The Purpose of the Lie Detector
A lie detector, or polygraph, is a mechanical device that measures the physical responses of your body as you are asked a series of questions. Theoretically, when you lie, your level of stress increases and the increased stress will show up in the polygraph's measurements.
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History
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The first lie detector was created in the 1890s by Cesare Lombroso, an Italian criminologist who used a mechanical device to monitor a suspect's heart rate and blood pressure while he was undergoing police interrogation. In the years that followed, other physicians and criminologists added their own measurements and came up with specific patterns of questions to make spotting deception easier.
Features
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The modern polygraph measures a suspect's breathing, heart rate and perspiration. The results of each measurement show up immediately in the format of three graphs following the suspect's answer to each question, hence the term polygraph.
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Uses
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Laws as to the admissibility of polygraph results are handled at the state level. Thirty-five states allow the use of lie detector results in criminal court, as long as both the prosecution and the defense agree.
Polygraphs also have limited uses among employers in the private sector, although these uses were curtailed by the 1988 Employee Polygraph Protection Act.
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References
- Photo Credit handcuffs image by Daniel Wiedemann from Fotolia.com
