A polygraph measures physiological traits, heart rate, blood pressure, respiratory rate and electro-dermal activity, to determine whether a person is telling the truth or not. Because the polygraph test measures bodily responses, a data subject can attempt to alter her bodily responses in order to interfere with the test. Several common ways to undermine the test include: taking sedatives to reduce anxiety; using antiperspirant to prevent sweating; and positioning pins or biting parts of the mouth after each question to demonstrate a constant physiological response. It's because of the ability to alter bodily response, that the scientific community remains divided about the reliability of polygraphs. |