Private investigators know how to recognize a lie. The body language and speech style of the liar may give him or her away, and it is therefore important to know what to look for when talking to a friend or any other person you may suspect of lying.
How to Detect a Lie – Human Polygraph Tests
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How to Detect a Lie – Human Polygraph Tests


Every one of us knows how to lie, naturally, without getting caught. But what happens when you are told a lie and want to know the truth? Is your girlfriend really going out to the movies with a female friend, or is she going out with her mythological ex-boyfriend? Was your best friend really overseas on your birthday, or did he just forget the date again? Did the car dealer give you a fair price, or is he trying to squeeze a few extra thousand shekels out of you?

If you don’t link every “suspect” up to a polygraph machine then you may never know the truth, unless you know how to identify Pinocchio’s lengthening nose by diagnosing key behaviors in the average liar (note: these tips are not necessarily true for lawyers or politicians).

Nice to Meet You

You don’t have to be a liar in order to identify a liar. It is very important, however, to be able to identify a potential liar. Presumably you will always be able to tell if your partner or best friend is lying, you will always be able to bet on the truthfulness of what is said by a work colleague, and above all, remember that the goal of any car dealer is to make a few extra thousand shekels at your expense.

In order to be able to tell when you’re being directly lied to, you must know the person well. If your girlfriend’s behavior is unusual, for example, this is a definite sign that she is hiding something from you under her hat, or in the new purse that she just bought.

For example, let’s say that your partner is an energetic woman who is full of life, and who tends to speak very quickly. Tonight, as she sits across from you, her arms are crossed and she is speaking slower than usual. This unusual behavior may testify to the fact that you don’t know everything. What’s more, your girlfriend is not looking you in the eye during conversation. Today, in continuing to talk with her, you noticed how her stare is boring through your pupils. You will most likely want to continue to interrogate and get the truth out of her at this point.

The behavior of a liar tends to be irregular because the liar is not calm, may feel guilty, or is straining his or her thoughts in order to develop a new lie while talking with you.

Body Language

In order to detect a lie, you must use a person’s natural behavior as the means of measurement to determine whether he or she is lying. When reading body language, there are a few gestures and behaviors that can be watched in order to identify lies (as long as they vary from a person’s normal behavior):

  • Eye movement (at high frequency).
  • Crossed arms.
  • Constant, restless movement of limbs.
  • Eyes focused towards the right (indicates use of the creative side of the brain).
  • Eyes focused on a particular object.
  • Rubbing the eyes.
  • Eyes wide open or partially closed.
  • Feet that are not planted on the floor while seated.
  • Holding an object, ankle, knee or other part of the leg while legs are crossed.
  • Touching facial features such as lips, cheeks, neck, nose, mouth, etc.
  • Playing with the hair.
  • Touching the ears.
 We have learned that a person who does not direct his glance and who cannot look in the eyes of his counterpart is lying. Surprisingly, this rule is not always a true indicator of lying. Most of us have become accustomed to looking straight into the eyes of a business partner or sports competitor, in order to penetrate their heads (and often as a part of psychological warfare). Therefore you cannot base your claim that someone is lying solely on the fact that he or she does not look into your eyes.

The aforementioned list of gestures teaches us that the body language of the liar screams, “I don’t believe the things that I’m saying!”

Verbal Clues

You can rely on body language as a partial indicator of lying, but irrational (unconscious) gestures are not a completely reliable measure every time. At this stage, you must be a detective and collect more pieces of the puzzle by using the suspect’s words.

Repeating the Question

When you are faced with a bad liar caught with his pants down, he’ll try to earn time in order to improvise or continue lying.  If the answer you receive is something like, “What did I do last night? ... Uh, I went to a movie,” or “Who did I go to a movie with? … Uh, I went with Shlomi, my cousin,” then you should keep questioning and find the truth.


Unless you are dealing with a professional actor, liars tend to stutter or hesitate out of guilt or inability to improvise.

More Information than Necessary

On the other side of the spectrum, a liar might get paranoid about the fact that he or she is lying and therefore provide you with more information than you asked for. Liars know that a good liar will provide as many details as possible in order to appear credible and innocent. Therefore, for example, if your coworker tells you that he never received your urgent message but got some text message on his cell phone that made him laugh and reminded him of the night when…, then maybe you should focus your friend’s attention and bring him back to the issue at hand. Don’t hesitate to ask questions.

Defensive?  I’m not being defensive!

Your friend (the liar) might be paranoid, but when he begins being defensive as a response to your questions, such as, for example: “Who wants to know?  Why are you asking me these questions? I have never disappointed you!” - that’s the time to continue asking questions.


If parts of the story you heard don’t match up, just ask for clarification. Don’t be aggressive, but ask for explanations.

My Word of Honor

Extreme defensiveness can definitely indicate guilt. So when you ask your girlfriend about the purple sign on her neck and she tells you about the neighbor’s cat that affectionately bit her that morning and adds a phrase like, “I would never lie to you,” “believe me,” “I’m serious,” or “I swear,” then trust me, friend, you’re dealing with a woman doing everything in her power to feel better about the fact that she’s lying.

Intuition Doesn’t Lie

Often times you don’t need clues to indicate lying; your intuition may be enough.  If you have a strange feeling about something, let the other side enjoy the benefit of the doubt until you can prove that he or she is lying. In any case, do not be afraid of asking questions and getting to the bottom of the matter on your own.

Remember - it’s relatively easy to tell if a person that you know well (or at least think you know well) is lying.  Watch for body language and gestures, while at the same time paying attention to what the person is saying and the things he or she may want you to believe.

My recommendation is that after you are certain that your friend is lying, don’t rush to scream “liar liar,” but rather go along with it and play your friend’s game. The liar won’t know that after exposing his or her method of lying, you will be able to tell the truth and expose any lie at any time.