Why do we love to believe Internet hoaxes?

When Brad Campbell saw that his next door neighbourhood had posted a disclaimer on Facebook declaring, “I do not give Facebook or any entities associated with Facebook permission to use my pictures, information, or posts, both past and future,” Campbell figured he’d repaste the declaration on his own page.

“My neighbour is a pretty responsible person so I thought if he posted it, I didn’t have to look into it,” says Campbell, who works at a Toronto-based film festival. “Privacy is important and I don’t really trust Facebook to protect it. I figured it was better to be safe than sorry.”

Of course, the declaration is about as legally effective as posting a raccoon video to avoid paying bank service charges. It cites an irrelevant section of the Uniform Commercial Code and the even more irrelevant Rome Statute, which gives the International Criminal Court the authority to try crimes against humanity and does nothing to override the Terms of Service every Facebook user must agree to when they sign up. Yet waves of Facebookers have been posting the declaration since it first appeared in 2012. The twist this time around is the addition of a (false) threat of $5.99 Facebook charge to keep posts from going public if users don’t copy and share the declaration.

Why do humans have such an appetite for such hoaxes? While the Internet has made checking facts easy, it’s done an even better job at making mistruths go viral. Deliberately circulated misinformation or simple misunderstandings, like when satire is taken seriously, have an amazing power to suck us in. We love joining in rumour-mongering about Facebook fees, celebrity deaths, satanic symbols on UPC barcodes and asteroids hitting the Earth. We post our outrage at horrors like a merciless triceratops hunter, neglecting to examine the photo closely enough to realize that it’s Steven Spielberg next to a prop on the set of Jurassic Park in the 1990s.

“All these things play upon these very fundamental psychological proclivities that we have,” says Jim Davies, an associate professor at Carleton University’s Institute of Cognitive Science and author of Riveted: The Science of Why Jokes Make Us Laugh, Movies Make Us Cry, and Religion Makes Us Feel One with the Universe. “Probably the most dominant factor in hoaxes is that people have a hope or fear that it’s true. The Facebook one is a great example because it plays on your hope and your fear. It reminds you that Facebook’s privacy practices are sometimes questionable, but it also gives you the hope you can do something about it. It’s candy for the mind.”

Davies says humans evolved to mostly believe the things others tell us. “If you’re in a tribe of 150 people and somebody goes to a neighbouring valley and comes back and say it’s dangerous there, you’d best believe it. You don’t need to learn all the dangerous things in the world yourself because they might kill you. The person who was skeptical of everything they were told wouldn’t survive to have offspring,” says Davies. Studies suggest that if you give people a mixture of true and false statements, they are more likely to believe that false things are true than vice versa. People even hold onto false information when they’ve been given a correction.

“Our brains are good at navigating the world. But they aren’t truth-detection machines, they’re achieving-our-goals machines,” says Darren McKee, host of The Reality Check podcast, where a panel applies critical thinking to popularly held beliefs.

In modern societies, where we rarely have to worry about wild animals lurking over the next ridge, the risks and costs of passing along whatever others tell us are remarkably low. In fact, if we are surrounded by people who believe something untrue, we may be better off keeping our doubts to ourselves. “If all of your friends believe in something like astrology—but don’t use it that much, so it’s a benign belief—and you didn’t believe in astrology, there’d be a social tension,” says McKee. “That’s a huge cost to you, but it’s not much of a cost if you just go along with them.”

A mistruth that people want to circulate usually starts a good story. “You don’t get hoaxes about, for example, how they found a different theory of how cement forms. People don’t care enough to believe it or disbelieve it,” says Davies. Sharing stories can be a way of publically demonstrating how good hearted we are, or that we’re smart insiders who know that if you post “@[4:0]” as a comment on Facebook, it will display as a photo of Mark Zuckerberg if your account hasn’t been hacked. The fear of missing out overrides any deep consideration. “Miracle cures and get-rich schemes can be very tempting,” says Davies.

Not only does social media allow us to share misinformation more widely and more speedily than ever before, it has become a source of misinformation itself. In earlier times, we might have used an amulet to dispel evil spirits or performed a ritual to make rain. Nowadays, when we know better how to treat disease and get crops to grow, we find ourselves mystified by privacy policies and the algorithms that shape and control our newsfeeds, our friend and follower recommendations or our search suggestions. So we invent ways to understand and control what is beyond our comprehension. The Facebook Terms of Service are long and complicated; the declaration is short and simple.

Widely circulated hoaxes and mistruths often tend to tap into what we already believe or suspect. If a post or tweet triggers our deepest anxieties, we are much more willing to overlook nonsensical claims. In the case of Facebook charging a fee, “in a climate of income uncertainty, people are concerned about a business model where something is free for a while and then the company charges us for it, so it makes sense to worry,” says David Toews, a Toronto-based sociological researcher focusing on social media.

You could argue that there are costs to sharing inaccurate information—wasted time, unnecessary anxiety and suspicion of actual truth. Some people were undoubtedly disappointed when they discovered that Bill Gates wasn’t giving money to people who shared his photo on Facebook. But there can be a value in the social cohesion created by participating in, debunking and joking about these rumours and memes. “Even information that’s not truthful can create bonds between people,” says Toews. “With the Facebook disclaimer, it’s sort of like a cry for help: We’re using Facebook, but we feel trapped and don’t know what to do about it.”

Some hoaxes can circulate over and over again before people start ignoring them. Did Campbell, for example, see the Facebook declaration back when it first went viral in 2012?

“I could have,” says Campbell, “and I probably did the exact same thing.”