Essay on A Polygraph Test

Essay on A Polygraph Test

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A polygraph test can record a person's breathing rate, pulse, blood pressure, perspiration and other significant physiological changes that suggest a person is lying, but it should not be used as evidence in a court of law because it does not provide reliable proof of a person's physical reaction to the stress of lying.
A lie detector is a machine that tries to detect if a person is lying (“Lie detector.”31 of 2). Over the centuries different people and cultures have tried to find a way to see if someone is lying. The Chinese would make a person who was a suspect of a crime chew and spit out some rice powder after being questioned. If the powder was dry the person was guilty because they thought someone whose mouth is dry is guilty and if it was moist they were innocent (Lie detector1 1 of 2). Also the english would give a suspect a slice of bread and cheese if they could swollow it they were innocent, but if they could not they were guilty this is saying that people would have trouble swolling if they were guilty (Lie detector1 1 of 2). “The first scientific instrument designed to measure physiological respones to questioning was used in 1895 by an italian criminologist, Cesare Lombroso, he took an existing device called a hydrosphygmegraph – a small, water-filled tank in which a subjects hand was submerged. The tank was then sealed by a thin sheet of rubber. Any changes in the subject’s pulse or blood pressure would be transferred through the hand to the water and would change the water level. When the water level changed, a difference in air pressure resulted. The air pressure was monitored by an air-filled tube connected to a revolving drum. Lombroso’s device coud detect any physical changes in pulse and blood pressure. Some...


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...n Context. Web. 19 November 2013."Lie detector."1 UXL Science. U*X*L, 2008 Student Resources in Context. Web. 14 November 2013.
"Lie Detector."2 Columbia Electronic Encyclopedia, 6Th Edition (2013): 1. Middle Search Plus. Web. 26 Nov. 2013.
"Lie detectors blend fact and fiction." Science News 1 Jan. 2011: 26. Student Resources in Context. Web. 20 Novenber 2013.
McLaughlin, Sabrina. "Liar, liar! Do polygraphs tell the truth?" Curent Science, a Weekly Reader puplication 5 Dec. 2003: 10+. Student Resources in Context. Web. 20 November 2013.
Perina, Kaja. "Brain scans may be foolproof lie detectors. (Truth Serum)." Psychology Today Jan.-Feb. 2002: \\. Student Resources in Context. Web. 26 Nov. 2013.
Ruscio, John. "Exploring controversies in the art and science of polygraph testing." Skeptical Inquirer Jan.-Feb. 2005: 34+. Student Resources in Context. Web. 2 Dec. 2013.

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