Towards a Neuroscience of Radicalization

Sepideh Saadat, UvA-ID 10543716

M.Sc. Brain & Cognitive Sciences: Behavioral Neuroscience

University of Amsterdam

Supervisor: Prof. Jean Decety, University of Chicago

Co-Assessor: Prof. Bertjan Doosje, University of Amsterdam

Author Note

Master Literature Thesis

Abstract

This thesis converges key insights from research on terrorism and radicalization. By using an interdisciplinary approach, evidence from social psychology and social neuroscience is combined to explain how threats, group dynamics and individual dispositions interact with each other in the process of developing extreme beliefs and engaging in politically motivated violence. The role of threats is

illustrated by explaining the function of perceived threat and its influence on the development of political attitudes and neurobiological manifestations. The role of group dynamics and social forces is explained by highlighting key factors in the radicalization process, such as kinship and fictive-kinship, in-group favoritism, dehumanization, obedience, and empathy, supported by their neuronal representations. The role of individual dispositions are delineated by the contributions of genetic predictors, justice sensitivity, cognitive flexibility, and cognitive closure in the radicalization process.

Table of Contents

Abstract ... 2

Towards a Neuroscience of Radicalization and Terrorism ... 4

Theories of Radicalization: Pitfalls and Promises ... 5

The Role of Threats: Psychological and Neurobiological Manifestations ... 11

Perceived Threat ...11

Political Attitudes ...12

Neurobiology of Threat and Political Attitudes ...12

The Role of Group Dynamics and Social Forces ... 15

Kinship and Fictive-Kinship ...15

In-Group Favoritism ...15

Dehumanization ...16

Obedience ...17

Empathy ...18

The Role of Individual Dispositions ... 19

Genetic Predictors ...19 Justice Sensitivity ...21 Cognitive Inflexibility ...22 Cognitive Closure ...23

Discussion ... 24

References ... 27

Towards a Neuroscience of Radicalization and Terrorism

‘If the spring of popular government in time of peace is virtue, the springs of popular government in revolution are at once virtue and terror. Virtue without terror is fatal; terror without virtue is powerless.

Terror is nothing other than justice: prompt, severe, inflexible. It is therefore an emanation of virtue – a consequence of the general principle of democracy applied to our country’s most urgent needs.’

Maximilien Robespierre, Report upon the Principles of Political Morality, 1794

The history of mankind is marked by violence and brutality. The human species is responsible for producing noble and inspirational documents, such as the Universal Declaration of Human Rights, and capable of committing shameful atrocities, such as The Holocaust, Rwanda genocide, 9/11 and the dehumanizing conditions of Abu Ghraib. As radicalization and terrorism have become increasingly present in contemporary discourses of political violence, understanding what enables individuals and groups to commit such radical acts continues to be one of the most pressing questions of our time. Through investigating the origins and roots of terror and violence and by looking at the process of radicalization, a greater understanding of the proccesses and causes of these seemingly random and contingent acts may be understood. The working definition of ‘terrorism’ from the Global Terrorism Data Base, an open-source platform documenting domestic and international terrorist attacks, has been adopted for this thesis. As such, terrorism is defined as ‘the threatened or actual use of illegal force and violence to attain a political, economic, religious or social goal through fear, coercion or intimidation’ (Carson, Lafree, & Dugan, 2012), in addition to being a phenomenon that covers political and religious spectrums from: 1) left-wing; 2) right-wing; 3) nationalist-separatist; or 4) religious (Post, 2005). The process of radicalization is defined as ‘the development of a belief in opinions, views and ideas that might well result in a person committing acts of terror’ (Koomen & Pligt, 2016, p. 4).

The topic of radicalization has been extensively studied in various disciplines, such as political science, criminology, clinical psychology and social psychology. However, none of these areas have been able to yield a satisfactory working model for why certain individuals and/or groups commit acts of extreme political violence (Decety & Workman, 2017). One reason for this shortcoming is that research into terrorism generally falls into two broad categories, the first of which examines terrorist behaviour from a top-down approach by focusing on the political, social, and economic circumstances, while the second utilises a bottom-up approach, focusing on the characteristics of individuals and groups who turn to terrorism (Victoroff, 2005). Contrary to these lenses, this thesis argues in favour of an integrative approach for explaining the process of radicalization through combining both top-down and bottom-up approaches in order to examine multiple levels of analysis (Decety & Workman, 2017). To understand the process of radicalization, it is crucial to move beyond a one-dimensional analysis of sociogenic or

psychogenic approaches, as seen in social psychology, political psychology and criminology. Rather, an interdisciplinary approach, which includes not only the above-mentioned perspectives, but also biological approaches, are best equipped to fully grasp the process of radicalization. Such an interdisciplinary approach has been adopted by the social neuroscience perspective, which is an umbrella discipline that articulates levels of inquiry across multiple disciplines including behavioral economics, psychology, neuroscience and biology to explain social cognition and behaviour (Cacioppo & Decety, 2011). A recent review has shown how social neuroscience has added rich perspectives on, and valuable insights into areas of social and political psychology, such as 1) racial prejudice and intergroup relations; 2) the existence of partisan bias and motivated political cognition; 3) the nature of left-right differences in political orientation; and 4) the dimensional structure of political attitudes (Jost, Nam, Amodio, & Van Bavel, 2014). The evidence presented by Jost and colleagues (2014) underscores the assumption that political attitudes and beliefs are rooted in biological mechanisms and are subject to social and psychological influences that affect their expression in political behaviour.

This thesis attempts to break disciplinary boundaries, to unify research from social and political psychology, and for social and political neuroscience to shed light on the situational and individual factors underlying the development of political extremism and violence. First, a brief theoretical overview of current radicalization research is neccessary, followed by highlighting the role of social threats and their influence in the development of political attitudes. Group dynamics and social forces, such as kinship and fictive-kinship, in-group favouritism, dehumanisation, empathy, and obedience are outlined. Lastly, the contributions of individual dispositions such as genetic predictors, justice sensitivity, cognitive flexibility and cognitive closure in the radicalization process are discussed.

Theories of Radicalization: Pitfalls and Promises

In his review, Victoroff (2005) questioned the data quality, assumptions and methodological rigour of terrorism research. Victoroff (2005) demonstrated how behavioral science has failed to flesh out a ‘terrorist mind-set’ or ‘terrorist personality’ purely based on demographic data, such as religious orientation and/or racial and ethnic background, personality traits and psychopathology. His criticism addresses behavioural scientists and the counterterrorism community, who navigate a ‘potpourri of psychological theories’ (Victoroff, 2005, p. 31) to explain terrorism based on non-replicable studies, which do not use control conditions, instead utilizing unstructured interviews or even secondary accounts as their methods of data collection, resulting in a lack of empirical validity. Ever since Victoroff’s influential review, research on terrorism has made empirical and theoretical advancements, e.g. in successfully identifying the links between psychopathology and very specific types of terrorists, such as the ‘lone-actor terrorist’ (Corner, Gill, & Mason, 2016). In particular, research shows that ‘lone-actor

terrorists’, i.e. those who act alone and are not controlled by a terrorist organisation, have a particularly higher prevalence of schizophrenia, depression, or anti-social personality disorder when compared to the general population and to group-actor terrorists (Corner et al., 2016). These insights are important advancements in the field of terrorism research as they emphasize the need to stop ‘pathologizing’ terrorists and point to the diverse nature of terrorist actors (Victoroff, 2005).

One of the most popular theoretical models that attempts to explain how people move from radicalization to acts of violence is Moghaddam’s six-step ‘Staircase to Terrorism’ (2005) model, which posits that individuals are driven by a variety of psychological factors, moving from one stage into another higher-order stage during the radicalization process, which culminates in acts of violence

(Moghaddam, 2005). A critical review of 2,546 terrorism research studies yielded support for most of the theories presented by Moghaddam (2005), although the empirical data could not provide evidence for individuals moving linearly from one stage to another, as suggested in the staircase model (Lygre, Eid, Larsson, & Ranstorp, 2011). For this reason, the ‘Staircase to Terrorism’ model has since been updated to describe the process of radicalization from a continuum-based perspective, suggesting that radicalization is influenced by phases such as sensitivity, group membership and action, which are under the influence of factors happening at micro (individual), meso (group), and macro (society) levels (Doosje et al., 2016). According to Doosje and colleagues (2016) the process of radicalization can be distinguished into three phases (see Figure 1): 1) A sensitivity phase during which micro level factors within the individual, such as feelings of insignificance (as caused by for example loss of status, humiliation or poor future

prospects) and personal uncertainty attract individuals to join extremist groups to re-establish a sense of belonging in a solid group structure with a clear profile and a black-and-white world view. This phase is also influenced by factors happening at the meso level, which involves strong group identification and feelings of injustice and unfair treatment against the ingroup and the larger social environment (friends, family, and other groups). At the macro level, this phase is influenced by larger societal factors, such as for example globalization and Western imperialism; 2) The group membership phase is marked by the individual’s commitment and loyalty to the group cause at the micro level. At the meso level, the individual strengthens ingroup cohesion by engaging in bonding experiences with the new group and cutting ties with their old social environment. At the macro level, feelings of perceived group efficacy, such as the ability to challenge Western influence, are conveyed to the group members to attract followership; 3) The action phase is marked by using violence against other groups. At the micro level, personal loss of family, loved ones and friends at the hand of the outgroup can be important factors. At the meso level, violence against others is facilitated by dehumanization of the outgroup and

deindividuation of the individual who commits the violence. The macro level in this stage demands authorities to apply violence.

Figure 1. Overview of the three phases of radicalization: 1) Sensitivity, 2) Group Membership, and 3) Action. All phases are influenced by factors stemming from meso (group), and macro (society) levels (Doosje et al., 2016).

The theoretical shift in favour of a continuum-based approach to explain radicalization has occurred in spite of a recent study showing how stage models are generally preferred over continuum-based theories, as the former offers more order, structure, and predictability regarding human behaviour and life outcomes (Rutjens, Van Harreveld, Van Der Pligt, Kreemers, & Noordewier, 2013). As Rutjens end colleagues (2013) conclude, ‘[w]hen randomness lurks, stage theories provide us with the means to let order and predictability prevail over chaos and uncertainty.’ (2013, p. 317). In line with this reasoning, and given the chaotic aftermath of terrorist acts and the unpredictability of when a radicalized individual may or may not act in aggression, it becomes evident why stage theories are preferred for explaining radicalization and terrorism. The aftermath of terrorism is unsettling and imposes a great amount of uncertainty upon societies. However, a multitude of scientific fields, especially in the social and behavioural sciences, are benefitting from the fact that continuum-based theories offer a more adequate depiction of the real world (Koomen & Pligt, 2016).

Another interesting approach to understand the process of radicalization is given by the social neuroscience perspective. This perspective enriches social psychological approaches to understanding the process of radicalization by integrating the biological mechanisms underlying social structures, processes and behaviors (Decety & Workman, 2017). According to Decety and Workman (2017) the process of radicalization is under the influence of dynamic, reciprocal and interactive social and cognitive processes that happen at the group dynamics level, interpersonal level and micro-sociological level (see Figure 2).

All levels lie on a continuum and are underpinned by molecular influences, neuroendocrine influences and neural pathways, which mediate individual differences to engage in violence. At the level of group dynamics, individuals disconnect from close and distant social groups, such as family, friends, neighbors etc. holding competing values which are not in line with their newly held extremist beliefs (Decety & Workman, 2017). As such, these isolated individuals create deep social bonds with members of their new peers in radical groups and develop extended social bonds with fictive kin (e.g. joining ISIS and self-sacrifying oneself for fellow Muslims around the world) (Decety & Workman, 2017). These newly-formed social bonds are strengthened by social forces acting at the interpersonal level and reinforce ingroup-outgroup differentiations and facilitate the applciation of aggression and violence (Decety & Workman, 2017). At the micro-sociological level, individuals who have fewer bonds with groups of competing values experience less intra-individual conflict regarding beliefs, values and ideas and are therefore under greater influence by extremist narratives (Decety & Workman, 2017).

Figure 2. Overview of the group dynamic, interpersonal factors, and micro-sociological factors

interacting reciprocally and influencing the development of extreme beliefs and violent actions (Decety & Workman, 2017).

The radicalization model presented by Decety and Workman (2017) emphasizes the complex interactions across multiple levels of organization which are influenced by molecular, neuroendocrine and neural pathways. In particular, at the level of the brain, regions involved in social cognition and

decision-making play an important role in giving rise to the social, emotional, and behavioral processes (e.g. emotional saliency, mental state understanding, valuation of rewards, and decision-making) occurring during radicalization (Decety & Workman, 2017). Social neuroscientific research has identified in particular the ventromedial prefrontal cortex (vmPFC), dorsolateral prefrontal cortex (dlPFC), dorsomedial prefrontal cortex (dmPFC), anterior cingulate cortex (ACC), posterior temporal sulcus (pSTS), temporoparietal junction (TPJ), amygdala, anterior insula (aINS), striatum, and periaqueductal gray (PAG) (see Figure 3). These brain regions are crucially involed in processes of social cognition and decision-making (overview of these detailed brain functions see Figure 3).

Figure 3. Overview of brain regions implicated in social cognition and decision making. These brain regions control resources impacting group dynamic, interpersonal factors, and micro-sociological factors in the development of extreme beliefs and violent actions. The vmPFC with its connectivity with PAG, hypothalamus, striatum, amygdala and pSTS, plays a crucial role in social decision-making by regulating affective value of stimuli and deciphering their value. The dmPFC has been identified to be involved in the evaluation of social information from mental states, social norms and contextual factors and the dlPFC plays an important role in executive functioning, working memory, and response selection. The ACC, which is located in the medial cortex, is crucially involved in conflict monitoring and the pSTS/TPJ recruit resources such as awareness of bodily states, intentions and beliefs of others. The amygdala is a brain region which is primarily involved in the processing of the importance of positive and negative affective social stimuli and the insula is involved with the computation of emotional awareness and empathy. The striatum recruits reward and pleasure-related processes and the PAG accommodates autonomic, behavioral and antinoceptive stress responses (reproduced from Decety & Workman, 2017).

In addition to the social neurscience perspective, evolutionary theory also provides a valuable viewpoint to understanding the process of radicalization and gives us insight into the functions and reasons why humans apply violence in intergroup conflicts. Humans are hard-wired social animals who

learned that their prosperity and survival chances grow significantly when they are part of a strong, well-functioning group (De Dreu, Balliet, & Halevy, 2014). As such, humans created collaborations and coalitions to increase their biological fitness by securing reproduction and resources (De Dreu et al., 2014). Ethnographic and archeological evidence suggests that warfare was one of the major causes of death among some hunter-gatherer groups and was mostly due to conflicts over resource scarcity (Choi & Bowles, 2007). According to evolutionaly theory, warfare, i.e. a coalition of members of a group who inflict physical harm to out-group members (Bowles, 2009), is a powerful tool in intergroup conflicts that might have the purpose to strenghten social solidarity and altriusm towards in-group members (Choi & Bowles, 2007). According to De Dreu and colleagues (2014) intergroup competition and intergroup conflicts foster within-group cooperation, which in turn triggers intergroup distrust, rivalry and

aggression towards out-group members. According to Choi and Bowles (2007) the effects of warfare on the evolution of social behaviours are dependent on 1) the genetic differences between winners and losers of intergroup conflicts and 2) the effect of the number of altruists on the group members’ average fitness. Since during warfare some altruists are willing to die so that their group prevails during intergroup

contests, their presence is crucial to other group members’ survival and biological fitness (Choi & Bowles, 2007). The reason for this is because group members who die do not produce offspring or they leave behind children with high mortality risk due to lack of parental care (Choi & Bowles, 2007). The

evolution of this behavioral tendency in intergroup competition is described as ‘parochial atruism’, which is defined as an individuals’ tendency to self-sacrifice to benefit one’s in-group and to discredit and hurt competing out-groups (De Dreu, 2013). From an evolutionary perspective, parochial altruism increases survival and prosperity of one’s own group and can take well-intentioned and procial forms as well as heinous and destrucitive forms (De Dreu et al., 2014). The well-intentioned and prosocial form of

parochial altruiusm is exemplified by Jewish refugees from Germany who risked and eventually sacrified their own lives to rescue Jewish children in Amsterdam, and the heinous and destructive form of

parochial altruiusm can be exemplified by nearly all religiously or politically motivated acts of violence, for example seen in Chechnyan rebel suicide bombers, who self-sacrified themselves and killed others to further their goal of an independent North Caucasus by hurting Russians (De Dreu et al., 2014). As such, in the context of radicalization and terrorism, human self-sacrifice is fueled by ‘in-group love’ (e.g. devotion to ISIS, Nazism) and ‘out-group hate’ (e.g. despising the West or Jews) (De Dreu et al., 2014).

Taken together, the pitfalls of radicalization and terrorism research so far have been an overload of psychological theories explaining terrorist behaviors and motivations in non-replicable studies, which therefore lack empirical validity (Victoroff, 2005). Furthermore, stage theories of radicalization seem to be an unrealistic representation of real-life situations since empirical data cannot not provide the evidence that individuals move linearly from one stage into another, as suggested by the staircase model (Lygre et

al., 2011). Promising approaches to understanding radicalization can be found in continuum-based theories that suggest that individuals move between phases during the process of radicalization (Doosje et al., 2016) and are under the influence of various factors, such as group dynamics, interpersonal and micro-sociological factors (Decety & Workman, 2017). The integration of the social neuroscience perspective and evolutionary theory also adds a rich, multi-facetted perspective in understanding how group dynamics and individual dispositions interact in the development of extreme beliefs and acts of violence.

The Role of Threats: Psychological and Neurobiological Manifestations Perceived Threat

.

One of the most common traits that all radicalized groups and terrorist organizations share is their perceived threat of other individuals, groups, the government or people of authority within society (Koomen, & Pligt, 2016). In general, radicalization is driven by minority groups who feel threatened by majority groups. However, subgroups within the majority can also feel threatened by other subgroups within the same majority and other minorities. In recent years this case has been exemplified, by right-wing radical groups where individuals of low socioeconomic status may feel threatened by elite fractions of society, government authorities as well as immigrant minorities (Koomen, & Pligt, 2016). Indonesia, which is home to the largest Muslim community in the world, illustrates how subgroups within the same majority can feel threatened by each other (Juoro, 2017). Radical Islamists are a subgroup within the majority group in Indonesia and feel threatened by Chinese economic domination, which is why they endorse economic nationalism and target Indonesia’s ethnic Chinese population (Juoro, 2017). However, despite of the increase in Islamist populist movements in Indonesia in recent years, radical Islamists could not yet garner wide-spread support in the moderate Muslim majority population (Juoro, 2017).

Psychological approaches investigating interpersonal/intergroup perceived threats categorize them in the following way: 1) realistic threats; 2) symbolic threats; and 3) group esteem threats(Riek, Mania, & Gaertner, 2006). According to Riek and colleagues (2006), realistic threats are threats related to material matters, such as income, education and housing; political influence, such as power and control; or physical danger, such as vandalism, aggression and crime. To give an example of a realistic threat: in right-wing ideology prevalent in industrialised western nations such as the USA, UK and Germany, immigrants are seen as a threat to economic success because they are accused of “stealing” jobs, are “taking away” housing or “freeloading” on social benefits. Symbolic threats refer to opposing values and attitudes. This is reflected, for example, in Islamic radicalism which propagates the West as “decadent”, “culturally cold”, or “immoral” and therefore needs to be “destroyed”. Group esteem threats refer to the endangerment of the positive views a group has about itself. An example given by Koomen and Pligt

(2016) is the close relation between esteem and national identity in Germans. Positive group self-esteem of Germans is boosted when Germany performs well in sports, culture or science, while negative performances are experienced as hurtful and lower their group self-esteem and national pride.

Political Attitudes

.

Threats shape political attitudes and might play a role in how people develop extreme beliefs. The role of threats is especially relevant when placed in a larger political context where policy positions are tailored according to political orientations. For example, the political right uses (perceived) threats to design policies protecting society from out-group threats (e.g. increasing military spending, stricter immigration laws) (Dodd et al., 2012). Maoz and McCauley (2008) showed that public support of Israelis for aggressive retaliatory actions against Palestinians is largely mediated by threat perception of Palestinians. A meta-analytic study investigating the social, cognitive, and motivational bases of political conservatism revealed that right-wing conservatism is positively associated with fear of threat (Jost, Glaser, Kruglanski, & Sulloway, 2003). Further research confirmed that conservatives are also more perceptive to threats (Nail, McGregor, Drinkwater, Steele, & Thompson, 2009). A recent study extends these findings by showing that conservatives are more preoccupied with ideas of physical danger than liberals and became more socially progressive in their political attitudes when their feelings of safety were increased (Napier, Huang, Vonasch, & Bargh, 2018). Liberals, on the contrary, did not show any change in their progressive attitudes when their feelings of safety were increased (Napier et al., 2018). Interestingly, however, previous studies showed that liberals became as conservative as conservatives on social issues when mentally induced with threats (Nail et al., 2009). Specifically, the authors showed that their survey respondents were more supportive towards political conservatism, increasing the military budget and the favourability of President George W. Bush after the 9/11 terrorist attacks as compared to before 9/11 (Nail et al., 2009). These results support the idea that the nature of threats influences and shapes political attitudes. In particular, as Nail and colleagues (2009) conclude, ‘significant threats always induce a tendency towards conservative social cognition’ (p. 906). As such, the evidence shows that on a psychological level, threat perception shapes left-right tendencies arcoss political spectrums of

conservatives and liberals.

Neurobiology of Threat and Political Attitudes. The relationship between threat and political attitudes is also reflected on a neurobiological level. This area of research is important to emphasize when embedding politics into biology since physiological responses to threat are built-in evolutionary

mechanisms and determine the way we interact with our environment to increase the survival of our species. A number of studies have successfully identified the link between physiological responses to perceived threat with a variety of reliable physiological methods measuring emotion, arousal and attention (e.g. skin conductance responses and startle blink responses) (Dodd et al., 2012; Oxley, Smith, Alford, & Hibbing, 2008). Since physiological measures are able to index rapid, implicit and automatic responses,

they are an important supplement to refine behavioural measures, which rely on overt responses, when assessing political ideologies (Jost & Amodio, 2012). Dodd and colleagues (2012) demonstrated, for example, that right-leaning individuals show not only increased physiological responses to threatening images but they also spend more time interpreting the image as compared to their left-leaning

counterparts. As right-wing ideologies are founded around the idea of a dangerous world, it is conceivable to assume that they might spend more time processing threatening stimuli (Jost et al., 2003). Furthermore, Oxley and colleagues (2008) confirmed also that individuals with conservative attitudes on social issues showed increased electro-dermal activity when confronted with threatening stimuli compared to their liberal counterparts. Increased electro-dermal activity is an index of fear since it reflects heightened sweat gland activity, which is a correlate of the sympathetic nervous system and the fight-or-flight response (Jost & Amodio, 2012). While these results do not allow for any causations, they do however indicate psychophysiological differences among people of different political spectrums.

Psychophysiologcal differences of left-right ideologies are further expressed on a neural level. One of the earliest studies investigating the neural correlates underlying political orientations was conducted by Amodio and colleagues (2007). In this neuroimaging study, the authors hypothesized that conservatives and liberals might process conflicting information differently and that this difference is reflected on a neural level. This hypothesis was based on previous studies showing that right-wing conservatism is positively associated with dogmatic thinking and intolerance of ambiguity (Jost et al., 2003). To test this, the authors used a psychological paradigm (Go/No-Go Task), which measured conflict monitoring and has been associated with neurocognitive activity in the anterior cingulate cortex (ACC) (Botvinick, Braver, Barch, Carter, & Cohen, 2001). In the Go/No-Go Task participants are asked to only respond to the Go stimulus and withhold their responses to the No-Go stimulus. After repeated exposure, the response to the Go stimulus becomes habitual and the presentation of the No-Go stimulus conflicts with the dominant Go response. Behavioural evidence shows that conservative ideology was related to stronger persistence to change the habituated response to the Go stimulus when participants were signalled to withhold their response to the No-Go stimulus (Amodio, Jost, Master, & Yee, 2007).

Furthermore, the results of the study show that greater conservatism is associated with smaller volumes of the ACC and greater liberalism is associated with larger volumes of the ACC (Amodio et al., 2007). Amodio and colleagues (2007) concluded that conservatives have less neurocognitive sensitivities to respond to conflicts compared to liberals, which accounts for why individuals on those two political spectrums respond to new and unexpected information differently. These results have been replicated by Kanai and colleagues (2011) who confirmed that stronger liberalism is associated with increased grey matter volume in the ACC. The authors concluded that individuals with larger ACC volumes might be

more responsive to liberal ideology since they might have a higher capacity to deal with conflicts and tolerate uncertainties (Kanai, Feilden, Firth, & Rees, 2011).

Studies also found neurocognitive differences in political behaviour in the amygdala, which processes positive and negative emotions in the brain (Murray, 2007). Studies demonstrated the

importance of the social-evaluative role of the amygdala in voting decisions: For example, when Japanese and American participants voted for a political candidate of their choice, they demonstrated stronger bilateral amygdala activity as compared to a political candidate they did not choose to vote for (Rule et al., 2009). Furthermore, participants showed greater bilateral amygdala responses to faces of the opposite culture, which confirms previous findings showing that the amygdala is highly responsive to faces of out-group members (e.g. race, sex) (Cunningham et al., 2004; Rule et al., 2009). Further research shows that liberals exhibit a smaller volume of the right amygdala than conservatives (Amodio et al., 2007). This result was replicated by another study which confirmed that conservatism is positively associated with increased grey matter volume in the right amygdala (Kanai et al., 2011). Furthermore, differences in brain structures between conservatives and liberals are also consistent with differences in brain function. A recent study confirmed that conservatives exhibit greater activation in the right amygdala than liberals (Schreiber et al., 2013). Taken together, these results underscore the idea that political orientations are mapped on a neuroanatomical level.

However, caution is warranted when interpreting neuroscientific results since one brain region is never only involved in one cognitive function alone. While previous research demonstrates that the amygdala is crucially involved recruiting physiological and behavioural responses to threat, it is important to emphasize that it is probably not the entire amygdala that is involved in threat processing since certain nuclei, such as the basal nuclei, are also involved in reward processing (Jost & Amodio, 2012). The neural representations of political attitudes are not just limited to an identified brain region but rather involve multiple brain regions, which engage in the process of abstract thinking (Kanai et al., 2011). As such, it is important to emphasize that neural mappings of political attitudes do not illustrate direct

responses of political attitudes but rather show intricate processes involved in the development of political attitudes (Kanai et al., 2011). Furthermore, differences in brain structures do not necessarily imply the genetic foundations for differences in ideology (Schreiber et al., 2013). Despite of the fact that some studies have confirmed genetic contributions to political party identification (Alford, Funk, Hibbing, Alford, & Hibbing, 2013) and the strength of partisanship (Settle, Dawes, & Fowler, 2009), it is important to emphasize that all social behaviors, including political behavior, are not subject to gene interactions only but rather are under the influence of complex gene-culture interactions. Neuroplasticity demonstrates that brains are malleable and that the environment can contribute to significant changes in cognitive functions and brain structure (Woollett & Maguire, 2011). As such, in the context of radicalization and

terrorism, the effect of the environment on political attitudes might very well minimize or maximize the effect of genetic predispositions to develop extreme beliefs and committing violence (Schreiber et al., 2013).

The Role of Group Dynamics and Social Forces

Kinship and Fictive-Kinship

.

Humans have an evolved motivation for the need to belong and form deep bonds with their own kin from birth. The importance of belongingness is illustrated by the consequences of social rejection. Studies demonstrate that social rejection has clear physiological effects on the parasympathetic nervous systems (e.g. deceleration of heart rate) and recruits brain areas involved in pain processing (Moor, Crone, & van der Molen, 2010). The significance of social rejection is further highlighted by the fact that ostracized individuals were hurt even when rejected by groups they despise (e.g. KKK) (Gonsalkorale & Williams, 2007). According to Trivers (1985),kinship may drive individuals to sacrifice themselves to increase the survival of their family members, ethnic communities, and national groups. In the context of radicalization, fictive-kinship might play an important role. Decety and

Workman (2017) describe fictive-kinship as a concept where people feel ties of affection, concern, obligation, and responsibility to people who they are not related to by either blood or marriage bonds. During the process of radicalization, individuals develop kinship-like relationships with extremist organization and might become motivated to sacrifice their lives for their fictive-kin to support the group cause (Tobeña, 2009). This idea is supported by research linking the development of radical belief systems of Islamic youth in the Netherlands to feeling disconnected from the majority society (Doosje, Loseman, & van den Bos, 2013). Feeling alienated and disconnected from a social group might therefore pave the way for increased susceptibility to extreme ideologies (Mazaar, 2004).

In-Group Favoritism

.

Humans evolved to show prosocial and antisocial behaviors to members of their own species depending on perceived similarity and dissimilarity (Hare, 2017). Humans favor their own kind and their own group, which is why this “like-me psychology” (Hare, 2017) and in-group

favoritism facilitates collaboration and conforming to group norms (Burton-Chellew & West, 2012; Kurzban, Burton-Chellew, & West, 2015). Contrasting this, hostility and violence are directed towards out-group members. A study on 48 politically autonomous hunter-gatherer societies around the world revealed that social isolation and lethal aggression primarily target non-conformists and out-group members (Boehm, 1993). Boehm (1993) argues that intensifications of out-group aggression could be an evolutionary mechanism that promotes prosociality within the group, such as for example sharing information, resources and helping others or preventing individuals from monopolizing power. Human beings are inherently social beings, who learned to increase their long-term survival through group living and the fostering of interdependent bonds (Decety & Workman, 2017). As such, evolutionary theory

supports the idea that in-group favoritism and out-group hostility have likely emerged simultaneously as a successful strategy for long-term survival (Choi & Bowles, 2007). This is to show that humans have hard-wired capacities for in-group favoritism, which makes it the most “ultra-social species on earth but also the most ruthless” (Decety & Workman, 2017, p. 5).

As seen in the previous chapter, threats shape political attitudes and are an important factor underlying the process of radicalization by promoting polarizations between the in-group and out-group. When facing threats, in-groups can serve as safe havens and promote us-versus-them thinking. Koomen and Pligt (2016) point out that the group dynamics of us-versus-them thinking create the illusion of in-group superiority and thereby provide a fertile ground for more polarization between in-groups. One of the earliest studies investigating in-group membership and intergroup behavior was performed by Taijfel and colleagues (1971). By asking participants to choose between giving 17 points to both their own group and the out-group or giving their own group 11 points and the out-group 7 points, the authors confirmed over three studies that the latter option was significantly chosen over the first option (Tajfel, Billig, Bundy, & Flament, 1971). In fact, in-group favoritism is arguably the prime cause of discrimination in the United States rather than out-group hostility (Greenwald & Pettigrew, 2014). In extreme cases, this “in-group bias” (Tajfel et al., 1971) strips the out-group of the most fundamental human characteristics – a social force described as dehumanization.

Dehumanization

.

Dehumanization is described as a process during which a person is denied of dignity and individual qualities and is placed outside normal moral codes of a society. Conceptualizations of dehumanization distinguish between 1) animalistic dehumanization, which denies outgroups uniquely human traits that differentiate them from animals (e.g. being idealistic, or analytic) and 2) mechanistic dehumanization, which denies out-groups central traits of human nature (e.g. warmth, emotionality) (Haslam, 2006). Historically speaking, dehumanization has been, and still is, a powerful tool to set the stage for violence against minority groups. In 1925, Adolf Hitler described Jews as blood-sucking “spiders,” “vermin,” and “a parasite in the body of other peoples” in his book “Mein Kampf” (Hitler & Murphy, 1981). In the years leading up to the Rwandan genocide in 1994, extremist radio called upon ethnic Hutus to kill the “Tutsi cockroaches” (Mugsera, 1992). In 2018, Donald J. Trump describes illegal immigrants and members of gangs as “animals” (The White House, 2018). Investigations into left-wing terrorism in Italy revealed that members of the Red Brigade (Brigate Rosse) were convinced that dehumanization of their victims was a necessary premise to accept the idea of killing (Orsini, 2012). Interviews with Red Brigade members showed that their political enemies were often described as “filthy worms”, “swine”, rabid dogs” or “wretches” (Orsini, 2012).

Early work in dehumanization research demonstrated the conductive power of dehumanization to aggression (Bandura, Underwood, & Fromson, 1975). In a series of experiments, Bandura and colleagues

(1975) showed that participants acting as ‘teachers’ delivered stronger electric shocks to participants in the “students” group if the latter group ‘mistakenly’ overheard the experimenter describing the “teachers” in dehumanizing terms. Further research shows that feeling socially connected increased the tendency to dehumanize others and particularly increased endorsement to apply harsh interrogation practices to dehumanized others (i.e. terrorist detainees) (Waytz & Epley, 2012). A recent study measured blatant dehumanization, that is openly held beliefs about inherent inferiority of other groups, across seven studies conducted in three countries (Kteily, Bruneau, Waytz, & Cotterill, 2015). The results of the study showed that blatant dehumanization (as compared to subtle dehumanization) is a stronger predictor for support for torture, drone strikes and support of military interventions during intergroup conflicts (e.g. US-ISIS relations) (Kteily et al., 2015). Furthermore, dehumanization of out-groups increases quickly after incidents of real intergroup violence and predicts support for retaliatory violence (Kteily et al., 2015). A study on the Israeli-Palestinian conflict showed that perceived threat and the extent to which participants dehumanized Palestinians were significant predictors for aggressive retaliatory policies, such as

deportation from the occupied territories, against Palestinians (Maoz & McCauley, 2008).

Obedience

.

Obedience is the psychological mechanism that enables communal living in a system of authority (Milgram, 1963). Motivated to understand the heinous acts of Nazi war criminals, such as Adolf Eichman, whose trial was in place at the time, Stanley Milgram conducted a groundbreaking experiment in 1963 in which he investigated destructive obedience in the laboratory (Bègue et al., 2015). In this study, the experimenter instructed participants to deliver electric shocks to another person. The results showed that the majority of people carried out this command despite of the fact that they knew that 1) they had the right to end their participation in the experiment at any time and 2) the device used to deliver electric shocks explicitly said that it can harm or even kill the other person (Milgram, 1963). Fifty years following the original studies by Milgram, similar results of obedience to authority were replicated (Doliński et al., 2017). Research shows that individual differences in personality play an important role in the explanation of obedience to authority. Specifically, the personality factors conscientiousness and agreeableness predicted the highest intensity to which participants administered electric shocks to

someone (Bègue et al., 2015). Moreover, disobedience to authority was associated with left-wing political ideology. (Bègue et al., 2015). Further replications of the Milgram experiments showed that both state-anger and right-wing authoritarianism significantly predicted highest voltage shocks administered to others (Dambrun & Vatiné, 2010). These results show that situational context does not necessarily

override individual dispositions. Similar to the original findings by Milgram (1963), participants tended to distance themselves from personal responsibility and blamed the victim as well as the experimenter for their actions (Dambrun & Vatiné, 2010). This result fits with the rationalization of perpetrators of real-world mass killings, who dehumanize their victims and blame authorities (Waller, 2002). Neuroimaging

studies of the Milgram experiment showed that viewing virtual avatars in pain elicited increased

activation in the ventrolateral prefrontal cortex (vPFC) and the amygdala (Cheetham, 2009). The authors also reported that this pattern of activation was associated with trait personal distress, which corresponds to affective empathy (Cheetham, 2009). As such, the authors conclude that affective empathy might mediate the degree to which individuals are obedient to authority (Cheetham, 2009). This notion is underscored by the fact that group members, who compete with another team, are more likely to harm out-group members when they react to self-relevant moral statements with dampened activation in the medial prefrontal cortex (mPFC), which is one of the brain regions involved in empathic concern (Cikara, Jenkins, Dufour, & Saxe, 2014).

Empathy

.

Empathy is a construct and generally refers to the capacity to understand, share and respond to the unique thoughts and feelings of another person (Lamm, Batson, & Decety, 2007). Empathy is categorized in three different components: 1) Affective empathy (or emotional contagion), which reflects the capacity to share or become affected by someone else’s’ emotional states; 2) empathic concerns, which is defined as the motivation to care for someone else’s’ well-being; and 3) cognitive empathy (or perspective taking), which is the ability to actively put oneself into someone else’s mind in order to understand their thoughts or feelings (Decety & Yoder, 2015). Research confirms that people often are less willing to act prosocially and feel affective empathy towards individuals who belong to different ethnic, political, or social groups (Decety & Cowell, 2014). A study on stigmatized social groups showed that when participants viewed images of homeless people and drug addicts, they showed a lack of activation of the medial prefrontal cortex (mPFC) (Harris & Fiske, 2006). The mPFC is part of a cortical network involved in generating caring responses and the attribution of mental states, i.e. the reflection on feelings and intentions of ourselves and of others (Amodio & Frith, 2006). Participants also showed an increased activation of the insula and amygdala, which are associated with feelings of disgust and fear respectively (Harris & Fiske, 2006). A study measuring neural responses of pain perception in other people, compared video footage of drug addicts who contracted AIDS as a result of illegal drug use and drug addicts who contracted AIDS through blood transfusion (Decety, Echols, & Correll, 2010). Both imaging and behavioral data show that participants were significantly less sensitive to the pain of targets who were responsible for contracting AIDS (illegal drug use) and showed more empathy for targets who were not responsible for contracting AIDS (blood transfusion) (Decety et al., 2010). These results indicate that empathy towards stigmatized groups is moderated by prejudice towards those groups (Decety et al., 2010). In the context of radicalization, strengthening affective empathy (i.e. feeling what other people feel) in immigrant Muslims in the Netherlands, was associated with decreased support for ideology-based violence (Feddes, Mann, & Doosje, 2015). Interestingly, the same study found that increased reports of perspective-taking (i.e. cognitive empathy) were associated with increased support for ideology-based

violence (Feddes et al., 2015). This result fits with findings by Bruneau and Saxe (2012), who

investigated perspective-giving and perspective-taking in the context of intergroup conflicts. Their results showed that Palestinians had positive changes in their attitudes towards Israelis when they wrote about the difficulties of life in their society (i.e. perspective-giving) (Bruneau & Saxe, 2012). However,

Palestinians did not develop more favorable attitudes for Israelis when they had to summarize statements of the Israelis (i.e. perspective-taking) (Bruneau & Saxe, 2012). The authors observed the same patterns within low-status Mexican immigrants and high-status White Americans (Bruneau & Saxe, 2012). As such, these findings indicate that perspective-taking (i.e. cognitive empathy) in low-status minority groups might actually increase more radical attitudes and negative sentiments towards the high-status majority group whereas the act of perspective-giving and strengthening affective empathy might decrease violent radicalization (Bruneau & Saxe, 2012; Feddes et al., 2015).

The Role of Individual Dispositions

Genetic Predictors

.

The tendency to meet environmental stressors with violence can

undoubtedly be amplified by situational factors. However, the degree to which social forces give rise to violent behavior is partly determined by individual predispositions. A study by Huesman and colleagues (1984) tracked aggressiveness in 600 participants for 22 years. The results show that aggressive 8-year-olds at the beginning of the study were still aggressive 30-year-8-year-olds (Huesman, Eron, & Lefkowitz, 1984). The study showed that early-age aggressiveness is a stable predictor for later serious anti-social behavior and a stable trait across generations within a family (Huesman et al., 1984). These results were further supported by the fact that paternal criminal background in particular is among the strongest predictors of criminal activity later in life (Hjalmarsson & Lindquist, 2013). By conducting a study on approximately 1.3 million adoptees and non-adoptees, Hjalmarsson and Lindquist (2013) concluded that adoptees had a stronger likelihood to commit violent crimes if their biological parents had a history of violence as well. These results suggest that biological factors may aid an individual propensity for aggressive behaviors. Meta-analyses for behavioral genetic studies, including twin studies and adoption studies, place the level of heritable influences for antisocial and aggressive behavior between 40-60% (Glenn & Raine, 2014).

Animal research shows that early-life stress, such as maltreatment, maternal deprivation, peer rearing, have long-lasting negative consequences for the brain to develop the serotonin (5-HT),

norepinephrine (NE) and dopamine (DA) neurotransmitter system (Caspi et al., 2005). A study by Caspi and colleagues (2005) tested whether the monoamine oxidase (MAOA) gene, which encodes the MAOA enzyme and enable metabolizing 5-HT, NE, and DA, modified the influence of children’s propensity for anti-social behaviors later in life. The study found out that maltreated children with low levels of MAOA expression, i.e. who carry the respective alleles, had a higher likelihood to develop anti-social behaviors

and vice versa (Caspi et al., 2005). Furthermore, a study on a Dutch family whose males were affected by several types of abnormal behavior, such as impulsive aggression, arson, attempted rape and

exhibitionism, suggests that their disturbed regulation of impulsive behaviors is associated to complete MAOA deficiency (Brunner, Nelen, Breakefield, H, & Van Oost, 1993). At the level of hemodynamic activity in the brain, lower MAOA activity in cortical and subcortical regions has been associated with higher self-reported aggression (Alia-Klein et al., 2008).

Next to MAOA, several other neurotransmitters have been implicated in aggression (Glenn & Raine, 2014). One of the best replicated correlates of aggression is serotonergic (5-HT) hypofunction, which has been linked to increased impulsive aggressive behaviors (Moore, Scarpa, & Raine, 2002). In the context of radicalization and political violence, it is interesting to investigate whether neurochemical modulations of serotonergic functioning influence the degree to which people are willing to do harm to another person. Crockett and colleagues (2010) enhanced serotonin levels in healthy participants and compared moral judgements of moral dilemmas with highly utilitarian outcomes (e.g. saving five lives) against highly aversive harmful actions (e.g. killing an innocent person) with varied degrees of emotional saliency (i.e. high emotional saliency: pushing someone in front of a train to prevent it from hitting people vs. low emotional saliency: flipping a switch to divert a train to hit one person instead of five people) (Crockett, Clark, Hauser, & Robbins, 2010). The results showed that enhancing serotonergic functioning made participants judge harmful actions as more forbidden – but only in scenarios with high emotional saliency (Crockett, Clark, Hauser, et al., 2010). Furthermore, the authors investigated the modulation of moral behaviors by increasing serotonin and using the ultimatum game (UG), during which one player (responder) decides whether or not to accept financial offers from another player (proposer) (Crockett, Clark, Hauser, et al., 2010). Previous research showed that serotonin depletion increased rejection of unfair offers in the UG (Crockett, Clark, Lieberman, Tabibnia, & Robbins, 2010). However, increasing serotonin led to the increased acceptance of unfair offers in the UG (Crockett, Clark, Hauser, et al., 2010). The authors concluded that serotonin plays an important role in inducing a harm-avoidance bias and prosocial behavior by reducing the willingness to harm another person both in a hypothetical scenario (moral dilemma) and a real economic transaction (Crockett, Clark, Hauser, et al., 2010). As such, the evidence suggests that serotonin increases aversive emotional reactions to harming others and thereby reduces aggressive impulses (Crockett, Clark, Hauser, et al., 2010). It is important to note that the prosocial effects of increased serotonin on both moral judgements and moral behavior were stronger in participants with high trait empathy, which could imply that serotonin modulates and intensifies empathic responses to harm (Crockett, Clark, Hauser, et al., 2010). Taken together, the results clearly show the modulatory effect of serotonin on aggressive acts at the individual level. However, aggressive acts occur in a broader framework, which includes the role of impulse control, emotion regulation and social

functioning, which have an effect at the level of group dynamics (Krakowski, 2003). As such, violent behavior is best understood with the awareness of the bidirectional effect between genetic predicposition and the environment: Genes affect psychological characteristics and social interactions, and psychological and social factors affect the expression of genes (Krakowski, 2003).

Justice Sensitivity

.

Justice and injustice are key elements of human interactions and a critical element of morality (Decety & Yoder, 2017). Justice and morality are closely related but different in the sense that justice is primaly concerned with outcomes whereas morality is concerned with how

individuals treat each other (Decety & Yoder, 2017). From an evolutionary perspective, treating others in a just and fair way increases cooperation and therefore survival (Schmidt & Sommerville, 2011).

Research shows that humans develop a sense of fairness and injustice already during infancy and show relatively stable individual differences in sensitivity to justice issues throughout their lifetime (Baumert & Schmitt, 2009; Schmidt & Sommerville, 2011). Justice sensitivity is understood as a character trait reflecting the significance of justice issues in people’s everyday lives and is an important predictor for justice-related emotion and behavior (Decety & Yoder, 2015). Research shows individuals high in justice sensitivity have a strong motivation for restoring justice when they perceive injustice (Decety & Yoder, 2015).

In the context of radicalization, perceived injustice plays an important role since it might serve minority groups as a useful tool to endorse restoring justice with violence. Koomen and Pligt (2016) argue that perceived injustice combined with a sense of victimhood and unfair treatment, give rise to minority groups feeling entitled to reparations by means of violence. A study by Victoroff and colleagues (2010) shows that support for religio-political aggression was mostly supported by Palestinian youth who felt their group was treated unjustly. The authors conclude that perceived injustice evokes feelings of anger and motivates individuals to restore justice with aggression particularly in members of groups who live under repressive circumstances that curtail their human rights (Victoroff et al., 2010). Further research shows that support for radical belief systems is aided in Dutch Muslim youth by a strong

association between perceived injustice and societal-disconnectedness (Doosje et al., 2013). These results show that the degree to which individuals are sensitive and perceive injustice interacts with the

circumstances under which individuals live and might give rise to collective violence as a means to restore justice.

At the level of the brain, individual dispositions of justice sensitivity are linked to neural correlates in the dorsolateral and dorsomedial prefrontal cortex (dlPFC, dmPFC, posterior superior and temporal sulcus (pSTS) when individuals evaluate morally laden actions performed by others (Yoder & Decety, 2014). These regions are part of a network of brain areas involved in evaluations of justice, fairness, and moral judgement (Decety & Yoder, 2017). Interestingly, evaluating good moral actions is

associated with greater activity in the dorsal striatum, which is a brain region implicated in reward-processing (Yoder & Decety, 2014). Recent research shows that the ventral striatum is also implicated in justice sensitivity towards norm violations. By letting participants play the Justice Game, researchers investigated the underlying decisions involving punishing norm transgressors versus decisions to recompense victims of norm violations (Stallen et al., 2018). The Justice Game examines how people perceive and react to situations during which someone intentionally und unfairly takes away resources from either oneself or someone else (Stallen et al., 2018). The results showed that reward-processing-related brain areas, such as the ventral striatum, showed stronger neural activity when participants decided to punish an unjust and unfair player as compared to repay disadvantaged players (Stallen et al., 2018). This result was also reflected in behavioral data and points to the idea that there is a stronger preference to punish a wrongdoer, i.e. someone who violates fairness norms, over compensating disadvantaged people; and that the punishment is experienced as more rewarding too (Stallen et al., 2018).

Cognitive Inflexibility. Theories investigating the psychology of terrorism argue that terrorists view the world as ‘black or white’ and that extremist ideologies are especially preoccupied with a dichotomous, rigid, inflexible and absolutist thinking style in their religious and/or political belief system and for issues of morality (Borum, 2004). Extremist views are underpinned by strict moral dualism, where there is no ambiguity between what is right and wrong and therefore provides a mechanism for justifying violence in order to maintain the balance between good and evil (Decety & Workman, 2017). As such, in order for terrorism to succeed, both its leader and followers must rigidly adhere to the idea that their ideology is superior, righteous and worth fighting for (Borum, 2004). In 1985, a study

investigated the relationship between several dimensions of social political ideology and different types of cognitive functioning (Sidanius, 1985). By giving 195 Swedish high school students normed and

validated questionnaires assessing different types of cognitive factors, such as conservatism, cognitive flexibility, cognitive complexity, and intolerance of ambiguity, Sidanius (1985) found out that

participants who identified as 1) extreme leftists and moderate rightists had the highest cognitive complexity; 2) conservatives expressed highest cognitive inflexibility, which is defined as ‘black-and-white’ thinking and rigidity of values. Reduced cognitive inflexibility was also positively correlated with intolerance of ambiguity, and increased need for certainty, racism and ethnocentrism (Sidanius, 1985). These results tie in with a study on 1,247 Israeli university students showing that right-wing extremism among those students was associated with authoritarianism, xenophobia and supernatural beliefs, which is defined as a belief in the external control of one’s fate (Canetti & Pedahzur, 2002). In fact, a recent study found out that cognitive flexibility and openness are important (yet not sole) character traits for adapting one’s religious beliefs (Zhong, Cristofori, Bulbulia, Krueger, & Grafman, 2017). A such, these results support the argument given by Decety and Workman (2017) that ‘[i]ndividuals who are cognitively

inflexible and intolerant of ambiguity may become captive audiences for ideological, political, or religious extremists whose simplistic worldviews gloss over nuance’ (p. 11).

At the level of the brain, it was found that cognitive flexibility and trait openness critically rely on the processing of the prefrontal cortex (PFC) (Zhong et al., 2017). Specifically, it was found that patients with lesions in the ventromedial prefrontal cortex (vmPFC) reported greater support for religious

fundamentalism (Zhong et al., 2017). The authors concluded that the vmPFC plays a crucial role in social belief representations and maintenance (Zhong et al., 2017). Victoroff (2005) pointed out that cognitive inflexibility might be the reason why terrorist would fail to anticipate future consequences due to

diminished executive functions, which heavily rely on the PFC. Furthermore, he points out that enormous intolerance of ambiguity and cognitive inflexibility might render terrorists to be less adaptable, unable to appreciate nuance, and unreasonable in bargaining (Victoroff, 2005). Other brain regions associated with cognitive inflexibility are decreased activity in the dorsolateral prefrontal cortex (dlPFC) and the

orbitofrontal cortex (OFC) (Kaplan, Gimbel, & Harris, 2016). Both regions are strongly involved in the process of overriding old information with new one and could be important during the process of

developing extreme beliefs: diminished functioning in the dlPFC and OFC could aggravate the process of changing one’s beliefs in response to counterevidence (Kaplan et al., 2016). Further support for the rigidity of right-wing values comes from a meta-analytic review on the social, cognitive, and motivational bases of political conservatism (Jost et al., 2003). The review reported medium to large effect sizes between political conservatism and dogmatism (i.e. mental rigidity) (Jost et al., 2003). Furthermore there were strong associations between political conservatism and intolerance of ambiguity, lack of openness to experience, uncertainty avoidance, system threats, fear of death and personal needs for order, structure, and closure (Jost et al., 2003).

Cognitive Closure. A concept closely related to cognitive inflexibility is cognitive closure. Cognitive closure is described as the individual desire for a firm and certain answer on any given topic and the avoidance of ambiguity (Webster & Kruglanski, 1994). More specifically, individuals with a high need for cognitive closure desire order and structure in their environment, experience discomfort when faced with ambiguity, desire secure or stable knowledge that can be relied upon and is unchallenged across circumstances and have an unwillingness to have their own knowledge confronted by alternative opinions and evidence (Webster & Kruglanski, 1994). A study with Polish participants investigating real-life intergroup conflict between Germany and Poland and hostility against Arabs and Muslims, found out that 1) high need for cognitive closure and preference for aggressive actions against the out-group (i.e. Germany) and 2) high need for cognitive closure and hostile attitudes towards the out-group (i.e. Arabs and Muslims) was only found in participants who identify with political conservatism and not liberalism (De Zavala, Cislak, & Wesolowska, 2010). The authors concluded that need for cognitive closure and a

conservative world view might be individual factors that bias people to evaluate uncertain intergroup situations as conflicts, condone violence and therefore create them into open conflicts (De Zavala et al., 2010). Furthermore, they also concluded that need for cognitive closure and political conservatism are only associated to out-group hostility in participants who tend to perceive an ambiguous intergroup conflict, i.e. an intergroup situation that is not clearly defined as a conflict, as threatening and conflictual (De Zavala et al., 2010). The need for cognitive closure also interacts with perceived group status and promotes intergroup differentiation, which one of the key antecendents of extremism (Federico, Hunt, & Fisher, 2013). According to the authors, group membership is a key factor in providing certain, firm and stable knowledge since the beliefs, norms and values shared by group members provide certainty and closure about hat the world is like, how one should act in various situations and answers questions of identity and significance (Federico et al., 2013). As such, the authors assumes that individuals with a high need of cognitive closure and high, prestigious group status would identify more extremely with their in-group the “good us” and differentiate more strongly with their outin-group members the “bad them” (Federico et al., 2013). The study showed that individuals with high need for cognitive closure

differentiated more extremely between their White in-group and the Black and Latino out-group when they attributed a larger status advantage to their in-group (Federico et al., 2013). These results were replicated in a second study during which participants were randomly assigned to a high-status in-group of ‘nductive thinkers’ versus a low-status out-group of ‘deductive thinkers’ (Federico et al., 2013). The results of the second study showed that participants who received the feedback that their in-group of “deductive thinkers” is of high-status showed an extreme preference to cooperate with members of their in-group as compared to the out-group (Federico et al., 2013). Thus, the perception of prestigious status of an in-group contributes to individuals with high need in cognitive closure to accentuate the differences between them and an out-group more extremely (Federico et al., 2013).

Discussion

The study of radicalization remains important because of its universal presence that transcends borders and ideologies. To understand the process of radicalization, we need an interdisciplinary approach, which includes psychological and biological approaches. The approach of this thesis aimed to break disciplinary boundaries and unify research from social and political psychology and social and political neuroscience. The objective of this thesis was to outline the situational and individual factors underlying the development of political extremism and violence. A brief theoretical overview of current

radicalization research was presented, highlighting current shortcomings of radicalization and terrorism research and presenting how cognitive neuroscience, social neuroscience and evolutionary theory add rich perspectives on, and valuable insights into intergroup relations, intergroup biases and political cognition.

The evidence presented underscores the assumption that political attitudes and beliefs are rooted in biological mechanisms and are subject to social and psychological influences that affect their expression in political behaviour. Of special interest to this thesis was the social neuroscience perspective meshed with insights from evolutionary theory. This perspective enriches social psychological approaches to understanding the process of radicalization by integrating the biological mechanisms and evolutionary reasons underlying social structures, processes and behaviors (Decety & Workman, 2017).

Second, the role of perceived threats, their influence in the development of political attitudes and various forms of neurobiological manifestations were discussed. It was pointed out that one of the most common traits that all radicalized groups and terrorist organizations share is their perceived threat of other individuals and groups (Koomen, & Pligt, 2016). These results presented support the idea that the nature of threats influences and shapes political attitudes. In particular, as Nail and colleagues (2009) conclude, ‘significant threats always induce a tendency towards conservative social cognition’ (p. 906). The evidence presented indicates psychophysiological and neurocognitive differences among people on different ends of the political spectrum. However, caution is warranted when interpreting neuroscientific results since one brain region is never only involved in one cognitive function alone. Furthermore, it was also emphasized that neuroplasticity demonstrates the malleability of brains and that the environment can contribute to significant changes in cognitive functions and brain structure (Woollett & Maguire, 2011). As such, in the context of radicalization and terrorism, the effect of the environment on political attitudes might very well minimize or maximize the effect of genetic predispositions to develop extreme beliefs and committing violence (Schreiber et al., 2013).

Third, group dynamics and social forces, such as kinship and fictive-kinship, in-group

favouritism, dehumanisation, obedience, and empathy were outlined. It was argues that motivated by the hardwired need for belongingness, humans form deep bonds with their own kin from birth. In the context of radicalization, individuals also feel ties of affection, concern, obligation, and responsibility to people who they are not related to by either blood or marriage bonds, i.e. fictive-kin (Decety & Workman, 2017) and might become motivated to sacrifice their lives for their fictive-kin to support the group cause (Tobeña, 2009). Furthermore, humans evolved to show prosocial and antisocial behaviors to members of their own species depending on perceived similarity and dissimilarity (Hare, 2017). This “like-me psychology” (Hare, 2017) paves the way for us-versus-them thinking create the illusion of in-group superiority and thereby provide a fertile ground for more polarization between groups and out-group dehumanization (Koomen & Pligt, 2016). Obedience to authority is another important factor that can facilitate violence against others. Research was presented showing how obedience is mediated by affective empathy (Cheetam, 2009), which influences the likelihood to harm out-group members (Cikara et al., 2014). Moreover, in the context of radicalization, evidence was presented that perspective-taking