A few psychological factors may be at play. People tend to develop a preference for ideas they are familiar with, a social science phenomenon that’s known as the mere-exposure effect or the familiarity principle. Ideas, in this framing, work a bit like infectious viruses.

“The more often you see it, the more familiar something is, and the more familiar something is, the more believable it is,” says Jeff Hancock, communication professor and founding director of the Stanford Social Media Lab.

Conspiracy content is engineered to be persuasive. People accept these theories because they help make sense of a world that feels random; even if they seem far-flung to the rest of us, they can offer some sense of comfort or security. And seeing those theories repeatedly pop up in your Facebook news feed “starts to undermine the sense that they are fringe,” says James Grimmelmann, a professor at Cornell Law School who studies internet law and social networks.

While a Facebook user may be outraged the first time they see an objectionable video in their feed, it’s unlikely that they’ll muster an equally emotional negative reaction if that experience is repeated again and again. With enough viewings, they may find the messaging palatable or, at the very least, less jarring. Open the door to your mind a crack, and conspiracy can slink in.

“Repeated exposure could also make the moderators think that the conspiracy theory is more prevalent than it is actually in the population and therefore makes them slowly adhere to it,” says Dominique Brossard, professor in the life science communication department at University of Wisconsin-Madison. “This is why social norms are so powerful.”

Should those beliefs become instilled, people will work to reinforce them, simply because we tend to work hard to defend views when we hold them. “Once you start to believe, confirmation bias kicks in,” says Hancock, referring to the human tendency of seeking out information or news sources that support preexisting beliefs.

A smaller contributing factor may be the psychological phenomenon known as emotional contagion, which is when feelings or emotions spread from person to person. You may not know the term, but you know the feeling. Unconsciously mimicking the facial expression or mirroring the mood of someone you are spending time with are both examples of emotional contagion.

“Conspiracies exonerate them for their own misfortune.”

It could be that conspiracy videos instill or spread fear in viewers, who after mirroring that emotion, seek to attribute that unexplained fear to a tangible source. “‘I’m feeling weird and gross and scared. Why is that?’” asks Hopkins as a hypothetical. “‘That’s probably because the government is against us.’ You’re rationalizing why you’re upset”—even though what made you upset in the first place was the conspiracy content.

While Facebook moderators’ extreme psychological distress is likely linked to the high quantity of disturbing content they consume on the job—one moderator who spoke with the Verge sifted through up to 400 posts a day—Facebook may still serve conspiracy or simply false videos, news, and memes to the rest of us.

What does our collective exposure to conspiracy content on Facebook mean for public mental health at large? Are we all just clicks away from identifying as “flat-Earthers”—or worse?

Joseph Walther, director of the Center for Information Technology and Safety at the University of California-Santa Barbara, cautioned against extrapolating from the extreme experience of Facebook moderators. If the average social media user were akin to a casual smoker, moderators are consuming the equivalent of two packs-a-day.

“The moderators you describe, they’re clearly under duress,” Walther tells OneZero. “Their level of exposure to these messages isn’t normal. Their experience doesn’t map onto the rest of us.”

The ultimate difference between individuals who are unaffected by conspiracy content and those who become indoctrinated may come down to what’s happening to them offline. A major blow to an individual’s ego, such as being fired from a job or rejected by a romantic partner, can draw some people toward racism or conspiracy theories, which Walther says are often intertwined. When they’re hurting, humans like to find a scapegoat.

“If they’re already prone to racist ideology, and perceive some threat to the status or purity or privilege of their own race or sex, and then experience a particular vulnerability, conspiracies could be especially appealing,” he says. “Conspiracies exonerate them for their own misfortune.”