Despite the inherent difficulties of detecting a lie, social scientists are beginning to better understand the psychological, emotional, and behavioral cues associated with deceit. To date three approaches have demonstrated the most promise: 1) emotional, 2) cognitive, and 3) attempted control.12
Lies fail because of the difficulty concealing or falsifying emotions around others.13 Strong feelings and many of the behaviors they produce are beyond conscious control. Not all lies involve emotions, but those that do often present special problems for the liar.
People do not choose the type of emotion they will experience, when they will feel it, or how intense it will be.14 Sometimes it is possible for a person to dampen a response; however, it is almost impossible to eliminate all evidence of feelings. This is especially true when the stakes are high, as they often are during an investigative interview.
Strong emotional responses activate the sympathetic branch of the autonomic nervous system (ANS), which, in turn, produces physiological, behavioral, and cognitive changes.15Physiologically the release of adrenaline and glucocorticoids causes increased blood pressure, heart rate, respiration, and body temperature. Thus, a person facing a threat often exhibits flushing or blanching, perspiration, and nervous energy. Strong negative emotional responses may cause behavioral withdrawal—gaze aversion, decreased body orientation, and diminished illustrators.16 These changes accompany physical (imminent assault) and psychological (loss of self) threats.
Most liars only demonstrate signs of emotion, ANS activation, and other deceit-associated cues when the stakes are high. Emotional activation is strongest when the liar has something to gain or lose. When the stakes are low, there is little chance the subject will demonstrate any of the cues being discussed.17 Most investigative interviews involve high stakes and potentially negative consequences; however, subjects with high levels of confidence in their ability to lie or those who feel they have little to gain or lose may be difficult to identify.
Emotional cues fall into two broad categories—lying about feelings and feelings about lying.18 In the first instance, people lie about what they are feeling. For example, criminals who are fearful during an interview may laugh or cover their faces to hide true feelings. In the second case, lying often generates strong feelings of guilt, anxiety, or fear that are separate from actual guilt or innocence. A person who lies during an interview but recognizes that deceit is ethically wrong may feel guilty, or the individual might experience excitement at the thought of fooling the investigator. In either case, the person must conceal those feelings.
There are three emotions closely associated with deceit: 1) fear, 2) guilt, and 3) delight.19 Fear is a reaction to the threat of physical or psychological harm brought on by high-stakes lies. The body’s response is to produce physiological changes—muscle tension and increased body temperature, respiration, and heartbeat. The level of fear depends on the person’s belief in their lying skills and the stakes involved. Some people are naturally gifted liars who have learned from experience that it is easy to fool others. They rarely are detected, and they have a high degree of confidence in their ability to deceive.20