A polygraph, most commonly referred to as a lie detector, is a machine that is used by law enforcement to test the physiological responses of individuals to certain questions.  Despite its colloquial name, the polygraph does not detect lies and most polygraph examiners will say that they do not test specifically for lies, but for deceptive reactions.

Polygraphs are used under the theory that most people do not lie or deceive without some feelings of anxiety or nervousness.  This stems from the idea that most people either feel bad that they are lying or are afraid that they will get caught or will be in trouble if they lie.  It is this fear and guilt that produces the anxiety and nervousness.  When a person feels this way they exhibit difficult to detect involuntary physiological changes that can, theoretically, be detected with a polygraph.

A polygraph test can help in numerous situations to help uncover the truth. They are incredibly useful and accurate, with an average success rate of 90% or higher. There is no pain associated with the test and they are both affordable and accessible

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