School bullying is a subtype of proactive aggression and intentional behavior carried out by a group or an individual repeatedly against a victim who cannot easily defend him or herself [1]. During the school years, bullying is the most common expression of violence in the peer context [2]. Given the systematic nature of power abuse [3] to the detriment of weaker victims, school bullying has been considered a behavior of greater intrinsic moral relevance compared to other aggressive behaviors ^[4][5][6][4,5,6] and represents one of the most significant social problems affecting children and adolescents in all parts of the world [7].

Although a wide variation has been documented in the prevalence rates of bullying across countries [2], it has been estimated that, globally, almost one in three children experiences school bullying victimization, and one out of four in Europe [8]. From a developmental perspective, the bullying trend is characterized by an initial increase as youths make the transition from elementary to middle school, peak after school transitions, and then a gradual decrease during high school years ^[9][10][11][9,10,11].

The literature has widely documented the negative consequences, in terms of mental health and educational outcomes, associated with school bullying experiences [2]. Prospective studies found that bullying perpetrators are more likely, over time, to carry weapons (e.g., [12]), to be involved in criminal offending ^[13][14][13,14], or use drugs (e.g., ^[15][16][15,16]) as well as to drop out from school [17].

Given the detrimental effects of school bullying on youths’ adjustment, it is understandable that growing interest has developed over the decades for carrying out effective anti-bullying prevention efforts [18]. Several systematic and meta-analytical reviews (e.g., ^[18][19][18,19]) highlighted the effectiveness of some school-based programs in reducing bullying perpetration and victimization ^{[1][20][21][22][23]}[1,20,21,22,23]. However, given the high variability in the effectiveness of these programs, it has been suggested by Smith et al. [24] to pay greater attention in exploring the principles of “what and why, for whom, and under what circumstances” some interventions work.

2. Towards a Cognitive-Behavioral Program for Preventing and Counteracting School-Bullying: The “EQUIP for Educators”

Many prevention efforts designed to reduce antisocial behaviors among youths follow a multicomponent intervention approach targeting the multifaceted needs of behaviorally at-risk youths at the same time ^[25][32]. Cognitive-behavioral programs proved to be relatively effective—although significant variations have been found in the effect sizes across studies (e.g., ^{[26][27][28][29]}[33,34,35,36]), and the effects of such programs specifically on bullying behavior still warrant further evaluation ^[30][27]. Such programs are based on the primary assumption of the cognitive-behavioral approach, according to which dysfunctional thinking patterns contribute to the development and persistence of antisocial behavior. By altering these biased thinking patterns, it would be possible to modify antisocial aspects of personality and consequent behaviors ^[31][32][37,38]. Therefore, cognitive and behavioral changes are assumed to reinforce each other by teaching new skills in areas where at-risk youth show deficits ^[33][39]. Among others, some manualized cognitive-behavioral programs applied in juvenile correctional facilities, clinical or school settings, and aimed at counteracting conduct problems or aggressive behaviors, include the Aggression Replacement Training (ART; ^[34][40]), the Coping Power Program (CPP; ^[35][41]), and the “EQUIPping Youth to Help One Another (EQUIP)” program ^[36][42]. These interventions have been informed by theoretical models suggesting that a combination of social-cognitive, emotional, and neuropsychological processes contribute to the development and maintenance of aggressive behaviors in youth. By working on youths’ behavioral and cognitive abilities to recognize and communicate emotions and manage their feelings positively, these programs have yielded positive results in preventing externalizing problem behaviors among children and adolescents (e.g., ^[37][38][43,44]). More specifically, the “EQUIP for Educators” (EfE; ^[39][28]) is one of the promising multicomponent school-based cognitive-behavioral programs which results from an adaptation of the original treatment program “EQUIP” for juvenile offenders ^[36][42]. It is dedicated to both primary and secondary prevention in educational contexts. Developed within Gibbs and colleagues’ ^[40][45] “three Ds” model, the EfE program aims to equip young people with behavioral problems in thinking and acting more responsibly by targeting three core aspects generally characterizing antisocial youths’ social cognition ^[36][41][42][42,46,47]: the use of self-serving cognitive Distortions—defined as “inaccurate or biased ways of attending to or conferring meaning upon experiences” ^[43][48] (p. 1); social skills Deficiencies—defined as “imbalanced and unconstructive behavior in difficult interpersonal situations” ^[36][42] (p. 165), and sociomoral developmental Delay—that is, persistence, during adolescence, of immaturity in moral judgment and egocentric bias. Thus, combining a peer-helping (or mutual-help) and a skills-training (or cognitive behavioral) approach, that is based on the ART curriculum ^[34][40], the EfE program can be considered a multicomponent program aimed at: (i) decreasing self-serving cognitive distortions (particularly relating to anger management); (ii) improving social skills; and (iii) stimulating moral judgment development, in the context of a positive peer culture ^[44][49]. Based on the social-cognitive approaches (e.g., ^[45][46][50,51]), according to which, people act upon their interpretation of social events ^[47][52] and antisocial behavior is based on deficiencies in interpreting these events (i.e., cognitive distortions), at the heart of the EfE psychoeducational curriculum is the correction of “thinking errors” or self-serving cognitive distortions ^[25][32] since, as previous studies have demonstrated (e.g., ^[48][49][25,53]), when reaching high levels, they facilitate externalizing problems and some types of aggressive behaviors among peers, such as bullying. Cognitive distortions have been distinguished by Barriga and Gibbs ^[50][54] into primary and secondary, depending on their function. Primary distortions are “self-centered” attitudes, thoughts, and beliefs which reflect more immature moral judgment stages and serve as primary motivators or “pretexts” of aggressive behaviors. Secondary distortions take the form of pre- or post-rationalizations or “excuses” for facilitating aggressive behaviors. Indeed, their function is to overcome dissonance between individual moral standards and behavioral transgressions neutralizing potential empathy and guilt towards the victim, thus avoiding damage to one’s self-image when engaging in misbehaviors ^[51][52][55,56]. Such cognitive rationalizations may assume the form of: (i) blaming others (i.e., “misattribution of blame for victimization or misfortune to innocent others”; ^[50][54], p. 334); (ii) minimizing/mislabeling (i.e., antisocial behavior is depicted as not really harmful or even as an admirable outcome); and (iii) assuming the worst (i.e., gratuitous attribution of hostile intentions to others in a social situation; treating the worst scenario as inevitable; believing that improvement of one’s own or others’ behavior is impossible). These distorted thinking patterns are assumed to block moral judgment development because one does not consider oneself to be responsible for one’s antisocial behavior, as those fulfil a defensive or neutralizing role ^[53][57]. In line with these considerations, a growing number of research (e.g., ^[54][55][26,58]), developed within the theoretical framework of moral disengagement ^[45][56][50,59], confirmed the key role of moral neutralization processes in promoting and strengthening youths’ aggressive tendencies. However, to date, only a few studies have systematically investigated the predictive role of cognitive distortions, as conceptualized by Gibbs and colleagues ^[36][42], in explaining peer-related aggression or bullying behavior ^[31][48][25,37]. Based on the findings of these studies highlighting that youth need to construct attitudes and beliefs that justify their immoral actions in order to maintain a positive self-concept, it might assume that when they become able to correct their “thinking errors” or cognitive distortions, they can refute the rationalizations that block or neutralize their empathy for actual or prospective victims ^[39][28], thus reducing the probability to engage in aggressive behavior. Overall, most of the studies on the effects of the EQUIP program seem to indicate that behavioral change is possible after the cognitive change ^[57][60].

3. Empirical Evidence Supporting the Effectiveness of the “EQUIP” Program

The EQUIP was originally developed as a treatment program for juvenile offenders and it has been found to be effective in promoting social skills ^[58][61] as well as in reducing recidivism rates after the intervention ^[58][59][60][61,62,63]. The main focus of the intervention is to decrease the tendency to make self-serving cognitive distortions and to develop less positive attitudes towards antisocial behaviors ^[42][61][47,64]. Based on these promising results, an adapted version of the original treatment program for juvenile offenders ^[36][42], was developed (EfE; ^[39][28]), taking the form of a psychoeducational prevention curriculum targeting students from the general population. So far, only a few studies have evaluated the effects of the EfE in the school context and were mainly carried out in Canada, Spain, and the Netherlands. Their results have corroborated the efficacy of the program in equipping students with: (i) skills for managing anger and correcting cognitive distortions ^[25][32][62][32,38,65] as well as for reducing pro-violence attitudes ^[32][62][38,65]; (ii) social skills for constructive prosocial behavior ^[25][62][32,65]; and (iii) skills for remediating development delay in moral judgment ^[25][32]. More specifically, as regards the effects of the EfE program on the changes in moral cognitions, in line with previous research by Nas and colleagues ^[42][47], Van der Velden et al. ^[32][38] found more negative attitudes towards antisocial behaviors and lower levels of self-serving cognitive distortions among those students participating to the intervention compared with the control group. However, the effect sizes were small ^[63][66]. Instead, with respect to the effects of the EfE program on peer victimization and bullying among high school students, to date, only two quasi-experimental studies ^[62][64][65,67] have been carried out, both in the Spanish context. More in detail, in the earlier study by van der Meulen et al. ^[62][65] it was found that the EfE program was partially successful in working on various aspects involved in peers victimization such as in promoting an increase in prosocial behavior by bystanders towards the victims and in reducing some types of bullying and social exclusion behaviors (but only among students whose cognitive distortions reduced). However, there was no overall reduction in victimization and the interpretation of these findings requires several cautions because of the relatively small sample size. Similarly, some years later, van der Meulen et al. ^[64][67] found that the EfE yielded positive changes in students’ actions in bullying situations; however, no changes in cognitive distortions and perceived class climate were found after the program’s application.

4. “Why” and “for Whom” School-Based Anti-Bullying Interventions Could Work Better?

In recent years, the debate among scholars on the effectiveness of school-based programs aimed to prevent and reduce bullying has been focused on the detection of factors accounting for the high variability of their successful ^{[65][66][67][68][69][70][71][72]}[68,69,70,71,72,73,74,75]. The findings from the latest extensive systematic and meta-analytical review of the effectiveness of school-based bullying prevention programs [18] showed that the effectiveness of anti-bullying programs reached an average decrease approximatively of 19–20% for bullying perpetration and 15–16% for bullying victimization outcomes, although with differences across countries and specific interventions. Given the remarkable variety in the effectiveness of these programs, as a general indication has been suggested by Smith et al. [24] to move from “whether a specific program works or not” (i.e., main effects studies) to uncovering factors that may mediate and/or moderate intervention effectiveness in the sense of exploring “what works, through which mechanisms, for whom, and under what circumstances”. With regard to the potential mediation mechanisms involved in explaining “why” intervention programs may activate expected behavioral changes, previous meta-analyses focused on the key social-cognitive processes in the explanation of externalizing problem behaviors, that are the “self-exculpatory” cognitive distortions, a general umbrella term that refers to pseudo-justifications and rationalizations for deviant behaviors ^[73][74][75][76,77,78]. These studies investigating the role of distorted thinking patterns in promoting behavioral changes, as the reduction of externalizing problem behaviors, have not clarified whether treatment success comes about as a consequence of “cognitive restructuring”, i.e., the reframing or correction of cognitive distortions in the treatment which is expected to result in behavioral changes ^[74][75][77,78]. For example, some reviews ^[76][77][79,80] did not reach conclusive empirical evidence that intervention programs designed to address the cognitive attitudes or beliefs impact the subsequent behaviors. Referring specifically to the EQUIP program, the review by Helmond et al. ^[77][80] showed that, within the very small subsample of studies evaluating both cognitive and behavioral outcomes, a significant reduction was found neither in cognitive distortions nor in externalizing problem behaviors. Consequently, the question of whether reducing cognitive distortions could be an effective mediating mechanism for reducing externalizing behaviors remains to be proven. However, given the widely established link between cognitive distortions and aggressive or antisocial behaviors (e.g., ^[48][49][25,53]), there is good reason to believe that school-based interventions which address biased thinking patterns may, in turn, reduce the involvement in bullying behaviors ^[31][37]. In this regard, some studies have shown that cognitive-behavioral interventions, such as the EQUIP program which is specifically focused on the cognitive restructuring, are effective in the subsequent reduction of recidivism rates as well as in improving institutional conduct ^[59][60][62,63]. The study by Liau et al. ^[60][63] aimed at investigating if changes in the mediating variables, represented by cognitive distortions and social skills, would be associated with changes in the outcomes related to the treatment, i.e., institutional violations and recidivism rates. The authors found that a significant decrease in cognitive distortions and an increase in social skills promoted fewer serious institutional violations after the intervention, for males and females, respectively. Referring to individual sociodemographic and psychological characteristics which may improve ouresearchers' knowledge about “for whom” interventions could work better, some studies evidenced that anti-bullying interventions’ efficacy varies depending on age, gender, and the degree of pre-existing symptoms or problematic behaviors, with males ^[20][78][20,31], younger children ^[79][81], and children with more severe symptoms and problematic behaviors at baseline ^[68][80][71,82] benefiting more from anti-bullying interventions. Moreover, over the last decade, a growing number of studies suggested that the effectiveness of interventions varies also depending as a function of the inherent genetic (e.g., ^[81][83]), physiological, and psychological ^[82][84] characteristics of individuals. In this respect, the Vantage Sensitivity framework ^[83][84][29,30] provides the theoretical basis for the hypothesis that some children may be more likely than others to benefit from intervention because of their heightened sensitivity to positive aspects of the environment. Due to their heightened environmental sensitivity, that is the inherent ability to perceive and process environmental stimuli ^[83][29], they could register contextual changes resulting from schoolwide anti-bullying programs more easily and more deeply than other children with lower environmental sensitivity ^[83][85][29,85]. Applied to school-based anti-bullying programs and informed by the theories of Differential Susceptibility [86] and Vantage Sensitivity ^[83][84][29,30], previous studies ^[78][31] reported that, although the intervention significantly reduced bullying behaviors and mental health outcomes across the whole sample, individual differences in environmental sensitivity moderated the intervention effects on victimization and internalizing symptoms. More specifically, highly sensitive boys benefited significantly more from the effects of the intervention in reducing both victimization and internalizing symptoms compared to the majority of less sensitive boys. Such findings highlighted that the vantage sensitivity is a useful framework with significant relevance for ouresearchers' understanding of widely observed heterogeneity in treatment response, suggesting that such variability is partly influenced by people’s differing capacity for environmental sensitivity. Therefore, in light of the empirical evidence discussed above, the need for evidence-based anti-bullying prevention programs, as well as for clarifying the potential mediation and moderation mechanisms involved in explaining the effectiveness of the programs, is highlighted. Furthermore, given the lack of studies having investigated the effects of the EfE program in the Italian school context, the present enstrudy was intended to fill the gap in the literature by evaluating the effectiveness of an adapted version of the EfE—implemented as a universal prevention program—in reducing self-serving cognitive distortions and in counteracting the bullying perpetration, also examining “why” and “for whom” the program could be effective.

5. Conclusions and Policy Implications

Notwithstanding the limitations discussed above, this enstrudy integrates previous knowledge and provides some relevant suggestions to researchers and practitioners for implementing appropriate interventions aimed at reducing adolescents’ involvement in bullying behaviors. Guided by a clear theory of causal mechanisms related to ouresearchers' behavioral outcome, represented by the social-cognitive approaches (e.g., ^[45][56][50,59]), the current enstrudy highlighted the potential mechanisms involved in explaining “why” and “for whom” the EfE program could work better to promote the expected changes. Specifically, researcherswe found that the EfE program was effective in counteracting the bullying perpetration through the reduction of self-serving CDs, which are more likely to decrease among males higher in sensitivity to environmental influences. In sum, it can be concluded that, as originally intended ^[25][32], the EfE has the potential to change cognitions and problem behaviors by equipping youth to think and act more responsibly. As the correction of “thinking errors” or self-serving CDs has been found to play a crucial role in counteracting the bullying perpetration among youth participating to the program, ouresearchers' entr study points to the benefit of school-based approaches that target the strengthening of youths’ moral cognition and that makes cognitive restructuring techniques (i.e., the reframing or correction of CDs ^[74][75][77,78]) one of its main strengths. Moreover, the current enstrudy provided evidence of the enhancer effect of environmental sensitivity in improving adolescents’ response to intervention, thus suggesting that the implementation of anti-bullying intervention in the school context could benefit from the early identification by teachers of those students higher in environmental sensitivity. Indeed, while highly sensitive students may require shorter or lower intensity intervention programs, vantage-resistant individuals may require more intensive intervention approaches or rather alternative types of treatment to benefit from them. Overall, in terms of practical implications in the educational field, ouresearchers' findings provide some suggestions for preventing the detrimental outcomes associated with school bullying experiences, on both perpetrators, victims, and on the school community as a whole. According to the multi-modal approach of the EfE program, the current entrstudy calls specific attention to the need to support adolescents in developing skills that could help them to successfully cope with peer-related violence, including emotion self-regulatory abilities (particularly relating to anger), social problem-solving skills, and moral education. Based on positive peer culture, in which adolescents feel responsible for each other and help one another, it could be useful to implement the EfE program in other school contexts where it is expected to have a great public impact given that it promotes, in the long term, the development of a nonviolent and law-abiding culture, which represents the crucial condition for ensuring success in preventing and reducing bullying phenomena among youth in their daily school life.