Lie detection is the practice of determining whether someone is lying. Activities of the body not easily controlled by the conscious mind are compared under different circumstances. Usually this involves asking the subject control questions where the answers are known to the examiner and comparing them to questions where the answers are not known. Critics claim that "Lie detection" by use of polygraphy has no scientific validity because it is not a scientific procedure.[1]
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Polygraph
Lie detection commonly involves the polygraph. Voice stress analysis may also be commonly used because it can be applied covertly to monitor voice recordings. The polygraph detects changes in body functions not easily controlled by the conscious mind. This includes bodily reactions like skin conductivity and heart rate.[2]
Cognitive Polygraphy
Recent developments that permit non-invasive monitoring using functional transcranial Doppler (fTCD) technique led Njemanze to postulate that successful problem-solving employs a discrete knowledge strategy (DKS) that selects neural pathways represented in one hemisphere, while unsuccessful outcome implicates a non-discrete knowledge strategy (nDKS)[3]. A polygraphic test could be viewed as a working memory task. This suggests that the DKS model may have a correlate in mnemonic operations. In other words, DKS model may have a discrete knowledge base (DKB) of essential components needed for task resolution, while for nDKS, DKB is absent and, hence, a "global" or bi-hemispheric search occurs. Based on the latter premise, a 'lie detector' system was designed as described in United State Patent No. 6,390,979. A pattern of blood-flow-velocity changes is obtained in response to questions that include correct and incorrect answers. The wrong answer will elicit bi-hemispheric activation, from correct answer that activates unilateral response. Cognitive polygraphy based on this system is devoid of any subjective control of mental processes and, hence, high reliability and specificity; however, this is yet to be tested in forensic practice. See also cognitive biometrics.
fMRI
An fMRI can be used to compare brain activity differences for truth and lie.[4] Research does not currently support the use of fMRI to detect deception in "real world individual cases" (Kozel et al., 2004).
In episode 109 of the popular science show Mythbusters, the three members of the build team attempted to fool an fMRI test. Although two of them were unsuccessful, the third was able to successfully fool the machine, suggesting that fMRI technology still requires further development.
Eye Contact
Avoiding eye contact or too much eye contact. Occassional blinking or winking. Looking to the right is the part of the brain with imagination which is when you make up things, looking to the left is the part of the brain where you remember.
Right= Lying Left= Remembering
Brain observations
Electroencephalography is used to detect changes in brain waves.
Brain fingerprinting uses electroencephalography to determine if an image is familiar to the subject. This could detect deception indirectly but is not a technique for lie detecting.
Cognitive chronometry, or the measurement of the time taken to perform mental operations, can be used to distinguish lying from truth-telling. One recent instrument using cognitive chronometry for this purpose is the Timed Antagonistic Response Alethiometer, or TARA.
Drugs
Truth drugs such as sodium thiopental are used for the purposes of obtaining accurate information from an unwilling subject.[5] Information obtained by publicly-disclosed truth drugs has been shown to be highly unreliable, with subjects apparently freely mixing fact and fantasy.[6] Much of the claimed effect relies on the belief of the subject that they cannot tell a lie while under the influence of the drug.
Controversy
In the peer reviewed academic article "Charlatanry in forensic speech science", the authors reviewed 50 years of lie detector research and came to the conclusion that there is no scientific evidence supporting that lie detectors actually work.[7] Lie detector manufacturer Nemesysco sued the academic publisher for libel and forced a removal of the article from the online databases. In a letter to the publisher Nemesysco's lawyers wrote that the authors of the article could be sued for defamation if they wrote on the subject again.[8][9]
The cumulative research evidence suggests that machines do detect deception better than chance, but with significant error rates and that strategies used to "beat" polygraph examinations, so-called countermeasures, may be effective.[10] Despite unreliability, results are admissible in court in some countries such as the United States and Canada.
References
- ^ The Lie Behind the Lie Detector by George W. Maschke and Gino J. Scalabrini
- ^ Forensic Psychology. BBC Science & Nature.
- ^ Njemanze, P. C. (2005). Cerebral lateralization and general intelligence: Gender differences in a transcranial Doppler study. Brain and Language, 92, 234–239
- ^ Ganguli, I. (2007). Watching the Brain Lie: Can fMRI replace the polygraph? The Scientist, 21, 40
- ^ Kapoor, P., Chugh, Y., Kapoor, A. K. & Sinha, U. S. (2008). Torture, terrorist and truth serum. International Journal of Medical Toxicology & Legal Medicine. 10 (2)
- ^ Rowell Jr (1952). Admissibility of Evidence Obtained by Scientific Devices and Analyses. Florida Law Review. 5 (5).
- ^ Eriksson, A. & Lacerda, F. (2007). Charlantry in forensic speech science: A problem to be taken seriously. International Journal of Speech Language and the Law. 14 (2).
- ^ All lies? Scientists threatened with legal action over lie detector article. Stockholm University.
- ^ Threats over Swedish lie detector research. The Local. January 27, 2009.
- ^ The Truth About Lie Detectors. American Psychological Association.
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