Sometimes you just know something but you don't know why.

You decide not to ride mass transit and that's the day the train breaks down. You take a risk on a new job and it's the career of your dreams. Or even simpler, you make a right turn when you don't know where you're going because you just know that's the way home.

These intuitions are "gut feelings" that we can't easily explain. They don't seem to be controlled by any sort of logic, but they often appear to be right.

That's why you're often told to "trust your gut." And although it seems like trusting the lottery, scientists put some stock into the impact of those vague feelings.

Digby Tantam, a clinical professor of psychotherapy at the University of Sheffield, believes that human brains are interconnected through a type of Wi-Fi that allows us to pick up on tiny signals and movements that communicate what we're thinking.

Tantam, who wrote about his research in the new book "The Interbrain," says all this subliminal information explains why laughter is infectious and also why it can be difficult to make eye contact with strangers on a busy train.

"We can know directly about other people’s emotions and what they are paying attention to," Tantam told The Telegraph. "It is based on the direct connection between our brains and other people’s and between their brain and ours. I call this the interbrain."

The connection, he says, exists in the background, yet it's always there. We take it for granted unless our minds call it to the surface and then we credit it to some sort of instinct.

A catalog of experiences

When you do something based on intuition, you're not just making a rash decision, you're calling upon your history of experiences, says Melody Wilding, a licensed therapist and professor of human behavior at Hunter College.

"Your gut is this collection of heuristic shortcuts. It’s this unconscious-conscious learned experience center that you can draw on from your years of being alive," Wilding tells Fast Company. "It holds insights that aren’t immediately available to your conscious mind right now, but they’re all things that you’ve learned and felt. In the moment, we might not be readily able to access specific information, but our gut has it at the ready."

So when you're trusting your gut, you're actually trusting this collection of subconscious experiences, she says. Sometimes you have to free your mind to listen to those insights.

"You have to create space to listen to what your gut is saying. That’s why people say they get their best ideas in the shower," says Wilding. "Start to think back and do an audit of your day. It’s intentional mind wandering."

Emotions play a part

young man and woman on date If a new person reminds you of a loved one, you're likely to become fond of them quickly because of gut instinct. (Photo: View Apart/Shutterstock)

When the brain's calls upon its stored files of memories and knowledge, it's not just this scan of history that comprises a gut instinct. Emotional heft also plays a key role.

If you experience something during a heightened emotional period — when you're afraid or excited, for example — you are more likely to remember that event in detail.

"I don't think that emotion and intuition can be separated," cognitive scientist Alexandre Linhares from the Brazilian School of Business and Public Administration tells Psychology Today.

We store experiences in our brains as a combination of facts (what happened) and emotions (how we felt when it happened). When a new event recalls a past event, it doesn't just trigger a subconscious reminder of what happened, but it also stirs up the feelings you had at the time.

For example, if you meet someone new who reminds you of a loved one, you may also feel the same warm emotions you have toward the person in your past. And your gut instinct makes you like this new person.

"Intuition," says Linhares, "can be described as 'almost immediate situation understanding' as opposed to 'immediate knowledge.' Understanding is filled with emotion. We don't obtain knowledge of love, danger, or joy; we feel them in a meaningful way."

Your gut's not always right

Just because your "gut" draws on all these past events and experiences, doesn't mean its instincts are always right.

Los Angeles-based intuitive psychiatrist Judith Orloff believes there are benefits to listening to your instincts.

“Living more intuitively demands that you’re in the moment," Orloff tells Experience Life, "and that makes for a more passionate life."

But sometimes the right brain can trigger suspicions of things or people that are unfamiliar or offer unwarranted feelings of familiarity just because a person or situation reminds you of something else.

So how do you know when to trust your gut? Orloff says it’s a matter of "combining the linear mind and intuition," and finding the right balance between gut instinct and rational thinking. When you've had a gut instinct, then turn on your rational mind and figure out the best course of action to take.

Trust your gut. But fact-check with your brain.

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.

Why do we have 'gut feelings'?
A type of brain Wi-Fi helps us hone our gut instincts, and so do our experiences.