For most people, the term “bad guy” is sufficient to describe the suite of personality traits that can put us on high psychological alert. But, for psychologists, that’s just a starting point.

Terms such as narcissist, Machiavellian, sociopath, and callous exploiter have been developed by personality psychologists to define the intricacies of socially dangerous personality types.

Two dark personalities that are often confused in popular, non-scientific writing are the sadistic personality and the psychopathic personality.

A paper published in the European Journal of Psychological Assessment offers a clear distinction between the two. The authors, led by Delroy Paulhus of the University of British Columbia in Canada, write: "Consensus is emerging that the distinctive ingredient in sadism is the reward value of cruel behavior. Whereas psychopaths are indifferent to others’ suffering, sadists find it appealing. The former may exploit cruelty for its instrumental value; the latter value its intrinsic rewards."

Additionally, the research suggests that:

• Psychopaths are more likely to be impulsive, angry, and fearless.
• Psychopaths may be less inherently fearful or concerned with the possibility of retaliation.
• Sadists operate from a safe distance where rewards can be maintained and the threat of retaliation is minimized.
• Sadists often flex their harmful tendencies vicariously, such as by watching violent sports, violent media, and live fist-fights.

“To us, these findings suggest that psychopathy content is most critical to direct engagement with victims,” stated the researchers.

The authors further differentiate these two personality types via the following scales, which they developed through a series of self-report studies (responses are given on a scale from “strongly disagree” to “strongly agree”).

Sadism Scale

1. Watching a fist-fight excites me.
2. I really enjoy violent films and video games.
3. It’s funny when idiots fall flat on their faces.
4. I enjoy watching violent sports.
5. Some people deserve to suffer.
6. Just for kicks, I’ve said mean things on social media.
7. I know how to hurt someone with words alone.

Psychopathy Scale

1. People often say I’m out of control.
2. I tend to fight against authorities and their rules.
3. I’ve been in more fights than most people of my age and gender.
4. I tend to dive in, and then ask questions later.
5. I’ve been in trouble with the law.
6. I sometimes get into dangerous situations.
7. People who mess with me always regret it.

While some researchers have argued that sadism and psychopathy are too closely related to merit separation, the authors of these scales disagree. Through a series of advanced statistical grouping procedures, they show that people’s responses can be parsed out in a meaningful way—and, by separating sadism from psychopathy, other dark personality types such as narcissism and Machiavellianism are brought into clearer view. This, they argue, could help clinicians and personality psychologists identify such traits in clinical and sub-clinical patient populations.

Speculating on how these dark personality types might fit into the broader spectrum of personality traits, the authors look to the “honesty-humility” dimension of personality as a starting point. Honesty-humility reflects individual differences in sincerity, fairness, greed avoidance, and modesty. People high in honesty-humility tend to be honest, sincere, and modest. Those low in this dimension might be more self-serving and manipulative.

“The Dark Tetrad traits do not fall at the same level as the broad personality factors...but are nestled within one of them,” conclude the authors.