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Deceiving Others

Can you see if someone is telling a lie or telling the truth?

Trustworthiness and honesty are two central factors in the persuasive process.

In a life where people are often deceived to the point of unspeakable losses, it is understandable that the area of influence that has captured the attention of managers, negotiators, researchers and the general public in recent years is the act of lying.

Knapp and Hall (2005), discuss detection of lies in the following categories: The three major questions in this area are:

(1) What behaviors distinguish liars from truth-tellers?

(2) What thinking and emotional processes are at work during acts of lying?

(3) How accurate are we at detecting lies?

1. The Difference between liars and truth tellers

People have, until recently mainly focused on non-verbal signals (body language) in the detection of liars. They thought that liars could manipulate their speech and words easily, but could not control their ‘body language’ to the same extent.

Even Freud observed, many years ago: “He that has eyes to see and ears to hear may convince himself that no mortal can keep a secret. If his lips are silent, he chatters with his fingertips; betrayal oozes out of him at every pore”.

Some researchers believed it was more likely that clues to deception would be found in the feet and legs area first, the hands next, and the face last.

They thought that the face is more likely to be controlled by the liar, yet later they seem to agree that the face can reveal deception in many ways, for example, smiles made when people were trying to cover up and traces small muscular actions around the facial area.

Types of Lies

Attempts to develop a list of behaviors that distinguish liars from truth-tellers always have faced the problem that there are many types of lies such as prepared lies, short lying answers or extended ones, reactions when interrogated, and many reasons for lying such as protecting oneself or someone else, getting out of an obligation or promise, avoiding conflict.

In addition, no behaviour occurring during a lie is completely unique to lying (i.e. only happens during a lie). Someone put it this way: “There is no sign specific to deceit itself – no gesture, facial expression, or muscle twitch that in and of itself means that a person is lying.”

The ‘sure’ Signs

What we do know is that; when compared with truth-tellers, liars often smile less; have more hesitations during speech, more speech errors, and higher pitch.

Verbally, the response length is often shorter; more “allness” terms (all, every, always, none, nobody) are used; and there are fewer detailed reactions. More blinking, pupil dilation, and more acts of nervous self-touching are also commonly reported.

One behaviour that many people expect of liars is a sharp decrease in eye gaze (shifting eyes). Although this behaviour may occur with some liars in some situations, it has become so stereotypically associated with lying in some cultures that liars often consciously seek to control it. Therefore, the ability to display a normal pattern of gaze (fixed eyes) could signal that something is wrong just as too little eye contact does!

The Thinking and Feeling of Liars

If it is difficult to find behaviors that always characterize liars, it is easier to identify behaviors associated with key underlying thinking and emotional processes that occur during lies. In other words, what are liars thinking and feeling when they express a lie? Normal people who know they are lying and who know there will be important consequences if they are caught, are likely to experience tension in the way they feel and think. Their body language will possibly also show signs of pupil dilation, blinking, speech errors and higher voice pitch. Their words and voice might change noticeably, e.g. “Why do you have to always question me?” and there may be extremes in language usage.

Obviously, people experience aroused feelings for reasons other than lying, but aroused truth-tellers and aroused liars do not seem to behave the same. Liars commonly experience speech hesitations, shorter responses, pupil dilation, speech errors, conflicting verbal and nonverbal behaviour (they say ‘yes’ while their heads nod ‘no’), and lack of detailed explanations.

Two other visible reactions of liars are their attempt to control their emotions (while lying). They over-control their feelings to the point where they become ‘poker-faced’ or are rehearsing a poem. In 1991, military prisoners of war who were forced to make anti-U.S. statements on Iraqi television were reportedly trained prior to their capture to speak and behave in a wooden and mechanical manner to indicate they were lying. They do, though, often experience anxiety associated by fidgeting, stammering, and the like.

Other emotional states are also relevant to deception. Anger is very common and is reflected in liars’ tendencies to be reactive and defensive in their responses. Some liars feel enough guilt so that looking away for long periods or covering their eyes with their hands is not uncommon.

Some may even experience delight (pleasure in deceiving others) and may smile at the wrong time or exhibit feelings of triumph and contempt!

The more important the lie is to the deceiver, the easier (paradoxically) it is for others to detect it through nonverbal (the less controllable) channels.

Given what we have said about the nature of liar behavior, it should be no surprise that strangers, without the aid of any mechanical equipment such as a polygraph, are only about 50 to 60 percent accurate in identifying liars.

Overly ambitious lie detectors may find smiles that are not there and sometimes even elicit lies from people who might not have otherwise intended to lie. It is hoped that these and other issues related to truth and deception will continue to be hotly debated. Only when we stop searching for answers to questions of truth and deception will we be morally bankrupt.


Polygraphs usually have a higher rate of detecting liars (usually reported to be between eighty and ninety percent), but they can be beaten. People whose lies were detected at about eighty percent then received either feedback or relaxation training. After they were better able to control their bodily responses, the accuracy of the polygraphs was reduced to about twenty percent!

Lies in Marriage and Friendship

What about people in close relationships? Shouldn’t they be more accurate at detecting lies? Since trust is the fundamental reason couples have close relationships, either party is likely to get away with lying quite easily at first. But once suspicion is aroused, those who know a person’s behaviour best are likely to be the best detectors. However; it is not uncommon for people to detect deception. They may not want to confront the lie, or they may be afraid of destroying intimancy if they show distrust by their close ‘checking’. Effective detectors have been shown to have fewer friends and less satisfying relationships. People can be trained to be better detectors, but without training, people often use cues for detecting deception that are unrelated to actual liar and truth-teller behaviour.

Summarised and adapted from: Knapp, M L and Hall, J A; 2005; Nonverbal Communication in Human Interaction; Holt, Rinehart and Winston, Inc, N.Y.


Manie Spoelstra

Professor Manie Spoelstra has published numerous articles and books on negotiation, general management, strategy formulation and participative management, and has often consulted to many leading companies on these topics. By regularly attending advanced seminars at institutions such as the Harvard Center for Management Research in Boston and the Stanford Business… MORE >

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