Psychologists call it the dark triad: an intersection of three of the most malevolent tendencies of human nature – psychopathy, narcissism, and Machiavellianism.
But the truth goes deeper, and darker. There’s also egoism, sadism, spitefulness, and more.
And behind this rogues gallery of all our worst inclinations on the surface, a central, common core of human darkness lies, researchers say.
Over the past decade, researchers have found it’s more prominent than we ever expected.
In a 2018 study, psychologists from Germany and Denmark mapped this driving force behind all our darkest impulses and gave it a name. Meet D, short for the Dark Factor of Personality.
The theoretical framework of the D factor has its underpinnings in what’s known as the g factor: a construct proposed by English psychologist Charles Spearman over a century ago, when he observed that individuals who performed well on one kind of cognitive test were more likely to score well on other kinds of intelligence tests, too.
In other words, a ‘general intelligence factor’ could be measured. But it turns out that’s not all scientists are able to detect.
“In the same way, the dark aspects of human personality also have a common denominator, which means that – similar to intelligence – one can say that they are all an expression of the same dispositional tendency,” explained psychologist Ingo Zettler from the University of Copenhagen in Denmark back in September 2018.
In a series of four separate studies involving over 2,500 participants, Zettler and fellow researchers surveyed participants with questions designed to measure their levels of nine distinct dark personality traits: egoism, Machiavellianism, moral disengagement, narcissism, psychological entitlement, psychopathy, sadism, self-interest, and spitefulness.
To do so, participants were asked to disagree with a range of variable ‘dark’ statements, such as: “I know that I am special because everyone keeps telling me so”, “I’ll say anything to get what I want”, “It is hard to get ahead without cutting corners here and there”, and “Hurting people would be exciting”.
With all the responses in hand, researchers ran a statistical analysis, with the results suggesting that while these dark traits are all distinct, they all overlap to some extent, owing to the central core darkness factor, D, which reveals itself in different ways in different people.
“In a given person, the D factor can mostly manifest itself as narcissism, psychopathy or one of the other dark traits, or a combination of these,” Zettler said.
“But with our mapping of the common denominator of the various dark personality traits, one can simply ascertain that the person has a high D factor. This is because the D factor indicates how likely a person is to engage in behavior associated with one or more of these dark traits.”
It’s pretty provocative stuff, but you don’t just have to take the researchers’ word for it: You can take the D test yourself.
The team set up an online portal where you can measure your own D score via a questionnaire.
Since the D factor was first identified, Zettler and his colleagues have spent nearly a decade mapping its reach – and what they’ve found keeps getting more unsettling.
A 2021 longitudinal study published in Social Psychological and Personality Science tracked more than 1,200 adults over four years and found the D factor was the most stable personality measure of all – more consistent over time than any individual dark trait like narcissism or psychopathy.
Whatever D is measuring, it’s deeply embedded.
More recently, this year research across more than 8,000 people in Germany, the United States, and Denmark found a clear pattern in career choices: people with high D scores are significantly less likely to work in social professions – teaching, nursing, therapy – and less likely to even want to.
The darkest people, it seems, quietly sort themselves away from the jobs that require caring about others.
Perhaps most provocatively, a 2025 paper published in the Proceedings of the National Academy of Sciences (PNAS) found that the D factor doesn’t just vary between individuals – it varies between societies.
Countries and US states with more toxic social conditions tended to score higher on collective measures of dark personality, suggesting that while D is a stable personal disposition, the environment that surrounds us shapes just how dark we become.
Why would people want to know this stuff? Well, apart from personal curiosity about how dark you really are, the findings could one day lead to new discoveries in psychology and therapy, advancing our understanding of how we interpret people’s malevolent actions.
Related: Scans Reveal What The Brains of Psychopaths Have in Common
“We see it, for example, in cases of extreme violence, or rule-breaking, lying, and deception in the corporate or public sectors,” Zettler said.
“Here, knowledge about a person’s D-factor may be a useful tool, for example, to assess the likelihood that the person will re-offend or engage in more harmful behavior.”
The findings were reported in Psychological Review, Social Psychological and Personality Science, PNAS, and Journal of Personnel Psychology.
This article was fact-checked by Michael Irving and edited by Fiona MacDonald. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
