Reading the signs of lying is not an exact science, but it may still help. After an extensive research, I have come up with a relatively exhaustive listing, even though I may have missed some!
Before you use this information to catch a liar, there are a few caveats. To ascertain a person is lying, you need to identify several signs of lying, not just one. One sign by itself won’t be enough. For instance, many of those signs express emotions, such as fear or anger, which may be present even if the person is telling the truth. So be very careful before drawing any conclusions.
Also, you are never going to see all - or even most - of the numerous clues identified here. So just use your personal judgment.
The signs of lying are organized into physical and verbal signs, with a brief explanation of each one. To facilitate the reading when referring to the liar, I have use the masculine pronoun "he" for the Physical Signs of Lying, and the feminine "she" for the Verbal Signs of Lying, but all signs can apply equally to both men and women!
Also, take a look at the videos at the bottom of this article. My article on Pathological Liar is an interesting complement to this article.
Physical Signs of Lying
1. The liar has difficulty swallowing. You can hear it in his speech, or see it on his throat.
2. He is displaying a forced smile pasted on his face.
3. The liar is making a gesture that doesn't match the speech. For instance, he is frowning while saying something pleasant.
4. Instead of being natural, his gestures appear stiff or mechanical, as if you were watching a bad actor!
5. If you are in an intimate relationship with a liar, and especially if you are used to having physical closeness, you will notice he is not touching you.
6. He doesn’t pay attention to what is going on and appears distracted.
7. You notice he is sweating profusely.
8. He is less expressive with his arms and hands and he tends to hold them close to his body.
9. Usually, when they want to make a point, people make gestures – such as nodding, or hands and arms movements – before or while the point is being made; the liar tends to delay these movements after a point is made.
10. You notice nervous habits such as whistling, ear rubbing, etc.
11. If the liar is used to pointing while speaking on a regular basis, he will never point his finger when he is lying.
12. The liar makes no direct eye contact or, aiming to fool you, he is staring at you in a very unnatural way.
Politicians and Lies:
A Perfect Match!
"If an election is an all-out fight, the candidate using the most aggressive tactics will sway the most voters and win. So you can't afford to be reasonable. Candidates who overestimate the people invariably lose. If you've got to win because you're crusading for a higher moral value, it's actually more moral to cheat."
Jeremy Sherman - Evolutionary Epistemologist
13. You notice some rapid breathing or, if the liar is trying to control himself, he stops breathing for a while.
14. He speaks at a higher pitch than normal, since vocal chords tighten under stress.
15. The liar’s voice is barely audible or he is mumbling.
16. You detect shakiness in his hands or voice, or his voice pitch is inconsistent.
17. He is sitting hunched, instead of straight.
18. He has a tendency to move away from you or towards an exit.
19. His face becomes flushed or turns white.
20. He is touching different parts of his face (nose, mouth, eyes, ears)
21. He is using an object (glass, chair, pillow) as a barrier between you and him.
22. If the liar shrugs his shoulders, it is a very light shrug, not a full one, as if he didn’t want to rock the boat.
Verbal Signs of Lying
1. She is accusing you of lying or cheating out of the blue, and therefore reflecting her own feelings. She prefers to attack before being attacked!
2. The liar answers a question by depersonalizing it. If you ask: “Did you cheat on this test?” she might answer: “No, I think cheating is the worst thing you can do.”
signs of lying
3. She answers a question with another one designed to delay her reply, such as “Could you repeat your question?”, “Who told you that?”, “Are you really asking me whether...?” “Why would you ask such a thing?”
4. If you are questioning her, she may answer all of your questions, without thinking of asking any herself, even though that may seem a natural thing to do.
5. If she claims she is not doing something, chances are she is.
6. The liar delivers a statement with a flat voice, without any natural emphasis.
7. She provides more information than necessary, feeling the need to compensate. “This is my final price. There is not a lot of room for negotiation here.”
8. She is giving you too many facts and details, showing the answer has been rehearsed.
9. If after the liar replies to your question, you don’t say anything, she adds more details that you didn’t ask for.
10. She looks relieved when the subject of a conversation is changed.
11. She makes radical assertions such as "I never..." and "I always..."
12. The liar mentions something casually and downplays its importance, even though it should be a big deal to her. "By the way, I am going away on a business trip next week. How was your day?"
13. She is not answering directly to a direct question. Politicians excel at this sort of things!
14. When you make a serious accusation, she is not as offended as she should be, because she is more worried about how she will respond than with the accusation itself.
15. The liar overreacts in expressing an opinion, therefore covering up her true feelings.
16. While speaking casually, the liar may refrain using a contracted form. For instance, instead of saying: "It wasn’t me," she states: "It was not me," which gives her an opportunity to insist on "not."
17. Preferring to take as little responsibility as possible, the liar doesn’t use personal words such as I, me, my, we, us, our.
18. When being asked a question, she repeats the question almost literally, turning it into a statement "Did you read my diary last night?" "No, I did not read your diary last night!"
19. Many liars tend to start their sentences with a statement like "to be perfectly honest" or "quite frankly."
20. The liar takes more time than is necessary to give a simple answer and, if the answer requires an explanation, hers takes even more time to provide it.
21. You can almost always trust the Freudian slip, such as "I spent the evening with Alan... I mean, Alison..."
22. Using humor and sarcasm to answer a serious question is often a strategy to hide the truth.
23. If you have caught the person lying previously, it may happen again.
As I mentioned at the beginning of this article, the above signs of lying are not black and white, but a combination of several of them may help you uncover the liar. Be careful and good luck!