Detecting Deception Notes

Detecting Deception

Chapter Outline

Paper-and-pencil tests (p. 261)
The social psychological approach (p. 264)
Paradigms used to study deception-detection (p. 268)
Deception-detection accuracy (p. 270)
Expert lie-detectors (p. 274)
Computerised lie-detection (p. 280)
Physiological and neurological correlates of deception (p. 280)
Brainwaves as indicators of deceitful communication (p. 290)
Stylometry (p. 291)
Statement reality/validity analysis (SVA) (p. 292)
Reality monitoring (p. 297)
Scientific content analysis (p. 298)

Introduction to Deception

Lying is not a distinct psychological process with its own unique behavioural indicator.
Lies are pervasive in public and private life.
Few people have never lied or been deceived.
Human beings dislike being deceived, feeling violated and foolish.
Western culture fears deception, yet humanity may need lies to survive.
Emotions in deception can cause issues for liars due to involuntary physiological changes.
Deception is a global phenomenon varying across cultures, with some universal cues like gaze-aversion.
Deception involves intentionally inducing a false belief in someone else.
It can be viewed as a persuasive strategy rather than an end in itself.
Deception is a social phenomenon present in various contexts and across demographics.
The internet offers many avenues for deception.
Deception includes practical jokes, forgery, fraud, military strategy, white lies, and scams.
Manipulation of securities markets is a form of deception with significant consequences.
Deception can lead to sale swindles, export scandals, and political downfalls.
Fraudulent research data and deceptive practices in psychological experiments occur.
Using aliases is common for incarcerated offenders.
Undercover operations and disinformation are standard practice for police and security services.
Lying is an essential interpersonal skill, common in advertising and politics.
A lie is a statement intended to deceive, just one form of deception.
Lying is frequent in cultures and domains like politics and advertising.
DePaulo et al. (1996) found lying to be a frequent daily occurrence.
People lie in 25% of daily interactions and 34% over a week, often successfully and comfortably.
Detected only 18% of the time.
Reasons for lying include impressing others, gaining advantage, avoiding punishment, benefiting others, and facilitating social relationships.
Lies can be self-oriented (benefiting the liar) or other-oriented (benefiting others).
Lies to safeguard social relationships are both self- and other-oriented.
Women tend to tell more other-oriented lies, while men tell more self-oriented lies.
Women feel more uncomfortable when lying than men.
Cross-culturally, attitudes towards lying vary.
A World Values Survey (Inglehart et al., 2001) found that people in Bulgaria and South Korea are the strictest against self-interested lying, while the Netherlands and Germany are the least.
Self-interested lying is more condemned by females, older individuals, and less educated respondents.
The meaning of a written statement varies with context, liars often deceive friends, and lying became institutionalized in the 20th century.
People are more aware of lying due to increased exposure.
A lie can consist of true, false, or partly true statements, with truthfulness referring to the liar's intention.
Deception can occur without words, such as faking an injury or concealing income.
Even silence can be a form of deception.
This analysis excludes self-deception, focusing on acts involving at least two people.
Essential components of a lie include intentionality, no prior warning, definition from the deceiver's viewpoint, and involvement of at least two people (Vrij, 2002).
'Confabulation' differs from lying as the person is not conscious of lying.
'Pseudological fantastica' or 'pathological lying' involves believing one's fantasies.
Categories of lies include:
- Outright lies.
- Exaggerations.
- Subtle lies (e.g., evading the question).
Law defines several criminal and civil offenses involving deception.
Criminal offenses: obtaining property or financial advantage by deception.
Corporate law: fraudulent trading.
False complaints to the police or lying in court are criminal offenses.
Consumer-protection laws prohibit deceptive advertising; deceit can invalidate a contract.
Deception and detection interest psychologists, lawyers, and law enforcement.
Financial costs of deception are substantial.
This chapter focuses on lie detection methods.
Early psychology showed promise in studying deception, but behaviorism overshadowed pioneers like Binet, Dessoir, and Jastrow.
Early scholars focused on demystifying conjuring tricks.
A psychology of deception, as comprehensive as that of memory, is lacking.
No single framework accounts for psychological issues in deception contexts.
Psychologists focus on lying and lie-detection, drawing from areas like physiological, clinical, developmental, cognitive, and social psychology.
Interrogation techniques exemplify psychology's contribution to law enforcement.
Since the book's second edition, reviews on deception cues and detection have been published.
The aim is to provide an overview and conclusions based on empirical knowledge of lie detection methods.

Paper-and-Pencil Tests

Harding and Phillips (1986) found that honesty is ranked as the most important quality to pass on to children in nine out of ten west-European countries.
Having honest employees is vital to the success of business and the public sector.
Providing false information in an employment application/interview often leads to dismissal.
Theft by employees costs the private and public sectors all over the world a great deal of money, sometimes resulting in the collapse of companies.
There is, therefore, a big incentive for employers to try to screen out potential thieves among job applicants.
This practice is very widespread in western countries.
In the United States, the Employee Polygraph Protection Act 1988 prohibits the use of the polygraph in screening applicants for jobs except for local, State and federal personnel, members of the armed forces and the various secret services, security personnel guarding nuclear power stations, water supply facilities and those working in financial security businesses (Camara and Schneider, 1994).
Since the Act was introduced there has been a lot of interest in what are commonly referred to as integrity or honesty tests.
Such paper-and-pencil tests are used at the selection stage in an attempt to identify and minimise risks pertaining to employee theft, for example.
In other words, they are said to be tests of potential employee trustworthiness (Goldberg et al., 1991).
Possible reasons for the use of integrity/honesty tests include:
- The need for employers to reduce a large number of applicants for a small number of positions.
- The existence of applicants without prior employment history.
- The increasing unpreparedness by employers worried about libel suits to supply frank references concerning ex-employees.
Integrity tests are also used, though to a lesser degree, in post-employment investigations of employee misbehaviour such as theft.
Whether the tests are used in a pre- or post-employment context, some authors assume that certain characteristics of individuals are stable over time and are useful in determining whether an individual is capable of dishonest behaviour (Sackett, 1985).
Other authors assume that situational factors are more important in understanding why people cheat and so forth, than are characteristics of their personality (Hartshorne and May, 1928).
It seems unlikely that the person vs situation debate will be resolved in the near future, a factor that would appear to undermine the future of integrity testing.
There are two main types of integrity tests: overt and personality-based.
- The former measure attitudes towards theft.
- Personality-based ones, on the other hand, are supposed to measure traits such as conscientiousness (Wooley and Hakstian, 1992).
Of course, paper-and-pencil tests are but one method of testing for integrity that can be supplemented with a face-to-face interview, applicant background checks or, finally, graphology (that is, handwriting analysis; see Ben-Shakhar, 1989).
The predictive utility of graphology in the pre-employment context is rather doubtful (Murphy, 1995:223–4).
According to Camara and Schneider (1994:113), a survey of publishers of integrity tests carried out as part of the Goldberg et al. (1991) study by the American Psychological Association found that the constructs measured by 24 such tests were counter-productivity (15) honesty (9) job performance (9) attitudes (8) integrity (6) reliability (4) and ‘other’ (12).
The last category, inter alia, includes absenteeism/tardiness, admissions of dishonesty and drug abuse, credibility, dependability/conscientiousness, emotional stability, managerial/sales/clerical potential, probability of short-term turnover, stress tolerance and substance-abuse resistance.
Bernardin and Cooke (1993) inform us that different overt tests contain an honesty subscale that is based on five universal constructs, namely:
- Thinking about stealing more often than others do
- Being more tolerant to those who steal than other people are
- Believing most people commit theft regularly
- Believing in loyalty among thieves
- Accepting rationalisations for theft.
Bernardin and Cooke maintain that these five constructs exist in all the overt tests but different ones measure different areas in addition to honesty.
The use of integrity tests raises questions about their reliability and validity as well as broader questions about civil liberty concerns, such as one’s right to privacy.
The validity of integrity tests is very difficult to determine, irrespective of whether one validates them against background checks, self-reports of dishonest acts, contrasting those who appear to be honest with persons known to have been dishonest by virtue of their criminal records or, finally, by carrying out before-and-after testing comparisons of a company’s losses (Murphy, 1995:212–15).
Staunch critics of paper- and-pencil tests of integrity go as far as to propose a moratorium by Congress of their use until they have been independently verified.
Given the very wide use of, and the controversy surrounding, integrity tests, the US Congress Office of Technology Assessment (OTA) (1990) undertook a close and critical look at these tests, as did the American Psychological Association (APA) (Goldberg et al., 1991).
Not surprisingly, perhaps, the two bodies used different levels of validity, focused on different studies and arrived at different conclusions regarding the validity and usefulness of such tests.
The OTA concentrated on five predictive validity studies.
The APA report provides a review of 300 studies covering a broad range of criteria of validity.
The OTA report evaluated integrity tests against ‘absolute levels of validity’ (Goldberg et al., 1991:7) using a detected theft or a close approximation to it as their external criterion of validity.
The APA report assessed test validity in comparison, for example, with structured integrity interviews.
Neither of the reports examined whether such tests accurately predict total job performance (Camara and Schneider, 1994).
The OTA concluded that integrity tests over-predict dishonesty.
More specifically, it found that 95.6 per cent of people who are given such tests and fail are incorrectly labelled as dishonest.
In fact, the mean average percentage in the five studies examined that was detected for theft was 3 per cent.
Camara and Schneider (1994:115) cite studies that used self-reported data and found theft base rates from 28 per cent to 62 per cent (see Hollinger and Clark, 1983, Slora, 1989, respectively).
Consequently (and not surprisingly, the cynics might retort!), it is not possible to reach any definitive conclusions about the predictive utility of integrity tests.
Camara and Schneider (1994:115) identify three major difficulties in evaluating integrity tests:
- There is no consensus on what is meant by integrity
- There is an over-reliance on cut scores without the standard error of measurement and overlapping score ranges being reported
- Publishers are unlikely to encourage independent research into their integrity tests.
Camara and Schneider (1994)8 concluded that: ‘there is general agreement that integrity tests can predict a number of outcomes to employers and that they have levels of validity comparable to many other kinds of tests used in employment settings’ (p. 117).
Murphy (1995) lists the following caveats to the conclusion that integrity tests are useful:
- Definition of integrity is problematic.
- The distinction between personality-based tests of integrity and other personality tests is not clear-cut.
- Not informing examinees of integrity test scores when they are unsuccessful in their job applications poses serious ethical problems.
- From a psychometrician’s point of view, the scoring procedure of some integrity tests is a cause for concern.
- Finally, while integrity tests may help to identify high-risks among applicants they are not useful in screening the very honest individuals (pp. 215–17).
Camara and Schneider (1994) remind the reader that legislation and the judiciary may one day decide what becomes of paper-and-pencil tests in general, be it personality or pre-employment tests, and that ‘psychologists should wilfully participate in such public policy debates’ (p. 117).
One of the debates concerns the question of whether integrity tests should continue to be used in the employment setting in light of their limited predictive utility and their invasion of an individual’s privacy (see Stone and Stone, 1990).
The APA’s evaluation of integrity tests, unlike the OTA’s assessment, focused on the scientific validity of the test in employee theft prevention and failed to give due consideration to some of the likely social consequences for job applicants who are wrongly labelled as dishonest and blacklisted by companies whose use of such data is largely uncontrolled and whose test results can convey a false sense of security to other companies.9
In view of the extensive use of integrity tests in the United States the practice should be regulated by establishing an agency to oversee the industry concerned and an integrity test result should never be the only criterion in deciding whether to employ someone.
Staunch critics of paper-and-pencil tests of integrity go as far as to propose a moratorium by Congress of their use until they have been independently verified.

The Social Psychological Approach

Witness demeanour is relevant for judging credibility in British courts (Stone, 1991:822).
Appeal courts are reluctant to interfere with trial court decisions on veracity.
Judge Lord Devlin doubted his ability to detect lying from demeanour (Stone, 1991:828).
People generally have an exaggerated belief in their abilities to detect lies.
There is lack of concern about false positive errors of judgement in this context (Vrij, 2000).
A serving detective in England offered advice on verbal and non-verbal cues to deception in the Police Review Oxford (1991).
Such advice included delayed responses and phrases like 'If I remember correctly'.
Empirical evidence does not justify such confidence in verbal and non-verbal cues.
People generally have a grossly exaggerated belief in their abilities to detect lies in what others say and there is a lack of concern about false positive errors of judgement in this context (Vrij, 2000).

Beliefs About 'Lying Behaviour'

People’s apparent inability to discriminate reliably between truth and deception utilising non-verbal cues seems partly attributable to their beliefs about ‘lying behaviour’.
Popular beliefs about cues to deception, held by both lay persons and practitioners, have been shown to be generally incorrect.
The origin of such beliefs among law-enforcement personnel can be attributed to police interrogation manuals that recommend relying on verbal and non-verbal cues to deception but without generally accepted empirical support for the claims they make (Stromwall et al., ¨ 2004:237).
To illustrate, Mann et al. (2004) reported that in a sample of real police interviews the more the police officers endorsed views recommended by Inbau et al. (2001) regarding the utility of verbal and non-verbal cues to deception, the less accurate they were in detecting deception.
Akehurst et al. (1996) used a 64-item questionnaire to survey police officers and lay people in southern England regarding their own as well as other people’s beliefs about correlates of lying.
- People believed non-verbal behaviours like arm and leg movements and self-manipulations increase when lying; the reverse is true.
- No significant differences between lay people's and police officers' beliefs.
- No significant differences between those who read literature on deception and those who had not.
- People were more accurate regarding their own than other people’s lying behaviour (pp. 367–70).
Similar findings have been obtained in Spain by Garrido and Masip (2001).
Vrij and Semin (1996) investigated the relationships that police, detectives, patrol officers, customs officers, prisoners and prison guards believed existed between 16 non-verbal behaviours and deception.
Police officers were found to have the same stereotyped and inaccurate beliefs about non-verbal cues to deception as non- police.
Interestingly, the correctness of prisoners’ beliefs was significantly higher than any of the other five groups, which did not differ significantly.
In a worldwide study in 75 countries and 43 different languages by the Global Deception Research Team (2006)12 participants were, inter alia, asked ‘How can you tell when people are lying?’.
Using data from 58 countries, it was found that 63.6 per cent of the participants believed that liars avert gaze (that is, it is a dominant pan-cultural stereotype), followed by the belief that liars are nervous (28 per cent).
One possible explanation for the existence of the belief in gaze aversion as a useful cue to deception across cultures can be found in another belief worldwide that avoiding eye contact is associated with shame (Fessler, 1999) and the fact that even non-human primates indicate submission by looking away (Argyle and Cook, 1976).
Finally, it should be remembered in this context that when a police officer interviews a witness or a suspect, he/she has some kind of preconception as to this person’s credibility.
Furthermore, a na¨ıve and credulous attitude towards a witness by police has been the cause of miscarriages of justice (see, for example, Wagenaar et al., 1993).
Granhag and Stromwall ( ¨ 2000) investigated how observers’ (125 undergraduates in Sweden) judgements of deceit or truthfulness were affected by different types of background information presented before they watched a videotaped testimony.
Those observers who received crediting background information showed a pronounced truth-bias, whereas those who received discrediting information showed a small lie-bias.
- Those observers who made truth-judgements used significantly more non-verbal than verbal cues than did those observers who made lie-judgements.
- Contrary to what other researchers have reported, there was high inter-observer disagreement regarding how a large number of cues to deception are perceived and used.
Granhag and Stromwall’s findings indicate that studies of people’s beliefs about cues to deception as well as their ability to detect deceit should also consider the important role played by one’s preconceptions, the most common type of which is suspicion.
Investigator bias by law-enforcement officers is well documented in the literature (Meissner and Kassin, 2002).
One major concern, of course, is that a police officer’s misconceptions about what constitutes deceptive behaviour in a suspect may well be a starting point for a false confession and conviction of an innocent person.

Wrongful Beliefs about Cues to Deception

Incorrect beliefs by law-enforcement personnel about how liars behave are attributable to the fact that professional lie-detectors lack feedback about their deception-detection performance, learn from interrogation manuals regarding what cues to focus on and, finally, learn by observing their older and more experienced colleagues, thus perpetuating the same misconceptions (Granhag and Vrij, 2005).
By contrast, prison inmates have been shown to be significantly better than chance in detecting deception because they are more open-minded about cues to deception and their experience being interviewed by police gives them feedback about their own effectiveness in lying and detecting lies (Hartwig et al., 2004).
The same has been found with abused children living in an institutional environment14 (Bugent et al., as cited in Ekman, 2001).
Let us next consider in some detail the reported importance of cues to deception, drawing especially on DePaulo et al. (2003), Vrij (2000, 2007), Granhag and Hartwig (2008a) and Granhag and Vrij (2005).

Non-Verbal Cues to Deception

A number of different feelings may accompany deception, including detection apprehension and detection guilt.
Some categories of individuals may well feel no guilt about having to lie to conceal their deceptive communication.
Persons diagnosed with antisocial personality disorder (previously termed ‘psychopathy’) lack remorse and shame (Hare, 1970).
Many diplomats are well-versed in the art of lying, as are hardened career criminals and spies.
However, for many people, lying is stressful.
Strong deception guilt undermines attempts at lying because it produces non-verbal leakage or some other clues to deception (Ekman and Friesen, 1972).
To choose when to feel emotions and to control whether others become aware of them is a most uncommon skill possessed by only the most accomplished of actors.
Ekman and O’Sullivan (1989:305–6) list the following conditions that increase detection apprehension:
- When the person to be lied to has a reputation for being difficult to deceive; is initially suspicious.
- When the deceiver has limited practice or no previous success, is particularly vulnerable to the fear of being caught out.
- Not particularly talented, possesses no special skill at lying and when the consequences of being found out are serious, or serious punishment awaits the deceiver upon being found lying.
- When the deceiver has not much incentive to confess because ‘the punishment for the concealed act is so great’.
- When the person being lied to gains no benefit from the deceiver’s lie.
Non-verbal behaviours that can be used to identify liars comprise vocal and facial characteristics and movements.
Since the 1970s there has been a proliferation of empirical studies of non- verbal behaviour and there is one specialist journal dedicated to this field of study.
Drawing on Vrij (2000:33), non-verbal behaviours comprise three categories:
- Vocal characteristics: speech hesitations, speech errors, pitch of voice, speech rate, latency period, frequency of pauses and pause duration
- Facial characteristics: gaze, smile and blinking
- Movements: self-manipulations, illustrators, hand and finger movements, leg and foot movements, head movements, trunk movements and shifting position.
According to Vrij (2000:24–28), liars may experience the following three different processes during deception, but this does not mean that the presence of any of these indicators necessarily indicates deception:
- The emotional approach: deceit is associated with emotions such as excitement, fear and guilt that are different from those people experience when telling the truth (Ekman, 2001).
  - Despite attempts by liars to hide it, fear can cause them to experience stress and physiological arousal, increases the pitch of their voice, their sweating, blushing, pauses and stutters in their speech, while feeling guilt over the crime will cause liars to avoid eye contact.
- The content complexity approach maintains that lying can be a cognitive complex task because liars find it difficult to lie.
  - This, in turn, will manifest itself in a number of cues to deception such as gaze aversion (Ekman, 2001) and fewer hand movements (Ekman and Friesen, 1972).
- The attempted behavioural control approach: liars try to behave ‘normally’, to make an honest impression.
  - Liars may well over-control their behaviour and tend to sound less vocally expressive, more passive and more uncertain (Granhag and Vrij, 2005:69).
As Vrij (2000:29) reminds his readers, ‘The three approaches predict different and sometimes even contradictory behaviours during deception’.
In considering behavioural cues to deception it should be noted that there is no published study documenting differences in such cues between ethnic groups (Vrij and Winkel, 1991)16 but there are differences in behavioural patterns (Matsumoto, 2006).
Goffman (1959) emphasised self-presentation as a very important concept in under- standing social behaviour.
DePaulo (1992) defined ‘self presentation’ as regulating one’s behaviour to make a positive impression on other people.
A fourth approach to studying deceptive behaviour is the self-presentation approach (DePaulo et al., 2003), which emphasises that both liars and truth-tellers have the same goal – to do their best to appear honest; however, in doing so they will differ because liars’ claims are illegitimate (DePaulo and Morris, 2004:17) and the knowledge of what they are trying to do will make liars appear more unpleasant and tense and, in addition, will be able to provide less details concerning a crime, for example.
In DePaulo and Morris’ (2004) words, ‘Compared to truth-tellers, liars may seem less forthcoming, and may tell their stories in less compelling ways’ (p. 17).
In other words, differences in how liars behave compared to truth-tellers in terms of their feelings, psychological processes and beliefs and strategies, provide us with valid cues to deception (p. 18).
In considering conclusions to be drawn from the findings reported (see the meta-analysis by DePaulo et al., 2003), a major limitation of the existing literature is the small number of studies18 of suspects in real-life criminal investigations.
Spanish researchers have shown that the cognitive interview differentiates reliably between true and false statements intentionally made by witnesses to a crime.
An interesting new approach to detecting deception has been reported by two Spanish psychologists.
Hernandez-Fernaud and Alonso-Quecuty (1995) carried out experimental work aimed at dif- ferentiating between true and false statements by eyewitnesses who watched a videotape of a simulated incident involving attempted car theft, threatening behaviour against the car owner and a witness.
Subjects were interviewed using the traditional interview (TI) technique used by the Spanish police or the cognitive interview (CI) technique (Fisher and Geiselman, 1992) and found that:
- Witness accounts of events, persons and objects were more accurate in the CI condition (see chapter 3).
- True statements contained more contextual information and more sensory details than the false ones; and (c) the CI produced greater differences between truthful and false accounts than the TI by amplifying the differences between the types of account.
These findings indicate the CI is potentially very useful to those social workers and police interviewing crime victims/crime witnesses – it not only produces signif- icantly more accurate witness accounts but it also appears to differentiate reliably between true and false statements made intentionally by witnesses to a crime.

Verbal Cues to Deception

Vrij (2000:104) mentions seven objective verbal characteristics, some of which are cues to deception, namely: negative statements, plausible answers, [unsolicited] irrelevant information, over-generalised statements (for example, ‘never’, ‘every- body’, etc.), self-references, direct answers and response length.
As in the case of non-verbal behaviour, these seven verbal criteria are assumed to be influenced by emotions, content complexity and attempted control but, alas, again, there is no verbal behaviour that is typical of lying (p. 103).

Paradigms Used to Study Deception-Detection

A broad range of paradigms has been used by deception researchers to study the non-verbal and verbal leakage that normally occurs when people lie (see Miller and Stiff, 1993:39–49).
These have included uninterrupted message presentations, asking subjects to provide truthful and deceptive reactions to stimuli (known as ‘reaction assessment’) and implicating subjects in a cheating incident during an experimental task.
The last paradigm is known as the ‘Exline procedure’ (Exline et al., 1970) which has the advantage of both producing deceptive behaviour not sanctioned by the experimenter and motivating deceivers not to get detected (Miller and Stiff, 1993:43).
The most commonly used task in deception-detection research is to show subjects in laboratory studies video clips of people who have been instructed to lie about something or to tell the truth.
The experimenter then calculates the number of correct judgements made in relation to the total number.
In considering accuracy scores reported in this context, the reader should note the documented existence (see Granhag and Vrij, 2005:51) of a ‘veracity effect’ (that is, a ‘truth- bias’), a tendency by subjects to choose ‘The statement is true’ more frequently than ‘The statement is false’ (Levineet al., 1999).
The truth-bias is very pronounced among lay persons.
However, it is significantly less evident among prison inmates (Hartwig et al. 2004a) and police officers (Hartwig et al., 2004b); in other words, both police officers and prison inmates are suspicious of the answers people give to questions, the police officers due to their experience with having questioned large numbers of a biased sample of people and the inmates as a consequence of their own extensive experience deceiving others but, also, being lied to themselves (Granhag and Vrij, 2005:51).
In considering findings reported, the reader should also note that, unlike in laboratory studies, researchers using real-life material face problems in terms of ‘ground truth’ (p. 51).
As already mentioned, until relatively recently psychological studies of decep- tion have tended to use college students as subjects who lie or tell the truth about liking or not liking their friends and who are sometimes offered trivial incentives to take seriously what they are asked to do in experiments.
Such mock studies are generally very low on external validity, a far cry from the real world of deception- detection in a law-enforcement context (Ekman and O’Sullivan, 1989).
An addi- tional limitation of laboratory studies is some people’s inability to be precise about which cues to deception have led them to decide that someone is lying.
Studies of cues to deception vary in terms of: whether truth-tellers and liars are adults or children; whether subjects are lay persons or experts (by virtue of their professional experience) who are shown a video clip or experts who are shown a video clip and question a suspect face to face; or police officers who are shown videos of high-stake real-life interviews of suspects; or, finally, whether a study focuses on specific visible cues to deception or on micro-expressions that are normally not visible unless shown slowly frame by frame.
Regarding micro-expressions, Ekman (2001) provides adequate empirical evi- dence that observing and analysing such micro-expressions aids in deception because, generally speaking, such expressions (for example, one’s eyebrows being raised in response to fear and being lowered in response to anger) are involuntary and the great majority of people cannot convincingly fake an emotion other than the one they are feeling.
Vrij and Mann (2001) reported one such micro-expression (a suppressed smile) during a televised press conference by a man asking people to help find his missing girlfriend who he had in fact killed, as the police established later on.
Researchers have found that females are better at recognising micro-momentary expressions that are correlated with lie-detection accuracy (Ekman and O’Sullivan, 1991; Frank and Ekman, 1997).
One difficulty in evaluating the utility of micro- expressions as cues to deception-detection is that, despite Paul Ekman’s significant There is no verbal behavior that is typical of lying.
work in this context, as Granhag and Vrij (2005:71) point out, unfor- tunately there is no published study in a peer reviewed journal of the frequency of emotional micro-expressions when people lie and tell the truth.

Deception-Detection Accuracy

On the basis of the DePaulo et al. (2003) meta-analysis of deception-detection stud- ies, DePaulo and Morris (2004) concluded that: ‘The existing research on deception detection should instill little faith that people are particularly good at this elusive skill.
Although there are some ways in which liars behave differently from truth- tellers, there are no perfectly reliable cues to deception’ (p. 38).
A review of 37 stud- ies by Vrij (2000) found that for lay persons (primarily university students) accuracy for detecting truths was 67 per cent and for detecting lies 44 per cent, with the over- all accuracy rate being 57 per cent.
We see that people are better at detecting truths partly due to the truth-bias and perform below chance as far as detecting deceptive behavior is concerned.
What is perhaps equally interesting is the well-established finding (see below) that a broad range of professionals considered to be experts at questioning suspects and at lie-detection have an accuracy rate that is no better than ordinary members of the public, that is, at about chance level.
A review of the rele- vant literature by Vrij and Mann (2003) found an overall accuracy reported rate of 55 per cent.
Researchers have also found that:
- It is not easier for adults to detect deception in children than in adults (see below).
- Adults find it more difficult to detect deception in girls than in boys (Westcott et al., 1991).
Vrij (2000:34–5) surveyed 45 studies of 7 vocal indicators of deception (hesitation, errors, high- pitched voice, speech rate, latency period, pauses duration, frequency of pauses) and 44 studies of 10 non-vocal indicators (gaze, smile, self-manipulations, illustra- tors, hand/finger movements, leg/foot movements, head movements, trunk, shifting position and eye-blinking).
More recently, DePaulo et al. (2003) reported a compre- hensive meta-analysis of the literature on cues to deception, covering 120 samples of participants (all adults), 158 verbal or non-verbal cues, and 1338 estimates