Processes and Mechanisms of the Contagion of Violence
In the previous chapter, the spread and transmission of violence was documented across individuals, groups, and generations, as well as through different ecological levels. This chapter will explore the questions of how such violence spreads and what the processes and mechanisms are of the transmission of violence.
A well-known paradigm in public health called the Haddon Matrix (see Figure 3-1), which is a model used to conceptualize injuries and injury prevention, was described by speaker Jeffrey Victoroff of the University of Southern California Keck School of Medicine. The Haddon Matrix has two axes: (1) the vertical axis is temporal, divided in pre-, peri-, and post-event; and (2) the horizontal axis is ecological, divided into personal, agent or vector, physical environment, and social environment. At the intersection of each row and column, one asks what the relevant factors are. For example, what personal factors contributed to the injury before the event? What social factors need to be considered following the event (e.g., to mitigate the effects of the injury or to prevent the injury from occurring again)? The
|Individual||Agent/Vector||Physical Environment||Social Environment|
FIGURE 3-1 Haddon Matrix.
Haddon Matrix is also a useful model to consider how different elements interact with each other, from micro to macro, and from before the event to after the event (Haddon, 1968).
Speakers on the panel on theories, processes, and mechanisms explored the contagion of violence at the macro level, including social influences and group dynamics, and at the micro level, including social-cognitive learning and neurological mechanisms. While at each level there are risk and protective factors for violence occurring and being transmitted, there are also factors that result in violence moving from one level to another. For example, several speakers noted that types of violence rarely occur alone—family violence is more prevalent in the context of community violence, and community violence can have destabilizing effects at state or national levels. The panel also explored the potential application of this discussion to possible interventions, using the knowledge presented. In explaining the importance of this, moderator Robert Ursano of the Center for the Study of Traumatic Stress of the Uniformed Services University of the Health Sciences noted several examples in which understanding the mechanism clearly maximized the impact of the most effective intervention, including child neglect in military families and reducing suicide by addressing anxiety versus depression.
Forum member and planning committee chair Rowell Huesmann of the University of Michigan noted that infectivity of violence is not limited to victimization or perpetration, but also observation of violence (including via media). This implication of a wider susceptible population means that, unlike biological contagion, the contagion of violence does not require direct contact with an agent of infection. In addition, Dr. Huesmann suggested that, because observation also increases risk, the processes resulting in violence are related to that observation. Even in being directly involved in a violent act (as a victim or a perpetrator), a person is also observing that act (Huesmann and Kirwil, 2007).
In the short term, Dr. Huesmann posited, exposure to violence leads to increased risk of behaving aggressively, which is a risk factor for violence. However, as Dr. Huesmann pointed out, this is a predisposing factor to violence that would require other elements to definitively result in an act of violence. Speaker Deanna Wilkinson of The Ohio State University also addressed this point, noting that perpetrators are not violent all the time, but that they are moving through their social milieu responding to social cues; some lead to violence and some do not. She noted that determining why violence happens sometimes and not other times despite similar neurological processes occurring requires examining the external context as well.
The short-term mechanisms that Dr. Huesmann referenced include priming, mimicry, and excitation transfer (Huesmann, 1988). In priming, stimulating one part of the brain results in activation of related parts, and lowers the threshold for such activation to occur again when faced with the same or similar stimuli. Thus, being exposed to violence or an associated element causes a cascade of reactions in the brain, which is poised to process more quickly the next time it is exposed. If such a cascade results in a violent response, this same response might occur more readily in the future. Excitation transfer, Dr. Huesmann noted, is more subtle. Observation of violence increases emotional arousal, but how that is experienced depends on individual and contextual factors. However, Dr. Huesmann also noted that if such excitation is accompanied by provocation or other situation likely to result in anger, then the arousal experienced by observing violence is likely to include anger, thus heightening the excitatory response.
Mimicry and Imitation
Mimicry involves copying behavior of someone with whom one identifies. Children can learn from mimicry, so observing violence would provide examples for how others respond to specific events. Speaker Marco Iacoboni from the University of California, Los Angeles, further explored the process of mimicry. He described cells within the brain called mirror neurons, which fire both when performing certain actions and when observing others perform those same actions. In firing during observation, the brain is simulating the action as a learning mechanism. Dr. Iacoboni described such neurons in particular regions of the brain, most notably those related to motor functioning and vision and memory, as explored through emerging research. Thus, Dr. Iacoboni notes, mirror neurons fire when performing certain motor activities such as grasping a door knob, when watching another person grasp a doorknob so as to learn the action, and when recording the memory of the action. Such a process is useful in learning behavior and also in recognizing behavior immediately, without taxing the brain with complex neural processing. Dr. Iacoboni also noted that the ability of mirror neurons to mimic others’ behaviors is an important element in social bonding and empathy, as well as the flip side of socially detrimental behavior of aggression and violence. For further information on the research involving imitation and mirror neurons, see Part II.
In the long run, Dr. Huesmann noted, violence is transmitted because observation results in changes in the cognitive functioning of the brain relevant to cues in the social environment. Specifically, the brain responds
to stimuli by creating scripts, schemas, and attributions about the external environment and the individual’s role within it. These processes allow the brain to develop consistent responses to repeated stimuli. If the stimuli cause intense emotional arousal, the brain’s response is to become desensitized. Dr. Huesmann suggested that such an adaptation was evolutionarily advantageous so as to prevent incapacitation caused by a strong stress response.
Such schemas and scripts are created through the shorter term processes described previously, and establish consistent “shortcuts” of behavior. Those who have observed violence repeatedly, particularly violence as a response to stressful, provocative, or other emotionally charged situations, create schemas of the world in which more hostility is assumed than might truly exist. They also create scripts, like “programs” of behavior, which provide instruction on how to react to certain stimuli, primed by previous exposure, observation, and response. In situations in which hostility is attributed to the other party (whether or not the hostility exists, known as hostile attribution bias), the brain immediately processes this shortcut and retrieves the appropriate script in response.
Dr. Huesmann referred to this observational learning as a complex process potentially specific to the higher intellectual functioning of intelligent mammals, because it is not simply a biological response, but also an emotional and cognitive one. In addition, observational learning requires interpretation of others’ actions as well as inferences into the meaning of others’ words, actions, and thoughts.
Dr. Huesmann noted that experiencing violence increases aggression and the risk of retaliatory violence. However, he also noted that aggression itself does not always result in violence, but instead requires other precipitating factors for further violence to occur. He also noted that the attribution of aggression in others is one social cognition that plays a role in the contagion of violence.
Dr. Victoroff elaborated further on individual and collective aggression, noting that aggression is not necessarily antisocial. Dr. Victoroff noted that from an evolutionary perspective, aggression can often have an advantage, such as in cooperative hunting. Such “prosocial” aggression occurs via the same brain and social mechanisms as antisocial aggression, but has beneficial results. Aggression is also correlated with age: peaking early and then declining through life.
Dr. Victoroff also noted that collective aggression resulted in conditions favorable to the genetic success of altruism. This point was echoed later in the discussion of the hormone oxytocin and social bonding, as a result of
an audience question. Though it is normally thought of as a hormone that encourages human bonding and altruism, several speakers also noted that oxytocin most likely operates by making social information more salient. So, rather than always encouraging prosocial behavior, it actually heightens existing tendencies. Speaker Jamil Zaki of Stanford University highlighted an example of someone with borderline personality disorder being less trusting under the influence of oxytocin. He also noted that oxytocin will encourage parochialism toward the members of the in-group, and potentially hostility toward the out-group. Dr. Victoroff agreed, also noting that some research shows that oxytocin increases prejudice to out-groups and nationalistic feelings for in-groups. Dr. Victoroff also indicated that such a mechanism is important in considering altruism as a potential antidote to violence because, barring grave physical threat, it is difficult to select for those individuals with a heightened tendency toward altruism.
In further exploring the notion of contagion and aggression, Dr. Victoroff posited that for such behaviors to be transmitted intergenerationally, brain structures would have to adapt and evolve, and systems would have to develop to support the various mechanisms being described. Not everyone participates in and imitates aggression, and some choose prosocial versus antisocial violence. Individuals vary as to their susceptibility to these mechanisms, and various exogenous factors influence this susceptibility. Dr. Victoroff noted that biological mechanisms might also play a role, specifically noting two brain structures involved: the ventral tegmental area and the nucleus accumbens, the latter being involved in subjective reward. He referenced studies that show differences in these brain structures in psychopaths and non-psychopaths. He also noted research showing higher basal testosterone levels in youth who were more sympathetic to terrorism than those who were not. Dr. Victoroff speculated that these exogenous and endogenous factors interacted in ways that resulted in tendency to aggression or not, and that the context in which aggression occurs plays a major role in whether such aggression leads to favorable or unfavorable outcomes. For further information on aggression and reciprocal altruism, please see Part II.
SOCIAL INTEGRATION AND REINFORCEMENT LEARNING
Dr. Zaki further examined the neurobiological processes of contagion through his discussion of social integration and the structures of the brain associated with rewards. Dr. Zaki noted that rewards are an important motivator for human behavior, both in that they are indicators of positive outcomes and that people actively seek out rewards. Rewards are essential in reinforcement learning to strengthen a desired behavior. He pointed out that not all rewards are material, and that social scientists have long
regarded social integration as a type of reward (Baumeister and Leary, 1995).
Dr. Zaki noted that reinforcement learning has two essential elements: (1) prediction of reward, and (2) adaptation. While the brain responds to rewards, it eventually learns to predict when such rewards occur by identifying social and other temporal cues preceding the presentation of a reward (O’Doherty et al., 2003). A well-known example of this is Pavlov’s experiments in which dogs identified the ringing of a bell with a reward of a treat. What is noteworthy in this, Dr. Zaki points out, is that the brain eventually stops responding to the reward itself and instead responds to the predictor of the reward. This response occurs in the nucleus accumbens. In addition to predicting rewards, people adapt behavior in order to actively gain rewards. Often this adaptation occurs in ways in which people do not necessarily understand.
Given this, Dr. Zaki posited that one predictor of the reward of social integration is consensus with other people. This indicates that an individual will not only respond to agreement with other people, but will also actively seek such conformity, even to the point of changing their own behavior. Dr. Zaki demonstrated through research that this seems to be the case, both psychologically and neurologically. In one such study, participants were asked to rate attractiveness of various faces. They were then told the ratings their peers gave. Upon being asked to rate the faces again, the responses of the participants changed, at a statistically significant level, so as to conform to the opinions of their peers. He also noted that this change occurred not just at a superficial level, but also at a deeper level in which participants truly believed in their new opinions, as observed by viewing whether the structures of the brain responding to facial attractiveness were activated (Zaki et al., 2011). Dr. Zaki speculated that, given the power of this mechanism, reinforcement learning could indicate that those in situations of high violence might be internalizing their attempts at conformity. Over time, this may lead to intractability. He also noted, however, that research indicates this mechanism is very generalizable, and it would be useful to consider how it could be used to promote the spread of prosocial behavior.
Psychological and physiological processes within individuals have the potential to shed light on the mechanism of the contagion of violence. Speakers also noted the importance of such processes interacting with the context or environment in which stimuli, observation, and conformity occur. Other speakers considered the importance of that context or environment itself, as well as the interplay of multiple factors. In particular, the role of group dynamics, alluded to previously in terms of collective aggression,
altruism, and conformity, has a synergistic effect with the role of neurobiology in influencing decision making.
Dr. Wilkinson explored the mechanism of group dynamics and its role in the contagion of violence. She echoed the comments of several speakers in noting the importance of schemas, scripts, attribution, collective responsibility, conformity, and imitation, and explored these within the context of group violence. In particular, she noted the strong influence of peers and an individual’s reputation.
Group affiliation, such as in gangs, is correlated with increased risk of violence, as victim, perpetrator, or witness. Often, these groups exist within a social ecology in which allegiance is seen as protective against outside danger (Wilkinson and Carr, 2008). As previously noted, youth create their identities through observational learning and socialization, and much of the violence that occurs within groups is public. Dr. Wilkinson especially noted that expectations of behavior are created collectively, versus individually. This is more than peer pressure, she argues, but also a diffusion of responsibility throughout the group. Thus, social integration brings with it the scripts and schemas that underlie behavior.
In unpacking the violent event, Dr. Wilkinson noted that in her research she was very interested in knowing what was occurring in the participants’ minds, and also in the co-occurrences of the event. In one study of hers, she noted two major additional factors: (1) the presence of a third party, and (2) the gossip that occurs before and after the event. Both speak to peers and reputation, and the status of the antagonists and protagonists within the group. She also pointed out the implication of retaliation, which she noted occurred about one third of the time. From this research, she posits five types of peer group influence related to violence, with implications for why violence spreads:
1. Planning involvement in advance
2. Coming to the aid of an associate who is losing
3. Being an observer who is threatened during the interaction
4. Seeking justice or righting a perceived wrong
5. Addressing gossip to protect reputation
Social Influence and Intersectionality
At the macro level, factors within society influence not only how and when violence occurs, but also how it might be transmitted. Speaker Anita Raj of the University of California, San Diego, discussed the interaction of multiple social factors in the context of intimate partner violence. She noted that her original research in HIV prevention indicated that expectations of behavior based solely on social-cognitive models would not always
accurately predict outcome because of the influence of other intersectionalities, both within a community and a larger, national, or global scale. In particular, one major impact on the risk of intimate partner violence is the role of gender inequality and race. But, despite interventions that might seek to empower women, violence might not necessarily be reduced because of the other contextual factors involving perpetrators, norms around behavior, other inequities such as lack of education or increased substance abuse, and other structural issues. Dr. Raj also the noted the importance of moving upstream and thinking about interventions that address larger social issues such as incarceration and homelessness.
In thinking about an ecological framework within which to explore intimate partner violence, Dr. Raj also noted the importance of addressing “biology, behavior, state.” The first is the physiological or neurological processes that might be occurring at the individual level, as noted by other speakers. The second might include comorbidities such as substance abuse or risk-taking behavior. The third might include mental health. Also at the individual level, she highlighted the importance of gender equality in the context of the relationship (versus as a social norm) as a possible point of interruption. She also highlighted the importance of family norms, particularly in the context of reinforcement learning, noting how certain violent behaviors might lead to a favorable outcome and no repercussions; and in observational learning, children modeling parents’ behavior as socialization. She closed on the importance of understanding that the acceptability of violence is also transmitted through generations and across communities.
INTERRUPTING THE TRANSMISSION OF VIOLENCE
In thinking about how violence is transmitted across the ecological dimensions, through generations, and from individual to individual, speakers also examined the possibility for interruption. Dr. Ursano stated that not all interventions present themselves so readily:
But we must keep in mind that strep throat is not a penicillin deficiency and yet penicillin is a marvelous intervention for the infection of strep. Similarly perhaps the most important psychological intervention ever invented is in fact the seatbelt because the seatbelt prevents a psychiatric illness. It prevents posttraumatic stress disorder (PTSD) because people who are injured are at four times greater risk of developing PTSD. As we begin to think from mechanisms to interventions, we are going to have to take on several different lenses to be able to accomplish that.
Dr. Raj noted several interventions in her presentation designed to prevent violence specifically, but with applicability for interruption as well, as they focus on the transmission of social norms. She also noted some
interventions that focused on mitigating factors, such as unemployment or reproductive coercion, which could have an impact on vulnerability. She mentioned the importance of looking at interventions which, while intending to address one type of violence, might have the benefit of addressing other types of violence as well, further highlighting the interaction of multiple forms of violence.
Speakers also hypothesized, based on the information presented, possible types of interventions that might be successful. Dr. Huesmann speculated that inoculating children against developing negative schemas and scripts and instead teaching prosocial and compassionate scripts would result in decreased uptake of observed violence. However, he noted the issue of not preventing emotional dysregulation that would still naturally occur because of the exposure to violence. Dr. Wilkinson suggested that programs that intervene in social situations in which isolation and lack of opportunity occur have proven to be very successful; she cited Cure Violence (formerly known as CeaseFire) as an example. Dr. Raj noted that, given the role of modeling and mirror neurons described by Dr. Iacoboni, being able to provide positive role models to emulate would be essential. She advocated for putting further effort into identifying such positive role models, as well as confronting the structural issues that lead to the removal of such models from communities. Dr. Victoroff found that giving men the opportunity to be a provider and get married would reduce their likelihood of joining terrorist cells, and he speculated this could apply to other group affiliations. Several others cautioned that marriage, while being beneficial for men, is not always beneficial for women, so it would be important not to unintentionally increase risk of other types of violence. Dr. Zaki reiterated the potentially powerful use of social conformity, and indicated that one possible approach would be—through social network analysis—to identify the most influential individual in a group or community and change his or her behavior or norms, with the expectation of uptake of that change throughout the group. Dr. Iacoboni noted that even though mirror neurons might fire, people do not constantly mimic each other, so some measure of self-control is being exerted. He suggested exploring the idea of an intervention that could augment self-control.
Participants also explored further application of their ideas in discussing interventions that might reduce social isolation or might increase integration among groups. Dr. Zaki speculated that breaking down barriers between groups could increase prosocial behavior toward those not part of the in-group. He also noted that identities are generally flexible. It is possible to consider oneself part of a very narrow group and also as part of a larger group at any given time. He cited a study in which fans of two soccer teams expressed hostility toward each other when discussing their own teams, but when discussing soccer in general were complimentary toward
each other and somewhat hostile toward non-soccer fans. He noted that one thing that creates an in-group is having an out-group as a counterpoint, and wondered if it would be possible to create a large enough group identity to include everyone. Dr. Huesmann noted that one way to reduce barriers between groups is to have them believe they are more alike than unalike.
Speakers and audience members also challenged assumptions about violence and its contagion. In response to an audience member’s question about why violence is not always contagious, Dr. Raj brought up the notion of positive deviance. Dr. Wilkinson noted that people are not divided into “violent” and “nonviolent,” but that violence is emergent from situations. She also emphasized that violence is functional, and is not always the response that will garner the most advantageous outcome. She urged additional research into why siblings exposed to similar factors will not all end up committing or being a victim of violence. Dr. Ursano summarized these thoughts with proposing the idea of thinking about “absence of violence as deviance.” Speaker and planning committee member Gary Slutkin of the University of Illinois at Chicago closed the discussion by commenting on the possibility that infection still occurs at high rates, but few actually develop the syndrome.
Key Messages as Noted by Individual Speakers
• It is important to take into account complex interaction of social and biological factors (Raj, Ursano, Wilkinson, Zaki).
• It would be illuminating to further explore how violence is not contagious (Iacoboni, Raj, Ursano, Wilkinson) and how non-violence can be contagious (Victoroff, Zaki).
• Multiple processes within the brain could explain physiological changes resulting in increased risk of violence (Huesmann, Iacoboni, Victoroff, Zaki).
• Important social processes and group dynamics could explain increase risk of violence (Huesmann, Raj, Wilkinson, Zaki).
• The interruption of violence could be explored not only from the perspective of proximal causes and effects, but also thinking about upstream or more distal factors (Iacoboni, Raj, Ursano).
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