Here's the one frightening psychological characteristic that online trolls tend to share

Trolling has literally changed culture, both online and off. The word is now used to categorize a wide and varying swath of behaviors, from absurdist contrarian comment posts, to harassment and abuse disproportionately aimed at women of all races and people of color, to entire presidential campaigns. There now exist troll scholars, many of whom have been studying trolls for years, and an academic area of study, trollology. That’s evidence of just how widespread trolling is, and how it’s sparked a sort of anthropological interest in troll behavior and culture. The question for non-trolls is, behind the layer of protective anonymity, what lies at the core of the troll psyche. The findings of a few studies suggest that trolls who are mean-spirited and manipulative online have offline personalities to match, and that insecurity drives a fair amount of their trollery.

Case in point are two 2014 studies from Canada’s University of Manitoba that looked at the personalities of some 1,200 people who engage in trolling, which the researchers described as “behaving in a deceptive, destructive, or disruptive manner in a social setting on the internet” for seemingly no purpose at all. (The trolls would likely say they do it for the "lulz,” or laughs that come at another person’s expense.)

In the first study, participants were given tests measuring sadistic tendencies to get a feel for how much they enjoyed hurting other people. One a scale of 1 to 5, those surveyed were asked to rate the extent to which they agreed with statements like, "hurting people is exciting’’ and, ‘‘I enjoy hurting people.’’ They were also posed questions that gauged their levels of psychopathy, and asked about fairly mundane things, like the amount of time they spend on the internet and their favorite online activities (with trolling given as one option). The second study “assessed trolling behavior, identification and enjoyment” along a rating scale, along with a few other things.

“Both studies revealed similar patterns of relations between trolling and the Dark Tetrad of personality: trolling correlated positively with sadism, psychopathy, and Machiavellianism,” the researchers wrote. In other words, those who took part in trolling generally enjoyed watching others suffer, were pathologically self-absorbed and lacked “conscience and empathy.”

“Of all personality measures, sadism showed the most robust associations with trolling and, importantly, the relationship was specific to trolling behavior,” study authors note. “Enjoyment of other online activities, such as chatting and debating, was unrelated to sadism. Thus cyber-trolling appears to be an internet manifestation of everyday sadism... Both trolls and sadists feel sadistic glee at the distress of others. Sadists just want to have fun… and the internet is their playground!”

A 2015 collaborative study from the University of New South Wales and Miami University found that male trolls who exhibited sexism in gaming, hurling misogynist threats and insults at women online, were particularly likely to be among the crappy players. The scientists observed players in the online first-person shooter game Halo 3, and found that the success of male players informed how they behaved toward women.

“Men who were of lower skill were more positive towards men and more negative towards women,” Michael Kasumovic, one of the study authors, told Wired magazine. “But the really neat result is that when men were of higher skill, they were much more positive to women.”

“In other words,” the Washington Post suggests, “sexist dudes are literally losers.” The Post helped provide a bit more insight into the study findings:

A recent influx of female participants has disrupted a pre-existing social hierarchy. That’s okay for the guys at the top—but for the guys at the bottom, who stand to lose more status, that’s very threatening.... “As men often rely on aggression to maintain their dominant social status,” Kasumovic writes, “the increase in hostility towards a woman by lower-status males may be an attempt to disregard a female’s performance and suppress her disturbance on the hierarchy to retain their social rank.”

What else might be at work here? There’s a fairly popular theory that much of the bullying that happens online can be chalked up to online disinhibition effect, first written about by John Suler in 2004. The theory holds that when people are online, where their identities and physical bodies are hidden and a sort of lawless virtual environment presents itself, social conventions fall by the wayside, and they behave in ways they never would in real life. Innocuous behavioral shifts (like becoming more honest or emotionally open) are labeled benign disinhibition; yucky behaviors (like the racist name-calling often seen in comment sections and social media feeds) is toxic disinhibition. The latter is more likely to occur among members of privileged groups who target those from historically oppressed communities.

Wikipedia points to a 1978 New Yorker article that mentioned similarly disgusting behavior—proto-trolling, you might say—among the anonymous users of CB radio in the 1970s:

Most of what you hear on CB radio is either tedious (truck drivers warning one another about speed traps) or banal (schoolgirls exchanging notes on homework), but at its occasional—and illegal—worst it sinks a pipeline to the depths of the American unconscious. Your ears are assaulted by the sound of racism at its most rampant, and by masturbation fantasies that are the aural equivalent of rape. The sleep of reason, to quote Goya's phrase, brings forth monsters, and the anonymity of CB encourages the monsters to emerge.

For more proof, Wired points to a study from Israel’s University of Haifa that found a way to put the kibosh on bad behaviors using eye contact. When college students were asked to debate topics over instant messenger, they were far more civil when forced to maintain eye contact with those they IM’d with.

For a real-life application of this idea, watch men in the following video read actual offensive tweets directed to sports writers Sarah Spain and Julie DiCaro. Despite the fact that the guys reading the comments didn’t write the tweets, as they turn from standard insults to full-on abuse, the men grow increasingly uncomfortable and visibly troubled. It feels gross in real life (IRL), because it is gross. And because real life includes the internet, making it as real and authentic as every other thing we experience each day.