Experts say we've been reading the classic pose all wrong.
"I say the number one myth [about body language] is crossed arms. It sends the message that you are bored, disinterested, want to be somewhere else. Many people perceive it that way," Janine Driver, president of the Body Language Institute, tells TODAY.
In fact, crossing our arms can help us solve tricky problems and feel comforted and stronger.
"Research shows that when you cross your arms you are 30 percent more likely to stay on a difficult problem," Driver says.
The reason? Crossing our arms causes both sides of our brains to be engaged on a problem. Driver says when she gives presentations and sees people in the audience with crossed arms, she knows that they are interested in what she is saying.
Joe Navarro, a former FBI agent and body language expert, says there are many reasons people cross their arms, but being closed off to others is rarely one of them.
"Most of the time we cross our arms because we are comforting ourselves. It is very comfortable," he says.
He thinks that people also cross their arms when they're trying to relieve stress, mirror others or feel stronger, among other reasons.
"As long as you look comfortable doing it there is nothing wrong with doing it," Navarro says.
Know when to unfold 'em
However, there are certain situations when people should refrain from crossing their arms.
"On a job interview and a date it will be perceived as bored or disinterested," Driver says. "On those first impression moments, uncross your arms."
But feel free to cross your arms around friends, partners, and colleagues with whom you feel comfortable.
While some believe that body language is a soft skill, the experts think that what people say with their bodies is as important as what they say with their words.
"Your body language is without a doubt valuable and can be measured. I would say [communication] is 50/50—50 percent of the words and 50 percent of the body language," Driver says.
You're not a mind reader
Research shows that body language and movements and the brain interact in interesting ways. Amy Cuddy, an associate professor at Harvard Business School, has found in her studies that assuming the "Superman pose" increases testosterone and lowers the stress hormone cortisol. Just by striking a pose people immediately feel more powerful.
While body language does impact how people perceive one another, Driver says, don't go overboard trying to interpret every move other people make. Misinterpretation can lead to mistakes.