Why you believe everything your Facebook friends tell you

This funny Facebook post has been making the rounds:

“Facebook will begin stealing your undies at midnight if you don’t copy & paste this message in the next hour,” it begins. “This is real. I got the message first hand from Elvis who was having lunch with Bigfoot, while riding the Loch Ness monster.

“If you don’t repost this status, Facebook code has been set up to automatically set your computer on fire & harm an innocent bunny in the forest!” it continues.

“Facebook users will believe anything their friends copy & paste into their status,” the post concludes.

Funny – and true.

No, Facebook hasn’t changed its privacy settings. No, what you post doesn’t belong to Facebook now.

Think about all the things people have believed on social media without proof. Facebook has changed your privacy settings and owns what you’ve posted! Facebook will charge fees!

Eighty-four members of Congress arrested for drunken driving in one year! Girl kicked out of KFC because her face scared customers!

Sometimes, it even goes beyond believing. People donated money to the family who claimed their daughter was kicked out of KFC because of her disfigured face. (An independent investigation later contradicted the family’s story.) The Bey Hive bullied fashion designer Rachel Roy on social media because they were sure she was the “Becky with the good hair,” allegedly having an affair with Beyonce’s husband, Jay Z. Then, of course some confused fans mistakenly turned on TV chef Rachael Ray, too.

Even super smart people trust what their friends say on Facebook.

A psychology graduate student at Dartmouth recently came to work all excited about a new breed of fruit he’d read about on Facebook. On the outside, it looked like a banana, but cut into it, and it’s a juicy green kiwi.

A professor, Luke Chang, told him there was no such thing as a crossbreed between a banana and a kiwi. If there were, wouldn’t it be on supermarket shelves?

Chang showed the student reports debunking the “baniwi” hoax.

“He said, ‘I can’t believe I fell for that!’ But everyone else in the lab said, ‘Don’t worry, we fell for it, too,’ ” said Chang, assistant professor of psychological and brain studies at Dartmouth.

Mauricio Delgado, a professor of psychology at Rutgers University, says it’s simply part of our nature as human beings to trust what other human beings say.

“Our brains are wired that way,” Delgado said.

Here are five reasons why our psyches are designed to trust our friends on Facebook and in real life, even when it doesn’t necessarily make sense to do so.

1. Not trusting takes too many brain cells.

Imagine if you woke up every morning questioning and doubting everything and everyone in your life: whether you can trust your spouse, for example, or if the guy who drives the bus you take to work has had too much to drink, or if the lady making your coffee has washed her hands.

You’d be exhausted.

“That’s not a very efficient way to navigate your life,” said Emily Falk, a psychologist at the University of Pennsylvania. “We just don’t have the bandwidth to do that.”

2. If you don’t trust other people, a bear might eat you.

While we might not always recognize it in our modern world, there is indeed safety in numbers or, as Frank puts it, a “survival advantage” to being in a group.

At a recent conference in the Canadian Rockies, economist Robert Frank and other attendees were advised not to go out on hikes alone because a bear might pounce. But go in a group of five or six people, and the bear would probably turn around and walk away.

Falk, who’s also director of the Communication Neuroscience Lab at the Annenberg School of Communication, has another example: If you’re part of a group wandering in the forest, another member might warn you about a contaminated and potentially deadly water source that you wouldn’t have known about on your own.

“People who succeed almost always succeed as trusted members of teams,” said Frank, a professor of economics at the Johnson Graduate School of Management at Cornell University. “If you’re a lone wolf, that’s not a good path to success in this world.”

3. Being a skeptic might get you kicked off the team.

If you argue with your friends, even if you’re right, you could end up getting kicked off that team – and then you’re alone and dinner for that bear.

“There are skeptics who question every little thing. We all know those types of people, and they can be really caustic and annoying,” Chang said. “The skeptic might be right, but at what cost?”

4. Trusting someone gives your brain a warm glow.

Even Chang, who rightly questioned the “baniwi,” sometimes believes things he shouldn’t.

When he got a small burn in his kitchen, his mother told him to put egg whites on it.

You might think the guy with the Ph.D. and the professorship at an Ivy League school would consult a first aid manual, but no – he just slathered on those egg whites.

“Of course I did it, because I’ll do anything my mom tells me,” Chang said.

But she was wrong (sorry, Mrs. Chang). Egg whites can contain salmonella, and you wouldn’t want that on a burn.

Chang didn’t question his mom because over the course of his life, Chang’s brain has learned that his mother loves him and wants what’s best for him, and she’s had a good track record of being right.

Studies show that we like to trust other people. Scientists have asked study subjects to play games with a stranger and with a friend. The game is rigged so the subject is equally as successful with both partners, but on an MRI, the reward centers of the brain light up brighter when the subject has success with the friend.

“We feel a particularly warm glow when we play with a friend,” Delgado said.

And we have a hard time saying goodbye to that glow.

Even when psychologists set the game so the trusted friend steals all the money, the study subject keeps investing with him.

“If someone betrays you, your system of thinking should adapt pretty quickly, but it doesn’t,” said Delgado, the Rutgers psychologist.

5. We love an ‘attaboy’ or ‘attagirl’ even more than money or food.

Facebook friends love to tell us how wonderful we are. They admire our photos and never forget our birthdays. That’s powerful stuff.

In some studies, participants responded just as well – or even better – to comments like “you’re great at this!” as they did to rewards like food or money.

“There’s a real importance to being social,” Delgado said. “It’s always nice to have friends.”