Educing Information: Interrogation - National Intelligence University

What is most striking about this list, according to Vrij, is everything it does
not include. The findings “contradict[] the stereotypical beliefs that many people
hold about non-verbal indicators of deception.” 550 It turns out that Vrij’s metaanalysis
demonstrates that although “observers expect liars to show nervous
behaviour and behaviours which indicate intense thinking,” this is not the case
for the majority of liars. 551 Thus, “people are usually poor at detecting lies when
they pay attention to someone’s behaviour.” 552
Vrij does concede, as Inbau et al. argue, that experimental studies may not be
the most conducive to actually observing deceptive behavior; as he notes, it may
be that the subjects “simply [are] not nervous enough during these experiments.” 553
Moreover, in the majority of the studies the lie-catchers are college students
who volunteer for the studies. 554 In a meta-analysis of those studies that used
professional lie-catchers as observers, however, the professionals did no better
than the college students. 555 One might also suggest that in the real world, where
suspects are motivated to prevaricate for fear of losing their freedom, certain
indicators of deception would be more obviously on display. However, not enough
empirical studies of deception detection have been carried out in the field to know
whether extra motivation to lie will increase indicative behaviors. Fortunately for
interrogators, “it is possible to improve people’s ability to detect lies.” 556 Studies
using various training procedures all revealed limited improvements in the ability
to detect deceit, although, surprisingly, the studies show students benefiting more
from the training than did police officers. 557 Vrij speculates that police officers
may have scored lower because they did not believe the information they were
being taught. 558
In the end, Vrij concludes that the best hopes for lie detection are found in
observing both emotional expressions and those behaviors influenced by content
complexity (latency period, speech errors, speech hesitations, hand, arm, foot and
leg movements). 559 He gives interrogators several “Guidelines for the Detection
of Deception via Behavioural Cues:”
1. Lies may only be detectable via non-verbal cues if the liar experiences
fear, guilt or excitement (or any other emotion), or if the lie is difficult to
fabricate.
2. It is important to pay attention to mismatches between speech content
and non-verbal behaviour, and to try to explain those mismatches. Keep
550
Id., p. 38.
551
Id.
552
Id., p. 57.
553
Id., p. 39.
554
Id., p. 74.
555
Id., p. 75.
556
Id., p. 95.
557
Id., p. 94-95.
558
Id., p. 95.
559
Id., p. 97.
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