The Truth About Lying: What Investigators Need to Know

By Brian D. Fitch, Ph.D. 
Stock image of a man being interviewed by a woman and another man while sitting at a table in an office.

Often investigators express confidence in their ability to spot a lie. The belief that it is relatively easy to catch a liar has been fueled by literature that often lists so-called secrets of nonverbal communication. One book on body language claims “the common gestures we use and observe everyday…may already be revealing our deepest feelings and hidden thoughts to total strangers.”1 Similar advice is found in popular books on interviewing, including the suggestion that “a lying suspect’s eyes will appear foggy, puzzled, probing, pleading (as though seeking pity), evasive or shifty, cold, hard, strained, or sneaky.”2

﻿Despite the popular appeal of body language, no study has uncovered any single behavior that accurately reflects whether a person is lying. It seems that for every study that finds an increase in a particular behavior—eye contact, illustrators, or gestures—another reports a decrease in the same activity. This is due at least in part to the fact that people’s responses vary based on the kind of lie, time to prepare, interviewer’s strategy, and liar’s level of confidence.3 Any time an investigator misjudges an innocent subject’s behavior, there is the risk of a double injustice—an innocent person being subjected to the scrutiny of further investigation, while the actual offender remains free to commit additional crimes. 



All behavior—facial expressions, voice tone, posture, gaze, and proximity—can communicate important information. However, when assessing the accuracy of a subject’s demeanor, investigators often are plagued by deception myths, particularly the relationship between nonverbal behavior and deceit.

One of the most common misconceptions is the belief in universal signs of deception—consistent, reliable indicators that a person is lying. There are some signs that appear more frequently among liars than truth tellers; however, there has been no universal sign of lying identified.4 This is because not all liars demonstrate the same behaviors. One liar may decrease eye contact, while a second person may increase eye contact in response to the same question. This is complicated by the fact that the same person can respond differently in the same situation—interpersonal differences—and also in different contexts—intrapersonal differences.5﻿

It is likely that anyone who interviews criminals for a living will be lied to on a regular basis. In a study involving 509 people from a variety of career fields and agencies, only the U.S. Secret Service agents performed better than chance (50 percent).6 A number of other studies have provided similar results.7

Dr. Fitch
Dr. Fitch is a lieutenant with the Los Angeles County, California, Sheriff’s Department and holds faculty positions at California State University, Long Beach, and the Southwestern University School of Law in Los Angeles. 


Another myth is the belief that only guilty people appear nervous. This idea assumes that a person who has nothing to hide has no reason to be nervous or to demonstrate fidgeting and anxiety often associated with deceit. Questioning by law enforcement can be stressful for anyone, especially someone with little understanding of the criminal justice system. That anxiety can be heightened by accusatory questions or an aggressive interviewing style. Not surprisingly, innocent individuals often demonstrate many of the stereotypical behaviors associated with deception, including speech errors, fidgeting, and gaze aversion.8


Lie detection is a difficult task, and some techniques work part of the time and only with some people. No single technique is effective all of the time under all conditions. There is no approach or question that enables an interviewer to separate lying from truthfulness in every situation. In fact, some methods may decrease the accuracy.

Deception is a fact of life that people seldom think about. There are two primary ways that people lie—concealment and falsification.9 Concealment occurs when a person evades the question or omits relevant details. Liars often prefer this because it can be difficult to reveal. Without evidence it can be challenging or nearly impossible to validate the truth or falsity of a person’s statement. Concealment is easier than falsification because the liar does not have to remember what was said previously, and it provides numerous built-in excuses. For example, the liar can claim ignorance or a faulty memory.10

Concealment often is all that is necessary to mislead another person; however, there are times when falsification is necessary. For example, lying about one’s whereabouts during the time a crime was committed cannot be accomplished by concealment alone. The subject must fabricate a story.11

Regardless of the type of lie, the goal is the same—to intentionally mislead another person into believing something the liar knows is false. People who unknowingly provide false information do not demonstrate emotional arousal or other cues associated with deception. It is only when a lie is told knowingly and intentionally that the liar can be expected to display signs.


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

Emotional Approach

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.15 Physiologically 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

Deception guilt refers to a person’s feelings about lying, not whether someone is guilty or innocent. It is different from feeling guilty about the content of a lie. A person does not have to feel guilty about the lie itself to feel guilty about the act of lying. The amount of deception guilt that people experience varies, but strong feelings of guilt or shame sometimes are enough to produce a confession. Some people are more susceptible to deception guilt, such as those raised in a home with strict beliefs about dishonesty, particularly where lying was characterized as a sin.21

Excitement, or “duping delight,” is the positive feeling a liar experiences when anticipating the challenge of a lie or during the moment of lying when one’s success has yet to be assured.22 A person experiencing duping delight can display a number of emotions—contempt, enjoyment, or excitement. It is common for criminals to confess their crimes to friends or strangers and, in some cases, to investigators to receive acknowledgement for their ingenuity and intelligence.

Emotional expressions sometimes provide clues to what a person is feeling; however, they do not reveal the source of the feelings.23 For example, a person interviewed regarding a spouse’s murder may express signs of fear and guilt when asked for whereabouts during the crime. Although the subject is innocent, a display of strong emotion may occur because the individual was carrying on an extramarital affair at the time of the murder. The expressions of fear about being discovered and guilt concerning the actions are real but unrelated to the crime.

Because feelings do not reveal their sources, they must be considered in the context in which they occur. People differ in their expressiveness and ability to conceal emotions.24 It is only when the expression does not match the spoken word that attention should be paid to the details of the person’s story. Investigators should follow up with open-ended questions, attend closely to the subject’s responses, monitor emotional triggers, and compare the person’s answers with the facts of the case.

Cognitive Approach

A second reason that lies fail is the mental effort required to create and communicate a plausible story. Lying persuasively is hard for many people, especially those who are unprepared. Although, even when a liar is prepared, it may be difficult to lie convincingly.25 The liar must construct a story consistent with what the interviewer knows or may discover, keep track of everything being said, anticipate future questions, and avoid providing too much information. The effort required to lie varies among people; however, evidence suggests that liars are more likely than truth tellers to exhibit certain behaviors—hesitating, making errors, speaking slower, pausing more, and waiting longer before answering.26

A study of 99 police officers who viewed fragments of 54 videotaped interviews with murderers, rapists, and arsonists indicated that officers who relied on verbal cues (e.g., vague responses or contradictions) distinguished between truth and deception better than those who depended on more visual signs (e.g., gaze aversion or postural shifts). Researchers found an opposite relationship between nonverbal behaviors (e.g., fidgeting and looking away) and accuracy.27 The police officers who specifically mentioned that liars looked away and fidgeted obtained the lowest scores, while those who paid attention to verbal responses were more accurate in their judgments.

The cognitive approach to deception is based on the idea that lying requires more mental resources than truth telling. The increase in mental load required to formulate and communicate a plausible story, monitor body language and emotional expressions, and anticipate future questions is believed to make liars vulnerable to additional questions they failed to anticipate.28 Investigators can take advantage of this by focusing on nonaccusatory, open-ended questions designed to elicit narrative responses.

Studies have suggested that investigators rely on two interviewing styles—information gathering and accusatory.29 An investigator using the information-gathering style asks open-ended questions (e.g., “In your own words, tell me what happened”) that require the interviewee to provide detailed statements. With an accusatory style, the interviewer uses allegations (e.g., “Obviously you are hiding something”) in the hope of obtaining an admission or confession. The purpose of each interview and the quality and quantity of information obtained are different. Interviews are for gathering facts, and the more detailed and complete the information, the more successful the interview.

The more information an investigator can secure, the more chances exist to compare those facts with available evidence. The longer the interview, the more opportunities to examine the interviewee’s responses.30 Investigators should focus on information-gathering interviews because they do not accuse the subject of any wrongdoing and are less likely to result in false confessions.31

Attempted Control Approach

The third reason lies fail is the unnatural appearance of liars who attempt to control their behavior, known as using countermeasures.32 Liars know that observers pay close attention to behavior, so they manage their nonverbal behaviors to make themselves appear honest and sincere. These individuals often are mindful of stereotypical behaviors—gaze aversion, fidgeting, and postural shifts—commonly associated with deception. They sometimes go to great lengths to maintain eye contact, control gestures, and present an emotionally cool demeanor.33

Despite a liar’s best efforts, it is impossible to monitor, control, or disguise all behavior. Some behaviors, such as the physiological changes that accompany strong emotions, are beyond conscious control.34 This is further complicated because people usually are unaware of their own behavior and how they appear to others, so subtle changes in their demeanor may leak valuable information.

One strategy liars use to limit the amount of untruthful information is to embed the lie in a number of truths. Instead of telling a complex, blatant lie, the person inserts untruths into an otherwise truthful account.35 For instance, robbery suspects who want to conceal their whereabouts on the evening of a crime may provide details of activities that occurred the night before the incident, significantly reducing the amount of untruthful information they must remember. They only change the date of the activities, not the activities themselves. Individuals who embed lies in otherwise truthful accounts and who monitor their behaviors often are difficult to spot.


People’s speech and behavior vary. Some individuals make several movements, some are articulate and persuasive, while others demonstrate major differences in their physiological responses.36 Rather than assessing responses as they occur during an interview, investigators first should determine how the subject looks and sounds when communicating truthfully. Then they should watch for behaviors that deviate from that normal style or baseline.

When comparing verbal and nonverbal behaviors with the baseline, the investigator must ensure the person’s responses are from the same interview setting, about similar topics, and from interviews that occurred within a short time period.37 This is important because conversations are low-stakes situations where it is unlikely that the person’s responses will result in negative consequences. In contrast, interviews to discuss the elements of a crime are high-stakes situations that could bring about grave penalties.

There is no universal sign of deception. Investigators should avoid focusing on any one behavior and look for clusters (e.g., a subject rubbing the face, shifting posture, and shrugging shoulders). Although none of these behaviors indicate that a person is lying, they often reveal signs of emotional arousal, discomfort, or ANS activation, especially if they break with the subject’s normal baseline demeanor.

The timing and location of a person’s behavior are critical. For example, if a subject shifts posture, smiles, pauses, and touches the face during a break in small-talk conversation, the behaviors probably are of little value.38 Conversely, if the individual demonstrates the same pattern immediately following a material question, it may indicate emotional arousal or deceit and would require further questioning.


Investigators spend time attempting to sort fact from fiction. Despite the belief that it is easy to spot a liar, it actually is difficult to distinguish between truthfulness and deception. This is because no single behavior accurately predicts whether a person is lying. Therefore, rather than focusing on a single behavior, investigators initially should conduct a baseline assessment. They must ask open-ended questions to glean as much information as possible while watching for indicators of emotion, cognition, and control. After completing these steps, investigators may ask closed-ended questions intended to elicit specific responses. Regardless of how promising a particular method may appear, investigators should approach every interview with an appropriate level of skepticism and appreciation for the vast individual differences in behavior and speech, as well as a strong understanding of the case facts. Overall, there is no substitute for a thorough investigation.

For additional information Dr. Fitch may be contacted at 


Julius Fast, Body Language: The Essential Secrets of Non-Verbal Communication (New York, NY: MJF Books, 1970).

Fred E. Inbau, John E. Reid, Joseph P. Buckley, and Brian C. Jayne, Criminal Interrogation and Confessions, 4th ed. (Sudbury, MA: Jones and Bartlett, 2004), 152.

Aldert Vrij, Detecting Lies and Deceit: Pitfalls and Opportunities, 2nd ed. (West Sussex, UK: John Wiley and Sons, 2008).

Paul Ekman, Telling Lies: Clues to Deceit in the Marketplace, Politics, and Marriage, rev. ed. (New York, NY: W.W. Norton and Company, 2009).

Vrij, Detecting Lies and Deceit: Pitfalls and Opportunities, 51.

Paul Ekman and Maureen O’Sullivan, “Who Can Catch a Liar?” American Psychologist 46, no. 9 (1991): 913-920.

Bella M. DePaulo and Roger L. Pfeifer, “On-the-Job Experience and Skill at Detecting Deception,” Journal of Applied Social Psychology 16, no. 3 (1986): 249-267.

Paul Ekman and Mark Frank, “Lies that Fail,” in Lying and Deception in Everyday Life, ed. M. Lewis and C. Sarni (New York, NY: Guilford Press, 1993), 184-200.

Ekman, Telling Lies, 28.

10 Vrij, Detecting Lies and Deceit: Pitfalls and Opportunities, 17.

11 Ekman, Telling Lies, 31.

12 Miron Zuckerman, Bella M. DePaulo, and Robert Rosenthal, “Verbal and Nonverbal Communication of Deception,” in Advances in Experimental Social Psychology, ed. L. Berkowitz (New York, NY: Academic Press, 1981), 14:1-57.

13 Ekman, Telling Lies, 48.

14 Paul Ekman, Emotions Revealed: Recognizing Faces and Feelings to Improve Communication and Emotional Life (New York, NY: Henry Holt and Company, 2003).

15 Daniel Goleman, Emotional Intelligence: Why It Can Matter More Than IQ (New York, NY: Bantam Books, 1995).

16 Vrij, Detecting Lies and Deceit: Pitfalls and Opportunities, 39.

17 Ekman, Telling Lies, 59.

18 Aldert Vrij, Detecting Lies and Deceit: The Psychology of Lying and Implications for Professional Practice (West Sussex, UK: John Wiley and Sons, 2000).

19 Ekman, Telling Lies, 49.

20 Aldert Vrij, Pär Anders Granhag, and Stephen Porter, “Pitfalls and Opportunities in Nonverbal and Verbal Lie Detection,” Psychological Science in the Public Interest 11 (2010): 89-121.

21 Ekman, Telling Lies, 66.

22 Ekman, Telling Lies, 76.

23 Paul Ekman, “Deception, Lying, and Demeanor,” in States of Mind: American and Post-Soviet Perspectives on Contemporary Issues in Psychology, ed. D.F. Halpern and A.E. Voiskounsky (New York, NY: Oxford University Press, 1997), 93-105.

24 Vrij, Detecting Lies and Deceit: Pitfalls and Opportunities, 51.

25 Vrij, Detecting Lies and Deceit: Pitfalls and Opportunities, 18.

26 Frieda Goldman-Eisler, Psycholinguistics: Experiments in Spontaneous Speech (New York, NY: Academic Press, 1968).

27 Samantha Mann, Aldert Vrij, and Ray Bull, “Detecting True Lies: Police Officers' Ability to Detect Suspects' Lies,” Journal of Applied Psychology 89, no. 1 (2004), 137-149.

28 Vrij, Detecting Lies and Deceit: Pitfalls and Opportunities, 40.

29 Stephen J. Moston and Terry Engelbert, “Police Questioning Techniques in Tape Recorded Interviews with Criminal Suspects,” Policing and Society 3, no. 3 (1993): 223-237.

30 Vrij, Granhag, and Porter, “Pitfalls and Opportunities in Nonverbal and Verbal Lie Detection,” 106.

31 Gisli H. Gudjonsson, The Psychology of Interrogations and Confessions: A Handbook (West Sussex, UK: John Wiley and Sons, 2003).

32 Vrij, Granhag, and Porter, “Pitfalls and Opportunities in Nonverbal and Verbal Lie Detection,” 94.

33 Bella M. DePaulo and Susan E. Kirkendol, “The Motivational Impairment Effect in the Communication of Deception,” in Credibility Assessment, ed. J.C. Yuille (Norwell, MA: Kluwer Academic Publishers, 1989), 51-70.

34 Ekman, Telling Lies, 46.


36 Bella M. DePaulo and Howard S. Friedman, “Nonverbal Communication,” in vol. 1 and 2, 4th ed., The Handbook of Social Psychology, ed. D.T. Gilbert, S.T. Fiske, and G. Lindzey (New York, NY: McGraw-Hill, 1998), 3-40.

37 Vrij, Detecting Lies and Deceit: Pitfalls and Opportunities, 402.

38 Ekman, Telling Lies, 149.

















