that restorative parental discipline, family climate, and parental support were directly and indirectly related to adoption of the defender role (Valdés-Cuervo et al., 2018). However, family factors (e.g., parental attachment) are only a partial reflection of the family ecosystem from the perspective of parent–child affectional bond or interaction with others.

According to the McMaster family functioning model (Epstein et al., 1983; Miller et al., 2000), one part of the family ecosystem cannot be understood in isolation from the rest. Thus, more emphasis should be placed on family functioning, which refers to the quality of life at the systemic level, and comprises problem solving, communication, roles, affective responsiveness, affective involvement, behavior control, and general functioning. Family functioning is viewed as a comprehensive variable that affects the psychological development of family members (Olson, 1993). There is considerable evidence suggesting that family functioning is a powerful predictor of adolescents’ psychological well-being (Shek, 2002), depression (Tamplin & Goodyer, 2001), and externalization of problems (Henderson et al., 2006). Among the few researchers who have examined the relationship between family functioning and bullying-related behavior, Mazzone and Camodeca (2019) found that adolescents who had been exposed to a higher level of family functioning were more likely to perform defending behavior, and less likely to perform assistant, reinforcer, and outsider behavior, and vice versa, but these associations were nonsignificant in the regression model. They proposed that several sociocontextual factors (e.g., peer group, relationship with the teacher), rather than family functioning, may have a more prominent role in explaining bullying and defending behavior. For example, Murphy et al. (2017) found that outsider behavior was not significantly associated with family functioning, which may be because outsiders with mixed personality characteristics and differences in familial background do not constitute a homogeneous group.

Although a growing number of researchers have examined peer bystander behavior in bullying incidents and its relationship to family factors, there are three limitations in the literature. First, most empirical studies have focused on some aspects of adolescents’ bullying bystander behavior (Caravita et al., 2012; Mazzone & Camodeca, 2019; Nickerson et al., 2008; Pozzoli & Gini, 2010), but they have not examined in detail all bullying bystander behavior, especially the reinforcer and assistant behaviors. Second, a limited number of researchers examining family factors related to bystander behavior have focused on variables such as parent attachment and communication, which are only a partial reflection of the family system (Murphy et al., 2017; Nickerson et al., 2008). Third, as previous studies have been conducted predominately in Western cultures, relatively little is known about bystander behavior in Mainland China (Xie & Ngai, 2020; W. Zhang et al., 2016). Chinese people, influenced by Confucian culture and collectivism, strongly emphasize maintaining social harmony and the importance of family. Thus, the family continues to be dominant in Chinese adolescents’ interpersonal life and plays a very important role in their adjustment (Bao et al., 2015). Cultural differences have been identified between countries in the Western world and China in terms of bullying bystander behavior and family functioning. For instance, Chen et al. (2020) found that in bullying incidents, 35.4% of Chinese adolescents took the role of defender, a higher percentage than for any other participant role, whereas outsider was the most common role in studies conducted with students in Finland (Salmivalli et al., 1996) and in the Netherlands (Pouwels et al., 2015). Thus, we proposed that the influence of family functioning on bystander behavior in China would also differ from the findings of studies conducted in Western cultures, and we formed the following hypotheses:
Hypothesis 1a: Family functioning will have a positive impact on defending behavior in bullying incidents in China.
Hypothesis 1b: Family functioning will have a negative impact on bystander behavior other than defending in bullying incidents in China.

Mediating Role of Moral Disengagement

Moral disengagement, which is conceptualized within the framework of social cognitive theory of moral agency, refers to a series of psychological mechanisms through which people can justify their negative behavior morally without the constraint of self-sanctions (Bandura, 1986; X. Wang & Yang, 2010). According to social cognitive theory, people usually have personal standards to guide good behavior and deter bad behavior (Bandura et al., 1996). However, these standards can be deactivated selectively through moral disengagement, such as cognitive restructuring, advantageous comparison, and diffusion of responsibility (Bandura, 1999). Harmful behavior is, thus, cognitively reconstructed to make it appear less harmful or not harmful at all to oneself and to others. Many researchers have shown that moral disengagement is positively associated with problem behaviors, such as bullying (Bao et al., 2015; Hymel et al., 2005; Obermann, 2011; Thornberg et al., 2015) and negatively associated with prosocial behavior (Bandura et al., 1996). In longitudinal research, scholars have also confirmed these associations, showing that moral disengagement positively predicts future bullying (Sticca & Perren, 2015; C. Wang et al., 2017).

Few studies have been conducted on the relationship between moral engagement and bystander versus bullying behavior. The previous findings regarding the relationship between moral disengagement and bystander defending have not been consistent, with some confirming a negative relationship (Gini, 2006; Gini et al., 2011; Menesini et al., 2003; Pozzoli & Gini, 2010; Thornberg & Jungert, 2014). For example, Gini et al. (2020) found that moral disengagement was significantly and negatively associated with defending, which is consistent with Bandura’s (1986) theory of moral agency. However, other researchers have found this association is present only under specific conditions, such as low empathy and sympathy for the victim (Thornberg et al., 2015), or among girls in their late childhood (Caravita et al., 2012). Similar findings have been reported in outsider behavior studies, with some researchers proposing a positive correlation between moral disengagement and outsider behavior (Doramajian & Bukowski, 2015; Gini et al., 2020). Others have reported a negative correlation (Mazzone & Camodeca, 2019) or even no relationship that reaches significance (Mazzone et al., 2016). Gini (2006), who examined the relationships between moral disengagement and reinforcer and assistant behavior among children, found that reinforcers and assistants (vs. defenders) scored significantly higher on moral disengagement, and that there was a positive correlation between moral disengagement and assistant and reinforcer behaviors. Therefore, we proposed the following hypotheses:
Hypothesis 2a: Moral disengagement will have a negative impact on defending behavior in bullying incidents in China.
Hypothesis 2b: Moral disengagement will have positive impact on bystander behavior other than defending in bullying incidents in China.

However, little is yet known about the developmental precursors of disengagement regarding its crucial role in adolescents’ bystander behavior. As suggested in social cognitive theory, children’s moral behavior standards are formed within their social cultural context. Children learn through observation of how others’ behavior is rewarded or punished, and imitate the rewarded behavior (Bandura, 1986, 1999). The more dysfunctional the family is, with an inharmonious parent–child relationship and ineffective parent–child communication, the more probable it is that the children in that family will form biased perspectives on bullying, such as “Those who are bullied deserve it” and “Let things drift if they do not affect one personally.” These perspectives may contribute to adolescents dismissing their moral standards, and may lead on to them generating assumptions that problem behavior is acceptable (Fontaine et al., 2014). Such behaviors may include internalization problem behaviors of withdrawn, anxiety, depression, and somatic complaints and/or externalization problem behaviors of aggression and delinquency. Thus, these adolescents are more likely to seek to justify their immoral behavior to themselves and others, and develop high moral disengagement. According to this analysis and the associations among family factors (e.g., strength of parental attachment; Bao et al., 2015), lower family functioning is likely to be a precursor to moral disengagement.

To our knowledge, few researchers have examined moral disengagement as a mediator in the relationship between family functioning and bystander behavior in bullying incidents. Some empirical studies have indicated that moral disengagement serves as a mediator in explaining the associations among family-functioning variables (e.g., parental attachment, interparental conflict, childhood maltreatment), children’s problem behaviors of bullying, delinquency, and aggression (Bao et al., 2015; Pelton et al., 2004; X. Wang et al., 2017; Yang & Wang, 2012), and children’s prosocial behaviors, such as defending (X. Wang et al., 2017). Therefore, we proposed the following hypothesis:
Hypothesis 3: Family functioning will have an indirect effect on bystander behavior in bullying incidents in China through the mediator of moral disengagement.

Method

Participants

We carried out a survey among students in Grades 1, 2, and 3 at two junior high schools in a region of China, using cluster sampling. Participation was voluntary. Students were informed about the survey’s goals and procedure, and told that their responses would be kept anonymous and used only for this research. We distributed 1,075 surveys and recovered 1,035 valid forms (rate of response = 96.28%). Of the participants (M_age = 13.97 years, SD = 1.06, range = 11–16), there were 285 students (160 boys, 125 girls) in Grade 1, 372 students (201 boys, 171 girls) in Grade 2, and 378 students (205 boys, 173 girls) in Grade 3.

Procedure

We gave special training to some applied psychology undergraduate students on the subject of school bullying, and instructed them in the goals and procedure of the study before they undertook the role of experimenters. School principals and head class teachers gave permission for their students in Grades 1 to 3 to participate in this study, and we obtained parental consent before data collection. The adolescent participants were informed that they could withdraw at any time, which none did. When the survey was finished, we undertook a quality assessment review of the collected data to eliminate survey forms with inadequate responses, and we also checked for extreme values. We analyzed the data using SPSS 22.0 and Amos 22.0.

Measures

Bullying Bystander Behavior
We used the Chinese version (W. J. Zhang & Ma, 2016) of Salmivalli et al.’s (1996) Participant Role Questionnaire to assess bystander behavior, with reference to a previous study (Pozzoli & Gini, 2010) to change peer rating to a self-report of school bullying bystander behavior. Participants were asked to quantify, using a 5-point Likert-type scale ranging from 1 (never) to 5 (always), how often they behaved in the manner described in each item. The measure comprises 18 items on school bullying peer bystander behavior in four domains: assistant behavior (e.g., “When someone is bullying others, I am used to assisting in the bullying”), reinforcer behavior (e.g., “When witnessing bullying, I make fun of the victim”), outsider behavior (e.g., “I choose to neglect the bullying incident even when seeing one”), and defender behavior (e.g., “I try to comfort the victim when seeing such an incident”). Cronbach’s alpha was .76. The confirmatory factor analysis results were as follows: chi-square/degrees of freedom ratio = 1.81, comparative fit index = .96, incremental fit index = .96, Tucker–Lewis index = .95, root mean square error of approximation = .04.

Family Functioning
We used the Chinese version (X. D. Wang et al., 1999) of the Family Assessment Device (Epstein et al., 1983) to measure family functioning. The 60-item measure comprises seven subscales: problem solving (e.g., “We try to think of different ways to solve problems”), communication (e.g., “When someone is upset the others know why”), roles (e.g., “We discuss who is to do household jobs”), affective responsiveness (e.g., “We express tenderness”), affective involvement (e.g., “If someone is in trouble, the others become involved too”), behavioral control (e.g., “We have rules about hitting people”), general functioning (e.g., “We don’t get along well together”). Participants assess family functioning on a 4-point Likert scale ranging from 1 (very much like my home) to 4 (completely different from my home). Following an existing study (B. Wang et al., 2018), we reversed-scored items to cater to positive thinking, so that the higher the overall score was, the healthier was the family functioning. Cronbach’s alpha was .92 in this study.

Moral Disengagement
We used the Chinese version (X. Wang & Yang, 2010) of the 26-item Moral Disengagement Scale (Bandura et al., 1996) to measure moral disengagement. The measure comprises eight moral disengagement mechanisms: moral justification (e.g., “It is all right to fight to protect your friends”), euphemistic labeling (e.g., “Slapping and shoving someone is just a way of joking”), advantageous comparison (e.g., “Stealing some money is not too serious compared to those who steal a lot of money”), displacement of responsibility (e.g., “Kids can’t be blamed for misbehaving if their friends pressured them to do it”), diffusion of responsibility (e.g., “A kid in a gang should not be blamed for the trouble the gang causes”), distortion of consequences (e.g., “Teasing someone does not really hurt them”), attribution of blame (e.g., “If people are careless about where they leave their things it is their own fault if they get stolen”), and dehumanization (e.g., “Some people deserve to be treated like animals”). Participants assess the items on a 5-point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree). Higher scores indicate greater moral disengagement. Cronbach’s alpha was .82 in this study.

Results

Common Method Bias

As recommended by Malhotra and colleagues (2006), we used Harman’s single-factor test to assess common method bias. Results of an unrotated exploratory factor analysis suggest that the eigenvalues of 27 factors were greater than 1. Of the factors, the first common factor accounted for 13.56% of the total variance, which is below the 40% threshold for common method bias being of concern. Thus, there was no obvious common method bias in this study.

Preliminary Analysis

Means, standard deviations, and correlations among variables are presented in Table 1. Assistant, reinforcer, and outsider behavior were negatively correlated with family functioning and positively correlated with moral disengagement. Defender behavior was positive correlated with family functioning, which was negatively correlated with moral disengagement.

Mediation Test

We tested (Wen & Ye, 2014) the mediating effect of students’ moral disengagement on family functioning and bullying bystander behavior. With defender behavior as an example, a direct effects model (Model 1) to predict defender behavior with family functioning was established. Moral disengagement was then added to construct the mediation model (Model 2). Bootstrapping analysis was adopted to verify the role of moral disengagement in mediating the effect of family functioning on defender behavior. Repeated random sampling was applied to the original data to determine 2,000 bootstrapped resamples. The average path of the mediating effect and 95% confidence interval (CI) path coefficients were then calculated according to the sample fit model. When the CI excludes zero, the mediating effect is considered significant (Wen & Ye, 2014). We analyzed the other bystander behaviors following the above procedure. The fit indicators of each model are shown in Table 2.

Regarding defender behavior, the fit indices for both models were acceptable. In the nonmediated model, a high level of family functioning positively predicted defender behavior, β = .26, p < .001. Thus, Hypothesis 1a was supported. After moral disengagement was added as a mediating variable, the positive effect of family functioning on the prediction 0f defender behavior remained significant, β = .32, p < .001; 95% CI [0.565, 0.763]. This suggests that moral disengagement partly mediated the relationship of family functioning and defender behavior. When every path had been verified, family functioning was found to have a negative effect on moral disengagement, β = −.38, p < .001; 95% CI [−0.523, −0.321], and moral disengagement negatively predicted defender behavior, β = −.12, p < .01; 95% CI [−0.203, −0.085]. Therefore, Hypothesis 2a was supported. Further, the mediating effect was .046, accounting for 12.57% of the total effect. Therefore, Hypothesis 3 was supported.

Regarding outsider behavior, the fit indices for both models were also acceptable. In the nonmediated model, a high level of family functioning negatively predicted outsider behavior (β = −.17, p < .001). Thus, Hypothesis 1b was supported. This predictive effect remained significant, β = −.08, p < .05; 95% CI [−0.300, −0.001], after moral disengagement was added as a mediating variable. Results show there was a partial mediating effect of moral disengagement on family functioning and outsider behavior. A test of each path shows that family functioning negatively predicted moral disengagement, β = −.39, p < .001; 95% CI [−0.530, −0.325], whereas moral disengagement positively predicted outsider behavior, β = .23, p < .001; 95% CI [0.264, 0.579]. Thus, Hypothesis 2b was supported, and the mediating effect was .048, accounting for 37.5% of the total effect. Hypothesis 3 was, therefore, supported.

Regarding reinforcer behavior, the fit indices for both models were also acceptable. In the nonmediated model, a high level of family functioning negatively predicted reinforcer behavior, β = −.21, p < .001. Thus, Hypothesis 1b was supported. After moral disengagement was added as a mediating variable, the predictive effect remained significant, β = −.09, p < .05; 95% CI [−0.194, −0.028], indicating a partial mediating effect of moral disengagement on family functioning and reinforcer behavior. A test of each path suggests that family functioning negatively predicted moral disengagement, β = −.35, p < .001; 95% CI [−0.465, −0.285], which could have the same effect on reinforcer behavior, β = .37, p < .001; 95% CI [0.340, 0.592], supporting Hypothesis 2b. Thus, it can be inferred that the mediating effect was .130, accounting for 59.09% of the total effect. Hypothesis 3 was, therefore, supported.

For assistant behavior, the fit indices of both models also reached an acceptable level. In the nonmediated model, a high level of family functioning negatively predicted assistant behavior, β = −.18, p < .001. Thus, Hypothesis 1b was supported. After moral disengagement was added as a mediating variable, the predictive effect remained significant, β = −.08, p < .05; 95% CI [−0.135, −0.022], suggesting that moral disengagement partially mediated the relationship between family functioning and assistant behavior in bullying incidents. A test of each path revealed that family functioning negatively predicted moral disengagement, β = −.34, p < .001; 95% CI [−0.462, −0.284], and moral disengagement had a positive effect on assistant behavior, β = .27, p < .001; 95% CI [0.141, 0.306]. This result supported Hypothesis 2b. Further, the mediating effect was .092, accounting for 53.48% of the total effect. Hypothesis 3 was, therefore, supported.

Discussion

In this study we found that family functioning significantly and directly affected adolescent bystander behavior in a bullying incident in different ways. Students who had been exposed to healthier (higher) family functioning were more likely to form stricter moral standards, and more likely to perform positive defending behavior. In contrast, students with less healthy (lower) family functioning were more likely to be a conniver in a bullying incident by playing the role of an outsider, reinforcer, or assistant. When the family is functioning well, the basic conditions for healthy physiological, psychological, and social development of family members are provided (Miller et al., 2000), and the better the family is functioning, the more likely it is that the family interaction will teach adolescents about social behaviors, such as communicating effectively and solving problems constructively. These adolescents will then probably comfort and defend their peers when these people are being bullied and will attempt to stop the bullying. Our finding is consistent with Murphy et al.’s (2017) finding of a positive relationship between strong parent–child attachment and defender behavior.

We also found that the higher the score for family functioning, the lower was the score for reinforcer and assistant behavior. To our knowledge, this is a new finding, implying that the relationship patterns between family functioning and these probullying behaviors are similar to those of bullying, as reported by Murphy et al. (2017), who found that family functioning was associated negatively with bullying; and also of victimization, as reported by Georgiou (2008), who found a negative association between family functioning and victimization. These similarities mean that there are negative relationships between family functioning and different bullying-related behaviors. Our finding differs from a previous result that outsider behavior was not significantly associated with family functioning (Mazzone & Camodeca, 2019). We confirmed that family functioning had a negative effect on outsider behavior, which may be caused by the Chinese cultural emphasis on the importance of family. In China, where the family plays a very important role in adolescent adjustment (Bao et al., 2015), the less healthy is family functioning, the less likely it is that adolescents will learn effective communication and problem-solving skills, and receive emotional support and behavior management (An & Li, 2010; Siu & Shek, 2005; D. Wang, 2011). Therefore, these adolescents will be more inclined to remain an outsider in bullying. The effect of family functioning is, thus, not limited to the parties involved in school bullying, but also involves student bystanders in different ways, further illustrating the importance of the family system in adolescent growth.

Consistent with Hypothesis 3, family functioning predicted bystander behavior through the mediating role of moral disengagement. That is, participants exposed to less healthy family functioning were more likely to score higher on moral disengagement, which led to an increase in assistant, reinforcer, or outsider bystander behavior in a bullying situation. This is consistent with findings that moral disengagement can mediate the effect of family factors (e.g., parental conflict) on aggression (Pelton et al., 2004; Yang & Wang, 2012) and bullying (X. Wang et al., 2017). Thus, as adolescents who experience risk family factors (e.g., less communication, more parental punishment, and family members treating each other with indifference) are more likely to view bullying as an acceptable way to respond to disagreement, they are more likely to engage in bullying and use moral disengagement mechanisms to justify, reconstruct, and rationalize their behavior (Mazzone & Camodeca, 2019). In contrast, family functioning can influence adolescents’ bystander behavior both directly by the parents setting a good example, and indirectly by changing adolescents’ moral cognition mechanism.

As adolescents in a family where the functioning is less healthy are more likely than are those who have more healthy family functioning to develop/act with higher moral disengagement and have rationalized excuses for immoral behavior, their behavior may deviate from moral standards (Zhao et al., 2016). Consequently, when they are bystanders in a bullying incident, they may choose to disregard the victim’s pain and assist, reinforce, or acquiesce with the bully. Parents in dysfunctional families can hardly provide a moral template for their children. Their acquiescence with or even practice of aggression or bullying, and negligence of or indifference to family members’ emotions may provide a context of modeling attitudes that support and reinforce bullying (Bibou-Nakou et al., 2013; Rigby, 1994; Stevens et al., 2002). Their children are, therefore, at increased risk of conniving and bullying (C. Wang et al., 2017).

In addition, parents in dysfunctional families may not solve family issues in an effective way or exert proper management of their family members’ behavior. Thus, as adolescents in such families probably do not know how to deal with bullying, when they are bystanders in a bullying incident, even if they do not agree with what is happening, they may do nothing to stop it and find an excuse to rationalize their inaction. The effect of moral disengagement may lead these adolescents to reconstruct, cover up, and rationalize their assisting, reinforcing, or outsider behavior to downplay their harmful behavior, consequential accountability, and cognition of the victim’s pain. For example, Yun (2020) found that, among outsiders in bullying incidents, only 9.5% remained indifferent to the victim’s pain, with the remaining 90.5% showing sympathy. However, although the latter group may feel guilt and self-reproach (Mazzone et al., 2016), as they exhibit moral disengagement, they tend to excuse themselves by advantageous comparison (e.g., “I was just an outsider; the bully should be held accountable for the incident”) and displacement of responsibility (e.g., “Others also stayed away and offered no help at all”). We found it noteworthy that, in our study, when the magnitude of the mediating effect was judged, moral disengagement had the lowest effect (12.75%) in the regulation of family functioning in regard to defender behavior. This may result from the complicated relationship between defender behavior and moral disengagement (X. Wang et al., 2017). A more profound analysis could be carried out to clarify this relationship further, by including both individual (e.g., antibullying attitude and empathy) and group (teacher support and school atmosphere) factors.

In general, moral disengagement offers a new theoretical perspective to explain the mechanism underlying the effect of family functioning on adolescents’ bystander behavior. Adolescents need to first remove inner self-reproach and guilt through moral disengagement when performing assistant, reinforcer, or outsider bystander behavior. Adolescents with higher moral disengagement are, thus, more likely to conduct this bystander behavior (Doramajian & Bukowski, 2015; Gini, 2006). Family functioning, however, substantially affects adolescents’ moral disengagement (Pelton et al., 2004; Yang & Wang, 2012). As family functioning may negatively influence adolescents’ moral cognition, those exposed to lower family functioning may form immoral cognition and then engage in higher moral disengagement (Zhao et al., 2016). In summary, the effect of lower family functioning on adolescents’ bystander behavior is not limited to their direct imitation of their parents’ behavior, but is also shown in their moral cognition mechanism change and formation of high moral disengagement so that they act as an assistant, reinforcer, or outsider in bullying incidents.

Our findings have implications for bullying intervention in schools. First, from the group perspective, the significance of bystanders in bullying incidents should be fully recognized so that multiple ways can be adopted to stop students from assisting with or reinforcing bullying, and to promote them becoming active defenders. Second, as family functioning also affects the occurrence of bullying incidents (Dussich & Maekoya, 2007; Stevens et al, 2002; X. Wang et al., 2017), importance should be attached to the overall functionality of the family ecosystem. Intervention in school bullying requires the full use of family functioning. In practical terms, parents should be properly trained so that they understand about bullying and they know how to establish harmonious parent–child relationships and communicate with their children. For example, offline and online parent training and workshops could be held by the government, community, or schools to educate parents on school bullying, parenting skills, and parental communication with children. The strengths and the limitations of students’ families can also be taken into consideration when developing and implementing bullying intervention programs. Adolescents will then have an example set by their parents to follow, a friend to turn to, and emotional support when caught in issues of conflict between/among students, and they will be protected from becoming passive bystanders of bullying. Finally, to change moral disengagement cognition among adolescents, it is necessary to help them establish explicit moral standards. Teachers and families should coordinate to strengthen the effect of moral education, provide students with accurate knowledge about the causes and effects of bullying, raise their sense of antibullying responsibility, and improve their moral sensitivity as bullying participants. The final goal is to prevent adolescents from finding excuses for passive behavior when witnessing bullying, and to help them to change from reinforcing or acquiescing with the bully, to actively intervening as a defender in school bullying incidents.

There are some limitations in this study. First, we chose a self-report method to measure bystander behavior in bullying incidents, which may have led to a social approval effect that influenced the results. Future researchers could incorporate methods like peer rating and teacher rating to collect more comprehensive information about adolescents’ bystander roles. Second, in this cross-sectional study, temporal sequence in the variable measures is lacking and only correlations between variables were determined, although the mediation model was based on a theoretical foundation and empirical studies. Shek (1998) showed that adolescents’ psychological well-being adjustment predicted their perceived family functioning. Future researchers could use a longitudinal study to examine over time the role of family functioning in bystander roles. Third, we discussed the mediating effect of only moral disengagement on adolescents’ bullying bystander roles. Other factors may influence the family functioning–bystander role relationship; thus, both individual factors, such as antibullying attitude (Rigby & Slee, 1991) and moral sentiments (Gini et al., 2020), and interpersonal factors, like peer status (Oh & Hazler, 2009), could be included in future studies to further unveil adolescents’ bullying bystander roles.

An, Q., & Li, X.-S. (2010). Relationship of adaptation to college with family function, social support, and coping style in college freshmen [In Chinese]. Chinese Mental Health Journal, 24(10), 796–800.

Andreou, E., & Metallidou, P. (2004). The relationship of academic and social cognition to behaviour in bullying situations among Greek primary school children. Educational Psychology, 24(1), 27–41.
https://doi.org/10.1080/0144341032000146421

Bandura, A. (1986). Social foundations of thought and action: A social cognitive theory. Prentice Hall.

Bandura, A. (1999). Moral disengagement in the perpetration of inhumanities. Personality and Social Psychology Review, 3(3), 193–209.
https://doi.org/10.1207/s15327957pspr0303_3

Bandura, A., Barbaranelli, C., Caprara, G. V., & Pastorelli, C. (1996). Mechanisms of moral disengagement in the exercise of moral agency. Journal of Personality and Social Psychology, 71(2), 364–374.
https://doi.org/10.1037/0022-3514.71.2.364

Bao, Z., Zhang, W., Lai, X., Sun, W., & Wang, Y. (2015). Parental attachment and Chinese adolescents’ delinquency: The mediating role of moral disengagement. Journal of Adolescence, 44, 37–47.
https://doi.org/10.1016/j.adolescence.2015.06.002

Bibou-Nakou, I., Tsiantis, J., Assimopoulos, H., & Chatzilambou, P. (2013). Bullying/victimization from a family perspective: A qualitative study of secondary school students’ views. European Journal of Psychology of Education, 28(1), 53–71.
https://doi.org/10.1007/s10212-011-0101-6

Bronfenbrenner, U. (1979). The ecology of human development: Experiments by nature and design. Harvard University Press.

Caravita, S. C. S., Gini, G., & Pozzoli, T. (2012). Main and moderated effects of moral cognition and status on bullying and defending. Aggressive Behavior, 38(6), 456–468.
https://doi.org/10.1002/ab.21447

Chen, G., Zhang, W., Zhang, W., & Deater-Deckard, K. (2020). A “defender protective effect” in multiple-role combinations of bullying among Chinese adolescents. Journal of Interpersonal Violence, 35(7–8), 1587–1609.
https://doi.org/10.1177/0886260517698278

Doramajian, C., & Bukowski, W. M. (2015). A longitudinal study of the associations between moral disengagement and active defending versus passive bystanding during bullying situations. Merrill-Palmer Quarterly, 61(1), 144–172.
https://doi.org/10.13110/merrpalmquar1982.61.1.0144

Due, P., Holstein, B. E., Lynch, J., Diderichsen, S., Gabhain, S. N., Scheidt, P., … The Health Behaviour in School-Aged Children Bullying Working Group. (2005). Bullying and symptoms among school-aged children: International comparative cross sectional study in 28 countries. European Journal of Public Health, 15(2), 128–132.
https://doi.org/10.1093/eurpub/cki105

Dussich, J. P. J., & Maekoya, C. (2007). Physical child harm and bullying-related behaviors: A comparative study in Japan, South Africa, and the United States. International Journal of Offender Therapy and Comparative Criminology, 51(5), 495–509.
https://doi.org/10.1177/0306624X06298463

Epstein, N. B., Baldwin, L. M., & Bishop, D. S. (1983). The McMaster Family Assessment Device. Journal of Marital and Family Therapy, 9(2), 171–180.
https://doi.org/10.1111/j.1752-0606.1983.tb01497.x

Fluke, S. M. (2016). Standing up or standing by: Examining the bystander effect in school bullying (Unpublished doctoral dissertation). University of Nebraska Lincoln, NE, USA.

Fontaine, R. G., Fida, R., Paciello, M., Tisak, M. S., & Caprara, G. V. (2014). The mediating role of moral disengagement in the developmental course from peer rejection in adolescence to crime in early adulthood. Psychology, Crime & Law, 20(1), 1–19.
https://doi.org/10.1080/1068316X.2012.719622

Georgiou, S. N. (2008). Parental style and child bullying and victimization experiences at school. Social Psychology of Education, 11(3), 213–227.
https://doi.org/10.1007/s11218-007-9048-5

Gini, G. (2006). Social cognition and moral cognition in bullying: What’s wrong? Aggressive Behavior, 32(6), 528–539.
https://doi.org/10.1002/ab.20153

Gini, G., Pozzoli, T., & Hauser, M. (2011). Bullies have enhanced moral competence to judge relative to victims, but lack moral compassion. Personality and Individual Differences, 50(5), 603–608.
https://doi.org/10.1016/j.paid.2010.12.002

Gini, G., Thornberg, R., & Pozzoli, T. (2020). Individual moral disengagement and bystander behavior in bullying: The role of moral distress and collective moral disengagement. Psychology of Violence, 10(1), 38–47.
https://doi.org/10.1037/vio0000223

Goossens, F. A., Olthof, T., & Dekker, P. H. (2006). New Participant Role Scales: Comparison between various criteria for assigning roles and indications for their validity. Aggressive Behavior, 32(4), 343–357.
https://doi.org/10.1002/ab.20133

Hawker, D. S. J., & Boulton, M. J. (2000). Twenty years’ research on peer victimization and psychosocial maladjustment: A meta-analytic review of cross-sectional studies. Journal of Child Psychology and Psychiatry, 41(4), 441–455.
https://doi.org/10.1111/1469-7610.00629

Hawkins, D. L., Pepler, D. J., & Craig, W. M. (2001). Naturalistic observations of peer interventions in bullying. Social Development, 10(4), 512–527.
https://doi.org/10.1111/1467-9507.00178

Henderson, C. E., Dakof, G. A., Schwartz, S. J., & Liddle, H. A. (2006). Family functioning, self-concept, and severity of adolescent externalizing problems. Journal of Child and Family Studies, 15(6), 721–731.
https://doi.org/10.1007/s10826-006-9045-x

Hymel, S., McClure, R., Miller, M., Shumka, E., & Trach, J. (2015). Addressing school bullying: Insights from theories of group processes. Journal of Applied Developmental Psychology, 37, 16–24.
https://doi.org/10.1016/j.appdev.2014.11.008

Hymel, S., Rocke-Henderson, N., & Bonanno, R. A. (2005). Moral disengagement: A framework for understanding bullying among adolescents. Journal of Social Sciences, 8, 1–11.

Malhotra, N. K., Kim, S. S., & Patil, A. (2006). Common method variance in IS research: A comparison of alternative approaches and a reanalysis of past research. Management Science, 52(12), 1865–1883.
https://doi.org/10.1287/mnsc.1060.0597

Mazzone, A., & Camodeca, M. (2019). Bullying and moral disengagement in early adolescence: Do personality and family functioning matter? Journal of Child and Family Studies, 28(8), 2120–2130.
https://doi.org/10.1007/s10826-019-01431-7

Mazzone, A., Camodeca, M., & Salmivalli, C. (2016). Interactive effects of guilt and moral disengagement on bullying, defending and outsider behavior. Journal of Moral Education, 45(4), 419–432.
https://doi.org/10.1080/03057240.2016.1216399

Menesini, E., Sanchez, V., Fonzi, A., Ortega, R., Costabile, A., & Lo Feudo, G. (2003). Moral emotions and bullying: A cross-national comparison of differences between bullies, victims and outsiders. Aggressive Behavior, 29(6), 515–530.
https://doi.org/10.1002/ab.10060

Miller, I. W., Ryan, C. E., Keitner, G. I., Bishop, D. S., & Epstein, N. B. (2000). The McMaster approach to families: Theory, assessment, treatment and research. Journal of Family Therapy, 22(2), 168–189.
https://doi.org/10.1111/1467-6427.00145

Murphy, T. P., Laible, D., & Augustine, M. (2017). The influences of parent and peer attachment on bullying. Journal of Child and Family Studies, 26(5), 1388–1397.
https://doi.org/10.1007/s10826-017-0663-2

Nickerson, A. B., Mele, D., & Princiotta, D. (2008). Attachment and empathy as predictors of roles as defenders or outsiders in bullying interactions. Journal of School Psychology, 46(6), 687–703.
https://doi.org/10.1016/j.jsp.2008.06.002

Nishina, A., & Juvonen, J. (2005). Daily reports of witnessing and experiencing peer harassment in middle school. Child Development, 76(2), 435–450.
https://doi.org/10.1111/j.1467-8624.2005.00855.x

Obermann, M.-L. (2011). Moral disengagement in self-reported and peer-nominated school bullying. Aggressive Behavior, 37(2), 133–144.
https://doi.org/10.1002/ab.20378

O’Connell, P., Pepler, D., & Craig, W. (1999). Peer involvement in bullying: Insights and challenges for intervention. Journal of Adolescence, 22(4), 437–452.
https://doi.org/10.1006/jado.1999.0238

Oh, I., & Hazler, R. J. (2009). Contributions of personal and situational factors to bystanders’ reactions to school bullying. School Psychology International, 30(3), 291–310.
https://doi.org/10.1177/0143034309106499

Olson, D. H. (1993). Circumplex model of marital and family systems: Assessing family functioning. In F. Walsh (Ed.), Normal family processes (2nd ed., pp. 109–133). The Guilford Press.

Pelton, J., Gound, M., Forehand, R., & Brody, G. (2004). The Moral Disengagement Scale: Extension with an American minority sample. Journal of Psychopathology and Behavioral Assessment, 26(1), 31–39.
https://doi.org/10.1023/B:JOBA.0000007454.34707.a5

Pouwels, J. L., Lansu, T. A. M., & Cillessen, A. H. N. (2016). Participant roles of bullying in adolescence: Status characteristics, social behavior, and assignment criteria. Aggressive Behavior, 42(3), 239–253.
https://doi.org/10.1002/ab.21614

Pozzoli, T., & Gini, G. (2010). Active defending and passive bystanding behavior in bullying: The role of personal characteristics and perceived peer pressure. Journal of Abnormal Child Psychology, 38(6), 815–827.
https://doi.org/10.1007/s10802-010-9399-9

Rigby, K. (1994). Psychosocial functioning in families in Australian adolescent schoolchildren involved in bully/victim problems. Journal of Family Therapy, 16(2), 173–187.
https://doi.org/10.1111/j.1467-6427.1994.00787.x

Rigby, K., & Slee, P. T. (1991). Bullying among Australian school children: Reported behavior and attitudes toward victims. The Journal of Social Psychology, 131(5), 615–627.
https://doi.org/10.1080/00224545.1991.9924646

Rivers, I., Poteat, V. P., Noret, N., & Ashurst, N. (2009). Observing bullying at school: The mental health implications of witness status. School Psychology Quarterly, 24(4), 211–223.
https://doi.org/10.1037/a0018164

Sainio, M., Veenstra, R., Huitsing, G., & Salmivalli, C. (2011). Victims and their defenders: A dyadic approach. International Journal of Behavioral Development, 35(2), 144–151.
https://doi.org/10.1177/0165025410378068

Salmivalli, C. (2010). Bullying and the peer group: A review. Aggression and Violent Behavior, 15(2), 112–120.
https://doi.org/10.1016/j.avb.2009.08.007

Salmivalli, C. (2014). Participant roles in bullying: How can peer bystanders be utilized in interventions? Theory Into Practice, 53(4), 286–292.
https://doi.org/10.1080/00405841.2014.947222

Salmivalli, C., Lagerspetz, K., Björkqvist, K., Österman, K., & Kaukiainen, A. (1996). Bullying as a group process: Participant roles and their relations to social status within the group. Aggressive Behavior, 22(1), 1–15.
https://doi.org/10.1002/(SICI)1098-2337(1996)22:1<1::AID-AB1>3.0.CO;2-T

Salmivalli, C., Voeten, M., & Poskiparta, E. (2011). Bystanders matter: Associations between reinforcing, defending, and the frequency of bullying behavior in classrooms. Journal of Clinical Child & Adolescent Psychology, 40(5), 668–676.
https://doi.org/10.1080/15374416.2011.597090

Shek, D. T. L. (1998). A longitudinal study of the relationship between family functioning and adolescent psychological well-being. Journal of Youth Studies, 1(2), 195–209.
https://doi.org/10.1080/13676261.1998.10593006

Shek, D. T. L. (2002). Family functioning and psychological well-being, school adjustment, and problem behavior in Chinese adolescents with and without economic disadvantage. The Journal of Genetic Psychology, 163(4), 497–502.
https://doi.org/10.1080/00221320209598698

Siu, A. M. H., & Shek, D. T. L. (2005). Relations between social problem solving and indicators of interpersonal and family well-being among Chinese adolescents in Hong Kong. Social Indicators Research, 71(1/3), 517–539.
https://doi.org/10.1007/s11205-004-8034-y

Spriggs, A. L., Iannotti, R. J., Nansel, T. R., & Haynie, D. L. (2007). Adolescent bullying involvement and perceived family, peer and school relations: Commonalities and differences across race/ethnicity. Journal of Adolescent Health, 41(3), 283–293.
https://doi.org/10.1016/j.jadohealth.2007.04.009

Stevens, V., De Bourdeaudhuij, I., & Van Oost, P. (2002). Relationship of the family environment to children’s involvement in bully/victim problems at school. Journal of Youth and Adolescence, 31(6), 419–428.
https://doi.org/10.1023/A:1020207003027

Sticca, F., & Perren, S. (2015). The chicken and the egg: Longitudinal associations between moral deficiencies and bullying: A parallel process latent growth model. Merrill-Palmer Quarterly, 61(1), 85–100.
https://doi.org/10.13110/merrpalmquar1982.61.1.0085

Sutton, J., & Smith, P. K. (1999). Bullying as a group process: An adaptation of the participant role approach. Aggressive Behavior, 25(2), 97–111.
https://doi.org/10.1002/(SICI)1098-2337(1999)25:2<97::AID-AB3>3.0.CO;2-7

Tamplin, A., & Goodyer, I. M. (2001). Family functioning in adolescents at high and low risk for major depressive disorder. European Child and Adolescent Psychiatry, 10(3), 170–179.
https://doi.org/10.1007/s007870170023

Thornberg, R., & Jungert, T. (2014). School bullying and the mechanisms of moral disengagement. Aggressive Behavior, 40(2), 99–108.
https://doi.org/10.1002/ab.21509

Thornberg, R., Pozzoli, T., Gianluca, G., & Jungert, T. (2015). Unique and interactive effects of moral emotions and moral disengagement on bullying and defending among school children. The Elementary School Journal, 116(2), 322–337.
https://doi.org/10.1086/683985

Troop-Gordon, W. (2017). Peer victimization in adolescence: The nature, progression, and consequences of being bullied within a developmental context. Journal of Adolescence, 55, 116–128.
https://doi.org/10.1016/j.adolescence.2016.12.012

Valdés-Cuervo, A. A., Alcántar-Nieblas, C., Martínez-Ferrer, B., & Parra-Pérez, L. (2018). Relations between restorative parental discipline, family climate, parental support, empathy, shame, and defenders in bullying. Children and Youth Services Review, 95, 152–159.
https://doi.org/10.1016/j.childyouth.2018.10.015

Wang, B., Tian, R., & Dong, X. (2018). The relationship between family functioning and adolescent negative risk-taking behavior: A moderated mediation model [In Chinese]. Psychological Development and Education, 34(2), 146–154.
https://doi.org/10.16187/j.cnki.issn1001-4918.2018.02.03

Wang, C., Ryoo, J. H., Swearer, S. M., Turner, R., & Goldberg, T. S. (2017). Longitudinal relationships between bullying and moral disengagement among adolescents. Journal of Youth and Adolescence, 46(6), 1304–1317.
https://doi.org/10.1007/s10964-016-0577-0

Wang, D. (2011). Relationships between adolescents’ emotional and behavioral problems, family functioning, and cognitive emotion regulation strategies [In Chinese]. (Unpublished doctoral dissertation). East China Normal University, Shanghai, China. https://bit.ly/3hor5wa

Wang, X., & Yang, J. (2010). Reliability and validity of the Moral Disengagement Scale in Chinese students [In Chinese]. Chinese Journal of Clinical Psychology, 18(2), 177–179.
https://doi.org/10.16128/j.cnki.1005-3611.2010.02.025

Wang, X., Yang, L., Gao, L., Yang, J., Lei, L., & Wang, C. (2017). Childhood maltreatment and Chinese adolescents’ bullying and defending: The mediating role of moral disengagement. Child Abuse & Neglect, 69, 134–144.
https://doi.org/10.1016/j.chiabu.2017.04.016

Wang, X. D., Wang, X. L., & Ma, H. (1999). Handbook of Mental Health Assessment Scale [In Chinese]. Chinese Journal of Mental Health Publishing.

Wen, Z., & Ye, B. (2014). Analyses of mediating effects: The development of methods and models [In Chinese]. Advances in Psychological Science, 22(5), 731–745.
https://doi.org/10.3724/SP.J.1042.2014.00731

Xie, H., & Ngai, S. S.-Y. (2020). Participant roles of peer bystanders in school bullying situations: Evidence from Wuhan, China. Children and Youth Services Review, 110, Article e104762.
https://doi.org/10.1016/j.childyouth.2020.104762

Yang, J.-P., & Wang, X.-C. (2012). Effect of moral disengagement on adolescents’ aggressive behavior: A moderated mediating effect [In Chinese]. Acta Psychologica Sinica, 44(8), 1075–1085.
https://doi.org/10.3724/SP.J.1041.2012.01075

Yun, H.-Y. (2020). New approaches to defender and outsider roles in school bullying. Child Development, 91(4), e814–e832.
https://doi.org/10.1111/cdev.13312

Zhang, W., Chen, L., & Chen, G. (2016). Research on school bullying in mainland China. In P. Smith, K. Kwak, & Y. Toda (Eds.), School bullying in different cultures: Eastern and Western perspectives (pp. 113–132). Cambridge University Press.
https://doi.org/10.1017/CBO9781139410878.009

Zhang, W. J., & Ma, X. C. (2016). The basic features of participant roles in bullying and its relation to peer network during early adolescence [In Chinese]. Educational Science Research, 2016(2), 38–43. https://bit.ly/3xmotn4

Zhao, H., Ke, Y., Zhang, H., Xu, Y., & Cheng, Q. (2016). The effect of family functioning on adolescents’ moral disengagement: Roles of conscientiousness and moral identity [In Chinese]. Psychological Science, 39(4), 907–913.
https://doi.org/10.16719/j.cnki.1671-6981.20160422

This study was supported by the Foundation Program

Humanities and Social Sciences Research Planning Youth Fund

Ministry of Education (17YJC880129)

and Shandong Provincial Science of Education Important Research Project (ZZ2017008).

Wenjuan Zhang, School of Education, Linyi University, Shuangling Road, Linyi, Shandong 27600, People’s Republic of China. Email: [email protected]