Accessible Published by De Gruyter August 20, 2021

Concept of and approaches toward a developmental prevention of radicalization: Promising strategies to keep young people away from political, religious, and other forms of extremism

Andreas Beelmann

Abstract

Radicalization and violent extremism in young people are growing problems in almost every society around the globe. This article starts by briefly summarizing the result of several comprehensive reviews on the prevention of radicalization and violent extremism. Based on a new social-developmental model of radicalization, it then introduces the concept of developmental prevention and presents a review of prevention principles, approaches, and programs derived from a developmental perspective within four different fields of proximal radicalization processes. These include (1) identity problems; (2) prejudice and negative intergroup attitudes; (3) extremist narratives, beliefs, and ideologies; and (4) antisocial development. Overall, several approaches and programs reveal promising effect sizes for a developmentally founded prevention of radicalization. However, more sound evaluations are needed to further promote this field.

Introduction

Despite the urgency of the current Covid19 pandemic, radicalization and extremism continue to be pressing problems throughout the world. According to the Global Terrorism Index, about 16,000 people lost their lives in 2019 as a result of politically or religiously motivated terrorist attacks (Institute for Economics and Peace, 2019). Although these are mainly people from the so-called MENA states (Middle East, North Africa), problems of radicalization and extremism are still a realistic threat within European societies. For example, about 42,000 politically motivated offenses were registered in Germany in 2019—an increase of about 14 percent compared to 2018 (BMI, 2020). Of these, 27,500 offences and 2,800 violent crimes had an explicit extremist background. In addition, about 30,000 people have been observed as suspected cases of being right-wing, left-wing, or religious extremists, and a substantial number of these express a readiness to use violence. These and other data underline the need for effective prevention measures as a prominent future challenge facing the world community. However, when designing and implementing programs, it will be important to do this against the background of scientific knowledge on how radicalization and extremism emerge. This article presents an overview of relevant issues and promising approaches with which to tackle growing radicalization in young people from a developmental science perspective.

State of the art in radicalization prevention

Although several comprehensive reviews have been published within the last decade (e.g., Aerts, 2019; Feddes & Gallucci, 2015; Jugl, Lösel, Bender, & King, 2021; Madriaza & Ponsot, 2015; Pistone et al., 2019; van Hemert et al., 2014), knowledge on radicalization prevention is still relatively sparse due to several methodological limitations. First, there have been a lot of projects but only a few examples of sound evaluation studies. This holds especially for true preventive programs compared to de-radicalization projects. Second, most studies are anecdotal case reports or implementation studies without any measurement of radicalization and extremism outcomes with valid assessment tools. Third, different definitions of radicalization and extremism make it hard to compare projects and programs or their outcomes. Finally, it seems especially difficult to conduct randomized control trials, at least for high-risk target groups. As a result, the state of the art in radicalization prevention permits only a few general substantial conclusions and implications. These include:

  • Several authors recommend a reorientation of the field toward empirically confirmed risk and protective factors or more generally toward promoting skills to strengthen mental health and positive development in young people (e.g, Stephens, Sieckelinck & Boutellier, 2019; Trip et al., 2019).

  • Several authors call for a better integration of the social context of the target groups into prevention concepts—for example, by not only addressing the ideology of extremist groups but also integrating their emotional and pragmatic bonds such as their financial dependence (e.g., Madriaza & Ponsot, 2015; Stephens et al., 2019; van Hemert et al., 2014).

  • Programs aiming to promote empathy, perspective taking, and other social-cognitive abilities have frequently been recommended (e.g., Feddes & Gallucci, 2015; Jugl et al., 2021; Trip et al., 2019; van Hemert et al., 2014).

  • In addition, critical media and communication competencies that immunize against indoctrination have been viewed as of special value in preventing extremist ideologies, particularly in the context of internet-based propaganda and activities in the social media (e.g., Aerts, 2019; Briggs & Feve, 2013; Pratchett et al., 2010; Madriaza & Pensot, 2015; van Hemert et al, 2014).

  • Some reviews argue in favor of well-educated administrators with high credibility and authority possibly with the same social background as the target group (e.g., Christmann, 2012).

  • At the same time, programs should allow concrete learning experiences (e.g., via role play or concrete exercises) instead of only information-based programs possibly tailored to the leaders of peer groups (e.g., Aerts, 2019; Madriaza & Ponsot, 2015; Pratchett et al., 2010).

  • Finally, prevention or deradicalization concepts should be sensitive to stigmatization effects—for example, when programs and resources are allocated to risk groups, thereby implying latent or implicit prejudice against them (Aerts, 2019, Madriaza & Ponsot, 2015).

In addition to these findings, a few positive examples of sound evaluation studies revealing some further knowledge on radicalization prevention are worth mentioning. For example, a first meta-analysis of existing evaluations was presented recently by Jugl et al. (2021). They integrated eight quantitative primary studies with at least acceptable methodological standards (three with control group designs). Overall, these studies yielded a moderate effect size on different radicalization and extremism outcomes (d = 0.50). Although the number of studies was clearly limited and does not allow sound conclusions about what works best, the authors did conclude that the best-working programs are those with social-learning elements and approaches with mixed target groups as a combination of primary, secondary, and tertiary prevention in the sense of a contact intervention (Beelmann & Lutterbach, 2020; Pettigrew & Tropp, 2006). In addition, Jugl et al. (2021) pointed to related fields of prevention such as antisocial behavior and crime in which radicalization prevention probably can profit from the extensive literature in this field (Beelmann & Raabe, 2009; Farrington, Gaffney, Lösel, & Ttofi, 2017).

Two further experimental studies have been conducted recently in Germany. Walsh and Gansewig (2019) evaluated a school-based workshop conducted by a former extremist who dropped out of his extremist group. The study had a randomized controlled design, using multimethod assessment and follow-up measures. Unfortunately, the workshop could not report positive effects on right-wing attitudes, violence, and crimes—probably because this was only a less intensive intervention with only one 4-hour session. Hence, very short programs even when conducted with good intentions, obviously do not guarantee significant effects. In contrast, Beelmann and Karing (2015) have reported results of a long-term follow-up of their prejudice prevention program PARTS for elementary school children. The program was conducted in elementary schools within a block-randomized, controlled trial combining an experimental and longitudinal study starting in Grade 2 with 7- to 9-year-old school children and ending at the age of 14 to 16. The program PARTS consists of fifteen 45-min sessions with three modules (intercultural knowledge, reading and discussing indirect contact stories, and promotion of social-cognitive skills such as empathy and perspective taking; Beelmann, 2018). More than 5 years after the termination of the program, the program participants—now aged between 14 and 16 years (n = 173)—showed several significant differences in prejudice and radicalization outcomes compared to the control group (n = 148). For example, they showed lower negative evaluations of ethnic outgroups (effect size d = 0. 36), lower levels of intolerance against social diversity (d = 0.30), lower national-authoritarian attitudes (d = 0.32), and lower levels of contact to right-wing materials and groups (d = 0.18). The final result, although marginally significant and on a low intensity level, is especially noteworthy, because contact with radical peers and extremist groups seems to be an important risk factor for the ideologization of young people (e.g., LaFree, Jensen, James, & Safer-Lichtenstein, 2018; Vergani, Iqbal, Ilbahar, & Barton, 2018; Wolfowicz, Litmanovitz, Weisburd, & Hasisi, 2020).

In sum, the results of reviews and a few sound primary studies illustrate that an early developmentally founded prevention can have long-lasting effects on radicalization parameters. However, looking at the entire field of radicalization prevention, there is still a paucity of knowledge on how to keep young people away from entering radicalized developmental trajectories. Therefore, we shall continue to outline several further opportunities based on the concept of developmental prevention (Beelmann, 2012).

The Concept of Developmental Radicalization Prevention

The term developmental prevention has its roots in applied developmental and prevention science as well as in the tradition of positive youth development in a lifelong perspective (Lerner, Jacobs, & Wertlieb, 2005). It refers to measures or programs designed to promote positive development or to prevent undesired pathways based on tested developmental theories and empirical knowledge about normal and deviant developmental processes from birth to adulthood (Kurtines et al., 2008). For radicalization prevention, this includes:

  • Relying on causal developmental factors that impact on or buffer against radicalization (risk and protective factors)

  • Considering age-related differences and trajectories of radicalization processes (including level and rang-order stabilities)

  • Applying developmental theories of radicalization that explain intraindividual differences and interindividual differences within intraindividual change—that is, developmental differences depending on moderators (e.g., gender, relevant subgroups, social context) and mediators (e.g., cognitive development, identity development, etc.) that promote or buffer radicalization processes

  • Following general developmental principles and theories that deliver an understanding of developmental processes and dynamics (e.g., Bronfenbrenner, 1992; Sameroff, 2009)

  • Considering a perspective on individual change along with social and societal change and taking a social policy perspective (e.g., Wilson, Hayes, Biglan, & Embry, 2014)

Based on these considerations, we have proposed a new social-developmental model of radicalization (see Beelmann, 2020). We defined radicalization as a process by which an individual becomes a politically, religiously, or in some other way motivated extremist. We defined extremism as a significant deviation in attitudes and behavior from certain system-related norms and values of the political constitution (human rights, democracy, and rule of law). The model is based as an integrated summary of diverse information sources such as general models of problem behavior (e.g., Jessor, 2016), special radicalization theories (McCauley & Mouskalenko, 2011, 2017; Kruglanski, Bélanger, & Gunaratna, 2019; Kruglanski et al., 2014); fundamental motivational and social-psychological theories of human attitudes and behavior (Borum, 2011 a, b); specific theories on normal and deviant development of identity, prejudice, and other characteristics (e.g., Crocetti, 2018; Raabe & Beelmann, 2011); research on risk and protective factors for radicalization (e.g., Emmelkamp, Asscher, Wissink, & Stams, 2020; Lösel, King, Bender, & Jugl, 2018; Jahnke, Abad Borger, & Beelmann, 2021; Wolfowicz et al., 2020); and the results of relevant studies on preventing radicalization (see above). According to this radicalization model, extremism emerges within a risk-protection process that takes three developmental steps (see Figure 1): The first step is characterized by an interplay between risk factors for and protective factors against radicalization on a societal, social, and individual level. If developmental processes result in an imbalance between risk and protective factors, this will lead to four so-called proximal radicalization processes that evolve their full dynamics mainly between young adolescence and early adulthood. The four proximal processes concern:

  1. (1)

    identity problems as the motivational base characterized by an unfulfilled need for appreciation expressed in feelings of injustice, marginalization, insignificance, threatened identity, or specific identity constellations such as narcissism (see Hogg & Blaylock, 2014; Kruglanski et al., 2014);

  2. (2)

    prejudice and negative intergroup attitudes and behavior as the social and social-cognitive link for cognitions, emotions, and behavior that contain negativity toward and de-evaluation of members of social outgroups (e.g., »foreigner«; Brown, 2010);

  3. (3)

    extremist narratives, beliefs, and ideology as the legitimation base for prejudice, inequality, and the use of violence and illegitimate means for political purposes; and

  4. (4)

    antisocial development as the development of attitudes and behavior that mark rule-breaking of age-appropriate informal and formal norms and values.

These four processes are the psychological core of the radicalization of young people during the development from childhood up to the early and middle adulthood.

Figure 1 
A social-developmental model of radicalization

Figure 1

A social-developmental model of radicalization

Naturally, these four proximal processes can occur in various ways (i.e., based on different risk-protective factor combinations) and in various strengths. A potentially high risk for developing extremist attitudes and behavior may emerge if all four processes attain a certain critical value and if they are triggered by crises in the social context (e.g., societal conflict, individual victimization). In addition, depending on their trajectory and their degree, we can probably differentiate between various radicalization pathways and trajectories—for example, between different types of extremism (e.g., right-wing, left-wing, religious), between different subgroups (»follower« vs. »leader«; see Jasko & LaFree, 2019), or between different manifestations (extremist attitudes, extremist offenses, terrorist attacks). However, up to now, we have only a few sound longitudinal studies (e.g., Nivette, Eisner, & Ribeaud, 2017) and lack empirical verification of these issues.

Nonetheless, much is known about the development of the four proximal processes themselves. As outlined in Figure 2, all branches contain special sensitive periods during the development from childhood to adulthood that can serve as eligible phases for applying prevention measures. Naturally, this does not mean that other developmental periods are unimportant for radicalization processes and its prevention. Rather, they mark identified periods of high developmental dynamics that possess a high sensitivity for external stimulation and therefore a potentially high impact as a »window of opportunity« (Masten, Long, Kuo, McCormick, & Desjardins, 2009).

Figure 2 
Sensitive periods (in gray boxes) for the four proximal radicalization processes.

Figure 2

Sensitive periods (in gray boxes) for the four proximal radicalization processes.

Figure 2 also gives some indication on the order in which the proximal radicalization processes can be expected to occur. Starting at preschool age, an early antisocial development (»early starters« or a »life-long persistent trajectory,« see Fairchild et al., 2013) marks the beginning of a progredient radicalization with a high probability of heterotypical continuation during the whole period of childhood and adolescence (Moffitt, 2015). In addition, adolescence is another sensitive period for antisocial development because of the high prevalence of »adolescence-limited« and »late-starter« trajectories. However, the risk of stable behavior problems is somewhat lower compared to »early starters« in general, but probably also with respect to radicalization processes (Fairchild et al., 2013). Within prejudice development, research has found a characteristic decrease around the age of 7 to 10 years (Raabe & Beelmann, 2011). Any failure of this to occur for different reasons (e.g., low empathy or a lack of intergroup experiences) could be viewed as the second developmental step toward radicalization. Early adolescence, as a prominent period for identity formation (Crocetti, 2018), holds the risk of identity problems if, for example, young people do not find opportunities for identity exploration or are exposed to rejection and discrimination. A final consequence of these steps can be an increase in the probability of approaching extremist groups and adopting their narratives, beliefs, and ideology during these »impressionable years« of civic development and political socialization (Sears & Levy, 2003).

Of course, it should be mentioned that this prototypic developmental course of radicalization can show great interindividual variation. This applies not only to the assignment of the proximal processes to the age of individuals but also the sequence of the proximal processes themselves. For example, identity problems can also emerge at later ages (e.g., in adulthood as a consequence of losing one’s job). However, the probability of a permanent identity crisis depends largely on whether or not individuals have developed a diverse and reflected identity in their earlier development. In a similar way, radicalization processes can vary according to influences of the social context that can serve as triggers and accelerators of proximal processes (Doosje et al., 2016). For example, one can imagine that individuals with a high risk for radicalization will be protected in times of generally favorable economic living conditions, but will become radicalized at later ages if these conditions are no longer given. Nonetheless, because most individuals have been radicalized by the age of 30 (Borum, 2011b), later radicalization is comparably unlikely, even though the impact of fundamental societal crises such as forced migration, climate change, and economic inequality have increased within the last decade and will probably increase even further in the future.

With these conceptual premises, we shall now turn to research on prevention principles and programs that try to buffer radicalization processes and trajectories by addressing the four proximal radicalization processes from a developmental or ontogenetic perspective.

Developmental Prevention Approaches

Prevention programs can be directed toward all known risk or protective factors on Level 1 of the outlined radicalization model. However, because correlations between risk and protective factors and extremism outcomes are only low and causal processes are quite unspecific and characterized by both equi- and multifinality, it seems more promising for prevention initiatives to address the four proximal processes with their clear causal connection to radicalization. In addition, developmentally founded prevention activities should be oriented toward natural development within the field considered, and we assume that the sensitive periods for the proximal processes outlined here provide the best timing for prevention programs. This runs somewhat counter to principles such as »early is better,« because some prevention approaches need a certain level of development (e.g., specific cognitive competencies) before they can be applied soundly. Hence, prevention initiatives should be oriented toward the principle of »timely and developmentally appropriate« (Beelmann, 2012).

Bearing these considerations in mind and based on our developmental radicalization model (Beelmann, 2020), we shall now turn to promising prevention principles and prevention approaches within a twofold presentation. First, we shall give an overview of central prevention principles and aims within the four proximal process areas (see Table 2). These principles and aims provide a more general preventive orientation independent from programs and approaches that corresponds to integrated concepts of positive youth development (e.g., Biglan, 2015, Lerner, 2004, Scales & Leffert, 2004). Second, we shall briefly outline the evidence on different approaches and programs that have been applied within the fields of proximal radicalization processes (Table 3Table 3). It should be noted, however, that how far these programs and approaches reduce radicalization and lower extremism outcomes has yet to be tested. Instead, they are evaluated in terms of their primary outcomes that should have at least some impact on the radicalization processes as well. In addition, as in every summary, we have to skip differential outcomes and details that would be required for a differentiated discussion on the application of these programs (see for a more comprehensive debate; Beelmann et al., 2021).

Table 1

Important prevention principles according to the four proposed proximal processes of radicalization

Proximal processes Prevention principles and aims
Identity problems –Provide opportunities to establish an evolved, diverse, and reflected identity for young people and prevent adopted, unilateral, inflexible, unreflected social identities

–Create a sense of belonging and prevent young people experiencing rejection and discrimination
Prejudice –Provide positive experiences of diversity including positive contact experiences and intergroup friendships

–Prevent excessive identification with fixed social categories (nationality, ethnicity, gender, etc.)

–Promote abilities such as empathy and perspective taking; establish norms based on human rights

Extremist attitudes, beliefs, and ideologies –Encourage developmentally appropriate and individually tailored responsibilities for the social mediation of universal (fairness, equity, justice) and political values (democracy, human rights)

–Teach the handling of digital media and the problems they raise (not technical)
Antisocial development –Strengthen social learning (including social rules and norms)

–Provide a consistent reaction to rule-breaking behavior and prevent entry into deviant antisocial groups

–Provide psychological and practical support for high-risk groups

In the field of identity, we need to provide young people with opportunities and support to explore and test various identity-relevant areas of life (school, leisure activity, sport, culture, politics, friends, hobbies etc.) so that they can build up a healthy self-concept and construct a diverse and reflected identity (Crocetti, 2018). This is especially important for young people between the ages of 12 and 18; but, of course, also beyond that age. Children and adolescents (and adults too) have a need to belong (Baumeister & Leary, 1995) and to experience affiliation and significance (Kruglanski et al., 2019). Hence, it is necessary to avoid repeated experiences of failure or social rejection and discrimination without any opportunity to solve such problems constructively. Likewise, we should prevent the adoption of identity concepts consisting of single inflexible characteristics (nationality, religion, gender) that are held to be important across all social contexts. Such identities are easily threatened and can lead, at least when permanent, to identity problems. A number of different prevention approaches and programs aim to strengthen the self-concept and identity (Table 3). For example, self-concept interventions are likely to increase a positive self-concept for those individuals who already had low self-confidence (O’Mara, Marsh, Craven, & Debus, 2006). The same holds for outdoor activities (Bowen & Neill, 2013) especially for older target groups. Sport has massive effects on physical health, but its potential to strengthen the self-concept is perhaps limited to noncompetitive sports, because competition could harm when negative experiences prevail (Spruit et al., 2016). A relatively new approach to promote identity-related processes is self-affirmation interventions in which participants have to select a certain number of individually important values from a presented list (e.g., family, friends, sport) and write short texts on these values (Cohen & Sherman, 2014). This should lead to more reflected and diverse identities and lower the vulnerability to identity threats. However, up to now, these effects have been confirmed only in short-term experimental studies (Sweeney & Moyer, 2015). Nonetheless, the concept could perhaps be used as an additional exercise within the framework of more comprehensive programs. Finally, we should say a word on social work practice and cultural activities that probably have great potentials to support and strengthen the self-concept and identity formation of young people. Unfortunately, extended and sound evaluation research on these broadband activities does not exist.

Positive experiences of diversity based on contact and cross-group friendships are probably the best way to prevent prejudice development (Table 2). In addition, an exaggerated positive evaluation of social categories—especially those with fixed affiliation (nationality, gender)—should be avoided. This does not mean that group-based identities are not desirable. In fact, belonging to a social group is indeed a source of essential social bonding. However, there is a narrow line between sound group-related belonging and excessive identification. As a basic rule, identification should not lead to a de-evaluation of social outgroups, and the ingroup should therefore be viewed as different but not superior. Finally, prejudice prevention could also be buffered by promoting competencies such as empathy and perspective taking as well as the establishment of moral values such as fairness, equity, and justice. Programs against prejudice are manifold (Beelmann & Lutterbach, 2020). Particularly positive effects have resulted from contact interventions (Lemmer & Wagner, 2015; Pettigrew & Tropp, 2006), and this holds for a broad range of applications across types, settings, target groups, and potentially prejudiced and discriminated outgroups. There is also empirical support for multicultural and antibias programs, although to a lower extent in terms of the number and outcomes of sound evaluation studies (Bezrukova, Spell, Perry, & Jehn, 2016; Paluck & Green, 2009). Media campaigns are a further and widely applied measure to lower prejudice. However, several studies have pointed to the risk of negative side effects (e.g., increased perception of threat, higher prejudice in the program group) if certain design rules are violated (e.g., using a negative instead of a positive social context, expressing similarities between ingroup and outgroup instead of differences; see Vrij, Akehurst, & Smith, 2003). Finally, a large range of social-cognitive programs also reveal significant effects on prejudice reduction (Beelmann & Heinemann, 2014) especially those that address the promotion of empathy and perspective taking as well as the mediation of basic social norms and values (e.g., justice).

To protect young people from extremist narratives, beliefs, and ideologies, we should provide them with age-appropriate opportunities to engage in commitment to the social community. Respective measures should allow them to learn a sense of responsibility for fair and just social interactions, but also the competence to claim human and political rights in a socially acceptable way. In general, socialization agents should promote a distribution of values such as fairness, equity, and justice as basic norms of civilized societies. These are cultural achievements that must be learned, just like the political values of democracy and human rights. Based on the increasing importance of online communication (internet, social media), it is essential for young people to learn about the problems and risks involved in using these communication and information channels. Without these competencies, they can easily become victims of extremist movements and their interests. Several prevention approaches are designed to meet these objections (Table 3). For example, research on civic education (Goren & Yemini, 2017; Manning & Edwards, 2014), character and value education (Berkowitz & Bier, 2007; Jeynes, 2019), and service-learning programs (Celio, Durlak, & Dymnicki, 2011) provide sound evidence that young people can learn social responsibilities, establish human values, and show more prosocial behavior. However, one problem that remains is the difficulty in recruiting at-risk groups, pointing to the necessity to make participation in these programs more attractive. Trainings in media competence are also promising. However, research on outcomes is limited (Blayer, 2019) and should be extended to establishing an enlightened »digital citizenship« (Reynolds, 2017). One possible content of digital education lies in learning to argue against extremist agitation via counternarratives (Briggs & Feve, 2013). These strategies have been used on- and offline and outcomes are positive (Braddock & Dillard, 2016) although sound evaluations studies are rare.

Finally, to prevent antisocial developments, societies should be committed to the general objective of offering opportunities not only for academic but also for social learning and, moreover, providing special support for high-risk families who are affected by multiple social risk factors. This is particularly important to remove young people who are at risk from deviant and extremist peer groups. It also includes attractive offers for leisure activities and opportunities to assume responsibility (see above). Special importance should be addressed to the mediation of social rules and a consistent reaction to rule breaking and antisocial behavior by diverse developmental agents (parents, schools, youth services). However, in the field of radicalization and from the perspective of a democratic state, the threshold between desirable political activities that are sometimes expressed in illegal (rule breaking) behavior (e.g., civil disobedience), and radicalized antisocial development is not easy to determine. It is especially unclear whether this should be viewed as activities in the sense of (more or less inappropriate) civic engagement, which should be generally supported (but without accepting illegal behavior), or as the beginning of a problematic radicalization process in the sense of our definition that call for an early and consist reaction from the police, courts, and other authorities. The distinction between political activism and radicalization have been discussed intensively (e.g., Moskalenko & McCauley, 2009) and answers depend largely on the seriousness of offenses (and possible victims), the underlying values of the activities within the social context (i.e., what are the real aims of the activities?), and finally on the biographic or developmental history of the young person or the group under consideration. Although strong research on the differentiation between political activism and radicalization is rare, our radicalization model does suggest that a long history of (political and unpolitical) antisocial development is the real proximal risk factor for extremism and not occasional antisocial behavior driven by a positive goal orientation (e.g., human rights, environmental protection, justice, equality, etc.). This does not inevitably mean that these behaviors are acceptable or should be ignored by law enforcement, but that they should probably not be treated under the heading of radicalization and extremism.

However, going beyond the discussion on the reactions to more or less deviant political activities, a large number of approaches and programs for preventing antisocial developments have been developed during the last decades (e.g., Farrington et al., 2017; Welsh & Farrington 2012). Several programs have been evaluated extensively, resulting in numerous comprehensive meta-analyses on the state of the art (Beelmann & Raabe, 2009; Farrington et al., 2017). In general, social training programs (e.g., Beelmann & Lösel, 2020), parent training programs (e.g., Piquero et al., 2016), and early intervention programs for high-risk families (e.g., Dekovics et al., 2011; Reynolds et al., 2010) have demonstrated high effectiveness although not without any limitations (e.g., implementation problems in parent trainings). Evidence on school- and community-based strategies (e.g., antibullying programs, community that cares) is somewhat lower. However, positive outcomes have been achieved here too (e.g., Gaffney, Ttofi, & Farrington, 2019; Hawkins et al., 2009).

Table 2:

Overview of proposed prevention approaches and programs to prevent proximal developmental radicalization processes

Approach/Program Overall

outcome

evaluation
Appropriate

age groups1
Comments
Prevention of identity problems
Self-concept interventions + EA, AD Not indicated for target groups/young people with high self-esteem
Outdoor-activities/Sport +/O AD, EAH Not always effective (e.g., not within competitive sport)
Self-affirmation programs + AD, EAH Only short-term effects
Social work practices ? AD, EAH Only theoretical potentials; outcomes depend on implementation and relationship quality
Cultural activities (theater, dance, music) ? AA Only theoretical potentials; active participation
Prejudice prevention
Contact interventions ++ AA Broad empirical confirmation; contact conditions important; suitable for different kinds of contact.
Diversity, multicultural, and antibias programs + AD, EAH Partially cognitive demanding and therefore not suitable for all target groups
Media campaigns +/- AD, EAH, ADH Focus on the rules of persuasive communication or social marketing
Social-cognitive learning programs ++ EA, EAD Highest effects for programs promoting empathy/perspective taking, norms, and values (e.g., fairness)
Preventing extremist narratives, beliefs or ideologies
Civic education + AD, EAH, AH Problems in recruiting at-risk groups; effects of information-based programs are limited
Service learning,

character education
+ AD, EAH, AH Problems in recruiting at-risk groups
Media competence + AD, EAH, AH Only little empirical research; outcomes mainly on knowledge not on behavior; partially cognitively demanding
Counternarratives + AD, EAH, AH Only little empirical research; outcomes mainly on knowledge; partially cognitively demanding
Preventing antisocial development
Social training programs ++ PA, EA, EAD Smaller effects on antisocial behavior than for social competence outcomes
Parent training ++ PA, EA Long-term effects vague; implementation problems
Early intervention ++ PA Impressive long-term effects; requires intensive resources
School- or community-based prevention approaches + AA High implementation requirements

Notes. ++ = highly evidence-based, + = evidence-based, O = some indication for positive outcomes, +/- = mixed outcomes. 1 Ages should be viewed as rough estimations of the developmental status. AA = all age groups (up to 35 years), PA = preschool age (up to 6 years), EA = elementary school age (7 to 12 years), EAD = early adolescence (12 to 15 years), LAD = late adolescence (16 to 18 years), AD = adolescence (12 to 18 years), EAH = emerging adulthood (18 to 25 years), ADH = adulthood (20 to 35 years).

In sum, several evidence-based opportunities to buffer young people from radicalization based on developmentally founded strategies could be applied with some probability for prospects of success. The field of prejudice prevention and the prevention of antisocial behavior provide the best opportunities here, whereas evidence for preventing identity problems and the acquisition of extremist ideologies needs to be gained from future scientific research. However, simply providing prevention programs alone is not enough. In recent years, international research has demonstrated impressively that prevention depends not only on good programs but also on the ­implementation modalities and the quality of implementation (Beelmann & Karing, 2014; Ghate, 2016). When carrying out interventions in childhood and adolescence, for example, the focus should not be solely on imparting knowledge, but additionally on ensuring that programs offer concrete practical exercises and address the emotions of young people. In addition, a positive focus on strengthening skills and competencies often proves to be a better strategic approach than applying the avoidance perspective frequently associated with prevention. Such a perspective also prevents stigmatization effects—which are a real risk in radicalization prevention (Madriaza & Ponsot, 2015). Moreover, it is also necessary to consider the numerous variables that can influence the implementation quality, especially if the aim is to integrate programs into regular psychosocial and educational care. In addition, more successful ­strategies for recruiting children, adolescents, and families who are particularly stressed and in urgent need of help, the establishment of a sustainable service structure, and the dynamic adaptation of programs to real-world practice are just three of the many important topics pointing to the major challenges facing any successful implementation of prevention measures (Beelmann, Malti, Noam, & Sommer, 2018; Malti, Noam, Beelmann, & Sommer, 2016).

Despite all the prospects that the concept of developmental prevention of radicalization outlined above may elicit, it is still necessary to mention some societal aspects that impede the implementation of prevention principles and programs. For years, for example, we can observe how social inequality is growing in many societies, and how this is a constant source of social comparison processes in which certain population groups do poorly in almost all areas­ (Wilkinson & Pickett, 2009). Making such negative experiences can be a major source of identity problems that can lead, at least in the long term, to serious social problems. Because the trend toward increased social inequality seems to be unbroken, it can be assumed that this situation is partially due to functional principles of the economic system and therefore difficult to change. Massive economic interests often stand in the way of rational prevention strategies and thus the ­opportunities for young people to develop. For example, one can ask whether the ­demand to strengthen media skills is not only rejected by extremist groups with their indoctrination intentions but also ­runs counter to the business­ models of influential digital corporations and an advertising industry ­geared toward consumption. Admittedly, this touches on fundamental issues in our society and ­on shaping its future in ways that affect all areas of life. Nonetheless, when thinking about this more concretely and pragmatically, we should­­ not underestimate such interests when implementing and establishing preventive­ measures and, if necessary, we should actively include them in our efforts.

Funding

This research was supported by grants from the German Federal Ministry of Education and Research (Grand No. 13N14284) and the Crime Prevention Council of Lower Saxony (Hannover).

References

Aerts, S. (2019). European Crime Prevention Monitor 2019/1: Radicalisation and violent extremism. Brussels: European Crime Prevention Network. https://eucpn.org/sites/default/files/document/files/monitor_radicalisation_and_violent_extremism.pdf Search in Google Scholar

Baumeister, R. F., & Leary, M. R. (1995). The need to belong: Desire for interpersonal attachments as a fundamental human motivation. Psychological Bulletin, 117, 497–529. doi: 10.1037/0033-2909.117.3.497 Search in Google Scholar

Beelmann, A. (2012). The scientific foundation of prevention. The status quo and future challenges of developmental crime prevention. In T. Bliesener, A. Beelmann, & M. Stemmler (Eds.), Antisocial behavior and crime. Contributions of developmental and evaluation research to prevention and intervention (pp. 137–164). Cambridge, MA: Hogrefe Publishing. Search in Google Scholar

Beelmann, A. (2018). Toleranzförderung und Vorurteilsprävention bei Kindern. Ergebnisse des Grundschulprogramms PARTS [Promoting tolerance and preventing prejudice in children: Results of the PARTS elementary school program]. In A. Beelmann (Ed.), Toleranz und Radikalisierung in Zeiten sozialer Diversität. Beiträge aus den Sozialwissenschaften (pp. 9-27). Schwalbach/Ts, Germany: Wochenschau Verlag Search in Google Scholar

Beelmann, A. (2020). A social-developmental model of radicalization: An integration of existing theories and empirical research. International Journal of Conflict and Violence, 14(1), 1–14. doi: 10.4119/ijcv-3778 Search in Google Scholar

Beelmann, A., & Heinemann, K. (2014). Preventing prejudice and improving intergroup attitudes. A meta-analysis of child and adolescent training programs. Journal of Applied Developmental Psychology, 35, 10–24. doi: 10.1016/j.appdev.2013.11.002. Search in Google Scholar

Beelmann, A., & Karing, C. (2014). Implementationsfaktoren und -prozesse in der Präventionsforschung: Strategien, Probleme, Ergebnisse, Perspektiven [Implementation factors and processes in prevention research: Strategies, problems, results, perspectives]. Psychologische Rundschau, 65, 129–139. doi: 10.1026/0033-3042/a000215 Search in Google Scholar

Beelmann, A., & Karing, C. (2015). Förderung toleranter Einstellungen und die Prävention von Vorurteilen. Langzeitwirkungen des Programms zur Förderung von Akzeptanz, Respekt, Toleranz und sozialer Kompetenz (PARTS) [Promotion of tolerant attitudes and the prevention of prejudice. Long-term effects of the program to promote acceptance, respect, tolerance, and social competence]. forum kriminalprävention, 1/2015, 51–58. Search in Google Scholar

Beelmann, A., & Lösel, F. (2020). A comprehensive meta-analysis of randomized evaluations on the effect of child social skills training on antisocial behavior. Journal of Developmental and Life-course Criminology 7, 41–65. doi: 10.1007/s40865-020-00142-8 Search in Google Scholar

Beelmann, A., & Lutterbach, S. (2020). Preventing prejudice and the promotion of intergroup relations. In L. Benuto, M. Duckworth, A. Masuda, & W. O’Donohue (Eds.), Prejudice, stigma, privilege, and oppression. A behavioral health handbook (pp. 309–326). New York, NY: Springer. Search in Google Scholar

Beelmann, A., Lutterbach, S., Rickert, M., & Sterba, L. S. (2021). Entwicklungsorientierte Radikalisierungsprävention. Was man tun kann und sollte. [Developmental radicalization prevention. What you can do and should do.]. Jena, Germany: Friedrich-Schiller-University Jena, Research Center on Right-wing Extremism, Civic Education, and Social Integration. Search in Google Scholar

Beelmann, A., Malti, T., Noam, G., & Sommer, S. (2018). Innovation and integrity: Desiderata and future directions for prevention and intervention science. Prevention Science, 19, 358–365. doi: 10.1007/s11121-018-0869-6 Search in Google Scholar

Beelmann, A., & Raabe, T. (2009). The effects of preventing antisocial behavior and crime in childhood and adolescence. Results and implications of research reviews and meta-analyses. International Journal of Developmental Science, 3, 260–281. doi: 10.3233/DEV-2009-3305 Search in Google Scholar

Berkowitz, M., & Bier, M. C. (2007). What works in character education? Journal of Research in Character Education, 5, 1–37. Search in Google Scholar

Bezrukova, K., Spell, C. S., Perry, J. L., & Jehn, K. A. (2016). A meta-analytical integration of over 40 years of research on diversity training evaluation. Psychological Bulletin, 142, 1227–1274. doi: 10.1037/bul0000067 Search in Google Scholar

Biglan, A. (2015). The nurture effect. How the science of human behaviour can improve our lives and our world? Oakland, CA: New Harbinger. Search in Google Scholar

Blayer, C. (2019). Cyberhate: A review and content analysis of intervention strategies. Aggression and Violent Behavior, 45, 163–172. doi: 10.1016/j.avb.2018.05.006 Search in Google Scholar

BMI – Bundesministerium des Innern, für Bau und Heimat (BMI). (2020). Verfassungsschutzbericht 2019 [2019 report on the protection of the constitution]. https://www.verfassungsschutz.de/de/download-manager Search in Google Scholar

Borum, R. (2011a). Radicalization into violent extremism I: A review of social science theories. Journal of Strategic Security, 4, 7–36. doi: 10.5038/1944-0472.4.4.1 Search in Google Scholar

Borum, R. (2011b). Radicalization into violent extremism II: A review of conceptual models and empirical research. Journal of Strategic Security, 4, 37–62. doi: 10.5038/1944-0472.4.4.2 Search in Google Scholar

Bowen, D. J., & Neill, J. T. (2013). A meta-analysis of adventure therapy outcomes and moderators. The Open Psychology Journal, 6(1), 28–53. doi: 10.2174/1874350120130802001 Search in Google Scholar

Braddock, K., & Dillard, J. P. (2016). Meta-analytic evidence for the persuasive effect of narratives on beliefs, attitudes, intentions and behaviors. Communications Monograph, 83, 446–467. doi: 10.1080/03637751.2015.1128555 Search in Google Scholar

Briggs, R., & Feve, S. (2013). Review of programs to counter narratives of violent extremism. What works and what are the implications for government. London: Institute for Strategic Dialogue. https://www.dmeforpeace.org/peacexchange/wp-content/uploads/2018/10/Review-of-Programs-to-Counter-Narratives-of-Violent-Extremism.pdf Search in Google Scholar

Bronfenbrenner, U. (1992). The ecology of human development: Experiments by nature and design. Cambridge, MA: Harvard University Press. Search in Google Scholar

Brown, R. (2010). Prejudice: Its social psychology. Chichester, UK: Wiley. Search in Google Scholar

Celio, C. I., Durlak, J., & Dymnicki, A. (2011). A meta-analysis of the impact of service-learning on students. Journal of Experiential Education, 34, 164–181. doi: 10.1177/105382591103400205 Search in Google Scholar

Christmann, K. (2012). Preventing religious radicalisation and violent extremism: A systematic review of the research evidence. Huddersfield: University of Huddersfield. http://eprints.hud.ac.uk/id/eprint/16198/ Search in Google Scholar

Cohen, G. L., & Sherman, D. K. (2014). The psychology of change: Self-affirmation and social psychological intervention. Annual Review of Psychology, 65, 333–371. doi: 10.1146/annurev-psych-010213-115137 Search in Google Scholar

Crocetti, E. (2018). Identity dynamics in adolescence: Processes, antecedents, and consequences. European Journal of Developmental Psychology, 15(1), 11–23. doi: 10.1080/17405629.2017.1405578 Search in Google Scholar

Deković, M., Slagt, M. I., Asscher, J. J., Boendermaker, L., Eichelsheim, V. I. & Prinzie, P. (2011). Effects on early prevention programs on adult criminal offending: A meta-analysis. Clinical Psychology Review, 31, 532–544. doi: 10.1016/j.cpr.2010.12.003 Search in Google Scholar

Doosje, B., Moghaddam, F. M., Kruglanski, A. W., de Wolf, A., Mann, L. & Feddes, A. R. (2016). Terrorism, radicalization and de-radicalization. Current Opinion in Psychology, 11, 79–84. doi: 10.1016/j.copsyc.2016.06.008 Search in Google Scholar

Emmelkamp, J., Asscher, J. J., Wissink, I. B. & Stams, G. J. J. M. (2020). Risk factors for (violent) radicalization in juveniles: A multilevel meta-analysis. Aggression and Violent Behavior, 55. Advance online publication. doi: 10.1016/j.avb.2020.101489. Search in Google Scholar

Fairchild, G., van Goozen, S. H. M., Calder, A. J., & Goodyer, I. M. (2013). Research review: Evaluating and reformulating the developmental taxonomic theory of antisocial behavior. Journal of Child Psychology and Psychiatry, 54, 924–940. doi: 10.1111/jcpp.12102 Search in Google Scholar

Farrington, D. P., Gaffney, H., Lösel, F., & Ttofi, M. M. (2017). Systematic reviews of the effectiveness of developmental prevention programs in reducing delinquency, aggression, and bullying. Aggression and Violent Behavior, 33, 91–106. doi: 10.1016/j.avb.2016.11.003 Search in Google Scholar

Feddes, A. R., & Gallucci, M. (2015). A literature review on methodology used in evaluating effects of preventive and de-radicalisation interventions. Journal for Deradicalization, 5, 1–27. http://journals.sfu.ca/jd/index.php/jd/article/download/33/31 Search in Google Scholar

Gaffney, H., Ttofi, M. M., & Farrington, D. P. (2019). Evaluating the effectiveness of school-bullying prevention programs: An updated meta-analytical review. Aggression and Violent Behavior, 45, 111-133. doi: 10.1016/j.avb.2018.07.001 Search in Google Scholar

Goren, H., & Yemini, M. (2017). Global citizenship education redefined: A systematic review of empirical studies on global citizenship education. Journal of Education Research, 82, 170–183. Search in Google Scholar

Ghate, D. (2016). From programs to systems: Deploying implementation science and practice for sustained real world effectiveness in services for children and families. Journal of Clinical Child and Adolescent Psychology, 45(6), 812–826. doi: 10.1080/15374416.2015.1077449 Search in Google Scholar

Hawkins, J. D., Oesterle, S., Brown, E. C., Arthur, M. W., Abbott, R. D., Fagan, A., & Catalano, R. (2009). Results of a type 2 translational research trial to prevent adolescent drug use and delinquency: A test of communities that care. Archives of Pediatrics and Adolescent Medicine, 163(9), 789–798. doi: 10.1001/archpediatrics.2009.141 Search in Google Scholar

Hogg, M. A. & Blaylock, D. B. (Eds.). (2012). Extremism and the psychology of uncertainty. Hoboken, NJ: Wiley-Blackwell. Search in Google Scholar

Institute for Economics and Peace. (2019). Global Terrorism Index 2019: Measuring the impact of terrorism. www.visionofhumanity.org/app/uploads/2019/11/GTI-2019web.pdf Search in Google Scholar

Jahnke, S., Abad Borger, K., & Beelmann, A. (2021). Predictors of political violence outcomes among young people: A systematic review and meta-analysis. Political Psychology. Advance online publication. doi:10.1111/pops.12743 Search in Google Scholar

Jasko, K., & LaFree, G. (2019). Who is more violent in extremist groups? A comparison of leaders and followers. Aggressive Behavior, 46, 141–150. doi: 10.002/ab21865 Search in Google Scholar

Jessor, R. (2016). The origins and development of problem behavior theory. New York, NY: Springer. Search in Google Scholar

Jeynes, W. (2019). A meta-analysis on the relationship between character education and student achievement and behavioral outcomes. Education and Urban Society, 51, 33–71. doi: 10.1177/0013124517747681 Search in Google Scholar

Jugl, I., Lösel, F., Bender, D., & King, S. (2021). Psychosocial prevention programs against radicalization and extremism: A meta-analysis of outcome evaluations. The European Journal of Psychology Applied to Legal Context, 13, 37–46. doi: 10.5093/ejpalc2021a6 Search in Google Scholar

Kruglanski, A. W., Gelfand, M. J., Bélanger, J. J., Sheveland, A., Hetiarachchi, M., & Gunaratna, R. (2014). The psychology of radicalization and de-radicalization: How significance quest impacts violent extremism. Advances in Political Psychology, 35, 69–93. doi: 10.1111/pops.12163 Search in Google Scholar

Kruglanski, A. W., Bélanger, J. J., & Gunaratna, R. (2019). The three pillars of radicalization: Needs, narratives, and networks. New York, NY: Oxford University Press. Search in Google Scholar

Kurtines, W. M., Ferrer-Wreder, L., Berman, S. L., Lorente, C. C., Silverman, W. K., & Montgomery, M. J. (2008). Promoting positive youth development: New directions in developmental theory, methods, and research. Journal of Adolescent Research, 23, 233–244. doi: 10.1177/0743558408314372 Search in Google Scholar

LaFree, G., Jensen, M. A., James, P. A., & Safer-Lichtenstein, A. (2018). Correlates of violent political extremism in the United States. Criminology, 56, 233–268. doi: 10.1111./1745-9125.12169 Search in Google Scholar

Lemmer, G., & Wagner, U. (2015). Can we really reduce prejudice outside the lab? A meta-analysis of direct and indirect contact interventions. European Journal of Social Psychology, 45, 152–168. doi: 10.1002/ejsp.2079 Search in Google Scholar

Lerner, R. M. (2004). Liberty: Thriving and civic engagement among America’s youth. Thousand Oaks, CA: Sage. Search in Google Scholar

Lerner, R. M., Jacobs, F., & Wertlieb, D. (Eds.). (2005). Applied developmental science. Thousand Oaks, CA: Sage. Search in Google Scholar

Lösel, F., King, S., Bender, D., & Jugl, I. (2018). Protective factors against extremism and violent radicalization: A systematic review of research. International Journal of Developmental Science, 12(1-2), 89–102. doi: 10.3233/DEV-170241 Search in Google Scholar

Madriaza, P., & Ponsot, A. (2015). Preventing radicalization: A systematic review. Montreal: International Centre for the Prevention of Crime. doi: 10.13140/RG.2.1.4862.1682. Search in Google Scholar

Manning, N., & Edwards, K. (2013). Does civic education for young people increase political participation? A systematic review. Educational Review, 66, 22–45. doi: 10.1080/00131911.2013.763767 Search in Google Scholar

Malti, T., Noam, G. G., Beelmann, A., & Sommer, S. (2016). Toward dynamic adaptation of psychological interventions for child and adolescent development and mental health. Journal of Clinical Child & Adolescent Psychology, 45 (6), 827–836. doi: 10.1080/15374416.2016.1239539 Search in Google Scholar

Masten, A. S., Long, J. D., Kuo, S. I.-C., McCormick, C. M., & Desjardins, C. D. (2009). Developmental models of strategic intervention. International Journal of Developmental Science, 3, 282–291. Search in Google Scholar

McCauley, C. & Moskalenko, S. (2011). Friction. How radicalization happens to them and us. Oxford, NY: Oxford University Press. Search in Google Scholar

McCauley, C. & Moskalenko, S. (2017). Understanding radicalization. The two pyramid model. American Psychologist, 72, 205–216. doi: 10.1037/amp0000062 Search in Google Scholar

Moffitt, T. E. (2015). Life-course persistent vs. adolescence-limited antisocial behaviour. In T. R. McGee & P. Mazerolle (Eds.), Developmental and life-course criminological theories. London: Routledge. doi: 10.4324/9781315094908 Search in Google Scholar

Moskalenko, S., & McCauley, C. (2009). Measuring political mobilization: The distinction between activism and radicalism. Terrorism and Political Violence, 21, 239–260. doi: 10.108009546550902765508 Search in Google Scholar

Nivette, A., Eisner, M., & Ribeaud, D. (2017). Developmental predictors of violent extremist attitudes: A test of general strain theory. Journal of Research in Crime and Delinquency, 54(6), 755–790. doi: 10.1177/0022427817699035 Search in Google Scholar

O´Mara, A. J., Marsh, H. W., Craven, R. G. & Debus, R. L. (2006). Do self-concept interventions make a difference? A synergistic blend of construct validation and meta-analysis. Educational Psychologist, 41(3), 181–206. doi: 10.1207/s15326985ep4103_4 Search in Google Scholar

Paluck, E. L., & Green, D. P. (2009). Prejudice reduction: What works? A review and assessment of research and practice. Annual Review of Psychology, 60, 339–367. doi: 10.1146/annurev.psych.60.110707.163607 Search in Google Scholar

Pettigrew, T. F., & Tropp, L. R. (2006). A meta-analytic test of intergroup contact theory. Journal of Personality and Social Psychology, 90, 751–783. doi: 10.1037/0022-3514.90.5.751 Search in Google Scholar

Piquero, A. R., Jennings, W. G., Diamond, B., Farrington, D. P., Tremblay, R. E., Welsh, B. C., & Gonzalez, J. M. R. (2016). A meta-analysis update on the effects of early family/parent training programs on antisocial behavior and delinquency. Journal of Experimental Criminology, 12, 229–248. doi: 10.1007/s11292-016-9256-0 Search in Google Scholar

Pistone, I., Eriksson, E., Beckman, U., Mattson, C., & Sager, M. (2019). A scoping review of interventions for preventing and countering violent extremism. Current status and implications for future research. Journal for Deradicalization, 19, 1–84. http://journals.sfu.ca/jd/index.php/jd/article/download/213/153 Search in Google Scholar

Pratchett, L., Thorp, L., Wingfield, M., Lowndes, V., & Jabbar, R. (2010). Preventing support for violent extremism through community interventions. A review of the evidence. London: Department for Communities and Local Government. https://pdfs.semanticscholar.org/6cb2/6647a92c0c375bf065d2bd4fe8d0c5ef9d03.pdf?_ga=2.21428664.2072036497.1575888162-1538954117.1567174913 Search in Google Scholar

Raabe, T., & Beelmann, A. (2011). Development of ethnic, racial, and national prejudice in childhood and adolescence: A multinational meta-analysis of age differences. Child Development, 82, 1715–1737. doi: 10.1111/j.1467-8624.2011.01668.x Search in Google Scholar

Reynolds, L. (2017). Internet citizens. Impact report. London: Institute for Strategic Dialogue. Search in Google Scholar

Reynolds, A. J., Rolnick, A. J., Englund, M. M., & Temple, J. A. (Eds.). (2010). Childhood programs and practices in the first decade of life. A human capital integration. Cambridge, MA: Cambridge University Press. Search in Google Scholar

Sameroff, A. (Ed.). (2009). The transactional model of development. How children and contexts shape each other. Washington, DC: American Psychological Association. Search in Google Scholar

Scales, P. C., & Leffert, N. (2004). Developmental assets: A synthesis of the scientific research on adolescent development (2nd ed.). Minneapolis, MN: Search Institute. Search in Google Scholar

Sears, D. O., & Levy, S. (2003). Childhood and adult political development. In D. O. Sears, L. Huddy, & R. Jervis (Eds.), Oxford handbook of political psychology (pp. 60–109). Oxford, NY: Oxford University Press. Search in Google Scholar

Spruit, A., Assink, M., van Vugt, E., van der Put, C., & Stams, G. J. (2016). The effects of physical activity interventions on psychosocial outcomes in adolescents: A meta-analytic review. Clinical Psychology Review, 45, 56–71. doi: 10.1016/j.cpr.2016.03.006 Search in Google Scholar

Stephens, W., Sieckelinck, S., & Boutellier, H. (2019). Preventing violent extremism: A review of the literature. Studies in Conflict & Terrorism, 1–16. doi: 10.1080/1057610X.2018.1543144 Search in Google Scholar

Sweeney, A. M., & Moyer, A. (2015). Self-affirmation and responses to health messages: A meta-analysis on intentions and behavior. Health Psychology, 34(2), 149–159. doi: 10.1037/hea0000110 Search in Google Scholar

Trip, S., Bora, C. H., Marian, M., Halmajan, A., & Drugas, M. I. (2019). Psychological mechanisms involved in radicalization and extremism. A rational emotive behavioral conceptualization. Frontiers in Psychology, 10:437. doi: 10.3389/fpsyg.2019.00437 Search in Google Scholar

van Hemert, D. A., Berg, H., van Vliet, A. J., Roelofs, M. L., Huis in ‘t Veld, M., Marret, J., Gallucci, M., & Feddes, A. (2014). Synthesis report on the state-of-the-art in evaluating the effectiveness of counter-violent extremism interventions. www.impacteurope.eu/wp-content/uploads/2015/02/D2.2-Synthesis-Report.pdf Search in Google Scholar

Vrij, A., Akehurst, L., & Smith, B. (2003). Reducing ethnic prejudice: An evaluation of seven recommended principles for incorporation in public campaigns. Journal of Community & Applied Social Psychology, 13(4), 284–299. doi: 10.1002/casp.736 Search in Google Scholar

Vergani, M., Iqbal, M., Ilbahar, E., & Barton, G. (2018). The three Ps of radicalization: Push, Pull and Personal. A systematic scoping review of the scientific evidence about radicalization into violent extremism. Studies in Conflict & Terrorism, 43, 854. doi: 10.1080/1057610X.2018.1505686 Search in Google Scholar

Walsh, M., & Gansewig, A. (2019). A former right-wing extremist in school-based prevention work: Research findings from Germany. Journal for Deradicalization, 21, 1–42. Search in Google Scholar

Welsh, B. C., & D. P. Farrington (Eds.). (2012). The Oxford handbook of crime prevention. Oxford, NY: Oxford University Press. Search in Google Scholar

Wilkinson, R. G., & Pickert, K. E. (2009). Income inequality and social dysfunction. Annual Review of Sociology, 35, 493–511. doi: 10.1146.annurev-soc-070308-115926 Search in Google Scholar

Wilson, D. S., Hayes, S. C., Biglan, A., & Embry, D. D. (2014). Evolving the future: Toward a science of intentional change. Behavioral and Brain Sciences, 37, 395–460. doi: 10.1017/S0140525X13001593 Search in Google Scholar

Published Online: 2021-08-20
Published in Print: 2021-09-14

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