Lie detection is the practice of determining whether someone is lying. A lie (also called prevarication) is a type of Deception in the form of an untruthful statement especially with the intention to deceive others often with the further 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.

Lie detection commonly involves the polygraph. A polygraph (popularly referred to as a Lie detector) is an instrument that measures and records several physiological responses such as Blood pressure Voice stress analysis may be also be more commonly used because it can be applied covertly to monitor voice recordings. Voice Stress Analysis (VSA is a Lie detection technology- and uniquely deployed as such- which is newer than the Polygraph, but still controversial

The polygraph detects changes in body functions not easily controlled by the conscious mind. A polygraph (popularly referred to as a Lie detector) is an instrument that measures and records several physiological responses such as Blood pressure This includes bodily reactions like skin conductivity and heart rate.

An fMRI can be used to compare brain activity differences for truth and lie^[1]. Functional MRI or functional Magnetic Resonance Imaging (fMRI is a type of specialized MRI scan In episode 109 of the popular science show Mythbusters, the three members of the build team attempted to fool an fMRI test. MythBusters is a Popular science Television program produced by Australian firm Beyond Television Productions originally for the Although two of them were unsuccessful, the third was able to successfully fool the machine, suggesting that fMRI technology still requires further development.

Electroencephalography is used to detect changes in brain waves.

Brain fingerprinting uses electroencephalography to determine if an image is familiar to the subject. "Brain Fingerprinting" is a controversial forensic science technique that determines whether specific information is stored in a subject’s brain by measuring electrical Brainwave This could detect deception indirectly but is not a technique for lie detecting.

Truth drugs such as sodium thiopental are used for the purposes of obtaining accurate information from an unwilling subject. A truth drug (or truth serum) is a Psychoactive drug used to attempt to obtain information from an unwilling subject most often by a police intelligence or military The fictional truth drug Hyoscine-pentothal does not describe real pentothal accurately Information obtained by publicly-disclosed truth drugs has been shown to be highly unreliable, with subjects apparently freely mixing fact and fantasy. 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.

Cognitive chronometry, or the measurement of the time taken to perform mental operations, can be used to distinguish lying from truth-telling. Cognitive chronometry refers to the systematic measurement of response time as a means of illuminating either mental operations or mental associations One recent instrument using cognitive chronometry for this purpose is the Timed Antagonistic Response Alethiometer, or TARA. The Timed Antagonistic Response Alethiometer, or TARA is a type of Lie detection technique that relies upon Cognitive chronometry.

Cognitive Polygraphy

Recent developments that permit noninvasive 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)^[2]. 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 Wrong and Correct 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. Biometrics ( ancient Greek: bios life metron measure refers to two very different fields of study and application

REFERENCES

1. ^ Ganguli, I. (2007). Watching the Brain Lie Can fMRI replace the polygraph? The Scientist, 21, 40
2. ^ Njemanze, P. C. (2005). Cerebral lateralization and general intelligence: Gender differences in a transcranial Doppler study. Brain and Language, 92, 234–239

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