A new study published in the European Journal of Neuroscience has found that certain personality traits associated with the so-called Dark Triad are linked to specific patterns in brain structure. Using a machine learning approach to analyze brain scans, the researchers discovered that these traits are associated with different brain networks involved in reward processing, social reasoning, and executive control. While narcissism was linked to reduced brain concentration in reward-related areas, Machiavellianism showed an opposite pattern in brain regions associated with strategic thinking.
The Dark Triad refers to a group of personality traits that share features like manipulation, a lack of empathy, and disregard for others, but each also has distinct features. Narcissism is characterized by inflated self-importance and a need for admiration. Machiavellianism reflects manipulative, strategic, and often cynical behavior. Psychopathy involves emotional coldness, impulsivity, and antisocial tendencies. These traits have been linked to social and interpersonal problems, but scientists have long debated how they relate to the brain. The new study sought to clarify whether structural patterns in the brain could offer insights into how these traits develop and manifest.
“In recent years, societal changes—particularly the rise of individualism, social media culture, and increased polarization—have coincided with what seems to be a growth in behaviors associated with the Dark Triad traits (narcissism, Machiavellianism, and psychopathy),” said study author Richard Bakiaj, a psychologist and doctoral student working in the Clinical and Affective Neuroscience Lab at the University of Trento.
“Given the significant social, economic, and psychological costs these traits impose, understanding their origins and neural underpinnings could provide crucial insights. By exploring the biological foundations alongside psychological and social factors, we aim not only to better grasp why these traits manifest, but also to inform more targeted prediction, prevention, and rehabilitation strategies, especially for individuals at risk of developing severe antisocial or pathological behaviors.”
The researchers analyzed brain scans from 201 adults, nearly evenly split by gender and averaging 32 years old. The participants completed a psychological questionnaire measuring each of the three Dark Triad traits. The team then used a machine learning technique called transposed independent vector analysis, or tIVA, to identify distinct networks in the brain’s grey and white matter—two types of tissue responsible for processing and transmitting information, respectively.
Rather than focusing on single brain regions, the tIVA algorithm identified 15 large-scale brain networks based on how different regions covary across individuals. Four of these networks were found to be associated with overall Dark Triad scores. One of these networks involved areas commonly linked to reward and motivation, such as the thalamus, caudate nucleus, prefrontal cortex, and anterior cingulate cortex.
Another involved regions associated with executive control, such as parts of the prefrontal and posterior parietal cortex. A third network included areas in the default mode network, which plays a role in self-reflection and social reasoning. The fourth included regions in the visual system, primarily located in the occipital and temporal lobes.
“The involvement of areas typically linked to the visual cortex was particularly unexpected and intriguing,” Bakiaj told PsyPost. “Based on theoretical support from previous research—that individuals high in psychopathy might have an imbalance between posterior (visual) and anterior (frontal) brain areas, potentially favoring visual processing regions, we speculate that individuals high in psychopathic traits might effectively process social cues visually, yet fail to engage the emotional or cognitive processes needed for appropriate social behavior. This could partly explain why people high in psychopathy can often remain detached, engaging in antisocial or reckless behaviors without fully grasping their emotional impact on others.”
Upon closer examination, the researchers found distinct associations between two of these networks and specific traits. The network related to reward processing showed a negative association with narcissism. In other words, people with higher narcissism scores tended to show reduced grey and white matter concentration in this network. The default mode network showed a positive association with Machiavellianism, with higher levels of the trait linked to increased concentration in these areas.
These findings suggest that narcissism may be associated with diminished structure in brain regions that help regulate emotional rewards and self-esteem. Previous research has proposed that narcissistic individuals may seek external validation to compensate for internal deficiencies in reward processing. The observed reductions in prefrontal and reward-related brain areas align with this theory and support the idea that narcissistic traits may emerge in part from structural brain differences.
Machiavellianism, in contrast, was associated with increased brain concentration in regions involved in social reasoning and long-term planning. These areas, which include parts of the posterior cingulate cortex and angular gyrus, are known to be active when people think about others’ thoughts, weigh moral decisions, or simulate future outcomes. The enhanced brain structure in this network may support the strategic and manipulative tendencies seen in individuals high in Machiavellian traits.
Interestingly, psychopathy did not show a strong relationship with any single brain network identified in the analysis. The researchers noted two possible explanations for this. First, the sample may not have included enough individuals with high levels of psychopathy to detect meaningful patterns. Second, psychopathy may rely on a broader combination of brain circuits, including both the reward and executive networks. The absence of a specific correlation highlights the complexity of this trait and suggests that future studies may need to use different methods or larger samples to capture its neural basis.
This research provides a new perspective on how personality traits associated with antisocial and manipulative behavior are reflected in the brain. By showing that traits like narcissism and Machiavellianism are linked to differences in large-scale brain networks, the findings may eventually help inform psychological or even neurological interventions.
“Our study highlights that personality traits traditionally seen as purely psychological are also associated with distinct brain patterns, meaning that our biology plays a significant role in how we behave and interact with others,” Bakiaj explained. “Importantly, these brain differences do not necessarily mean individuals are born with them. Instead, they might emerge through complex interactions between biological predispositions, life experiences, upbringing, and social environments. Understanding that these traits are associated with both brain structure and function can help us approach these individuals with greater insight—recognizing the need for targeted psychological and possibly neurobiological interventions.”
The study also confirmed a consistent finding in personality research: men scored significantly higher than women on all three Dark Triad traits. While this does not necessarily imply biological determinism, the structural brain differences observed may help explain why some traits are more common in men than in women. Importantly, the study found no significant relationship between age and any of the three traits, suggesting that these personality characteristics may remain relatively stable across adulthood.
But the study does have some limitations. “Our study relies primarily on structural brain imaging data (gray and white matter), and while structural differences provide meaningful clues, they cannot directly tell us about real-time brain activity or causation,” Bakiaj noted. “Additionally, the traits were measured using self-report questionnaires, which, despite their utility, can introduce biases such as social desirability, exaggeration, or underreporting.”
“Finally, the population studied consisted of individuals largely within normal trait ranges; thus, the findings might differ when examining clinical populations or those with extreme manifestations of these traits. Future studies incorporating functional brain data, behavioral assessments, and clinical samples are needed to confirm and extend our results.”
Despite these limitations, the research represents a significant step forward in understanding the biological basis of personality. It shows that traits like narcissism and Machiavellianism are not just psychological labels but are reflected in the brain’s architecture. The more scientists learn about these neural signatures, the better we may become at predicting, preventing, or managing behaviors that can damage relationships, communities, and even broader social systems.
“Currently, my research is moving toward a deeper exploration of psychopathy and its influence on group decision-making and social interactions,” Bakiaj said. “This direction has potential practical implications in various contexts, such as workplaces, correctional facilities, and rehabilitation programs. Understanding how individuals with pronounced psychopathic traits behave in group scenarios can guide interventions and inform decisions about group composition—potentially mitigating negative outcomes and enhancing group functioning. Additionally, my research aims to better conceptualize psychopathy from a neuropsychometric perspective, ultimately facilitating more accurate diagnosis and intervention strategies.”
“One crucial point to emphasize is the interplay between societal forces and individual vulnerabilities,” he added. “Societal trends—such as the rise of social media, increased individualism, reduced face-to-face interactions, and heightened competition—can shape psychological and even biological processes over time. However, individuals vary greatly in their resilience to these pressures.”
“Someone with a resilient personality structure and robust emotional processing (such as a well-functioning amygdala, crucial for emotional and social responses) may remain relatively unaffected by these social forces. Conversely, someone with inherent vulnerability, like pre-existing emotional or neural impairments, might be dramatically shaped or negatively impacted by these same societal trends. Understanding this interaction between social context, psychology, and individual biology can significantly inform our approach to personality development, mental health, and interventions aimed at improving social outcomes.”
The study, “Unmasking the Dark Triad: A Data Fusion Machine Learning Approach to Characterize the Neural Bases of Narcissistic, Machiavellian and Psychopathic Traits,” was authored by Richard Bakiaj, Clara Isabel Pantoja Muñoz, Andrea Bizzego, and Alessandro Grecucci.