The passage cited in the cops2be message board post, RCMP Polygraph is the following, from his affidavit submitted in Commonwealth of Massachusetts v. Louise Woodward: Quote:In 1987, a field study conducted with the cooperation of the Royal Canadian Mounted Police reported that R.C.M.P. polygraph examiners were 100% accurate on suspects who were later confirmed to be guilty and 90% accurate on suspects later confirmed to be innocent. In 1988, we completed a 3-year study at the University of Utah funded by the National institute of Justice, U.S. Department of Justice, using polygraph examinations conducted in criminal investigations by the U.S. Secret Service. The results showed an overall accuracy rate of approximately 95% both on suspects later confirmed to be guilty and those later confirmed to be innocent. In 1997, another field study using criminal cases from the R.C.M.P. indicated the examiners were 100% correct In detecting guilty suspects and 94% correct in identifying innocent suspects. It should be noted that research findings demonstrate that the confidence in test outcomes that indicate truthfulness is slightly higher than confidence in tests that indicate deception. Thus, a truthful polygraph test outcome is more likely to be correct than a test result that indicates deception. In other words, courts can be more confident in accepting a polygraph report that the accused person was truthful in her denials than a report indicating deception on the part of the accused. I don't believe that any of these studies passed peer review for publication in a refereed scientific journal, though it's possible that his reference to a 1997 study might have been a mistaken reference to a 1996 study done by his former student, Charles R. Honts. Polygraph testing has not been proven to reliably operate at better than chance levels under field conditions. It is appropriate to cite here David T. Lykken's treatment of the topic in A Tremor in the Blood: Uses and Abuses of the Lie Detector (2nd edition, 1998) (pp. 133-135): Quote:
Field Studies There are four field studies of the CQT that have been published in scientific journals.20 Three of the four include casse where the verification of guilt and innocence was not entirely dependent on polygraph-induced confessions. Although not published in a peer-reviewed journal, the Barland and Raskin study (Barland's Ph.D. research under Raskin's direction,21 which its authors have repudiated, produced two interesting results. First, the principal scientific advocate of the CQT, Dr. Raskin, who independently scored all the charts, classified more than half of the innocent suspects as deceptive. Second, knowing that most of the suspects tested were probably guilty, Raskin scored 88% of them as deceptive. Since 78% of them were in fact guilty, if we classified 88% of the total group as deceptive and the rest as truthful entirely at random, we should achieve an average accuracy of 71%. Raskin's average accuracy, based on the polygraph charts, was also 71%.
The studies by Horvath and by Kleinmuntz and Szucko both used confession-verified CQT charts obtained respectively from a police agency and the Reid polygraph firm in Chicago. The original examiners in these cases, all of whom used the Reid clinical lie test technique, did not rely only on the polygraph results in reaching their diagnoses but also employed the case facts and their clinical appraisal of the subjects' behavior during testing. Therefore, some suspects who failed the CQT and confessed were likely to have been judged deceptive and interrogated based primarily on the case facts and their demeanor during the polygraph examination, leaving open the possibility that their charts may or may not by themselves have indicated deception. Moreover, some other suspects were cleared by confessions of others, even though the cleared suspects, judged truthful using global criteria, colud have produced charts indicative of deception. That is, the original examiners in these cases were led to doubt these suspects' guilt in part regardless of the evidence in the charts and proceded to interrogate an alternative suspect in the same case who thereupon confessed. For these reasons, some undetermined number of the confessions that were critical in these two studies were likely to be relatively independent of the polygraph results, revealing some of the guilty suspects who "failed" it. The hit rates obtained in these studies are indicated in Table 8.2.
In the study by Patrick and Iacono, 13 of the 20 innocent suspects were confirmed as such independently of polygraph results (e.g., the complainant later discovered the mislaid item originally thought to have been stolen). As can be seen in Table 8.2, 9, or 45% of these 20 innocent suspects were wrongly classified as deceptive by the CQT. Only one guilty suspect colud be confirmed as such from file data independent of CQT-induced confessions; his charts were classified as inconclusive by the CQT. The remaining guilty suspects in the Patrick and Iacono study were all classified solely on the basis of having been scored as deceptive on the polygraph and then interrogated to produce a confession. Understandably, when examiners trained in the same method of scoring independently rescored these charts, they agreed with the original examiners in 98% of cases.
Table 8.2. Summary of Studies of Lie Test Validity That Were Published in Scientific Journals and That Used Confessions to Establish Ground Truth
| | Horvath
(1977) | Kleinmuntz
&Szucko
(1984) | Patrick &
Iacono
(1991) | Honts
(1996) | Mean | Guilty correctly
classified | 21.6/28
77% | 38/50
76% | 48/49
98% | 7/7
100% | 114.6/134
85.5% | Innocent correctly
classified | 14.3/28
51% | 32/50
64% | 11/20
55% | 5/5
100% | 62.3/103
60.5% | | Mean of above | 64% | 70% | 77% | 100% | 73% |
[table notes omitted]
The recent study by Honts illustrates that publication in a refereed journal is no guarantee of scientific respectability. The meticulous study by Patrick and Iacono was done with the cooperation of the Royal Canadian Mounted Police (RCMP) in Vancouver, B.C., and showed that nealy half of the suspects later shown to be innocent were diagnosed as deceptive by the RCMP polygraphers. This prompted the Canadian Police College to contract with Honts, one of the Raskin group, to conduct another study. A polygraphy instructor at the college sent Honts charts from tests administered to seven suspects who had confessed after failing the CQT and also charts of six suspects confirmed to be innocent by these confessions of alternative suspects in the same crimes. Knowing which were which, Honts then proceeded to rescore the charts, using the same scoring rules employed by the RCMP examiners. Those original examiners had, of course, scored all seven guilty suspects as deceptive; that was why they proceeded to interrogate them and obtained the criterial confessions. Using the same scoring rules (and also knowing which suspects were in fact guilty), Honts of course managed to score all seven as deceptive also. The RCMP examiners had scored four of the six innocent suspects as truthful and two as inconclusive. We can be confident that all innocent suspects classified as deceptive were never discovered to have been innocent because, in such cases, alternative suspects would not have been tested, excluding any possibility that the truly guilty suspect might have failed, been interrogated, and confessed. Honts, using the same scoring rules and perhaps aided by his foreknowledge of which suspects were innocent, managed to improve on the original examiners, scoring five of the six as truthful and only one as inconclusive. The difference in Hons' findings from those of the other studies summarized in Table 8.2 is striking.
Surely, no sensible reader can imagine that these alleged "findings" of the Honts study add anything at all to the sum of human knowledge about the true accuracy of the CQT. How it came about that scientific peer review managed to allow this report to be published in an archival scientific journal is a mystery. Since the author, Honts, and the editor of the journal, Garvin Chastain, are colleagues in the psychology department of Boise State University, it is a mystery they might be able to solve.
[Notes:]
20. F. Horvath, The effect of selected variables on interpretation of polygraph records, Journal of Applied Psychology, 1977, 62, 127-136; B. Kleinmuntz and J. Szucko, A field study of the fallibility of polygraphic lie detection, Nature, 1984, 308, 449-450; C. Patrick and W.G. Iacono, Validity of the control question polygraph test: The problem of sampling bias, Journal of Applied Psychology, 1991, 76, 229-238; C. Honts, Criterion development and validity of the CQT in field application, Journal of General Psychology, 1996, 123, 309-324.
21. G.H. Barland and D.C. Raskin, Validity and Reliability of Polygraph Examinations of Criminal Suspects, (Report 76-1, Contract 75 NI-99-000), Washington, D.C.: U.S. Department of Justice, 1976.
For further reading on the validity of polygraphy, see Chapter 1 of The Lie Behind the Lie Detector and the sources cited there.
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Interesting poly thread on cops2be.com (Read 4101 times)
