Compare and contrast the traditional method of polygraphs and the newer method of fMRI scans to "detect lying.". Include in your answer what each procedure measures, how each is administered, and the limitations and accuracy of these methods

What will be an ideal response?

Answer will include that the most popular method for detecting falsehoods measures the bodily changes that accompany emotion. However, the accuracy of "lie detector" or polygraph tests is doubtful, and they can be a serious invasion of privacy. Although popularly known as a lie detector because the police use it for that purpose, in reality the polygraph is not a lie detector at all. A suspect is questioned while "hooked up" to a polygraph, which typically records changes in heart rate, blood pressure, breathing, and the galvanic skin response (GSR). The GSR is recorded from the hand by electrodes that measure skin conductance, or, more simply, sweating. Because the device records only general emotional arousal, it can't tell the difference between lying and fear, anxiety and excitement. Many cases have been documented in which innocent people were harmed by the use of polygraph evidence. To minimize this problem, skilled polygraph examiners might use the guilty knowledge test. A series of multiple-choice questions are asked; one answer is correct. For example, one question might be: "Was the gun that killed Hensley a) a Colt, b) a Smith & Wesson, c) a Walther PPK, or d) a Luger? A guilty person who knew which gun she had used may show an elevated response to the correct answer. Since an innocent person couldn't know which gun was involved, she could only respond similarly to all four alternatives. Although proponents of lie detection claim it is 95 percent accurate, errors may occur even when questioning is done properly. But in one study, accuracy was dramatically lowered when people thought about past emotional experiences as they answered irrelevant questions. Similarly, the polygraph may be thrown off by self-inflicted pain, by tranquilizing drugs, or by people who can lie without anxiety. Worst of all, the test is much more likely to label an innocent person guilty, rather than a guilty person innocent. In studies involving real crimes, an average of one innocent person in five was rated as guilty by the lie detector. For such reasons, the National Academy of Sciences has concluded that polygraph tests should not be used to screen employees. A new technique involves the use of brain scans like fMRI, which directly measures brain activity, thus bypassing the traditional approach of measuring indirect signs of emotional arousal. For example, researchers have found that different brain areas are involved in telling a lie. Psychiatrist Daniel Langleben theorizes that a liar must inhibit telling the truth in order to lie. Thus, extra brain areas must be activated to tell a lie, which can be seen in brain images when people are lying.