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The psychology behind mass shootings

Updated: May 30, 2022

To deny the reality that mental illness is not only one of, but the largest factor that drives the occurrence of mass shootings accomplishes nothing but inviting more of these events to transpire. Motives for mass shootings are nearly always conceptualized broadly and prioritize sociological and ideological over psychological explanation. It is this dismissal of the psychological motivations of mass shootings and their perpetrators almost entirely that has led to the two recent and devastating mass shootings that have occurred a mere ten days apart – the Tops Supermarket shooting that left 10 people dead in Buffalo, New York, and the Robb Elementary School shooting that left 22 people dead, 19 of which being children under the age of ten, in Uvalde, Texas. When we fail to understand and prioritize mental wellbeing, especially for those among us who suffer from violent symptoms of mental illness (persistent rage, aggression, or obsessive homicidal thoughts), then we are communicating to potential mass shooters that their symptoms and resulting behaviors are normal and acceptable; they might think there is no help for them and that they must suffer in silence due to the heavy stigma associated with violent tendencies, in which their rage and urges to harm others have the potential to boil over into action.

It is understandable that those who have mental illness themselves – or the loved ones of those who have mental illness – tend to be the vocal majority of those who immediately object to any acknowledgement that a perpetrator of horrendous violence, such as mass shootings, had a documented history, or had shown symptoms, of mental illness prior to their attack. Throughout history, people have heavily stigmatized the mentally ill, especially through affixing the liberal and arbitrary label of violence onto them, adding to their mistreatment and misunderstanding of them by others. This was due to the widespread belief that all violent people are mentally ill – which is largely true, as violence and violent symptoms manifest directly from a mental disturbance rather than on their own. However, the problem that derives from this belief is the subsequent belief that all mentally ill people are therefore violent as well by default. This could not be further from the truth: Research population studies show that the majority of people with a serious mental illness are not violent; less than 5% of violent crimes in the United States are committed by people with serious mental illness [1].

Can one claim, however, with absolute certainty that mass shooters aren’t mentally ill or have the potential to be, and that any possible ailments could not have been a contributing factor to the planning and the execution of their attacks when studies show that nearly half of the entire United States population will, at some point during their lives, meet the criteria for being diagnosed with a mental illness [1]? The understanding, or lack thereof, from the general population regarding the very context of mental illness and how one is even defined, with consideration to our knowing of what traits of our very thoughts and behaviors would even constitute this definition, speaks volumes about this issue. We tend not to be able to fully comprehend or fathom just how prevalent mental abnormality is amongst our population, and yet, we tend to be so confident in our assertions that the perpetrators of mass gun violence are not mentally unsound in any way. Thus, following the wake of yet another preventable tragedy, we choose to abandon entirely our consideration of any possible psychological motives that could have been responsible for the attack, and we opt instead to begin and end every debate regarding prevention of these events by focusing almost solely on the political forces that, seemingly alone, are what influences a sane individual to want to commit such acts of violence.

Let us shift our attention to the truth of the psychology regarding these perpetrators to demonstrate the true extent of the damage and harm that results from upholding the misconception that mental illness plays no role in the occurrence of mass shootings.

Though it has been established how widespread mental illness is within our society, research has also shown that, while those with severe mental illness hardly account for a fraction of violent crimes, such as mass gun violence, the rate with which mental illness is present amongst perpetrators is much higher. If we are speaking in regard to the amount of mass shooters who have actually received a formal diagnosis, research has shown that more than half of mass shooters have been diagnosed with a mental illness, while research which includes diagnosis, self-reporting, and symptoms of mental illness suggest that around 2/3 (67%) of all perpetrators had clearly exhibited symptoms of mental illness leading up to their attack [2]. Studies also show that a history of mental health issues is associated with increased violence among mass shooters when a disorder is identified, yet no specific formal diagnosis has been reported [3]. Additionally, a federal report on active shooters found that mental health was the top stressor that had been identified as leading up to the attack in the prior year [3]. Finally, mass shooters with undiagnosed and untreated mental illness have a much higher rate of victimizing more people during their attacks [3].

Violence, whether we condone it or not, is still an indicator of mental health problems or distress. While not all people who experience violent symptoms will go on to harm themselves or others, the hostility and stigma surrounding them and the refusal to acknowledge that they, too, are experiencing mental illness only reinforces the idea that those affected by these symptoms are not suffering, as well. It suggests they do not need or want to be helped and that they are not qualifying and deserving of help because they can’t be helped. All mental illnesses and all of their symptoms, regardless of how unpleasant they may be, are still deserving of more understanding, less stigma, and better access to care and treatment. Providing better support for those who have violent symptoms can help prevent tragedies such as the Sandy Hook Elementary School or the Stoneman Douglas High School shootings.


1. Peterson, J. K., Densley, J. A., Knapp, K., Higgins, S., & Jensen, A. (2022). Psychosis and mass shootings: A systematic examination using publicly available data. Psychology, Public Policy, and Law, 28(2), 280–291.

2. Lankford, A., & Cowan, R. G. (2020). Has the role of mental health problems in mass shootings been significantly underestimated? Journal of Threat Assessment and Management, 7(3-4), 135–156.

3. Yelderman, L. A., Joseph, J. J., West, M. P., & Butler, E. (2019). Mass shootings in the United States: Understanding the importance of mental health and firearm considerations. Psychology, Public Policy, and Law, 25(3), 212–223.



Author: Chantelle Moore

Editor: Lauryn Agron

Health scientist: Chantelle Moore

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