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Whilst everyone tells a certain amount of ‘un-truths’ throughout the day with no malice or forethought, there are those that would deceive with criminal intent or to knowingly harm another. A practiced liar can achieve a certain level of successful deception by attempting to control or hide their nervousness or fear through careful and calculated responses. It is however, not possible to control all aspects of behaviour and many ‘non-verbal’ cues will leak through due to cognitive load (overloading the limits of working memory to perform multiple tasks) and it is these non-verbal cues that can lead to the truth far more quickly than the spoken word. It is therefore through gaze aversion, rigid body posture, expression and through irregular speech patterns that the liar may be revealed.
The three main approaches to non-verbal deceptive behaviour are emotional, cognitive and the attempted control approach. The emotional approach deals with arousal and purports that a particular internal process will result in a specific non-verbal response. In effect, feelings will determine how the body reacts to give a person away as a liar. The cognitive approach deals with how taxing it is on memory and composure to maintain a lie and therefore suggests that an individual will make far more verbal disturbances than his truthful counterpart. This can include long pauses, repetition of words and an absence of logical structure. Finally, the attempted control approach relies on an individual’s ability to convince another of his truthfulness by adapting his behaviour to appear more honest. However, in actuality the modified behaviour often highlights a lack of natural facial and bodily movements, which appears as a rigid and rehearsed manner indicating falsehoods (Granhag & Stromwall, 2002).
It is not just through verbal statements that anomalous events occur and the written statement can be equally revealing of a lie. Statement validity analysis (SVA) compares the content and quality of true statements with made up events and proposes that there will be a significant difference between the two. An assessor can determine the likelihood of a statement’s validity by utilising a ‘checklist’ of criteria formulated from previous comparisons of known truthful and fabricated events. Even a written statement can offer clues to the reader as to the truthfulness of an event; however, this can be limited to detect known falsehoods and may be less successful in detecting a lie that is subjectively true for the individual making the statement (Gitlin et al., 2009).
Although many details may change over the course of recounting an event, the main facts, the aspects that make the event significant for an individual should always stay the same. In an untruthful statement the behaviour both spoken and silent along with body language can tell a completely different story. Body language or ‘non-verbal’ cues will be present no matter how small the lie at the point of the lie. As individuals attempt to conceal a lie with other ‘more believable’ behaviours they in fact behave less natural and are often unaware of the cues they are presenting; If they do become aware and try to compensate for this with additional ‘unusual’ behaviour it simply brings more suspicion as to the merit of their statement (Gamson et al., 2012). Providing the interviewer remains unbiased and does not rush to accept these cues as an indication of a lie but proceeds with information gathering to determine the facts the truth should reveal itself.
Non-verbal cues will only exist if the individual that is providing a statement believes the statement to be false. An intentionally deceptive recall of events will provide micro expressions, speech disturbances and unnatural body movements that are outside of the individual’s conscious control. The listener can observe these unintentional gestures and if there are a significant number can reasonably conclude that a lie is being told. Being deceptive is far more demanding on cognitive load than truth telling and this is why there is this ‘leak through’ of emotion or ‘tells’ that alert to deception. Working memory is an essential tool to performing well in recollection tasks (Gathercole & Alloway, 2007) and relatively easy to access when remembering an experience but much more difficult to utilise when being deceptive. It would therefore be possible to place additional load on the working memory during an interview to increase the difficulty of maintaining a lie (Vrij et al., 2008).
Whilst there are many non-verbal behaviours that may indicate a lie in a verbal or written statement, these same behaviours can simply be misread natural expressions of an individual. It is important to contextualise each indicator as it is not possible to determine a lie from a single cue but using the SVA it becomes more reliable as a means for detecting false statements. All of the approaches to deception should be considered when interviewing as one or all could come in to play at any given time and remaining objective will give the interviewer the best chance of determining the truth.
1. Liars reveal their lies unintentionally
2. Emotional leakage and facial expressions appear to be a reliable indicator of attempted deception
3. No method for detecting deception is foolproof
4. Non-verbal indicators are exactly that, indicators-not definitive proof.
5. Deception detection in itself can be deceptive
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