7 ways to tell if someone is cheating on you

Ever wonder if your significant other isn't being entirely truthful?

First of all, there's a good chance you're right — it's perfectly normal to lie.

But if you're worried that someone's fibbing extends into the important stuff, like happiness or fidelity, you might have considered trying to catch them in a lie.

Unfortunately, science can't tell you if your partner is sleeping around, but it is getting better at spotting when someone — especially a significant other — is being deceptive.

Here are seven ways to tell if your partner might be keeping something important from you.

SEE ALSO: Psychologist says these 2 patterns of behavior are the most common signs that a couple is going to divorce

READ MORE: 5 things that happen to couples who've been together a long time

Ask a friend.

Other people — strangers, even — have an uncanny ability to detect when something's not right in someone else's relationship.

BYU psychologists tested out this idea by having couples draw an object together, with one participant blindfolded and the other one giving instructions on what to draw. The whole thing was videotaped. Before they started, the scientists had the couples answer a few questions about their relationship in private, including whether or not they'd ever cheated. 

Then, the researchers had a group of strangers watch the footage and guess which couples included a partner who'd ever cheated. The volunteers were surprisingly accurate.

Although preliminary, the research suggests that, simply by watching a couple doing something that requires working together, an outside observer may be able to detect infidelity or unhappiness.

"People make remarkably accurate judgments about others in a variety of situations after just a brief exposure to their behavior," the researchers wrote in the study.

Mull it over while doing something else.

People are generally bad judges of character — consciously, at least. When we are given time to process another person's actions subconsciously, however, we're far better at telling truth from deceit.

In 2013, a team of psychologists had a panel of student judges watch people give testimony and decide if they'd lied or told the truth. The students who were given time to think before they made a decision — so long as they were made to think about something other than the case they were assessing — were better at figuring out whether the person they were judging had been deceitful.

"These findings suggest that the human mind is not unfit to distinguish between truth and deception," write the researchers in the study, "but that this ability resides in previously overlooked processes."

Listen carefully to the words they use.

For a recent study, Southern Methodist University professor of psychology James W. Pennebaker looked at some data he and his colleague Diane Berry had gathered from a text analysis program. They found that some specific patterns of language were helpful at predicting when someone was avoiding the truth.

Liars, they found, tended to use fewer of the following three types of words:

• First person words, like "I," "me," or "my"
• Cognitive words, like "realize" or "think"
• Exclusive words, like "but" or "except"

But they tended to use more of the following types of words:

• Negative emotion words, like "hate," "anger," or "enemy"
• Motion verbs, like "walk" or "move"