First off -- thanks to LifeTrainingOnline.com and Blifaloo.com for this information. :)
Become a Human Lie-Detector
Some Quick Facts:- Human communication is an extremely complex exchange. While speaking, a person produces around 75-100 verbal and nonverbal cues per second.
- The average person can only detect lies with about 50% accuracy.
The following techniques to telling if someone is lying are often used by police, and security experts. This knowledge is also useful for managers, employers, and for anyone to use in everyday situations where telling the truth from a lie can help prevent you from being a victim of fraud/scams and other deceptions.
Verbal Indication of Lying- The person may take longer to start answering.
- The person may answer too quickly or before the question is completed.
- They ask for the question to be repeated or they may repeat it themselves.
- A slip of the tongue. (Ex. "What could have I done?" when they mean "What could I have done?")
- Complaining
- Long silences
- A statement with a contraction is more likely to be truthful: "I didn't do it," instead of "I did not do it."
- Liars sometimes avoid "lying" by not making direct statements. They imply answers instead of denying something directly.
- Words may be garbled and spoken softly, and syntax and grammar may be off. In other words, his sentences will likely be muddled rather than emphasized.
- If you believe someone is lying, then change subject of a conversation quickly, a liar follows along willingly and becomes more relaxed. The guilty wants the subject changed; an innocent person may be confused by the sudden change in topics and will want to back to the previous subject.
Macro-Patterns of Liars
General:- Anxiety
- Resistance
- Hostility
- Anger towards you
Posture:- Posture changes caused by topic changes.
- Not facing you.
- Distancing or leaning away from you.
Gestures and Movements:- The person who is lying to you may avoid eye contact most of the time.
- Touching their face, hands, neck, mouth.
- Physical expression of the face will be limited and stiff.
- Hands, legs, objects put in front of body to form a barrier (folding arms, crossing legs, etc.).
- Lip licking and hard swallowing.
- Wringing hands.
- Hiding the eyes.
- Gestures/expressions don't match the verbal statement, such as frowning when saying "I love you."
Interactions and Reactions:- A guilty person gets defensive. An innocent person will often go on the offensive.
- A liar is uncomfortable facing his questioner/accuser and may turn his head or body away.
- A liar might unconsciously place objects (book, coffee cup, etc.) between themselves and you.
Micro-Patterns of Liars
General Expressions:- Averting the eyes.
- Focusing the eyes - some will try to stare down to show control. (A truthful person stares only half the time on average).
- Face flushing (indicates anger or shame).
Facial-Expressions and IndicationsA liar may force a smile rather than smiling naturally.
Eye-Accessing CuesBy the direction of where the person's eyes are looking, you can determine whether they are using vision, sound or kinesthetic (feeling) to trigger their thinking.

This represents a person who is facing you.
If a person looks
up and to the
left, they are accessing a visual memory (remembering).
Up and to the
right: They're visually constructing (imagining) something.
Right: Remembering a sound.
Left: Creating a sound.
Down and to the
right: The person is accessing a bodily feeling or emotion.
Down and to the
left: Accessing inner dialog (talking to themselves).
Obviously, just because someone exhibits one or more of these signs does not make them a liar. The above behaviors should be compared to a person's normal behavior whenever possible.
I hope this was interesting. I might edit this later on with more information.