They are sometimes called "malevolent" personalities in everyday language, but in psychology, they are referred to as "dark" personality traits (the Dark Triad). As explained in a study published in Personality and Individual Differences , these traits are associated with a greater likelihood of unethical behavior (lying, cheating), although this is not a medical diagnosis.
What is the "Dark Triad"?
The Dark Triad comprises three traits:
- Narcissism (self-centered, need for admiration),
- Machiavellianism (manipulation, social strategy),
- Psychopathy (impulsivity, low empathy, sensation-seeking).
The most prominent characteristic here is Machiavellianism.
In the study, participants were presented with two situations where they could cheat or lie to gain something. The results showed that Machiavellianism was a stronger predictor of cheating in situations where deception is at someone else's expense (a more "social," more strategic form of deception), while psychopathy was a stronger predictor of lying about one's performance (a more direct, more opportunistic form of deception). In other words, it's not a single trait that explains everything: the links vary depending on the type of behavior.
And what about the famous "we're less moral in the evening"?
There's a well-known hypothesis, the Morning Morality Effect, which suggests that we tend to be more "moral" in the morning than in the afternoon. But the Dark Triad study also tested this point… and didn't find this effect: in their results, the time of day doesn't change cheating or lying, nor does it reinforce the impact of "dark" traits.
Key takeaways
- Machiavellianism is the trait most associated here with strategic deception.
- Psychopathy is more closely linked to lying in the other task.
- And unlike other studies, the time of day (morning/evening) doesn't make much difference in this study.
This study reminds us that we're not talking about "monsters" or diagnoses, but rather personality tendencies: when certain "dark" traits are elevated, the likelihood of unethical behavior can increase. Here, Machiavellianism stands out primarily for its more strategic deception (at the expense of others), while psychopathy is more closely linked to opportunistic lying. And above all, contrary to the idea that we are "less moral" in the evening, the researchers found no clear effect of the time of day: what matters most are the traits themselves… not the hour.
