actively observing simultaneously, another important aspect in the accurate
evaluation of truthfulness.
Bad habits can also refl ect ignorance about why truths and lies succeed, as
well as why they fail. For example, although lies sometimes succeed in light
of factors beyond evaluators ’ control, such as the liar ’ s skill and preparation,
lies too often succeed because of a lack of knowledge or skill in the recipient
of the lie. Moreover, lies too often succeed because the recipient of the lie
wants to believe the liar (i.e., collusion), has no baseline information about
the liar or has failed to seek collateral information. It is extremely important
to seek collateral information in order to confi rm or disconfi rm the informa-
tion provided, particularly in forensic contexts. Understanding one ’ s context
is also important, as base rates of truth - telling/lying can also have a negative
impact on one ’ s decision - making, with environments characterized by high
incident rates of lying (e.g., prisons) resulting in an over - sceptical viewpoint
and relatively honest contexts (e.g., churches) creating an overly trusting
attitude.
Clearly, the more one knows about his/her biases, bad habits and environ-
mental infl uences, the better able one will be at avoiding bad practices when
it comes to evaluating truthfulness. However, the best way to counteract these
Evaluating Truthfulness
313
errors is to treat each case on its own merit by looking for behavioural change,
that is, changes from how a person typically behaves when telling the truth
(their baseline behaviour). Indeed, viewing changes from baseline is essential
to the accurate evaluation of truthfulness and is a fundamental aspect to the
approach introduced in the present chapter.
Acquiring evidence - based knowledge
Research suggests that a basic training component for evaluating truthfulness
consists of the acquisition of empirically - derived knowledge. At the very least,
individuals should learn about what causes people to lie or tell the truth and
the typography of truths and lies. Research indicates that there are many moti-
vations for lying − to avoid punishment, to obtain an underserved reward, to
protect a loved one, for amusement or to reduce shame (Ekman, 1992 ) − and
that personality may impact on one ’ s penchant for particular motivations (e.g.,
Spidel et al ., 2003 ). Research also indicates that lies can vary in terms of their
content. That is, people can misrepresent their emotional state, their opinion
on a particular subject, factual information or their future intents. Knowing
about the different content of lies will assist in the accurate evaluation of
truthfulness.
In addition, research has identifi ed different types of lies, including, but not
limited to, concealment and/or falsifi cation or fabrication, as well as telling
the truth falsely and the incorrect - inference dodge (Ekman, 1992 ). Concealment
lies are the simplest form but the most diffi cult to detect because the liar is
not actively engaging in lying. The outcome is less data to evaluate truthfulness
than would result from, for example, spinning an elaborate web of deceit.
Falsifi cation refl ects a deliberate misrepresentation of information. It is harder
for the falsifi cation lie to succeed in comparison with the concealment lie, as
the liar has – at the very least – to remember the false statement if asked again.
No less important, but often forgotten, is the need to learn about what the
truth looks like. As suggested above, if individuals only know what lies look
like, they are likely to become susceptible to not believing the truth when they
see it. As the truth refl ects the end - result of generic emotional and cognitive
processes, evaluators must acquire this basic knowledge. For example, if inves-
tigating some past event, individuals should understand how memory works,
as well as how stress and emotions can disrupt cognitive processes in general
and memory functioning in particular (see Herv é , Cooper & Yuille, 2007 ). In
short, it is important to know about the motivations, nature and types of
truths/lies because they have different emotional and/or cognitive conse-
quences for the individual and, therefore, will reveal important clues during
evaluations of truthfulness.
To understand and appreciate the differential impact of emotions and cogni-
tions on lying and truth - telling, one should gain knowledge about ‘ the psy-
chology of lying and truth telling ’ (see Figure 17.1 ). As implied above, in
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Handbook of Psychology of Investigative Interviewing
Motivation
(event / context / personality)
Truth / lie
Emotion
Cognition
Behaviour
Change from baseline
(within and/or across channels)
Leakage
Figure 17.1: The psychology of truthfulness
order to understand the psychology of lying and truth - telling, background
knowledge on how emotional and cognitive processes typically operate and
how they impact on certain behavioural channels are required. As Figure 17.1
depicts, a person
’ s motivation to lie or tell the truth must be taken into
account, as well as the context of the assessment and knowledge about the
personality of the person being evaluated (if available). These factors interact
to delineate the particular psychological state of the individual being assessed.
When an individual lies or tells the truth, there will be emotional and cogni-
tive consequences, which will, in some way, impact on their behaviour (Yuille,
1989 ; Ekman,
1992 ). The impact on their behaviour will be viewed as a
change from baseline − that is, a change in how the individual typically behaves
(e.g., in their facial expression, eye gaze, body language) and/or contradictory
behaviours that occur simultaneously or in close succession (e.g., head shake
indicating ‘ no ’ but answering ‘ yes ’ ). When someone demonstrates a change
from baseline via a behavioural (i.e., observable) channel, the result is leakage.
That is, in effect, the change from baseline leaks out (Ekman, 2003 ; Herv é ,
Cooper & Yuille, 2008 ). Identifying leakage via active listening and observing
is crucial to the process of evaluating truthfulness. That is, behavioural change
is not random; it occurs for a reason (see below for further details).
Skill acquisition
In addition to empirically - based knowledge, the literature indicates that train-
ing in evaluating truthfulness should involve the development of specifi c,
Evaluating Truthfulness
315
evidenced - based skills. The knowledge base discussed above would form the
foundation for the development of certain skills and, more importantly, for
the appropriate application of these skills. One skill involves identifying leakage
(i.e., emotional or cognitive leakage), that is, how lies leak out through non-
verbal channels (e.g., facial expressions and body language) and verbal chan-
nels (e.g., verbal style and content). In order to identify lea
kage, attention
should focus on what people do and say and how they do it and say it. In
other words, for leakage to be identifi ed, ‘ active listening ’ and ‘ active observ-
ing ’ must occur simultaneously. Through active listening and observing, emo-
tional and cognitive leakage can be observed through a number of observable
behavioural channels.
Emotional leakage can be viewed through a number of observable channels,
such as the face or voice and via body language. The face, however, is the
primary and clearest channel through which to observe emotional reactions,
and it is also the most researched (for a review, see Ekman, 2003 ). Ekman has
demonstrated that there are seven universal facial expressions of emotion that
can be observed
− fear, sadness, disgust, happiness, surprise, contempt,
anger − research suggests that they appear in all cultures regardless of language.
It has been shown that, by developing the skill of observing the facial repre-
sentations of these seven basic emotions, one ’ s ability to identify different
emotional states accurately can be increased (Frank & Ekman, 1997 ).
Most of the time, when a facial expression of emotion is observed, it is a
macro - expression, that is, it is full and relatively long
- lasting (
> 1 second)
(Ekman, 2003 ). However, macro - expressions of emotions are usually ignored
due to verbal overrides (see above) and, more importantly, are relatively easily
faked. In addition to facial macro - expressions of emotion, subtle and micro -
expressions have been identifi ed (Ekman, 2003 ). In general, subtle or micro -
expressions of emotion refl ect attempts to conceal the emotion to one ’ s self
or to others (Ekman, 2003 ). A subtle expression is a partial facial expression
of emotion resulting from one ’ s inability to fully control emotional expression.
A subtle expression may also occur when an emotion is just beginning to
develop. Micro - expressions are full expressions of emotion that occur fl eet-
ingly, typically between 0.04 and 0.2 of a second (Ekman, 2003 ). Most people
miss micro - expressions in their day - to - day interactions, however, training in
their detection in the context of active observing can improve individuals ’
ability to detect them (Frank & Ekman, 1997 ). Training can also improve an
individual ’ s ability to detect subtle expressions. Although identifying micro -
and subtle expressions can inform individuals as to the emotional state of
others, on their own, they cannot inform individuals of why that emotional
state is being felt (see below).
Another channel that has been heavily researched is verbal content (Yuille,
1988 ), a domain in which cognitive leakage could be observed. Although
cognitive reactions to lying and truth - telling can be observed across a number
of behavioural channels, verbal content is, however, the primary and clearest
channel with which to observe such cognitive reactions. The analysis of verbal
content stems, in part, from the assumption that, in general, it takes more
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Handbook of Psychology of Investigative Interviewing
mental effort to lie than it does to tell the truth. That is, lying causes more
cognitive load than does truth - telling (Yuille, 1989 ; Vrij & Granhag, 2007 ).
Indeed, as a liar does not have a memory of a false account of an event, it
takes more cognitive capacity for him or her to keep the story consistent. In
contrast, a truth - teller can rely on his or her memory when relating an event.
Thus, an increased cognitive load is one of the factors that may betray a liar.
Based on factors associated with memory and cognition, such as cognitive load,
Undeutsch (1989) formulated a hypothesis, which essentially posits that mem-
ories of experienced events differ in quantity and quality from memories of
invented experiences. The Undeutsch hypothesis formed the basis of Statement
Validity Analysis (SVA), which has received empirical support (Horowitz,
1991 ). The core of SVA is CBCA, criteria that research has demonstrated to
be more likely to be found in credible accounts as opposed to non - credible
accounts of events (e.g., Lamb et al ., 1997 ; Colwell, Hiscock & Memon,
2002 ). Research indicates that CBCA is a complex qualitative assessment pro-
cedure and should be combined with the other skill - based components to
evaluating truthfulness (Cooper et al ., 2007 ; Cooper, Herv é & Yuille, 2007 ).
Unlike many other skills associated with the evaluation of truthfulness (e.g.,
the ability to detect micro - expressions), CBCA focuses on factors associated
with truth - telling and, therefore, nicely complements other approaches or skills
that focus on detecting clues associated with lying.
Although there is extensive research support for facial expressions and verbal
content in evaluating truthfulness, other important evolving areas include
reading the face together with body language and detecting changes in the
voice and verbal style (Ekman et al ., 1991 ). In terms of the former, changes
in body language are complex and can betray both the emotional and cogni-
tive aspects of lies. For example, research indicates that knowing the baseline
of use of different types of gestures (e.g., emblems, illustrators and manipula-
tors) is important to detect change in these gestures (Ekman et al. , 1978 ;
Ekman et al ., 1991 ). For example, one person may show a decrease in illustra-
tors (i.e., hand movements used to illustrate speech) when he or she has an
increase in cognitive load, yet another person may show an increase in illustra-
tors when their cognitive load has been taxed. Detecting change within a given
individual is crucial to the evaluation of truthfulness.
In terms of detecting changes in the voice, this can betray emotional and,
to a lesser extent, cognitive aspects of lying (Ekman et al. , 1978 ; DePaulo,
1992; 1994 ). For example, the voice may get softer when someone is lying,
however, a softer/lower voice can also refl ect sadness, which highlights the
importance of always considering alternative hypotheses before making a deci-
sion about the signifi cance of what has been heard and/or observed (i.e., using
a hypothesis - testing approach). As indicated above, some companies advertise
voice - based lie detectors but, as these devices measure changes in voice pitch,
they are not lie detectors but change detectors. Change can be due to lying
but can also be due to many other factors, which once again highlights the
need to utilize a hypothesis - testing approach.
Evaluating Truthfulness
317
Finally, it has been demonstrated that verbal style can leak both emotional
and cognitive aspects of lying. Such would include increased duration of pauses
or greater use of fi lled pauses, changes in pronoun use or responding without
answering the question. For example, if a suspect in a robbery, during the
recounting of his or her version of events in the fi rst person pronoun, pauses
at the point of entering the location of the robbery and then drops the use of
the fi rst person pronoun ( ‘ I ’ ), the change may refl ect a lie of omission
− more
may have transpired than what was being revealed. It should be noted, however,
that the change does not imply that the person committed the robbery. Rather,
it highlights a point in the account that should be reviewed again, as a signifi -
cant change in verbal style has been observed (i.e., a signifi cant change from
baseline verbal style).
Although implied throughout this chapter, it is nevertheless important to
highlight the reality that none of the aforementioned channels are in and of
themselves clues to deception; they are clues of importance. As noted above,
changes in these channels simply refl ect a change in emotional and/or cogni-
tive load. At times, the channels may be revealing different messages, thereby
suggesting internal confl ict. These changes and inconsistencies are important
in conducting evaluations of truthfulness, not because they necessarily reveal
lies but because they reveal topics that need further exploration; hence the
need for a method by which to conduct such evaluations.
Method
Research and practice suggest that an evidence - based method that helps evalu-
ators organize the information collected and, thereafter, make an informed
decision is a vital component of clinical decision
- making in general (see
Monahan et al ., 2001 ) and evaluating truthfulness in particular (Herv é , Cooper
& Yuille, 2008 ). At the very least, this method should promote critical think-
ing − the objective evaluation of data in the context of multiple hypothesis -
testing. We believe that using a ‘ single case design ’ can help evaluators achieve
this goal. With this design, each case can be evaluated on its own merits. This
design not only advocates collecting data rich in quantity and quality (as
detailed above), it also emphasizes the importance of considering multiple
hypotheses; that is, using a hypothesis - testing approach, both when consider-
ing the meaning of particular data points and when making overall decisions.
The evaluator is encouraged to check and double - check his or her hypotheses
against the available evidence − changing/updating hypotheses as the evidence
to support the hypotheses changes. Even when the issue at hand appears to
be quite simplistic, multiple hypotheses should be considered. As noted above,
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