Authorities on investigative interviewing have long emphasized the importance of developing the ability to detect deception by observing nonverbal behaviour. As a result, deception detection has come to be regarded by many as a fundamental investigative skill. Empirical research on the relationship between nonverbal behaviour and deception, however, indicates that there may be an unwarranted over-reliance on this approach to investigation. Specifically, studies indicate that an individual's overall ability to detect deception from nonverbal behaviour is about as accurate as chance. While it is inevitable that assessments of credibility will be made during investigations, it is argued that such assessments are best made tentatively in the context of an overarching analysis, as constructed from all suspect, victim, and witness interviews, as well as any physical evidence, rather than on the basis of a single investigative interview and supposed specific behavioural indicators of deception. This article reviews several behavioural deception-detection claims and the corresponding empirical research. Based on this review, several recommendations are proposed with regard to the utility and employment of deception-detection as an investigative tool.
"No man was ever so much deveived by another as by himself." Greville (1554-1628)
The idea that liars can be separated from truth tellers by observing their nonverbal behaviour, or body language, is a widely held belief among investigative professionals as well as the general public. For the most part, this belief is based on the premise that the internal stress generated by engaging in deception will manifest itself in the form of distinctive nonverbal behaviour, or cluster of behaviours, that can be used to differentiate deceivers from non-deceivers. It may be argued that this belief is so well entrenched that it has become a standard reference in literature, both fictional and non-fictional. For example, Sir Arthur Conan Doyle (1890) certainly reflected the belief in deception detection through his character Sherlock Holmes, who believed that it was impossible to deceive one trained in the observation of nonverbal behaviour, and that he could, "by a momentary expression, a twitch of a muscle or a glance of an eye ... fathom a man's inmost thoughts". Other, real-life, historical figures have echoed Holmes's words in their own writings. Francis Bacon (1601), for example, wrote that "[t]he discovery of a man by the lines and expressions of his countenance is a great weakness and betraying". Similarly, Sigmund Freud (1901) argued that, "[h]e that has eyes to see and ears to hear may convince himself that no mortal can keep a secret. If his lips are silent he chatters with his fingertips and betrayal oozes out of him at every pore."
Like those quoted above, contemporary writers have also perpetuated these notions of deception detection and nonverbal behaviour (e.g., Brougham, 1992; Inbau, Reid, Buckley, & Jayne, 2001; Walters, 1996, 2000). In fact, the idea that people can reliably detect deception by observing body language is so persistent that many consider behavioural deception-detection to be a fundamental investigative skill and one that can be acquired through training and experience, and employed reliably in the field (e.g., Brougham 1992; Navarro & Schafer, 2001; Rabon, 1992). Although the ability to detect deception by interpreting nonverbal behaviour would be a powerful investigative tool allowing investigators to efficiently employ scarce resources in their search for the truth, it may be argued that pursuing this option may cause more harm than good if there is little empirical evidence to support its effectiveness. Investigative professionals therefore have a responsibility to examine the basis for the many apparently authoritative claims made on behalf of nonverbal deception-detection. If scientific research supports the claim that deception can validly and reliably be detected by interpreting nonverbal behaviour, then this skill should be taught as part of a core investigative curriculum. If, on the other hand, research indicates that it is not possible to detect deception in this manner, then the continued promotion of behavioural deception-detection as a fundamental investigative skill should be approached cautiously.
The purpose of this article is to review the current professional and academic beliefs about two of the more commonly cited nonverbal cues to deception (i.e., eye contact/eye movement and body movement) and compare these beliefs to relevant scientific research in order to demonstrate the dearth of empirical evidence for these beliefs. The overarching contention of this paper is that there are few, if any, reliable scientific findings to support any claim that these cues are valid indicators of deception. The lack of empirical scientific support for virtually all deception-detection techniques is also discussed and a review of potential reasons for the continued belief in these techniques, despite the lack of empirical support, is presented.
The above position on the deception-detection issue is consistent with a generally sceptical scientific perspective (Sagan, 1994) on claims of all sorts, including a belief that: (a) many things are possibly true, but the burden of proof to support a claim rests squarely on the shoulders of those making it, and (b) people are prone to believing some claims based solely on their own experience, but personal experience is itself prone to judgment biases and outright errors. Some readers might not see an immediate connection between their views on "science" and determining the validity of deception-detection techniques, but the scientific perspective is not limited to understanding what can be mixed in a test tube or calculated with an elaborate equation. The scientific method was developed and has evolved primarily to find out "how the world works" in a variety of contexts by using techniques that eliminate, or at least minimize, the potentially biasing effects of relying on mere personal experience.
It is worth noting that it was personal experience that led our ancestors to …