Verbal Lie Detection
The most commonly used lie detection methods in investigations and courtrooms focus on the verbal content of statements to assess their veracity [1]. Verbal content refers to what is being said and does not relate to how things are being said (i.e., non-verbal behavior). Two well-known methods are the so-called ‘Criteria-based Content Analysis’ (CBCA) [2] and ‘Reality Monitoring’ (RM) [3]. These methods are based on the assumption that truthful statements based on actual experiences differ in quality and content from fictitious accounts [4][5]. For example, a person that has actually experienced an event can give a thorough explanation of perceptual, emotional and spatial information, types of details that are often lacking when people lie.
When using these lie detection methods, a statement is analyzed in regard to the presence or absence of certain verbal cues, which are thought to indicate truthfulness (e.g. richness in detail). A higher occurrence of these cues thereby indicates increased likelihood of truthfulness, meaning that the cues used in CBCA in RM are truth cues. CBCA in particularly, has a well-established history of application within the criminal justice system, especially in child sexual abuse cases, for which it was originally developed [6].
Embedded Lying
When talking to my friends about lying, most of them say that they use past experiences to make up a story. In legal psychology, this deceptive strategy is called ‘embedded lying’ and research shows that when free to choose a deceptive strategy, between 67% to 87% of people will choose to engage in embedded lies [7]. Although this is a common deceptive strategy, lie detection research and practitioners in the field, such as investigator and expert witnesses, mostly focus on deception as a unitary concept [8]. A lie, is a lie, is a lie. Therefore, they usually do not consider the possibility of a suspect, witness or alleged victim is telling an embedded lie.
As previously mentioned, when engaging in embedded lies, liars incorporate deception into a true statement about a previous experience. Since embedded lies do not contain the same amount of deception as a ‘purely’ deceptive statement, they may very well differ in verbal qualities. Research has shown that embedded lies contain significantly more details than ‘pure‘ lies [8]. This creates a problem for the methods that are currently most commonly used in practice: CBCA and Reality Monitoring only consider similarities and differences between ‘pure’ truths and lies.
Embedded Lies: A danger to verbal credibility assessment?
When a suspect tells an embedded lie during their interrogation, such as describing activities the day before the crime rather than on the day of the crime, a police officer may perceive the statement as truthful. This is because the suspect's level of detail is similar to that of a genuine statement. Indeed, that would make sense based on the research that is underlying CBCA and Reality Monitoring. Truthful and deceptive statements are thought to differ in quality and content and if no such differences are being found, a deceptive statement may be wrongfully assessed as a true statement.
The question is whether such a faulty judgment is likely to occur within the context of embedded lies. Since the literature on the effects of embedded lies on verbal content of statements is very limited, research has no clear answer for this question. However, it is to be expected that embedded lies differ in quality from ‘pure’ lies, especially since they are often based on lived experiences. Hence, it is quite likely that they are easily assessed as truthful, although empirical research is necessary to test this hypothesis.
Incorrect assessment of embedded lies can of course have detrimental effects on court cases, especially when there is no corroborating evidence available and the jury and judge can only rely on statements for their verdict. In a case where one statement is put against the other, wrongfully assessing a deceptive statement as truthful when using highly regarded instruments, such as CBCA and RM, might result in a wrongful incarceration or acquittal.
Therefore, it is important for deception research to investigate the similarities and differences between ‘pure’ truths, lies and embedded lies. Embedded lies should be explored thoroughly. This involves assessing whether different proportions of lie and truth, as well as different content included in the embedded lie, may result in differences regarding verbal content. Findings from such research will have important implications for practice. For instance, investigators and expert witnesses can learn how to reliably differentiate embedded lies from truths using specific cues. Moreover, research may help developing strategies to make it more difficult for people to use embedded lying in context such as suspect interviewing.
This blog post is written by Rafail Dimopoulos. Rafail recently graduated from the Legal Psychology Master at Maastricht University and is now looking at receiving a PhD grant to conduct research on embedded lies.
References
[1] Vrij, A. (2019). Deception and truth detection when analyzing nonverbal and verbal cues. Applied Cognitive Psychology, 33(2), 160-167.
[2] Steller, M., & Köhnken, G. (1989). Criteria-based content analysis. The suggestibility of children's recollections.
[3] Johnson, M. K., & Raye, C. L. (1981). Reality monitoring. Psychological review, 88(1), 67.
[4] Amado, B. G., Arce, R., & Fariña, F. (2015). Undeutsch hypothesis and Criteria Based Content Analysis: A meta-analytic review. The European Journal of Psychology Applied to Legal Context, 7(1), 3-12.
[5] Sporer, S. L. (2004). Reality monitoring and detection of deception. In P.-A. Granhag & L. Strömwall (Eds.), The detection of deception in forensic contexts (pp. 64–101). Cambridge University Press. https://doi.org/10.1017/CBO9780511490071.004
[6] Vrij, A. (2005). Criteria-Based Content Analysis: A Qualitative Review of the First 37 Studies. Psychology, public policy, and law, 11(1), 3.
[7] Leins, D. A., Fisher, R. P., & Ross, S. J. (2013). Exploring liars’ strategies for creating deceptive reports. Legal and Criminological Psychology, 18(1), 141-151.
[8] Verigin, B. L., Meijer, E. H., & Vrij, A. (2020). Embedding lies into truthful stories does not affect their quality. Applied Cognitive Psychology, 34(2), 516-525.
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