Conventional wisdom suggests that if there is a liar in your midst, the person's body language will reveal it.

But here's the thing: every individual liar has his or own giveaways--some people frequently touch their face, while others are more prone to tapping their fingers. So, relying on body language to tell you when someone is lying isn't likely to get you the correct answer, says a recent BBC article

According to one study metioned by author David Robson, only 50 out of 2,000 participants who attempted to guess whether or not someone was lying managed to guess correctly at least 80 percent of the time. In fact, attempting to rely on the most commonly used identifier of a tall tale--physical expressions of nervousness--may actually make you less likely to pick up on the more concrete signs that someone is lying, says psychology professor and researcher Thomas Ormerod from the University of Sussex.

"It doesn’t give a chance to listen to what they say, and think about credibility, observe behaviour change--they are the critical aspects of deception detection," Ormerod tells BBC.

Instead of trying to pretend you're a body language expert for the FBI, look for these more straightforward cues to figure out which of your employees didn't actually have the flu when they took a sick day:

Casually ask them to verify small details.

When trying to figure out if someone's lying while they are talking to you, keep things light, say Ormerod and colleage Coral Dando. Don't make it obvious that you don't believe what the person is saying. But, do find a way to get the liar to expand on his or her tale--this will make the person more likely to trip up. "If a passenger says they are at the University of Oxford, ask them to tell you about their journey to work," writes Robson.

Ask them unexpected questions.

Another way to increase a person's "cognitive load"--that is, to force a person to think through more details before he or she has to answer the question--is to ask them questions they wouldn't expect to pop up in the conversation. For example, ask the person to "report an event backwards in time," writes Robson. 

See if the person becomes more timid throughout the conversation.

Keep an eye out for when the person becomes less confident the longer the conversation goes on--but don't rely on physical cues to do so. Instead, rely on verbal cues. Does the person become more evasive during the conversation? Is he or she giving more erratic responses? Look for changes from the person's normal speaking style.

While there is no one tactic to always spot a liar correctly, recent studies indicate that Ormerod and Dando are on to something with their emphasis on verbal communication. In an experiment conducted by Timothy Levine at the University of Alabama in Birmingham, federal agents who questioned students about whether or not they cheated on a simulated game were able to correctly identify the liars more than 90 percent of the time when they relied on verbal cues.