Why Do We Remember False Information?

This phenomenon could explain why myths like “vaccines cause autism” and “fat in food is bad” stick around

Even if we used to know the truth, our brains can start repeating false information that contradicts the facts.

Our brains are wired to believe information automatically—even if it’s false—because it helps us learn efficiently. “We’re not learning inaccurate information because we’re poor learners or dumb or not working hard,” says David Rapp, PhD, a psychology and education professor at Northwestern University. “In many instances, it’s a useful skill for us to accept what people tell us, because often what people tell us is true.”

When we hear new information, those fresh facts don’t override what we already knew before. Instead, both the new and old information live together in our minds. A few factors determine which one we’ll draw on when the situation comes up. Oftentimes, we’ll quote the information you heard most recently—even if it’s wrong.

Because they’re fresher in our minds, short-term memories are easier for our brains to access than facts we heard long ago. We’d have to think back further to remember previous knowledge, so people will often ignore those facts in favor of new inaccurate information, says Rapp, who published an article on recalling inaccurate information in the journal Current Directions in Popular Science. “It’s what we’re currently thinking about or has been recently presented to us,” he says. “Prior knowledge isn’t difficult to retrieve, but it isn’t as readily available.”

We are also inclined to buy into the facts that seem more plausible. Often, this means they fit better with what we want to believe, which could explain why people quote such different facts in political debates. “Both candidates said something that was objectively true or not, but people would ignore that information and go with their hopes, wishes, biases, preferences, or gut responses because it aligns with what they hope to be true,” says Rapp. (Check out these habits of people with great memories.)

Things get even trickier when the information is a mix of true and false. For instance, it’s easy to write off things in the fictional world of Game of Thrones as total baloney, but our brains aren’t sure whether to believe the descriptions of London in Harry Potter. “Don’t look for that terminal to Hogwarts, but there might be streets mentioned that are real,” says Rapp. “That adds another complication, which is that we encode information that is a mixture of true and false.”

Our brains can keep track of what’s true or false in those situations by compartmentalizing what we hear or read as total fiction, or mentally tagging individual facts as either true or false. The problem is, sorting all that information takes time. “The mind is good at encoding, but it takes more time to compartmentalize and tag,” says Rapp. “Often, it’s not worth doing all that extra work.”

You’re especially unlikely to bother critically thinking about information when you’re reading for pleasure, like with a novel, because your brain is in the mindset of relaxing, not keeping an eye out for falsehood, says Rapp.

With all that (potentially false) information overload on social media, it’s worth putting in the extra effort to double-check the information that strikes you as fishy. Seek out reliable sources that back up what they say with data, quotes, and other evidence, says Rapp. “With the ease that we can look things up on the Internet, there’s no reason not to,” he says. Next, check out the reasons you’re suddenly forgetting things.

Sources
Medically reviewed by Renata Chalfin, MD, on April 15, 2020