Psychopathy stands out as key trait behind uncommitted sexual behavior

A new study published in Sexual and Relationship Therapy sheds light on how certain personality traits are associated with people’s openness to casual, uncommitted sexual relationships. The researchers found that among the so-called “Dark Triad” traits—narcissism, Machiavellianism, and psychopathy—only psychopathy consistently predicted all aspects of sociosexuality. In contrast, traits linked to kindness and prosocial values, known as the “Light Triad,” were not significant predictors when controlling for other variables.

Human mating strategies vary widely. Some people prefer long-term monogamous relationships, while others pursue short-term or less committed sexual encounters. These differences are partly shaped by personality traits. Sociosexual orientation refers to a person’s general tendency toward or against casual sex. It includes three dimensions: behavior (actual experiences), attitude (moral and emotional beliefs), and desire (fantasies and impulses).

Previous research has linked high sociosexuality to traits from the Dark Triad—psychopathy, narcissism, and Machiavellianism. These traits are often associated with manipulation, impulsivity, and lack of empathy. However, past studies have largely treated these traits together, without testing which specific ones matter most when considered side by side. Moreover, research on the “Light Triad”—traits that reflect moral character and prosocial orientation—has been limited, especially in terms of how these traits relate to sociosexuality.

This new study aimed to fill that gap by examining the independent effects of each Dark and Light Triad trait on sociosexuality, both overall and across its three dimensions. The researchers also wanted to see whether these links differed between men and women.

“I’ve long been interested in how individual differences shape the ways people approach romantic relationships,” said study author Betul Urganci, an assistant professor of psychology at Koç University.

“In particular, I was intrigued by the growing literature on the Dark Triad traits which are often portrayed negatively but may serve certain strategic functions in mating behavior. At the same time, I was curious about the emerging concept of the Light Triad, which emphasizes prosocial and compassionate traits. Our goal was to explore how both the darker and lighter sides of personality relate to sociosexuality, known as people’s willingness to engage in casual sex, and to see how these traits might uniquely predict different facets of that tendency.”

The researchers collected data from 308 adults recruited through Amazon Mechanical Turk. The participants, who were primarily heterosexual and about evenly split between men and women, completed several personality questionnaires online. These included validated measures of Dark Triad traits, Light Triad traits, and sociosexual orientation. The sociosexual scale measured participants’ reported sexual behaviors over the past year, their comfort with uncommitted sex, and their frequency of sexual fantasies involving strangers or acquaintances. The study also collected basic demographic data, such as age, gender, and relationship status, which were used as control variables in the analysis.

When looking at the raw correlations, all three Dark Triad traits were positively associated with sociosexual orientation. People higher in narcissism, Machiavellianism, or psychopathy were more likely to have permissive attitudes toward casual sex, stronger sexual desires, and more uncommitted sexual experiences. However, when the researchers used regression analyses to control for the overlap between the traits and other variables, psychopathy stood out as the only consistent predictor. Narcissism and Machiavellianism no longer contributed meaningful variance.

“Only psychopathy, not narcissism or Machiavellianism, emerged as a unique predictor when we included all three Dark Triad traits in the same model,” Urganci told PsyPost.

Psychopathy is characterized by impulsivity, emotional detachment, and a tendency toward thrill-seeking. The researchers suggest that these characteristics likely contribute to greater openness to uncommitted sex. People high in psychopathy may be less concerned with the emotional consequences of their actions, more inclined to take risks, and more motivated by sensation-seeking behaviors, including sexual novelty.

On the other hand, the Light Triad traits showed only weak or inconsistent links with sociosexuality. While some negative correlations appeared in the bivariate analyses—particularly for Kantianism and Faith in Humanity—these relationships disappeared when the researchers controlled for the Dark Triad traits. In other words, the prosocial traits did not predict people’s sociosexual tendencies when accounting for darker personality features. The only exception was a small effect suggesting that, among men, higher Faith in Humanity was linked to less sociosexual behavior, although this effect was modest and not found among women.

“One finding that surprised us was the limited role of the Light Triad traits,” Urganci said. “We initially expected that the Light Triad traits would predict a lower tendency toward casual sex, and while we did find some weak associations, they didn’t hold up once we accounted for the Dark Triad and other variables.”

“The main takeaway is that not all personality traits influence mating behaviors equally. Among the traits we studied, psychopathy stood out as the strongest and most consistent predictor of interest in casual, uncommitted sex—across attitudes, desires, and behaviors. This doesn’t mean everyone high in psychopathy behaves the same way, but it does suggest that certain personality traits are linked to specific relationship strategies.”

It’s also important to note that the findings should not be interpreted to mean that only individuals with psychopathic traits enjoy or engage in casual sex. Sociosexual orientation exists along a continuum, and many people who are not high in psychopathy may still prefer uncommitted sexual relationships for a variety of reasons, including personal values, life stage, or cultural influences. The study highlights a statistical association, not a categorical distinction.

But like all research, the study has limitations. Because it relied entirely on self-report questionnaires, the findings may be affected by social desirability or inaccurate self-perceptions. Another important limitation is the study’s cross-sectional design, which prevents any firm conclusions about causality. Most participants were White, heterosexual, and in relationships.

“This may limit the generalizability of the findings to people in different cultures as well as single individuals,” Urganci said. “I’m interested in expanding this research cross-culturally to examine how social and cultural norms interact with individual differences to shape mating behaviors.”

The study, “Examining the role of Dark and Light Triad traits on sociosexuality,” was authored by Betul Urganci, Barış Sevi, Burak Dogruyol, and Ezgi Sakman.