Lie
Detection

The question of whether lies can be detected reliably through nonverbal has been the subject of frequent study. While people in many cultures believe that deception can be indicated by behaviors such as looking away, fidgeting, or stammering, this is not supported by research. A 2019 review of research on deception and its detection through nonverbal behavior concludes that people tend to overestimate both the reliability of nonverbal behavior as an indicator of deception, and their ability to make accurate judgements about deception based on nonverbal behavior.

Polygraph " lie detector " machines measure the physiological stress a subject endures in a number of measures while giving statements or answering questions. Spikes in stress indicators are purported to reveal lying. The accuracy of this method is widely disputed. In several well-known cases, application of the technique has been shown to have given incorrect results. Nonetheless, it remains in use in many areas, primarily as a method for eliciting confessions or employment screening. The unreliability of polygraph results is the basis of the exclusion of such evaluations as admissible evidence in many courts, and the technique is generally perceived to be an example of pseudoscience.

A recent study found that composing a lie takes longer than telling the truth and thus, the time taken to answer a question may be used as a method of lie detection. Instant answers with a lie may be proof of a prepared lie. A recommendation provided to resolve that contradiction is to try to surprise the subject and find a midway answer, not too quick, nor too long.
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