He was avoiding eye contact and fidgeting so much, that clearly means that he was lying! And the polygraph confirmed it, too... We see this in movies and TV shows all the time: police officers or psychologists claim to know when someone is lying simply by observing their non-verbal behaviour. But is this strategy effective in real life? Can we really spot if someone is lying? If so, what are the indicators of deception? And why do we even lie in the first place? Let’s find out!

This article will cover:

·       Why do we lie?

·       What are the signs of deception?

·       How accurate are lie detecting strategies?

Why do we lie?

Lying, or deceiving, is a very common behaviour that most people engage in [6]. Research shows that on average, a person lies once or twice per day [6]. Although still lacking clear consensus regarding its nature, researchers generally agree that there is a distinction between non-pathological, or ‘normal’, and pathological (compulsive) lying.

Normal lying is characterised as goal-oriented, meaning that the person has a clear motivation for lying [6]. This could be either avoiding punishment or embarrassment. People might also lie to gain something such as a reward or fulfilment of their internal need for control or manipulation. The so-called ‘white lies’ fall under non-pathological lying [6].

Lying becomes more problematic when the person has no clear motivation for lying. This is what the researcher Dike named pathological lying [6]. According to him, pathological liars lie frequently, compulsively and lack control over their lies. Their lies do not lead to any clear external benefit [3]. In fact, their lies might sometimes be damaging to themselves. Pathological liars might behave as if their lies were true, but they normally do not become delusional [6].  

Researchers uncovered several psychological factors that might be linked to pathological lying [6]: low self-esteem and development of false self. False self is characterised by a sense of grandiosity, idealisations and need for perfection: hence, pathological liars lie to preserve their false sense of self. This could explain why they often lie about their origin, status or past successes. Regarding biological factors, research suggests that pathological liars might have dysfunctional prefrontal cortex (PFC), which would explain the lack of control they have over their lies [6]. However, more research is needed to support this theory as it is possible that frequent lying might lead to structural changes in PFC.

What are the signs of deception?

Is there such a thing as signs of deception? If so, what are they and how can we spot them to effectively detect it? These are questions that we have been investigating for decades, yet there is still a lack of clear consensus. This is also because lying is a highly heterogeneous behavioural pattern that can vary per person and context [6].

Despite the fact that deception can be manifested in many ways, professionals such as police officers tend to hold stereotypical beliefs about the signs of deception. These include the belief that liars show an increase in fidgeting, hand movements and eye-contact aversion [9]. They believe that liars are nervous and that their nervousness is manifested via these non-verbal behavioural patterns. However, research shows that these beliefs are false.

Even though manifestation of deception is individual, there are several verbal and non-verbal patterns that might indicate that someone is lying. Generally, lying tends to be associated with a lack of hand and leg movements [9]. Moreover, liars tend to display more speech disturbances, longer pauses, slower speech and higher voice pitch [5, 9]. This applies not only to controlled laboratory settings, but also to real-life liars under high-stakes conditions [5, 9]. Some researchers also found that liars tend to keep their story simple and less detailed [7, 8] to avoid mixing up.

Three main frameworks have been proposed as explanations for these findings [9]. The emotional framework proposes that higher pitch and increased speech disturbances might be a result of arousal [9]. Lying can cause physiological reactions which lead to emotional arousal that manifests via these non-verbal speech patterns. Additionally, speech disturbances can also be explained by the cognitive framework [9]. Researchers propose that lying might be a cognitively demanding task and thus the person would show more speech disturbances. Moreover, this would also lead to less hand and bodily movements because higher cognitive load would lead to the neglect of body language. Lastly, lack of body language could also be explained by the attempted control framework which proposes that liars tend to control their movements to not give away that they are lying [9].  

How accurate are lie detecting strategies?

So, can we reliably detect if someone is lying simply by looking for these indicators while talking to someone? Unfortunately, it is not as simple as that.

Non-verbal behavioural cues

The ones mentioned above! These are not very accurate, though.

Polygraphs

Furthermore, polygraphs (frequently referred to as ‘lie detectors’) seem to be a popular tool believed to be able to show if someone is lying. But is this really the case? Most psychologists agree that polygraphs are generally unreliable and cannot with certainty reveal if someone is lying [1]. They are simply a tool to measure physiological responses such as heartbeat, breathing rate and skin conductance which are used by law enforcement to infer whether someone is being deceitful. The problem is that there is no clear pattern of physiological response associated with deception [1]! The interviewee might feel nervous simply due to the fact that they are being interrogated, and not because they are lying. Moreover, a dishonest person may not necessarily be nervous. In fact, there is also evidence that people can ‘beat’ the polygraph, for example by learning how to control their physiological responses [1].

Cognitive approach

If observing non-verbal behaviour or analysing physiological responses are not reliable strategies for lie detection, is there a strategy that might be more useful? Researchers Vrij and colleagues [11] proposed the cognitive lie detection approach. This approach is based on the assumption that lying is cognitively demanding. Therefore, they propose that asking questions that would increase the cognitive load would lead to amplification of non-verbal deception cues. This could be for example asking them to tell their story backwards, asking them to maintain eye contact (which tends to be distracting), or asking unanticipated questions that the liars likely did not prepare for. An evaluation of this technique revealed that it increases accuracy a little above chance levels but more research is still needed [4].

Extra resources:

1. Video – How to beat a lie detector test https://www.youtube.com/watch?v=v1-2K_pCWmI  

2. Video – Former FBI agent explains how to detect lying and deception https://www.youtube.com/watch?v=tpJcBozuF6A

3. Ted Talk – How to spot a liar https://www.youtube.com/watch?v=P_6vDLq64gE

4. Netflix show: Lie to me

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References

1. American Psychological Association. The Truth About Lie Detectors (aka Polygraph Tests). Retrieved on May 15th, 2021 from https://www.apa.org/research/action/polygraph

2.     Carlucci, M. E., Compo, N. S., & Zimmerman, L. (2013). Lie detection during high‐stakes truths and lies. Legal and Criminological Psychology, 18(2), 314-323. https://doi.org/10.1111/j.2044-8333.2012.02064.x

3. Dike, C. C. (2008). Pathological lying: Symptom or disease? Living with no permanent motive or benefit. Psychiatric Times, 25(7), 67-67. https://link.gale.com/apps/doc/A180555438/AONE?u=erasmus&sid=AONE&xid=a0a858da

4. Mac Giolla, E., & Luke, T. J. (2021). Does the cognitive approach to lie detection improve the accuracy of human observers?. Applied Cognitive Psychology, 35(2), 385-392. https://doi.org/10.1002/acp.3777

5.     Mann, S., Vrij, A., & Bull, R. (2002). Suspects, lies, and videotape: An analysis of authentic high-stake liars. Law and human behavior, 26(3), 365-376. https://doi.org/10.1023/A:1015332606792

6.     Muzinic, L., Kozaric-Kovacic, D., & Marinic, I. (2016). Psychiatric aspects of normal and pathological lying. International journal of law and psychiatry, 46, 88-93. https://doi.org/10.1016/j.ijlp.2016.02.036

7.     Porter, S., Doucette, N. L., Woodworth, M., Earle, J., & MacNeil, B. (2008). Halfe the world knowes not how the other halfe lies: Investigation of verbal and non‐verbal signs of deception exhibited by criminal offenders and non‐offenders. Legal and Criminological Psychology, 13(1), 27-38. https://doi.org/10.1348/135532507X186653

8.     Strömwall, L. A., Hartwig, M., & Granhag, P. A. (2006). To act truthfully: Nonverbal behaviour and strategies during a police interrogation. Psychology, Crime & Law, 12(2), 207-219. https://doi.org/10.1080/10683160512331331328

9.     Vrij, A., & Mann, S. (2001). Telling and detecting lies in a high‐stake situation: The case of a convicted murderer. Applied Cognitive Psychology: The Official Journal of the Society for Applied Research in Memory and Cognition, 15(2), 187-203. https://doi.org/10.1002/1099-0720(200103/04)15:2%3C187::AID-ACP696%3E3.0.CO;2-A

10.  Vrij, A., & Mann, S. (2001). Who killed my relative? Police officers' ability to detect real-life high-stake lies. Psychology, Crime & Law, 7(2), 119-132. https://doi.org/10.1080/10683160108401791

11.  Vrij, A., Granhag, P. A., Mann, S., & Leal, S. (2011). Outsmarting the liars: Toward a cognitive lie detection approach. Current Directions in Psychological Science, 20(1), 28-32. https://doi.org/10.1177%2F0963721410391245