Most people involved in the criminal justice system, or for that matter, any adversarial process, are often involved in attempting to detect lies. As a former prosecutor, people I worked with used all manners and techniques to detect lies, from determining whether or not someone “looked them in the eye” to polygraphs and computerized layer voice analysis. None of these techniques are known to be foolproof. Let’s examine what the research says about lie detection.
A recent meta-analysis of 247 samples was completed by researchers to determine the differences in ability of people to detect lies and the differences of the ability of people to lie without being detected.[i] First, it is well accepted that people are not accurate at detecting lies. The research literature confirms that an individual’s ability to detect a lie by merely watching a person tell it is little more than chance.[ii] In the real world, outside a research laboratory, such as in a court room, people attempt to detect lies by relying on motivational information of the person (does he have a reason to lie), other physical evidence, or other people’s testimony.[iii] If a statement conflicts with what the perceiver believes to be more credible evidence, the perceiver may decide someone is lying.
However, sometimes we have nothing other than the statement of the sender (the person making the statement) to make a judgment about whether or not they are lying. Bond et al (2008) attempted to measure if there were differences in individual’s ability to detect deception. Their answer was no. It does not appear that individuals vary in their ability to detect deception. They state: “These data provide no evidence that the best lie detection performances in this research literature reflect any extraordinary ability. The highest detection rates are no higher than chance would produce.[iv]
These researchers also looked at the differences in perceivers credulity--“the general predisposition to regards others’ statements as truthful.[v] The research showed that there was a difference among perceivers in their credulity. Some people are more likely to believe something as the truth regardless of whether or not it is true, and others are more likely to think something is a lie regardless of whether or not it is true or not. However, neither of these individuals were any better than the other in detecting lies in a laboratory setting.[vi]
Much larger differences were found among individual’s ability to lie without being detected, or their detectability. Some liars are more often detected than others—they are bad liars. The research shows that some people are much better liars than others—they are good at lying. (Not good liars!)[vii]
These researchers also identified another interesting differing trait among people—their natural appearance of credibility. This trait is the largest determinant of a judgment of deception. Some people appear truthful, regardless of whether or not they are telling the truth. Other people appear untruthful, regardless of whether or not they are lying. These researchers hypothesize that this difference is related to facial anatomy. “Some infants are anatomically gifted with an honest-looking face; others are facially disadvantaged. The gifted have baby faces and the disadvantaged look mature.” This trait carries forward throughout their lives.[viii]
The bottom-line of this research is that we all are poor at detecting lies from the observation of the declarant alone. Some people are inherently biased toward believing people are telling the truth, while others are inherently biased toward believing someone is lying. Both are just as wrong. Some liars are better than others. The most important trait in people believing someone is telling the truth or not, is their appearance of credibility. We believe people are telling the truth, regardless of whether or not they are, if they look like people who we believe tell the truth. We disbelieve people, regardless of whether or not they are lying, if they look like people who we believe are liars.
[i] Bond, Charles F. Jr., and Cella M. DePaulo, (2008), Individual Differences in Judging Decemption: Accuracy and Bias, Pyschological Bulletin, Vol. 134. No. 4 pp. 477-492.
[ii] Ibid, p. 477.
[iii] Ibid. p. 488.
[iv]Ibid. p. 483
[v] Ibid. p. 478
[vi] Ibid. p 483
[vii] Ibid. p. 484.
[viii] Ibid. p. 487.
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