1. Precautions
2. Hazards of Incorrect Lie Detection
3. Odds against spotting lies in the courtroom
4. Motives For Lying
5. Reasons we do not catch liars
6. THE BETRAYAL OF CONCEALED INFORMATION, ORGANIZED BY BEHAVIORAL CLUES
7. THE BETRAYAL OF CONCEALED INFORMATION, ORGANIZED BY TYPE OF INFORMATION
8. CLUES THAT AN EXPRESSION IS FALSE
9. LYING CHECK LIST

The accuracy of any technique of lie detection depends upon the nature of the lie, the liar and the lie catcher.

PRECAUTIONS

1. Try to make explicit the basis of any hunches and intuitions about whether or not someone is lying. By becoming more aware of how you interpret behavioral clues to deceit, you will learn to spot your mistakes and recognize when you don't have much chance to make a correct judgment.
2. Remember that there are two dangers in detecting deceit: disbelieving-the-truth (judging a truthful person to be lying) and Believing-a-lie (Judging a liar to be truthful). There is no way to completely avoid both mistakes. Consider the consequences of risking either mistake.
3. The absence of a sign of deceit is not evidence of truth; some people don't leak. The presence of of a sign of deceit is not always evidence of lying; some people appear ill-at-ease or guilty when they are truthful.
4. Search your mind for any preconceptions you may have about the suspect. Consider whether your preconceptions will bias your chance of making a correct judgment. Don't try to judge whether or not someone is lying if you feel overcome by jealousy or in an emotional wildfire. Avoid the temptation to suspect lying because it explains otherwise inexplicable events.
5. Always consider the possibility that a sign of emotion is not a clue to deceit but a clue to how a truthful person feels about being suspected of lying. Discount the sign of an emotion as a clue to deceit if a truthful suspect might feel that emotion because of: The suspects personality; the nature of your past relationship with the suspect; or the suspects expectations.
6. Bear in mind that many clues to deceit are signs of more than one emotion, and that those that are must be discounted of one of those emotions could be felt of the suspect is truthful while another could be felt if the suspect is lying.
7. Consider whether or not the suspect knows he is under suspicion and what the gains or losses in detecting deceit would be either way.
8. If you have knowledge that the suspect would also have only if he is lying, and you can afford to interrogate the suspect, construct a Guilty Knowledge Test.
9. Never reach a final conclusion about whether a suspect is lying or not based solely on your interpretation of behavioral clues to deceit. Behavioral clues, like the polygraph, can never provide absolute evidence.
10. Use the checklist provided in the appendix (table 4) to evaluate the lie, the liar, and you, the lie catcher, to estimate the likelihood of making errors or correctly judging truthfulness.

Jerry from John Updike's novel "Marry Me" does not suspect Ruth is deceiving him because his suspecting such behavior would also cause him to suspect his own failure as a husband.

Stalin: "[A] diplomat's words must have no relation to actions -- otherwise, what kind of diplomacy is it?...Good words are concealment of bad deeds. Sincere diplomacy is no more possible than dry water or iron wood."

Odds against spotting lies in the courtroom:
1. The guilty suspect is given many chances to prepare and rehearse her replies before her truthfulness is evaluated by a jury or a judge, thus increasing her confidence and decreasing her fear of being detected.
2. The direct examination and cross examination takes place months, if not years, after the incident, thereby blunting emotions associated with the criminal event.
3. Because of the long time delay before the beginning of the trial, the suspect will have repeated her false account so often that she may start to believe her own false story; when that happens, she is in a sense, not lying when she testifies.
4. When challenged in cross-examination, the defendant typically has been prepared if not rehearsed by her own attorney, and the questions asked often allow a simple yes or no reply.
5. The signs of fear of being disbelieved can be misinterpreted as a guilty person's fear of being caught.

Motives for Lying
1. To avoid being punished
2. To obtain a reward not otherwise readily obtainable
3. To Protect another person from being punished
4. To Protect oneself from the threat of physical harm.
5. To win the admiration of others.
6. To get out of an awkward social situation.
7. To avoid embarrassment.
8. To maintain privacy, without giving notification of the intention to maintain some information as private.
9. To exercise power over others, by controlling the information the target has.

Reasons we do not catch liars
1. Our evolutionary history did not prepare us.
2. Our parents did not teach us how to catch their lies.
3. We prefer to trust rather than be suspicious.
4. We often want to be misled. Most of us operate on the unwritten principle of postponing having to confront anything that is very unpleasant, and we may do so by collusively overlooking a liar's mistakes.
5. We are brought up to be polite in our interactions, not to steal information that is not given to us.

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THE BETRAYAL OF CONCEALED INFORMATION, ORGANIZED BY BEHAVIORAL CLUES
Clue to Deceit	Information Revealed
Slips of the tongue	May be emotion-specific; may leak information unrelated to emotion
Tirades	May be emotion-specific; may leak information unrelated to emotion
Indirect speech	Verbal line not prepared; or, negative emotions, most likely fear
Pauses and speech errors	Verbal line not prepared; or, negative emotions, most likely fear
Voice pitch raised	Negative emotion, probably anger and/or fear
Voice pitch lowered	Negative emotion, probably sadness
Louder, faster speech	Probably anger, fear, and/or excitement
Slower, softer speech	Probably sadness and/or boredom
Emblems	May be emotion-specific; may leak information unrelated to emotion
Illustrators decrease	Boredom; line not prepared; or, weighing each word
Manipulators increase	Negative emotion
Fast or shallow breathing	Emotion, not specific
Sweating	Emotion, not specific
Frequent swallowing	Emotion, not specific
Micro expressions	Any of the specific emotions
Squelched expressions	Specific emotion; or, may only show that some emotion was interrupted but not which one
Reliable facial muscles	Fear or sadness
Increased 'blinking	Emotion, not specific
Pupil dilation	Emotion, not specific
Tears	Sadness, distress, uncontrolled laughter
Facial reddening	Embarrassment, shame, or anger; maybe guilt
Facial blanching	Fear or anger

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THE BETRAYAL OF CONCEALED INFORMATION, ORGANIZED BY TYPE OF INFORMATION
Type of Information	Behavioral Clues
Verbal line not prepared	Indirect speech, Pauses, Speech errors, Illustrators decrease
Non Emotional information (e.g., facts, plans, fantasies)	Slip of the tongue, Tirade, Emblem*
Emotions (e.g., happiness, surprise, distress)	Slip of the tongue, Tirade, Micro expression, Squelched expression
Fear	Indirect speech, Pauses, Speech errors, Voice pitch raised, Louder and faster speech, Reliable facial muscles, Facial blanching
Anger	Voice pitch raised, Louder and faster speech, Facial reddening, Facial blanching
Sadness (Maybe guilt & shame)	Voice pitch lowered, Slower and softer speech, Reliable facial muscles, Tears, Gaze down, Blushing
Embarrassment	Blushing, Gaze down or away
Excitement	Increased illustrators, Voice pitch raised, Louder and faster speech
Boredom	Decreased illustrators, Slower and softer speech
Negative emotion	Indirect speech, Pauses, Speech errors, Voice pitch raised, Voice pitch lowered, Manipulators increased
The arousal of any emotion	Changed breathing, Sweating, Swallowing, Squelched expression, Increased blinking, Pupil dilation

*Emblems cannot convey as many different messages as slips of the tongue or tirades. Among Americans there are about sixty messages for which there are emblems. [Top]

CLUES THAT AN EXPRESSION IS FALSE
False Emotion	Behavioral Clue
Fear	Absence of reliable forehead expression
Sadness	Absence of reliable forehead expression
Happiness	Eye muscles not involved
Enthusiasm or involvement with what is being said	Illustrators fail to increase, or timing of illustrators is incorrect
Negative emotions	Absence of: sweating, changed respiration, or increased manipulators
Any emotion	Asymmetrical expression, Onset too abrupt, Offset too abrupt or jagged, Location in speech incorrect

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LYING CHECK LIST
Questions about the lie	Hard to detect	Easy to detect
1. CAN THE LIAR ANTICIPATE EXACTLY WHEN HE OR SHE HAS TO LIE?	YES: line prepared & rehearsed	NO: line not prepared
2. DOES THE LIE INVOLVE CONCEALMENT ONLY, WITHOUT ANY NEED TO FALSIFY?	YES	NO
3. DOES THE LIE INVOLVE EMOTIONS FELT AT THE MOMENT?	NO	YES: especially difficult if A. negative emotions such as anger, fear, or distress must be concealed or falsified. B. liar must appear emotionless and cannot use another emotion to mask felt emotions that have to be concealed
4. WOULD THERE BE AMNESTY IF LIAR CONFESSES TO LYING?	NO: enhances liar's motive to succeed	YES: chance to induce confession
5. ARE THE STAKES IN TERMS OF EITHER REWARDS OR PUNISHMENTS VERY HIGH?	Difficult to predict: while high stakes may increase detection apprehension, it should also motivate the liar to try hard
6. ARE THERE SEVERE PUNISHMENTS FOR BEING CAUGHT LYING?	NO: low detection apprehension; but may produce carelessness	YES: enhances detection apprehension, but may also fear being disbelieved, producing false positive errors.
7. ARE THERE NO SEVERE PUNISHMENTS FOR THE VERY ACT OF HAVING LIED, APART FROM THE LOSSES INCURRED FROM THE DECEIT FAILING?	NO	YES: enhances detection apprehension; person may be dissuaded from embarking on lie if she or he knows that punishment for attempting to lie will be worse than the loss incurred by not lying
8. DOES THE TARGET SUFFER NO LOSS. OR EVEN BENEFIT, FROM THE LIE? IS THE LIE ALTRUISTIC NOT BENEFITING THE LIAR?	YES: enhances detection apprehension, but may also fear being disbelieved, producing false positive errors	NO: increases deception guilt
9. IS IT A SITUATION YES IN WHICH THE TARGET IS LIKELY TO TRUST THE LIAR, NOT SUSPECTING THAT HE OR SHE MAY BE MISLED?	YES	NO
10. HAS LIAR SUCCESSFULLY DECEIVED THE TARGET BEFORE?	YES: decreases detection apprehension; and if target would be ashamed or otherwise suffer by having to acknowledge having been fooled, she or he may become a willing victim.	NO
11. DO LIAR AND TARGET SHARE VALUES?	NO: decreases deception guilt	YES: increased deception guilt
12. IS THE LIE AUTHORIZED?	NO: decreased deception guilt	YES: increased deception guilt
13. IS THE TARGET ANONYMOUS?	YES: decreases deception guilt	NO
14. ARE TARGET AND LIAR PERSONALLY ACQUAINTED?	NO	YES: lie catcher will be more able to avoid errors due to individual differences
15. MUST LIE CATCHER CONCEAL HIS SUSPICIONS FROM THE LIAR?	YES: lie catcher may become enmeshed in his own need to conceal and fail to be as alert to liar's behavior	NO
16. DOES LIE CATCHER HAVE INFORMATION THAT ONLY A GUILTY NOT AN INNOCENT PERSON WOULD ALSO HAVE?	NO	YES: Can try to use the guilty knowledge test if the suspect can be interrogated
17. IS THERE AN AUDIENCE WHO KNOWS OR SUSPECTS THAT THE TARGET IS BEING DECEIVED?	NO	YES: may enhance duping delight, detection apprehension, or deception guilt
18. DO LIAR AND LIE CATCHER COME FROM SIMILAR LANGUAGE, NATIONAL, CULTURAL BACKGROUNDS?	NO: more errors in judging clues to deceit	YES: better able to interpret clues to deceit
Questions about the liar	Hard to detect	Easy to detect
19. IS THE LIAR PRACTICED IN LYING?	YES: especially, if practiced in this type of lie	NO
20. IS THE LIAR INVENTIVE AND CLEVER IN FABRICATING?	YES	NO
21. DOES THE LIAR HAVE A GOOD MEMORY?	YES	NO
22. IS THE LIAR A SMOOTH TALKER, WITH A CONVINCING MANNER?	YES	NO
23. DOES THE LIAR USE THE RELIABLE FACIAL MUSCLES AS CONVERSATIONAL EMPHASIZERS?	YES: better able to conceal or falsify facial expressions	NO
24. IS THE LIAR SKILLED AS AN ACTOR, ABLE TO USE THE THE STANISLAVSKI METHOD?	YES	NO
25. IS THE LIAR LIKELY TO CONVINCE HIMSELF OF HIS LIE BELIEVING THAT WHAT HE SAYS IS TRUE?	YES	NO
26. IS SHE OR HE A "NATURAL LIAR" OR PSYCHOPATH?	YES	NO
27. DOES LIAR'S PERSONALITY MAKE LIAR VULNERABLE EITHER TO FEAR, GUILT, OR DUPING DELIGHT?	YES	NO
28. IS LIAR ASHAMED OF WHAT LIAR IS CONCEALING?	Difficult to predict: while shame works to prevent confession, leakage of that shame may betray the lie
29. MIGHT SUSPECTED LIAR FEEL FEAR, GUILT, SHAME, OR DUPING DELIGHT EVEN IF SUSPECT IS INNOCENT AND NOT LYING, OR LYING ABOUT SOMETHING ELSE?	YES: Can't interpret emotion clues	NO: signs of these emotions are clues to deceit
--. IS LIAR AWARE THAT HE OR SHE IS UNDER SUSPICION	YES: Detection apprehension will be lower	YES: guard on expressions will be lower.
Questions about the Lie Catcher	Hard to detect	Easy to detect
30. DOES THE LIE CATCHER HAVE A REPUTATION OF BEING TOUGH TO MISLEAD?	NO: especially if liar has in the past been successful in fooling the lie catcher	increases detection apprehension; may also increase duping delight
31. DOES THE LIE CATCHER HAVE A REPUTATION FOR BEING DISTRUSTFUL	Difficult to predict: such a reputation might decrease deception guilt, it may also increase detection apprehension
32. DOES THE LIE CATCHER HAVE A REPUTATION OF BEING FAIR-MINDED?	NO: liar less likely to feel guilty about deceiving the lie catcher	YES: increases detection
33. IS THE LIE CATCHER A DENIER, WHO AVOIDS PROBLEMS AND TENDS TO ALWAYS THINK THE BEST OF PEOPLE?	YES: probably will overlook clues to deceit, vulnerable to false negative errors.	NO
34. IS LIE CATCHER UNUSUALLY ABLE TO ACCURATELY INTERPRET EXPRESSIVE BEHAVIOR	NO	YES
35. DOES THE LIE CATCHER HAVE PRECONCEPTIONS WHICH BIAS THE LIE CATCHER AGAINST THE LIAR?	NO	YES: although lie catcher will be alert to clues to deceit, he will be liable to false positive errors.
36. DOES THE LIE CATCHER OBTAIN ANY BENEFITS FROM NOT DETECTING THE LIE?	YES: lie catcher will	NO: ignore, deliberately or unwittingly, clues to deceit
37. IS LIE CATCHER UNABLE TO TOLERATE UNCERTAINTY ABOUT WHETHER HE IS BEING DECEIVED?	Difficult to predict: may cause either false positive or false negative errors
38. IS LIE CATCHER SEIZED BY AN EMOTIONAL WILDFIRE?	NO	YES: liars will be caught, but innocents will be judged to be lying (false positive error)