Now you know how to spot a double-dealer.

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How to Tell If Someone is Lying

If you were accused of murder, you'd be under enormous pressure to lie if you were guilty. The stakes are high, and that kind of pressure can lead to physical cues that will give you away. A person serving a life sentence for murder, however, would feel virtually no pressure when lying about the murder because he or she is already in prison -- there won't be any further consequences for lying. In this case, it's the verbal details, and not body language, that will likely be his or her undoing.

Here's how you separate the liars from the truth-tellers:

  • Establish the baseline. Liars may look you directly in the eye, and truth-tellers may be fidgety and seem evasive, so don't look for one trait or the other. First, establish the person's behaviors, mood and mannerisms for that particular point in time, before the questioning begins. Is the person relaxed or nervous? Angry? Distracted? Notice how much eye contact and blinking is going on. Does the person touch his or her hands or face when speaking?
  • Look for deviations from the baseline. The key to detecting lies is to look for deviations from an established pattern of behavior. If a person normally makes no eye contact and blinks like crazy but stares straight through you when answering a particular question, there's your red flag. Look for slight pauses before answers -- this is the amount of time it takes their brain to fabricate data. The liar may act offended at being questioned at all but suddenly quite affable when the lie is being told, or vice versa.
  • Listen. Sometimes, there will be no body language or visual cues that accompany a lie. You have to rely on the verbal information you receive. Do the facts add up? Is the person telling you lots of information that is unrelated to the question? If someone provides lots of details, ask more questions. These details might be their undoing. After getting into the nitty-gritty of the details, bounce the questioning back to the overall time frame or arc of the story. Now, refocus on a small detail. Does the story still fit together? Is the person having to create new details to explain why other details aren't fitting well into the arc of the story?
  • Pause. For most people, lying -- and the circumstance that necessitates the telling of a lie -- is stressful. If you're questioning somebody, pause between one of his or her answers and your next question. Pauses are slightly uncomfortable for most people in a social interaction, and much more so for a person who is trying to pass off a lie. This pause may seem like a torturous eternity to a liar. Look for fidgeting, defensive posturing and microexpressions.
  • Change the subject. The best news a liar can receive is that the lie is over. When the person believes the topic of conversation has changed, he or she may be visibly relieved. A nervous person may loosen up; an agitated person may smile. This tactic also allows you to continue studying for deviations from the baseline or to look for a return to the baseline.

In the next section, we'll take a look at some famous lies.

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