polygraph polygraph a polygraph, often incorrectly referred to as a lie detector test, is a device or procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a person 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; however, there are no specific physiological reactions associated with lying, making it difficult to identify factors that separate those who are lying from those who are telling the truth. american inventor leonarde keeler (1903–1949) testing his improved lie-detector on kohler, a former witness for the prosecution at the 1935 trial of richard hauptmann 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, dea, cia, nsa, and many police departments such as the lapd and the virginia state police 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. the average cost to administer the test in the united states is more than $700 and is part of a $2 billion industry. assessments of polygraphy by scientific and government bodies generally suggest that polygraphs are highly inaccurate, may easily be defeated by countermeasures, and are an imperfect or invalid means of assessing truthfulness. a comprehensive 2003 review by the national academy of sciences of existing research concluded that there was "little basis for the expectation that a polygraph test could have extremely high accuracy." the american psychological association states that "most psychologists agree that there is little evidence that polygraph tests can accurately detect lies." the control question test, also known as the probable lie test, was developed to overcome or mitigate the problems with the relevant-irrelevant testing method. although the relevant questions in the probable lie test are used to obtain a reaction from people who are lying, the physiological reactions that distinguish lies may also occur in innocent individuals who fear false detection or feel passionately that they did not commit a 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. 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" ("is your name fred?"), others are "diagnostic" questions, and the remainder are the "relevant questions" 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. criticisms have been given regarding the validity of the administration of the control question technique. 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 administering the questions. an alternative is the guilty knowledge test (gkt), or the concealed information test, which is used in japan. 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. effectiveness although there is some debate in the scientific community regarding the efficacy of polygraphs, assessments of polygraphy by scientific and government bodies generally suggest that polygraphs are inaccurate, may be defeated by countermeasures, and are an imperfect or invalid means of assessing truthfulness. despite claims that polygraph tests are between 80% and 90% accurate by advocates, the national research council has found no evidence of effectiveness. in particular, studies have indicated that the relevant–irrelevant questioning technique is not ideal, as many innocent subjects exert a heightened physiological reaction to the crime-relevant questions. the american psychological association states "most psychologists agree that there is little evidence that polygraph tests can accurately detect lies." in 2002, a review by the national research council found that, in populations "untrained in countermeasures, specific-incident polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection". the review also warns against generalization from these findings to justify the use of polygraphs—"polygraph accuracy for screening purposes is almost certainly lower than what can be achieved by specific-incident polygraph tests in the field"—and notes some examinees may be able to take countermeasures to produce deceptive results. in the 1998 us supreme court case united states v. scheffer, the majority stated that "there is simply no consensus that polygraph evidence is reliable unlike other expert witnesses who testify about factual matters outside the jurors' knowledge, such as the analysis of fingerprints, ballistics, or dna found at a crime scene, a polygraph expert can supply the jury only with another opinion." the supreme court summarized their findings by stating that the use of polygraph was "little better than could be obtained by the toss of a coin." in 2005, the 11th circuit court of appeals stated that "polygraphy did not enjoy general acceptance from the scientific community". in 2001, william iacono, professor of psychology and neuroscience at the university of minnesota, concluded: although the cqt may be useful as an investigative aid and tool to induce confessions, it does not pass muster as a scientifically credible test. cqt theory is based on naive, implausible assumptions indicating (a) that it is biased against innocent individuals and (b) that it can be beaten simply by artificially augmenting responses to control questions. although it is not possible to adequately assess the error rate of the cqt, both of these conclusions are supported by published research findings in the best social science journals (honts et al., 1994; horvath, 1977; kleinmuntz & szucko, 1984; patrick & iacono, 1991). although defense attorneys often attempt to have the results of friendly cqts admitted as evidence in court, there is no evidence supporting their validity and ample reason to doubt it. members of scientific organizations who have the requisite background to evaluate the cqt are overwhelmingly skeptical of the claims made by polygraph proponents. polygraphs measure arousal, which can be affected by anxiety, anxiety disorders such as posttraumatic stress disorder (ptsd), nervousness, fear, confusion, hypoglycemia, psychosis, depression, substance induced states (nicotine, stimulants), substance withdrawal state (alcohol withdrawal) or other emotions; polygraphs do not measure "lies". a polygraph cannot differentiate anxiety caused by dishonesty and anxiety caused by something else. since the polygraph does not measure lying, the silent talker lie detector inventors expected that adding a camera to film microexpressions would improve the accuracy of the evaluators. this did not happen in practice according to an article in the intercept. us congress office of technology assessment in 1983, the us congress office of technology assessment published a review of the technology and found that there is at present only limited scientific evidence for establishing the validity of polygraph testing. even where the evidence seems to indicate that polygraph testing detects deceptive subjects better than chance, significant error rates are possible, and examiner and examinee differences and the use of countermeasures may further affect validity. national academy of sciences in 2003, the national academy of sciences (nas) issued a report entitled "the polygraph and lie detection". the nas found that "overall, the evidence is scanty and scientifically weak," concluding that 57 of the approximately 80 research studies that the american polygraph association relied on to reach their conclusions were significantly flawed. these studies did show that specific-incident polygraph testing, in a person untrained in counter-measures, could discern the truth at "a level greater than chance, yet short of perfection". however, due to several flaws, the levels of accuracy shown in these studies "are almost certainly higher than actual polygraph accuracy of specific-incident testing in the field". by adding a camera, the silent talker lie detector attempted to give more data to the evaluator by providing information about microexpressions. however adding the silent talker camera did not improve lie detection and was very expensive and cumbersome to include according to an article in the intercept. when polygraphs are used as a screening tool (in national security matters and for law enforcement agencies for example) the level of accuracy drops to such a level that "its accuracy in distinguishing actual or potential security violators from innocent test takers is insufficient to justify reliance on its use in employee security screening in federal agencies." the nas concluded that the polygraph "may have some utility but that there is "little basis for the expectation that a polygraph test could have extremely high accuracy". the nas conclusions paralleled those of the earlier united states congress office of technology assessment report "scientific validity of polygraph testing: a research review and evaluation". similarly, a report to congress by the moynihan commission on government secrecy concluded that "the few government-sponsored scientific research reports on polygraph validity (as opposed to its utility), especially those focusing on the screening of applicants for employment, indicate that the polygraph is neither scientifically valid nor especially effective beyond its ability to generate admissions". despite the nas finding of a "high rate of false positives," failures to expose individuals such as aldrich ames and larry wu-tai chin, and other inabilities to show a scientific justification for the use of the polygraph, it continues to be employed. countermeasures several proposed countermeasures designed to pass polygraph tests have been described. there are two major types of countermeasures: "general state" (intending to alter the physiological or psychological state of the subject during the test), and "specific point" (intending to alter the physiological or psychological state of the subject at specific periods during the examination, either to increase or decrease responses during critical examination periods). general state: asked how he passed the polygraph test, central intelligence agency officer turned kgb mole aldrich ames explained that he sought advice from his soviet handler and received the simple instruction to: "get a good night's sleep, and rest, and go into the test rested and relaxed. be nice to the polygraph examiner, develop a rapport, and be cooperative and try to maintain your calm". additionally, ames explained, "there's no special magic... confidence is what does it. confidence and a friendly relationship with the examiner... rapport, where you smile and you make him think that you like him". specific point: other suggestions for countermeasures include for the subject to mentally record the control and relevant questions as the examiner reviews them before the interrogation begins. during the interrogation the subject is supposed to carefully control their breathing while answering the relevant questions, and to try to artificially increase their heart rate during the control questions, for example by thinking of something