The Brains that Pull the Triggers: Syndrome E

Séjour d’étude de Itzhak Fried (Université de Californie Los Angeles, Etats-Unis), du 26 Septembre au 7 Octobre 2023.



German soldier taking aim at a Jewish mother and child in front of a photographer during mass killing operations in Ivangorod, Ukraine, 1942. Photograph sent home by mail (Yad Vashem, Jerusalem, Israel, courtesy US Holocaust Memorial Museum)

The transformation of groups of previously nonviolent individuals into repetitive killers of defenseless members of society has been a recurring phenomenon throughout history. This apparent transition of large numbers of seemingly normal, “ordinary” individuals, to perpetrators of extreme atrocities is one of the most striking variants of human behavior, but often appears incomprehensible to victims, bystanders and in retrospect even to the perpetrators themselves and to society in general.  This transition is characterized by a set of symptoms and signs for which I proposed a common syndrome, Syndrome E (Fried, Lancet, 1997).

The purpose of the residential study was to further explore the Syndrome E hypothesis and its relevance to present-day and future societies. The study was based on interdisciplinary conferences organized by Itzhak Fried at L’Institut d’études avancées de Paris in the years 2015-2017 (“The Brains that Pull The Triggers”),  and  on synthesis of new manifestations of Syndrome E, changes in social media  and artificial intelligence, as well as new findings in neuroscience. The fragmentation of social and political structures with concomitant avalanche of global spread of rampant information affecting billions of brains worldwide, have created new grounds for outbreaks of Syndrome E.  

German soldier taking aim at a Jewish mother and child in front of a photographer during mass killing operations in Ivangorod, Ukraine, 1942. Photograph sent home by mail (Yad Vashem, Jerusalem, Israel, courtesy US Holocaust Memorial Museum)



La transformation de groupes d’individus auparavant non-violents en tueurs répétés de membres sans défense de la société a été un phénomène récurrent tout au long de l’histoire. Cette transition apparente d’un grand nombre d’individus apparemment normaux et « ordinaires » vers les auteurs d’atrocités extrêmes est l’une des variantes les plus frappantes du comportement humain, mais elle apparaît souvent incompréhensible aux victimes, aux spectateurs et, rétrospectivement, même aux auteurs eux-mêmes et à la société. Cette transition est caractérisée par un ensemble de symptômes et de signes pour lesquels j’ai proposé un syndrome commun, le Syndrome E (Fried, Lancet, 1997). Le but de ce séjour d’étude était d’explorer davantage l’hypothèse du syndrome E et sa pertinence pour les sociétés actuelles et futures. L’étude s’appuie sur des conférences interdisciplinaires organisées par Itzhak Fried à l’Institut d’études avancées de Paris dans les années 2015-2017 (« Les cerveaux qui tirent sur les gâchettes »), et sur la synthèse des nouvelles manifestations du syndrome E, des changements dans les médias sociaux et l’intelligence artificielle, ainsi que les nouvelles découvertes en neurosciences. La fragmentation des structures sociales et politiques, accompagnée d’une avalanche de diffusion mondiale d’informations effrénées affectant des milliards de cerveaux dans le monde, a créé de nouveaux terrains pour l’apparition du syndrome E. Soldat allemand visant une mère et son enfant juifs devant un photographe lors d’opérations de massacre à Ivangorod, en Ukraine, 1942. Photographie envoyée à son domicile par courrier (Yad Vashem, Jérusalem, Israël, avec l’aimable autorisation du US Holocaust Memorial Museum).



In studying Syndrome E we adopt an approach based on dimensions of behavior or neurobehavioral constructs, such as those employed by Research Domain Criteria, a methodological approach developed in recent years to address neurobehavioral disorders. It integrates many levels of information- including  molecules, cells, brain circuits, psychology, behavior and self-report  and employs psychological constructs grouped into domains of human behavior and functioning.

The original Syndrome E hypothesis outlined a number of “symptoms and signs” based on observations of and self-reports by perpetrators including the seminal observations by Robert Browning  (1992) of German Einsatzgruppenduring WWII, and by Jean Hatzfeld (2005) of the Hutu perpetrators during the Rwandan genocide. The tantalizing common feature coming out of these observations was the “ordinary” nature of the perpetrators and the degree – up to 70-80% in studied populations- to which normal people, even when given a choice not to participate, would nevertheless go along becoming rapidly desensitized efficient  killers. The symptoms and signs of Syndrome E included: repetitive killings, obsessive ideation, rapid desensitization to violence, perseveration, diminished affective reactivity, hyperarousal, intact planning and executive function, compartmentalization and group contagion.

The first step in approaching the pathophysiology of Syndrome E is the rejection of the view that these acts of violence are a result of a primitive animal brain, such as MacLean’s reptilian brain, unleashed from cortical (or neopallium) control. We must also eject a Freudian view that these acts are those of a primitive id freed from suppression of a superego. We must first recognize that Syndrome E is unique to humans. A model of “Cognitive Fracture”  is proposed , opposite to the McLean-Freud model,  and is based on hyperactive hyper-aroused  prefrontal cortex , the very brain part responsible for human progress, now fractured from homeostatic feedback of subcortical and visceral centers that would normally guide behavior. Somatic markers associating slaughter with visceral-affective disgust and fear are lost, leaving a disconnected hyper-aroused prefrontal cortex fed by ideological framework, resulting in rapid desensitization to violence with obsessive compulsion to destroy an ever-increasing number of lives.

Three key psychological constructs characterize Syndrome E by linking the symptoms of the syndrome with the biological substrates. These are: dehumanization, empathy and agency.

“We no longer saw a human being when we turned up a Tutsi in the swamps. I mean a person like us sharing similar thoughts or feelings” (Hatzfeld, 2005). In precise self-report,  this Hutu perpetrator explains the essence of dehumanization. It is indeed a perceptual shift where a human body, a human face, fails to elicit the normal response in the brain’s perceptual centers.

Discussion of neuronal mechanisms of empathy often involve mirror neurons , neuronal systems that mirror the same systems of movement, perception and emotions in other minds and therefore may facilitate our reactions to other person pain or suffering. Yet it is often shocking how the same brain can generate great empathy for the in-group members and such lack  of empathy toward a member of the out- group. 

Milgram’s experiments in the 1960’s demonstrated human vulnerability to an authority and the potential role of obedience to authority in the actions of perpetrators. Indeed, people often claim reduced responsibility- a reduction of agency or owning their action when they obey orders. Haggard and colleagues (Caspar et al., 206) used subjects’ time perception of the consequences of pain infliction they caused either independently or by obeying orders, showing a reduced agency in the latter, with concomitant psychophysical physiological neurophysiological measures. 

Several changes have profoundly impacted the mechanisms facilitating outbreaks of Syndrome E in present and future societies. In the 20th century large-scale slaughter occurred sanctioned by states and  led by totalitarian regimes, most notably those of  Hitler, Stalin and Mao. In the 21st century mass killings  have occurred in smaller organizations and groups including  rebels in Sudan, Al-Qaeda, ISIS and others,  during  multiple intermediate states of conflicts on the spectrum between durable peace and total war. The creation, propagation and consumption of ever-increasing rampant unchecked information through social networks have had profound effect, exceeding brain capacity to filter or evaluate information. Furthermore the concept of the group has changed facilitating uncontrolled aggregation and radicalization of individuals into groups with extreme agendas.

The October 7th  2023,  massacre of Israeli civilians by Hamas perpetrators was a tragic “laboratory” of Syndrome E: massive killings of over a thousand people carried out in a few hours in one day with unparalleled visual documentation propagated in social media, with numerous ensuing reactions, interactions, and associations –massive barrage of information affecting millions of brains worldwide.  Signs and symptoms of Syndrome E and its constructs of dehumanization and loss of empathy were evident. Killings were carried out within an ideological framework in an obsessive desensitized manner with intent to spare no one. The perpetrators carried out systematic killings of entire families in flat affect and compartmentalization- shooting parents in front of their children, while at the same time texting their parents back home. The hyperarousal and elation with the increasing amount of destruction is demonstrated  in a Hamas terrorist texting his parents Dad, look at the WhatsApp, see how many I killed… I killed ten! 10! Their blood is on my hands. Let me speak to Mom…”. The destructive combination of cortical hyperarousal and focused executive function and concomitant flat affect- was probably enhanced by drugs- specifically Captogen, a mixture of amphetamine and caffeine also previously used by ISIS  terrorists.  

How can outbreaks of Syndrome E be prevented? Prevention efforts have usually focused on institutional, ideological and political dynamics. As example, the Simon-Skjodt Center for the Prevention of Genocide in the United States Holocaust Memorial Museum monitors warning  signs worldwide in order to take early action by individuals and governments to save lives.

But at the final common pathway of a perpetrator among perpetrators pulling the trigger,  prevention of Syndrome E requires first and foremost a Universal Code of Education where Humanization , Empathy and Agency should be imprinted in young brains. Technological,  possibly AI-assisted, tools of detecting false, inciting or harmful information will likely be improving in the coming years, fortified by increasing legal measures imposed on individuals and large media companies. However these may not suffice. The most important educational goal is to teach young brains how to be free thinkers, able to critically evaluate- and subsequently accept or reject incoming information- a challenge that has become increasingly  more difficult.

1.Fried I. SyndromeE   Lancet 1997; 350: 1845–47

2.Browning CR. Ordinary men: Reserve Police Battalion 101 and the final solution in Poland. New York, NY, USA: Harper Collins, 1992.

3.Hatzfeld, J. Machette Season : The Killers in Rwanda Speak. Picador. 2005

4.Milgram S. Obedience to authority: an experimental view. New York, NY, USA: Harper Colophon, 1969.

5.Caspar EA, Christensen JF, Cleeremans A, Haggard P. Coercion Changes the Sense of Agency in the Human Brain.   Curr Biol. 2016 Mar 7;26(5):585-92.

6.Fried I. , Berthoz A., Mirdal G (eds.) The Brains that Pull the Triggers, Odile Jacob Press, 2021

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