Lie detection - WikipediaAdditionally, those lying are perceived to appear more nervous than those telling the truth (which may be because the voices of those lying are higher pitched), while they also do not appear to be more fidgety, blink more, or have a less-relaxed posture but "are more likely than truth-tellers to press their lips together.آلة lting البوكسيت,How does a lie detector (polygraph) work? | HowStuffWorksThe goal of a lie detector is to see if the person is telling the truth or lying when answering certain questions. When a person takes a polygraph test, four to six sensors are attached to him. A polygraph is a machine in which the multiple ("poly") signals from the sensors are recorded on a single strip of moving paper ("graph").
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