The Psychology of Mass Shooters

headshot of Dr. KeffalaViolence in communities from mass attacks is a growing problem in the United States. Since the beginning of 2023 the number of incidents of gun violence in the United States against groups of individuals has risen significantly, with an average of more than one gun violence act per day. As of this writing, there have been 130 incidents of mass shootings in 29 states (for specific information about incidents this year see:

In January, 2023, the IPA Disaster Response Committee urged IPA members to attend a 3-hour training to learn from psychologist Dr. Peter Langman about The Minds, Lives and Motivations of Mass Attackers. Along with 2000 others, I participated in the training hosted by the Pennsylvania Psychological Association and the Council of Executives and Provincial Psychological Associations (CESPPA) organization. Dr. Langman shared his research on the dynamics of mass violence. While he believes that “no one profile for a perpetrator” exists, he shared some of the knowledge he has gleaned from his research into perpetrators of mass violence. On behalf of the Disaster Response Committee, I am sharing with you some of what he taught us.

Dr. Langman identifies 3 types of psychological typology found underlying perpetrator’s behavior: Traumatized, Psychotic, and Psychopathic. He describes traumatized attackers as: unstable, chaotic, and often the survivors of abuse. He notes psychotic perpetrators often meet the criteria for schizophrenia or schizotypal disorder. Some of the psychopathic traits he identifies are extreme narcissism; rejecting rules, laws, morality; callousness (lacking empathy, guilt, remorse); sadistic; and identifying as a victim. He identifies psychopathic types as either charming, charismatic, deceptive; abrasive and belligerent; or quietly callous and immoral.

He noted loss, conflict, stress, falling short of personal goals, thwarted aspirations and/or grandiose aspirations, failure to establish or maintain intimate or meaningful relationships, and failure to establish or maintain a job/career are often factors in the lives of attackers. He observed that violence can serve a transformational purpose for the perpetrator, moving one from a place of powerlessness to becoming powerful, known, and to gaining personal significance.

He described those committing this kind of violence are “not just ordinary people” but have underlying pathology and often have a sense of having been a victim of injustice and tend to “store up grievances” that lead them to engage in violent behavior.

He shared 3 categories by which perpetrators generally justify their violent behavior:

Personal rejection: Retaliation against specific individuals or groups of people who have caused them harm or “wronged” them. This example is often seen in school shootings or work-place shootings. 

Vicarious grievance: Retaliation toward individuals, who may individually be innocent, but who are associated with a group who committed a “wrong” against a group to whom the perpetrator feels related or connected. An example of this was seen in the bombing of the Alfred P. Murrah Federal Building (4/19/1995), in Oklahoma City which was justified as violence in retaliation for federal agents’ actions in Waco Texas. The bombing took place on the anniversary of the deadly fire ending the Waco standoff (4/19/1993). 

Fictional grievance: Retaliation against targeted individuals or targeted group based on paranoid beliefs, delusions, or thoughts of conspiracy against the perpetrator or group with whom they belong. Examples of this are racially motivated mass attacks based on delusions. For example, when a white man killed nine Black people on June 17, 2015, he reportedly stated “I have to do this because you’re raping our women and y’all taking over the world,” feeling he “had to” kill them, believed Hitler would be canonized as a saint, believed Jewish people were a threat and “trying to destroy Whites.” Another shooter in 2019 killed individuals in mosques and synagogues in the San Diego area. He wrote in his manifesto, “Every Jew is responsible for the meticulously planned genocide of the European race.”

Dr. Langman encourages psychologists to consider conducting threat assessments of individuals who present at risk and identify dangers based on their presentation and history. He has published multiple articles, books, and offers online resources to help us better learn how to do so. Here are a few:

Additional resources:

Please contact Ashley Freeman, chair of the Disaster Response Committee at [email protected], with any questions or to get involved with the IPA Disaster Response Committee.

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Comments on "The Psychology of Mass Shooters"

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Valerie Keffala - Sunday, April 16, 2023

Good points, Dan. I do not recall his sharing about messaging around risk assessment in a way that remains useful and non-stigmatizing. I think this is something important for psychologists to discuss for the reasons you mention. We know most gun owners do not commit violent crimes, and we know certain types of weapons (assault weapons) tend to be used in mass violence. The psychosocial interactions you mention play a role in behavior and he did a good job discussing some of them in his talk. He was clear in stating that there was not one profile under which those who commit mass violence could be placed, though did identify the 3 typologies noted above. I encourage you to reach out to him and see if he has thoughts to share about the concerns you raise. He is a member of the Pennsylvania Psychological Association and APA, and you can find his contact information on those sites. Otherwise, let me know. I'll see if I can get his email for you. If you have an opportunity to participate in this training, I encourage you to do so.

Dan Courtney - Tuesday, April 04, 2023

Very useful and pertinent material, thank you for sharing. To extend this topic in a bit more controversial direction for the sake of preparing for what lies ahead: I am concerned that the incremental expertise in risk-assessment that we develop through study and research unintentionally feeds the anti-reasonable-gun-regulation narrative that we can identify with a strong degree of reliability "the dangerous" ones so there is no reason to curtail the "limitless gun rights" of "the low risk" group. Instead, society can feel secure in knowing that there are valid ways to spot the at-risk individuals - thus stigmatizing them before they have even done anything illegal, so that an irrational policy of "the more guns the good guys have the safer we are" can be promulgated. We all know that purported "risk of gun violence" is a complex interaction of types of people, provocative situations, mind sets, drug use and other variables among which is the most critical variable - access and lethality/efficiency of means to cause harm to self and others. How we message our risk-assessment capabilities is critical so that our science-based knowledge isn't hijacked in the service of an anti-science agenda. Did Dr. Langman have any comments pertaining to this concern? Thanks again for your important update.

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