Different dark personalities may have more in common than their labels suggest.
Narcissists, psychopaths, sadists and manipulative people share a dark personality core that predicts selfish and antisocial choices.
This common tendency helps explain whether people exploit others, retaliate against them or refuse to trust them.
The crucial feature is a willingness to pursue personal interests at other people’s expense, accompanied by beliefs that justify doing so.
The common dark core
Known as the dark factor of personality, or D, this tendency brings together traits that can look quite different on the surface.
Narcissism involves an inflated sense of self-importance, Machiavellianism centres on manipulation, psychopathy includes callousness, and sadism involves enjoying others’ suffering.
The idea that these traits share an underlying disposition was established in earlier research examining their overlap and links to harmful behaviour (Moshagen et al., 2018).
The latest findings suggest that this shared core is more consistently associated with antisocial decisions than any of the four traits considered separately.
In other words, knowing what these personalities have in common may reveal more about their choices than knowing which particular label fits them.
Selfishness, revenge and distrust
The research involved over 10,000 people across ten studies using eight types of decision-making game.
Participants completed personality questionnaires before making hypothetical choices involving another person they did not know.
Depending on the game, they could decide how much money to share, whether to return someone’s trust, whether to retaliate or whether to cooperate.
Some situations allowed people to benefit themselves at someone else’s expense, while others explored whether they would trust another person when cooperation could benefit both.
People scoring higher on the dark factor consistently made fewer prosocial choices across all eight games.
The individual dark traits also generally predicted less prosocial behaviour, but their associations were weaker.
Once their shared dark core was taken into account, the separate traits usually added little to the explanation.
There were a few exceptions, particularly involving Machiavellianism in situations where distrust could influence decisions.
Why labels can mislead
One possible explanation is that dark personality traits combine harmful tendencies with other characteristics that are not inherently antisocial.
For example, boldness does not necessarily involve harming anyone, while wanting admiration does not automatically mean exploiting others.
Earlier research proposed that these additional characteristics help distinguish dark traits from one another, while their shared core captures what makes them socially harmful (Bader et al., 2023).
Measuring a broad trait such as psychopathy may therefore mix callous self-interest with features that have little relevance to a particular moral decision.
Focusing on the common core could provide a clearer picture of someone’s willingness to disregard other people’s welfare.
Importantly, the dark factor extends beyond wanting a larger share of the rewards.
It also encompasses a readiness to hurt others and beliefs that can make selfish conduct seem acceptable.
Distrust may fit this pattern because expecting other people to behave selfishly can provide a convenient justification for doing the same.
That is a proposed psychological explanation, rather than evidence that distrust caused the choices observed here.
Beyond imagined decisions
The findings do not mean that everyone with dark traits will behave selfishly in every situation.
Nor do they establish that personality caused the decisions participants made.
All the games were hypothetical, so participants were describing what they would choose rather than making decisions with real financial consequences.
This matters because associations between dark traits and antisocial choices can be stronger in hypothetical situations than when money is genuinely at stake.
Participants also volunteered through a website offering dark-personality assessments, so they were not a representative sample of the wider population.
Even with these qualifications, the results support a simpler account of apparently different dark personalities: much of their connection to harmful choices lies in the same underlying disregard for others.
The study was published in the journal Judgment and Decision Making (Hilbig & Thielmann, 2025).
