Expert Commentary

Mass murder, shooting sprees and rampage violence: Research roundup

Literature review of studies relating to various aspects of mass shooting/murder incidents in the United States and abroad.

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Sandy Hook, Aurora, the Washington Navy Yard, Fort Hood, and Emanuel African Methodist Episcopal Church in Charleston, S.C. These place names signify terrible tragedies that continue to prompt deep reflection from policymakers and the public about how to stop acts of mass violence in the United States.

While FBI statistics show that levels of violent crime in the United States, including murder, have steadily declined since 1991, acts of murder and non-negligent manslaughter still claim about 15,000 lives a year. More than half of all such violent crimes in a given year are typically committed with guns. Over the past 30 years, public mass shootings have resulted in the murder of 547 people, with 476 other persons injured, according to a March 2013 Congressional Research Service report. “[W]hile tragic and shocking,” the report notes, “public mass shootings account for few of the murders or non-negligent homicides related to firearms that occur annually in the United States.” For more on these dynamics, see the May 2013 Pew Research Center report titled “Gun Homicide Rate Down 49% Since 1993 Peak; Public Unaware.”

Even as the total gun homicide rate has fallen, however, some of the worst acts of violence in U.S. history have taken place within the past decade. Half of the deadliest shootings — incidents at Virginia Tech, Aurora, Sandy Hook, Binghamton, Fort Hood (2009), the Washington Navy Yard and a church in Charleston — have taken place since 2007. In September 2014 the FBI released a report confirming that U.S. mass shootings had risen sharply since 2007: From 2000 to 2006, there were an average of 6.4 annually; from 2007 to 2013, the average more than doubled, rising to 16.4 such shootings per year.

As a 2011 United Nations report notes, America has a “relatively high homicide rate compared to other countries with a similar socio-economic level,” but per-capita homicide rates in the Caribbean, Central America and Africa are often much higher and approach “crisis” levels there. The relationship between gun availability and homicide rates is, according to an American Journal of Criminal Justice paper, “not stable across nations.” Even so, a 2011 study in the Journal of Trauma compared the United States with similar nations and found that U.S. homicide rates were “6.9 times higher than rates in the other high-income countries, driven by firearm homicide rates that were 19.5 times higher. For 15-year olds to 24-year olds, firearm homicide rates in the United States were 42.7 times higher than in the other countries.”

For more on the relationship between firearm ownership and homicide rates, see this review for the National Academy of Sciences (more below), as well as this study in the American Journal of Public Health. There are multiple important questions about deterrence, restrictions, access to guns and criminal justice interventions that have yet to be resolved, as a group of the country’s leading researchers in the field concluded in 2007. Still, Australia’s experience with increased gun regulation, as detailed in a study in Injury Prevention, suggests that some laws in certain contexts can reduce firearm violence. The findings of research on the 1994 assault weapons ban and its effects are reviewed here.

For an overview of the technical and legal aspects of firearms and ammunition in the United States — and a brief history of gun control — see this article from the Poynter Institute. Among the many studies that look at the effectiveness of policies and programs to reduce gun violence, a 2012 metastudy in the journal Crime & Delinquency stands out for its comprehensiveness. The effectiveness of having guns in the home for self-defense is also an area of significant research.

What some researchers call “rampage violence” — such as the shootings in Newtown, Conn., at Columbine High and Virginia Tech, and at Rep. Gabrielle Giffords’s political event in Tucson — plays a prominent role in the national consciousness, often touching off political debates over gun control laws, shifts in the culture and the role of violent media, particularly video games.

Though each act of violence has a distinct context, over the past decade the social science research community has continued to search for more general frameworks of understanding. But some researchers believe that establishing more precise psychological/criminal profiles in the hope of preventing such events through interventions may ultimately prove elusive. Though much speculation is offered in the media immediately afterward, scholars often note the limits of existing knowledge. (For a review of the research literature on such profiling, see the first article below.) It should be said that the connection between violence and severe mental illness is often over-simplified in the news media, and claims should be framed and informed by the existing empirical research. A 2013 survey and report published in The New England Journal of Medicine has data on the public’s views on mental illness issues and violence, in the wake of the Newtown, Conn., school shooting incident.

In terms of violent acts in a school context, the FBI compiles useful background materials and data, as does the Centers for Disease Control.

Below are studies that provide an overview of the state of knowledge in this area:


“The Nature of Mass Murder and Autogenic Massacre”
Bowers, Thomas G.; Holmes, Eric S.; Rhom, Ashley. Journal of Police and Criminal Psychology, 2010, 25:59-66. doi: 10.1007/s11896-009-9059-6

Abstract: “Incidents of mass murder have gained considerable media attention, but are not well understood in behavioral sciences. Current definitions are weak, and may include politically or ideologically motivated phenomenon. Our current understanding of the phenomenon indicates these incidents are not peculiar to only western cultures, and appear to be increasing. Methods most prominently used include firearms by males who have experienced challenging setbacks in important social, familial and vocational domains. There often appears to be important autogenic components … including dysthymic reactions and similar antecedents. There have been observations of possible seasonal variations in mass murders, but research to date is inadequate to establish this relationship. It is recommended behavioral sciences and mental health researchers increase research efforts on understanding mass killings, as the current socioeconomic climate may increase vulnerability to this phenomenon, and the incidents are not well understood despite their notoriety.”


“Rampage Violence Requires a New Type of Research”
Harris Jr., John M.; Harris, Robin B. American Journal of Public Health, June 2012, Vol. 102, No. 6, pp. 1054-1057. doi: 10.2105/AJPH.2011.300545

Abstract: “Tragedies such as school shootings and the assault on Congresswoman Gabrielle Giffords share features that define them as acts of “rampage violence.” These types of events can lead to despair about their inevitability and unpredictability. To understand and prevent rampage violence, we need to acknowledge that current discipline-based violence research is not well suited to this specific challenge. There are numerous important, unanswered research questions that can inform policies designed to prevent rampage violence. It is time to develop alternative research approaches to reduce the risk of rampage violence. Such approaches should incorporate transdisciplinary research models; flexible, outcomes-focused organizational structures similar to those used to investigate other catastrophic events; and an expanded inventory of analytic tools.”


“The ‘Pseudocommando’ Mass Murderer: Part I, The Psychology of Revenge and Obliteration”
Knoll, James L. Journal of American Academy of Psychiatry and the Law, March 2010,  38:1:87-94

Abstract: “The pseudocommando is a type of mass murderer who kills in public during the daytime, plans his offense well in advance, and comes prepared with a powerful arsenal of weapons. He has no escape planned and expects to be killed during the incident. Research suggests that the pseudocommando is driven by strong feelings of anger and resentment, flowing from beliefs about being persecuted or grossly mistreated. He views himself as carrying out a highly personal agenda of payback. Some mass murderers take special steps to send a final communication to the public or news media; these communications, to date, have received little detailed analysis. An offender’s use of language may reveal important data about his state of mind, motivation, and psychopathology. Part I of this article reviews the research on the pseudocommando, as well as the psychology of revenge, with special attention to revenge fantasies. It is argued that revenge fantasies become the last refuge for the pseudocommando’s mortally wounded self-esteem and ultimately enable him to commit mass murder-suicide.” (Also see Part II of the article.)


“Attributing Blame in Tragedy: Understanding Attitudes About the Causes of Three Mass Shootings”
Haider-Markel, Donald P.; Joslyn, Mark R. American Political Science Association, 2011 annual meeting paper. Accessed through Social Science Research Network.

Abstract: “Individuals develop causal stories about the world around them that explain events, behaviors, and conditions. These stories may attribute causes to controllable components, such as individual choice, or uncontrollable components, such as systematic forces in the environment. Here we employ motivated reasoning and attribution theory to understand causal attributions to the 2007 Virginia Tech shootings, the 2009 Fort Hood shootings, and the 2011 Tucson, Arizona shootings. We argue that causal attributions stem from individual reasoning that is primarily motivated by existing dispositions and accuracy motives. Both motivations are present for attributions about these mass shootings and we seek to understand their significance and whether dispositional motives condition accuracy drives. We are able to test several hypotheses using individual level survey data from several national surveys to explain attributions about the shootings. Our findings suggest a substantial partisan divide on the causes of the tragedies and considerable differences between the least and most educated respondents. However, our analyses also reveal that while education has virtually no influence on the attributions made by Republicans, it heightens the differences among Democrats. We discuss these findings for the public’s understanding of these tragedies and more broadly for attribution research.”


“Psychological Profiles of School Shooters: Positive Directions and One Big Wrong Turn”
Ferguson, Christopher J.; Coulson, Mark; Barnett, Jane. Journal of Police Crisis Negotiations, 2011, Vol. 11, Issue 2. doi: 10.1080/15332586.2011.581523

Abstract: “A wave of school shootings in the mid- to late 1990s led to great interest in attempts to ‘profile’ school shooters with an eye both on identifying imminent perpetrators and preventing further incidents. Given that school shootings are generally rare, and many perpetrators are killed during their crimes, the availability of school shooters for research is obviously limited. Not surprisingly, initial profiles of school shooters were arguably of limited value. Although school shooting incidents, particularly by minors, have declined, some evidence has emerged to elucidate the psychological elements of school shooting incidents. School shooting incidents may follow extreme versions of etiological pathways seen for less extreme youth violence, and youthful school shooters appear more similar than different to adult perpetrators of mass shootings. The quest to understanding school shootings has led to several wrong turns, most notably the quixotic desire by politicians, advocates, and some scholars to link both school shootings and less extreme youth violence to playing violent video games, despite considerable and increasing evidence to the contrary.”


“The Autogenic (Self-Generated) Massacre”
Mullen, P.E. Behavioral Sciences and the Law, 2004, 22(3):311-23.

Abstract: “Mass killings can be of a variety of types including family slayings, cult killings, and the by-product of other criminal activities. This article focuses on massacres where the perpetrators indiscriminately kill people in pursuit of a highly personal agenda arising from their own specific social situation and psychopathology. Five cases are presented of this type of autogenic (self-generated) massacre, all of whom survived and were assessed by the author. Not only do these massacres follow an almost stereotypical course, but the perpetrators tend to share common social and psychological disabilities. They are isolates, often bullied in childhood, who have rarely established themselves in effective work roles as adults. They have personalities marked by suspiciousness, obsessional traits, and grandiosity. They often harbor persecutory beliefs, which may occasionally verge on the delusional. The autogenic massacre is essentially murder suicide, in which the perpetrators intend first to kill as many people as they can and then kill themselves. The script for this particular form of suicide has established itself in western society and is continuing to spread, and to diversify.”


“Mass Murder: An Analysis of Extreme Violence”
Fox, James Alan; Levin, Jack. Journal of Applied Psychoanalytic Studies. Vol. 5, No. 1 (2003), 47-64, doi: 10.1023/A:1021051002020.

Findings: “Mass murder involves the slaughter of four or more victims by one or a few assailants within a single event, lasting but a few minutes or as long as several hours. More than just arbitrary, using this minimum body count — as opposed to a two- or three-victim threshold suggested by others (e.g., Ressler et al., 1988, Holmes and Holmes, 2001) — helps to distinguish multiple killing from homicide generally. Moreover, by restricting our attention to acts committed by one or a few offenders, our working definition of multiple homicide also excludes highly organized or institutionalized killings (e.g., war crimes and large-scale acts of political terrorism as well as certain acts of highly organized crime rings). Although state-sponsored killings are important in their own right, they may be better explained through the theories and methods of political science than criminology. Thus, for example, the definition of multiple homicide would include the crimes committed by Charles Manson and his followers, but not those of Hitler’s Third Reich, or the 9/11 terrorists, despite some similarities in the operations of authority.”


“Predicting the Risk of Future Dangerousness”Phillipps, Robert T.M. Virtual Mentor. June 2012, Volume 14, Number 6: 472-476.

Abstract: “A consequence if not a driving force of the pendulum swing away from benevolence and toward the protection of others has been increased attention to an individual’s dangerousness, with the operative presumption that dangerousness is often the result of a mental illness. But dangerousness is not always the result of mental illness. Individuals who commit violent or aggressive acts often do so for reasons unrelated to mental illness…. Research, in fact, confirms the error in associating dangerousness with mental illness, showing that ‘the vast majority of people who are violent do not suffer from mental illnesses. The absolute risk of violence among the mentally ill as a group is still very small and … only a small proportion of the violence in our society can be attributed to persons who are mentally ill.’ Violence is not a diagnosis nor is it a disease. Potential to do harm is not a symptom or a sign of mental illness, rather it must be the central consideration when assessing future dangerousness.”


“Predicting Dangerousness With Two Million Adolescent Clinical Inventory Psychopathy Scales: The Importance of Egocentric and Callous Traits
Salekin, Randall, T.; Ziegler, Tracey A.; Larrea, Maria A.; Anthony, Virginia Lee; Bennett, Allyson D.
Journal of Personality Assessment, 2003, Vol. 80, Issue 2. doi: 10.1207/S15327752JPA8002_04.

Abstract: “Psychopathy in youth has received increased recognition as a critical clinical construct for the evaluation and management of adolescents who have come into contact with the law (e.g., Forth, Hare, & Hart, 1990; Frick, 1998; Lynam, 1996, 1998). Although considerable attention has been devoted to the adult construct of psychopathy and its relation to recidivism, psychopathy in adolescents has been less thoroughly researched. Recently, a psychopathy scale (Murrie and Cornell Psychopathy Scale; Murrie & Cornell, 2000) was developed from items of the Million Adolescent Clinical Inventory (MACI; Millon, 1993). This scale was found to be highly related to the Psychopathy Checklist-Revised (Hare, 1991) and was judged to have demonstrated good criterion validity. A necessary step in the validation process of any psychopathy scale is establishing its predictive validity. With this in mind, we investigated the ability of the MACI Psychopathy Scale to predict recidivism with 55 adolescent offenders 2 years after they had been evaluated at a juvenile court evaluation unit. In addition, we devised a psychopathy scale from MACI items that aligned more closely with Cooke and Michie (2001) and Frick, Bodin, and Barry’s (2001) recommendations for the refinement of psychopathy and tested its predictive validity. Results indicate that both scales had predictive utility. Interpersonal and affective components of the revised scale were particularly important in the prediction of both general and violent reoffending.”


“Violent Video Game Effects on Aggression, Empathy and Prosocial Behavior in Eastern and Western Countries: A Meta-Analytic Review”
Anderson, Craig A.; Shibuya, Akiko; Ihori, Nobuko; Swing, Edward L.; Bushman, Brad J.; Sakamoto, Akira; Rothstein, Hannah R.; Saleem, Muniba. Psychological Bulletin, March 2010, Vol. 136(2), 151-173

Abstract: “Meta-analytic procedures were used to test the effects of violent video games on aggressive behavior, aggressive cognition, aggressive affect, physiological arousal, empathy/desensitization, and prosocial behavior. Unique features of this meta-analytic review include (a) more restrictive methodological quality inclusion criteria than in past meta-analyses; (b) cross-cultural comparisons; (c) longitudinal studies for all outcomes except physiological arousal; (d) conservative statistical controls; (e) multiple moderator analyses; and (f) sensitivity analyses. Social-cognitive models and cultural differences between Japan and Western countries were used to generate theory-based predictions. Meta-analyses yielded significant effects for all 6 outcome variables. The pattern of results for different outcomes and research designs (experimental, cross-sectional, longitudinal) fit theoretical predictions well. The evidence strongly suggests that exposure to violent video games is a causal risk factor for increased aggressive behavior, aggressive cognition, and aggressive affect and for decreased empathy and prosocial behavior. Moderator analyses revealed significant research design effects, weak evidence of cultural differences in susceptibility and type of measurement effects, and no evidence of sex differences in susceptibility. Results of various sensitivity analyses revealed these effects to be robust, with little evidence of selection (publication) bias.”


“‘It’s Better to Overreact’: School Officials’ Fear and Perceived Risk of Rampage Attacks and the Criminalization of American Public Schools
Madfis, Eric. Critical Criminology, September 2015. doi: 10.1007/s10612-015-9297-0.

Abstract: “In recent decades, highly-publicized school rampage attacks with multiple victims have caused widespread fear throughout the United States. Pulling from in-depth interviews with school officials (administrators, counselors, security and police officers, and teachers), this article discusses officials’ perceptions of fear and risk regarding rampage shootings and how this relates to their justification for and acquiescence to the expansion of punitive discipline and increased security. Data collected in this study provide additional understanding of the causes of enhanced discipline and security from the perspective of those tasked with administering school safety in the wake of Columbine. Utilizing insight from moral panic theory, the findings suggest that, when the genuinely high potential cost of school massacres fused with an exaggerated perception of their likelihood and randomness, school rampage attacks came to be viewed as a risk that could not be tolerated and must be avoided at nearly any cost.”


“Posttraumatic Stress Among Students after the Shootings at Virginia Tech”
Hughes, Michael; Brymer, Melissa; Chiu, Wai Tat; Fairbank, John A.; Jones, Russell T.; Pynoos, Robert S.; Rothwell, Virginia; Steinberg, Alan M.; Kessler, Ronald C. Psychological Trauma: Theory, Research, Practice, and Policy, December 2011, Vol. 3(4), 403-411. doi: 10.1037/a0024565

Abstract: “On April 16, 2007, in the worst campus shooting incident in U.S. history, 49 students and faculty at Virginia Polytechnic Institute and State University (Virginia Tech) were shot, of whom 32 were killed. A cross-sectional survey of 4,639 Virginia Tech students was carried out the following summer/fall to assess PTSD symptoms using the Trauma Screening Questionnaire (TSQ). High levels of posttraumatic stress symptoms (probable PTSD) were experienced by 15.4% of respondents 3 to 4 months following the shooting. Exposure to trauma-related stressors varied greatly, from 64.5% unable to confirm the safety of friends to 9.1% who had a close friend killed. Odds ratios for stressors predicting high levels of posttraumatic stress symptoms were highest for losses (2.6-3.6; injury/death of someone close) and inability to confirm the safety of friends (2.5). Stressor effects were unrelated to age, gender, and race/ethnicity. The exposures that explained most of the cases of high posttraumatic stress symptoms were inability to confirm the safety of friends (30.7%); death of a (not close) friend (20.3%); and death of a close friend (10.1%). The importance of high-prevalence low-impact stressors resulted in a low concentration of probable cases of PTSD, making it difficult to target a small, highly exposed segment of students for mental health treatment outreach. The high density of student social networks will likely make this low concentration of probable PTSD a common feature of future college mass trauma incidents, requiring broad-based outreach to find students needing mental health treatment interventions.”


“Adjustment Following the Mass Shooting at Virginia Tech: The Roles of Resource Loss and Gain”
Littleton, Heather L.; Axsom, Danny; Grills-Taquechel, Amie E. Psychological Trauma: Theory, Research, Practice and Policy, September 2009, Vol. 1(3), 206-219. doi: 10.1037/a0017468

Abstract: “Unfortunately, many individuals will be exposed to traumatic events during their lifetime. The experience of loss and gain of valued resources may represent important predictors of psychological distress following these experiences. The current study examined the extent to which loss and gain of interpersonal and intrapersonal resources (e.g., hope, intimacy) predicted psychological distress among college women following the mass shooting at Virginia Tech (VT). Participants were 193 college women from whom pre-event psychological distress and social support data had been obtained. These women completed surveys regarding their psychological distress, coping, and resource loss and gain 2- and 6-months after the VT shooting. Structural equation modeling supported that resource loss predicted greater psychological distress 6 months after the shooting whereas resource gain was weakly related to lower levels of psychological distress. The study also revealed that social support and psychological distress prior to the shooting predicted resource loss, and social support and active coping with the shooting predicted resource gain. Implications of the results for research examining the roles of resource loss and gain in posttrauma adjustment and the development of interventions following mass trauma are discussed.”


“Murder by Numbers: Monetary Costs Imposed by a Sample of Homicide Offenders”
DeLisi, Matt; Kosloski, Anna; Sween, Molly; Hachmeister, Emily; Moore, Matt; Drury, Alan. Journal of Forensic Psychiatry & Psychology, 2010, Vol. 21, Issue 4. doi: 10.1080/ 14789940903564388.

Abstract: “Prior research on the monetary costs of criminal careers has neglected to focus on homicide offenders and tended to minimize the public costs associated with crime. Drawing on expanded monetization estimates produced by Cohen and Piquero, this study assessed the monetary costs for five crimes (murder, rape, armed robbery, aggravated assault, and burglary) imposed by a sample of (n = 654) convicted and incarcerated murderers. The average cost per murder exceeded $17.25 million and the average murderer in the current sample posed costs approaching $24 million. The most violent and prolific offenders singly produced costs greater than $150-160 million in terms of victim costs, criminal justice costs, lost offender productivity, and public willingness-to-pay costs.”


“More Support for Gun Rights, Gay Marriage than in 2008, 2004”
Pew Research Center, April 2012

Findings: Opinions on gun rights have shifted significantly over time. In 2000, 66% of Americans said controlling gun ownership was more important than protecting gun rights, while just 29% said rights were more important. By 2012, 49% supported gun rights versus 45% favoring gun control. Support for gun ownership among both men and women has increased from 2008, with a 14 percentage point increase in support for gun rights for men and a 9 percentage point increase for women. Partisan division over gun control has also grown in recent years. Republican support for gun rights increased from 65% in 2009 to 72% in 2012, while Independent support for gun rights increased from 48% in 2009 to 55% in 2012.


“Firearms and Violence: A Critical Review”
Wellford C.F.; Pepper J.V.; Petrie C.V. National Research Council of the National Academies, 2004. Washington, DC: National Academies Press.

Findings: “Empirical research on firearms and violence has resulted in important findings that can inform policy decisions. In particular, a wealth of descriptive information exists about the prevalence of firearm-related injuries and deaths, about firearms markets, and about the relationships between rates of gun ownership and violence. Research has found, for example, that higher rates of household firearms ownership are associated with higher rates of gun suicide, that illegal diversions from legitimate commerce are important sources of crime guns and guns used in suicide, that firearms are used defensively many times per day, and that some types of targeted police interventions may effectively lower gun crime and violence. This information is a vital starting point for any constructive dialogue about how to address the problem of firearms and violence. While much has been learned, much remains to be done, and this report necessarily focuses on the important unknowns in this field of study. The committee found that answers to some of the most pressing questions cannot be addressed with existing data and research methods, however well designed. For example, despite a large body of research, the committee found no credible evidence that the passage of right-to-carry laws decreases or increases violent crime, and there is almost no empirical evidence that the more than 80 prevention programs focused on gun-related violence have had any effect on children’s behavior, knowledge, attitudes or beliefs about firearms. The committee found that the data available on these questions are too weak to support unambiguous conclusions or strong policy statements.”


Tags: research roundup, crime, guns

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