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.

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