Opinion ID: 2623542
Heading Depth: 4
Heading Rank: 3

Heading: Rate of error.

Text: {28} The third factor of the Daubert/Alberico analysis requires us to examine the known or potential rate of error of the control question polygraph. Anderson, 118 N.M. at 291, 881 P.2d at 36. With regard to the rate of error of the control question polygraph, the district court concluded that [t]he potential rate of error is vague and unreliable and because the base rate is unknown the reliability of test results as reflected in an actual percentage misrepresents the confidence level in the test. {29} As noted in the preceding section of this opinion, a number of polygraph validation studies have been conducted and subsequently published. A review of those studies revealed that the median accuracy index of the polygraph in laboratory studies is 0.86 with an interquartile range of 0.81 to 0.91. NAS Report, supra, at 122. The controlled question test specifically had a median accuracy index of 0.85, with an interquartile range from 0.83 to 0.90. Id. at 125. The field studies reviewed had a median accuracy index of 0.89, with a range from 0.711 to 0.999. Id. The interquartile range of accuracy indexes for all the studies, laboratory and field, was 0.81 to 0.91. Id. at 126. Based on the foregoing, the NAS Report concluded the empirical data clearly indicate that for several populations of naive examinees not trained in countermeasures, polygraph tests for event-specific investigation detect deception at rates well above those expected from random guessing. Id. at 149. The State argues the high accuracy rates derived from the studies are invalid for a number of reasons. {30} Specifically, the NAS Report was concerned that the high accuracy rates for polygraph examinations in the studies may not correspond with what can be expected when the polygraph is used in real-life situations. The hypothesis underlying the control question polygraph technique is that physiological responses increase the more concerned the subjects are about being deceptive, which, if true, means polygraph accuracy in laboratory models [might] be on average somewhat below true accuracy in field practice, where the stakes are higher. Id. at 127. However, the NAS Report noted that [t]here is a plausible contrary hypothesis... in which examinees who fear being falsely accused have strong emotional responses that mimic those of the truly deceptive, in which case field conditions might have more false-positive errors than are observed in the laboratory and less accuracy. Id. Furthermore, the NAS Report noted that [s]ubstantial experience with clinical diagnostic and screening tests suggests that laboratory models, as well as observational field studies of the type found in the polygraph literature, are likely to overstate true polygraph accuracy. Id. at 128. {31} The NAS Report also identified several specific issues that may affect the accuracy of any polygraph examinations that have not been fully researched. First, while individual differences in physiological makeup, personality traits, and sociocultural group identity may affect the accuracy of the polygraph, the research on these individual differences is scant. See id. at 134-37. Second, while examiner expectancies of guilt may influence either the examiners' judgments of the polygraph charts or the examinees' physiological responses during the examination, [the] evidence is too limited to draw any strong conclusions about whether examiners' expectancies affect polygraph test accuracy. Id. at 138. Third, given the few studies performed, the few drugs tested, and the analogue nature of the evidence, a conclusion that drugs do not affect polygraph validity would be premature. Id. at 139. Fourth, while some empirical research indicates mental and physical countermeasures can decrease the likelihood of a polygraph examination detecting deceptive examinees, id. at 143, the NAS Report noted the limitations of that research, id. at 143-44. The NAS Report specifically stated we do not know of scientific studies examining the effectiveness of countermeasures in contexts where systematic efforts are made to detect and deter them. Id. at 151. {32} In Anderson, we considered the known or potential rate of error in the DNA profiling process at issue in that case. 118 N.M. at 298-99, 881 P.2d at 43-44. Similar to the State in this case, the defendant in Anderson argued that the accuracy rates of the DNA profiling process in that case were invalid for a number of reasons. While we noted that the deficiencies in calculating the rate of error was troubling, we stated the deficiencies in that case [spoke] to the weight of the evidence and not to its admissibility. Id. at 299, 881 P.2d at 44. In this case, we reach the same conclusion. Polygraph results are far from conclusive; however, as the NAS Report concluded, numerous studies have shown that polygraph tests can detect deception at rates well above chance. In fact, testimony at the evidentiary hearing indicates that the degree of accuracy of polygraph examinations is similar to many diagnostic techniques employed in the medical field, including magnetic resonance imaging (MRI), CAT scanning, ultrasound, and x-ray film. The opponent of polygraph evidence has ample opportunity through cross-examination and argumentation to cast doubt upon the results of any particular polygraph examination that have been admitted into evidence. {33} The State nevertheless argues that the rate of error for polygraph evidence is unknown because the base rate is unknown. The district court found that the base rate, or ground truth, is the proportion of people in a population as they relate to a particular trait in issue. In the context of the polygraph, the base rate is generally the percentage of persons in a sample who are telling the truth. For example, if a polygraph study involved 100 subjects, and 85 of the subjects were actually telling the truth, the base rate would be 85%. The base rate does not measure the accuracy of the polygraph, which is the ability of the polygraph itself to correctly identify deceptive subjects and truthful subjects. The base rate is a measure only of the percentage of truthful subjects in the sample population. The true base rate is unknowable, but is theoretically important because it defines the degree of confidence properly afforded a particular polygraph result. Following are two examples used by the State to illustrate the point. In both examples the polygraph is assumed to be 90% accurate in detecting deception. Therefore, with a population of 100 subjects, the polygraph would correctly identify 90 of the subjects as either truthful or deceptive, while incorrectly identifying the remaining 10 subjects. {34} In the first example, we assume a base rate of 50%, that is 50 of the 100 subjects are being truthful in their polygraph examination. Thus, with an accuracy rate of 90%, the polygraph will correctly identify 45 persons as deceptive and 45 persons as truthful, and it will incorrectly identify 5 persons as deceptive and 5 persons as truthful: Not Deceptive Deceptive Pass 45 5 Fail 5 45 In the second example, we assume that only 10% of the 100 subjects are being truthful, while the remaining 90% are being deceptive. As a result, 81 of the 90 deceptive subjects will be accurately identified as deceptive and the remaining 9 will be incorrectly identified as truthful. Therefore, in this sample of 100 subjects, 9 truthful subjects will pass, but 9 deceptive subjects will also pass. Of the 18 subjects deemed to have passed the polygraph, there is only a 50% likelihood that any individual subject was actually truthful: Not Deceptive Deceptive Pass 9 9 Fail 1 81 These examples illustrate the importance of the base rate: in a pool with a higher percentage of deceptive subjects, the likelihood that a passed polygraph indicates actual truthfulness decreases. Specifically, in the first example a passed polygraph examination is 90% likely to be correct; whereas, in the second example, a passed polygraph is only 50% likely to be correct. {35} We cannot determine the base rate in the context of the polygraph because we cannot determine in advance how many persons are telling the truth and how many are not. However, the base rate has no effect on the reliability of the polygraph  regardless of whether 50% or 90% of the sample population is deceptive, the accuracy of the polygraph remains unchanged. The base rate only affects the confidence that we have in making decisions based on the results of any one polygraph examination. The accuracy of the polygraph in both of the above examples was the same, but in the second example we would have less confidence than in the first example that a passed polygraph examination was correct. Nonetheless, even in the second example, evidence that a subject passed a polygraph examination has a tendency to make the existence of a fact more or less probable than it would be in the absence of the evidence. Prior to the subject passing the polygraph examination, we would have assumed only a 10% chance that subject was truthful. After passing the examination, though, the likelihood the subject was truthful has increased to 50%. Therefore, the fact that the base rate is unknowable does not preclude admissibility under Rule 11-702. It simply provides another basis for the opposing party to cast doubt upon the results of a particular polygraph examination through cross-examination and argumentation. We now turn to whether standards exist controlling the polygraph.