trical activity produced by the brain as recorded from electrodes placed on the scalp. -- Reference Wikipedia.org back to 236)
237 "introduced himself as Mr. John Reid ..." "John Edward Reid, American criminologist developed a Polygraph in 1945 which was a scientific recording device designed to register a person's bodily responses to being questioned. Popularly known as ab lie detector, the polygraph has been used chiefly
in criminal investigations, although it is also used in employment and security screening practices. Because no machine can unerringly recognize when a person is lying, the polygraph results are used in conjunction
with other evidence, observations, and information. Emotional
stress reflected by this test, for instance, need not be due to lying.
On the other hand, a subject maybe a pathological liar and therefore show no measurable bodily responses when giving false answers. Ordinary nervousness, individual physical
or mental abnormalities, discomfort, excessive
pretest interrogation, or indifference to a question also affect test accuracy. The polygraph can, however, provide a basis for an evaluation of whether or not the subject's answers are truthful. This test has also been helpful in exonerating innocent persons accused of crimes. A polygraph is actually several instruments combined to simultaneously record
changes in blood pressure, pulse, and respiration. The electrical conductivity of the skin's surface can also be measured—increased sweat-gland activity reduces the skin's ability to carry electrical current" -- Reference Wikipedia.org back to 237)
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