A lie detector test, also known as a polygraph test, refers to a standardized examination used to measure and record physiological responses that are believed to be associated with deception. Its main purpose is to determine the truthfulness of an individual's statements or claims. The process typically involves the attachment of various sensors to the subject's body, such as blood pressure cuffs, electrodes on the skin, and respiratory belts, that allow the measurement of indicators such as heart rate, blood pressure, and perspiration levels. During the test, a trained examiner administers a series of questions while monitoring the subject's physiological responses in real-time.
The underlying principle of a lie detector test is based on the notion that physiological changes occur when someone is being dishonest, as lying is often associated with increased stress levels and anxiety. The assumption is that deceptive individuals will exhibit distinctive patterns of physiological responses, such as an elevated heart rate or increased sweating, due to the internal psychological and emotional turmoil associated with lying. However, it is important to note that while these physiological indicators can suggest deception, they are not foolproof evidence of lying, as they can also be triggered by nervousness, fear, or other non-deceptive factors.
Despite its common usage in investigations and legal contexts, lie detector tests have been subject to significant debate regarding their reliability and validity. Critics argue that their accuracy is limited and that the results can be influenced by factors such as the subject's mental state, the skill of the examiner, and the subject's familiarity with the test procedure. Additionally, many jurisdictions either outright ban or heavily regulate the use of polygraph tests due to their perceived lack of scientific basis and potential for false positive or false negative results.
