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A polygraph, popularly referred to as a lie detector, measures and records several physiological indices such as blood pressure, pulse, respiration, and skin conductivity while the subject is asked and answers a series of questions. The belief underpinning the use of the polygraph is that deceptive answers will produce physiological responses that can be differentiated from those associated with non-deceptive answers; the polygraph is one of several devices used for lie detection. The polygraph was invented in 1921 by John Augustus Larson, a medical student at the University of California at Berkeley and a police officer of the Berkeley Police Department in Berkeley, California.〔(【引用サイトリンク】publisher=International League of Polygraph Examiners )〕 The polygraph was on the ''Encyclopædia Britannica'' 2003 list of greatest inventions, described as inventions that "have had profound effects on human life for better or worse." The efficacy of polygraphs is debated in the scientific community. In 2001, a significant fraction of the scientific community considered polygraphy to be pseudoscience.〔Iacono, W.G. "Forensic 'lie detection': Procedures without scientific basis," ''Journal of Forensic Psychology Practice'', Vol. 1 (2001), No. 1, pp. 75-86.〕 In 2002, a review by the National Academies of Science found that in populations untrained in countermeasures, polygraph testing can discriminate lying from truth telling at rates above chance, though below perfection. These results apply only to specific events and not to screening where it is assumed that polygraph would work less well.〔 Effectiveness may also be worsened by countermeasures.〔 In some countries polygraphs are used as an interrogation tool with criminal suspects or candidates for sensitive public or private sector employment. US law enforcement and federal government agencies such as the FBI and the CIA and many police departments such as the LAPD use polygraph examinations to interrogate suspects and screen new employees. Within the US federal government, a polygraph examination is also referred to as a psychophysiological detection of deception (PDD) examination. Polygraph testing is designed to analyze the physiological reactions of subjects. However, research has indicated that there is no specific physiological reaction associated with lying and that the brain activity and mechanisms associated with lying are unknown, making it difficult to identify factors that separate liars from truth tellers. Polygraph examiners also prefer to use their own individual scoring method, as opposed to computerized techniques, as they may more easily defend their own evaluations.〔Iacono, W. G. (2008). Effective policing: Understanding how polygraph tests work and are used. Criminal Justice and Behavior, 34(10), 1295-1308.〕 The validity of polygraph testing is again called in to question with the relevant-irrelevant testing technique, designed to gauge reactions of subjects against crime questions and other non-crime related questions. Studies have indicated that this questioning technique is not ideal, as many innocent subjects exert a heightened physiological reaction to the crime relevant questions.〔 The control question test, also known as the probable lie test, was developed to combat the issues with the relevant-irrelevant testing method. Although the relevant questions in the probable lie test are used to obtain a reaction from liars, it can also gain a reaction from the innocent subject who is afraid of false detection. The physiological reactions that "distinguish" liars, may also occur in individuals who fear a false detection, or feel passionately that they did not commit the crime. Therefore, although a physiological reaction may be occurring, the reasoning behind the response may be different. Further examination of the probable lie test has indicated that it is biased against innocent subjects. Those who are unable to think of a lie related to the relevant question, will automatically fail the test.〔 Iacono, W. G. (2008). Effective policing: Understanding how polygraph tests work and are used. Criminal Justice and Behavior, 34(10), 1295-1308.〕 Polygraph examiners, or polygraphers, are licensed or regulated in some jurisdictions.〔(【引用サイトリンク】title=State licensing boards )〕 The American Polygraph Association sets standards for courses of training of polygraph operators, though it does not certify individual examiners.〔(【引用サイトリンク】title=APA Accredited Polygraph Programs )〕 ==Testing procedure== The examiner typically begins polygraph test sessions with a pre-test interview to gain some preliminary information which will later be used to develop diagnostic questions. Then the tester will explain how the polygraph is supposed to work, emphasizing that it can detect lies and that it is important to answer truthfully. Then a "stim test" is often conducted: the subject is asked to deliberately lie and then the tester reports that he was able to detect this lie. Guilty subjects are likely to become more anxious when they are reminded of the test's validity. However, there are risks of innocent subjects being equally or more anxious than the guilty. Then the actual test starts. Some of the questions asked are "irrelevant" or IR ("Is your name Fred?"), others are "diagnostic" questions, and the remainder are the "relevant questions", or RQ, that the tester is really interested in. The different types of questions alternate. The test is passed if the physiological responses to the diagnostic questions are larger than those during the relevant questions (RQ). Criticisms have been given regarding the validity of the administration of the Control Question Technique (CQT). The CQT may be vulnerable to being conducted in an interrogation-like fashion. This kind of interrogation style would elicit a nervous response from innocent and guilty suspects alike. There are several other ways of administrating the questions. An alternative is the Guilty Knowledge Test (GKT), or the Concealed Information Test (CIT), which is being used in Japan.〔 (【引用サイトリンク】 title = The Admissibility of Polygraph Evidence in Criminal Courts )〕 The administration of this test is given to prevent potential errors that may arise from the questioning style. The test is usually conducted by a tester with no knowledge of the crime or circumstances in question. The administrator tests the participant on their knowledge of the crime that would not be known to an innocent person. For example: "Was the crime committed with a .45 or a 9 mm?" The questions are in multiple choice and the participant is rated on how they react to the correct answer. If they react strongly to the guilty information, then proponents of the test believe that it is likely that they know facts relevant to the case. This administration is considered more valid by supporters of the test because it contains many safeguards to avoid the risk of the administrator influencing the results.〔For more info on the GKT, see the (The Guilty Knowledge Test (GKT) as an Application of Psychophysiology: Future Prospects and Obstacles ).〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Polygraph」の詳細全文を読む スポンサード リンク
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