Science can't say whether people in your life are good or evil, per se. But it's getting better at figuring out whether they enjoy hurting you.
A fairly new field in personality research studies "misanthropic" traits: characteristics that lead people to hurt those around them for their own benefit. And psychologists have established a "dark triad" of harmful personality traits: narcissism, psychopathy (or a lack of empathy), and Machiavellianism (or a tendency to manipulate others.)
Any one of these traits makes a person stressful to those around them. Taken together they add up to an "antagonistic and selfish" strategy for getting ahead at other people's expense.
Now, some researchers suggest a fourth trait should join the triad: sadism, or joy in inflicting pain on others.
Why sadism matters
Sadism is a term with a long history. Sadists take pleasure in hurting other people. They're our most fearsome and evil villains — whether real or imagined, like Ramsay Bolton of Game of Thrones.
But the idea of sadism is fairly new to clinical settings. That's in part because the whole study of personality, and specifically of "dark" personality traits, is fairly recent and underdeveloped. But it's also because traits like sadism, along with the rest of the dark triad, are difficult to tease apart with clinical precision.
Even papers that support the idea of sadism as part of a larger "dark tetrad" acknowledge that its effects can be difficult to distinguish from the three existing triad traits.
But a growing body of work in just the last few years has shown that sadism correlates specifically and strongly with cruel behavior — for example, trolling and cyberbullying.
The sadism test
In order to develop a rigorous test for sadism, researchers assembled a list of questions designed to poke right at the heart of a sadistic personality.
The first version was 20 questions long. Subjects were asked to say how strongly they agreed or disagreed with a list of (rather chilling) statements, using a scale from one to five. (One meant completely disagree and five completely agree.)
1. I have made fun of people so that they know I am in control.
2. People do what I want them to because they are afraid of me.
3. When I tell people what to do, they know to do it.