Comparative Behavioural Analyses of Mental Illness across Terrorist Actors and Mass Casualty Offenders

Share Button

With the Society for Terrorism Research (STR) 8th Annual International Conference fast approaching, STR, partnered with the Center for Terrorism and Security Studies (CTSS), is launching a series of guest blog posts, written by those who will be presenting their research at STR14. In the third installment of this series Emily Corner, a Doctoral Student at University College London, discusses her research on behavioural analyses of mental illness in terrorists and mass casualty offenders.

Earlier this year researchers at the University of Massachusetts Lowell and University College London began a National Institute of Justice funded project examining the behavioural underpinnings of lone-actors who perpetrate mass acts of violence; some for an ideological cause, others not. The overarching consensus spanning terrorism literature views an act of targeted violence to be perpetrated by a rational terrorist, or a mentally instable civilian. Three interlinked factors drive this deeply entrenched view: A lack of statistical evidence, a focus on group dynamics, and stigma.

The convoluted history of terrorism literature concerning psychopathology mirrors a pendulum’s swing. The 1970s and 80s saw terrorists labelled as inherently ‘bad’ and damaged, with the flaunting of fashionable buzzwords such as psychopath and narcissist. These conclusions rested upon assumptions rather than statistics, and were invalidated in subsequent research where it was more feasible to gather larger amounts of data on individuals. More contemporary research almost exclusively focused on the importance of group dynamics and collective identity, downplaying the convoluted psychological processes inherent in individual motivations and behaviours, and reasoned psychopathology to play no role in terrorist behaviour (e.g. Post, 2005; Post 2009). These conclusions are fuelled, at least in part, by the stigma associated with mental illness; the actions of an individual with a psychopathological diagnosis are directly correlated to their illness. Terrorists are viewed as individuals with limited power and capability, utilising rational, strategic logic to counter political opponents. Actors with mental illness are seen to deviate from this model, as their presumed lack of rationality renders them incapable of planning, preparing, and executing politically motivated violence.

The rise in research concerning lone-actor terror has provided evidence that counters each of these factors. Lone-actor research is providing consistent, statistically valid, results concerning behaviours and motivations of individuals, highlighting the comparatively high incidence of mental illness and rationality amongst this group. Theodore Kaczynski successfully attacked and evaded capture for nearly two decades, despite suffering from paranoid schizophrenia. Timothy McVeigh had a history of depression and anxiety, yet killed 168 people and injured nearly four times that amount. Anders Breivik’s personality disorder did not impede his meticulous coordination of the Norway attacks killing 77 and injuring over 300. Recent research has provided statistical evidence supporting these case studies. Mentally ill lone-actors are more likely to carry out violent attacks, have a higher mortality and injury rate, stockpile weapons, and attack discriminate targets, than non-mentally ill lone-actors (see Corner and Gill, in Press).

Another highly effective actor type, not impeded by the confounding factor of disproportionately high rates of mental illness, are mass casualty offenders. Mass casualty offenders are not radicalised and lack a typical ‘ideology’, traits compulsory for lone-actor terrorist classification. Mass casualty offenders and lone-actors share certain behavioural outcomes, committing low frequency, high-intensity crimes, and acting independently from external influences. The fundamental difference between these actor types lies in motivation. As such this actor type has the potential to act as a control in empirical research concerning lone-actor terrorists, and has the potential to proffer further statistical evidence, aiding in the understanding of the behaviours of lone-actors. This understanding will inform investigative practice, advancing prevention techniques originally designed for group-actors.

At the Society for Terrorism Research (STR) 8th Annual International Conference, I will present my empirical analyses on two groups of data. The first, a comparative analysis, is regarding the fundamental differences in mental illness prevalence between group and lone-actor terrorists. This research identifies key differences in mental illness prevalence across ideologies, and provides statistical evidence supporting the long held assumption that terrorist groups identify potential cadres based upon their psychological ‘fitness’ and ability. The second facet of this data involves the inferential statistical analyses of 180+ variables concerning demographic, antecedent, event, and post-event specific behaviours of lone-actors and mass casualty offenders. This will identify similarities and differences between the two actor types, and suggest any potential behavioural profiles useful for prevention purposes. These results provide evidence highlighting the need for further comparative research between lone-actors and mass casualty offenders. I will also present results from empirical analyses conceptualising mental illness as a categorical variable, identifying the effect of the number and co-morbidity of diagnoses upon antecedents and behaviours of both lone-actors and mass casualty offenders. The resulting statistics from these analyses provide evidence for necessary changes in practitioner-led prevention efforts concerning lone-actors. They suggest the need for a multidisciplinary, cohesive, prevention-focused approach, identifying individuals who experience and exhibit similar behavioural indicators prior to the commission of attack related behaviours, and offering support from the most effective agency.

For me, the STR Conference offers a unique opportunity to present my research to highly respected researchers, who will help me to build my knowledge base. I hope to gather valuable feedback on my research, discuss what the implications offer to both academics and practitioners, and meet like minded researchers, with the view to setting up future collaborations. I am only starting out in my career and want to absorb as much knowledge and experience as possible, and the STR Conference is a great place to achieve all of this.

Emily Corner is a Research Assistant and Doctoral Student at the University College London Department of Security and Crime Science. Here her doctoral studies focus on mental illness in terrorists. Emily will be presenting her research at the Society for Terrorism Research Conference on Communication and Collaboration for Counter-Terrorism, September 17-19th, in Boston, MA. The *preliminary* program for this conference is now available here.

If you are also presenting at STR14 and would like the opportunity to write a blog post for this series please contact


Leave a Reply

Your email address will not be published.