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th , 2007
The Comparison Question Test: Does It Work & If so, How?
Dec 14th , 2007 at 4:55pm
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The Comparison Question Test: Does It Work and If So How? Dr.s Heinz Offe, Susanne Offe; Law and Human Behavior, Volume 31, Number 3, June 2007 , pp. 291-303(13) In a mock crime study of the comparison question test (CQT), 35 subjects decided to participate as guilty and 30 as innocent. Two conditions were varied: Explaining the comparison questions in the pretest interview and re-discussing comparison questions between charts. Higher identification rates (∼90% for guilty and innocent participants) were achieved in groups with explanation of comparison questions than in groups without explanation. Re-discussing comparison questions had no effect on identification rates. Ratings of subjective stress due to relevant and comparison questions were also obtained and can be seen as indicators of the significance of the questions. The significance of comparison questions was hardly affected by the different testing conditions. When effects are detectable at all, they contradict theoretical expectations in their direction. Results are discussed in terms of the significance of comparison questions used in polygraph testing. Here, we have yet another peer reviewed scientific study, this time published in 2007 from researchers in Germany, that demonstrates the value of the comparison question polygraph test. The authors title question says it all. Does it work and if so how? Their methods were some of the best I have seen in over 20 years as a polygrapher The usual arguments about mock crime studies center around the argument that mock crime studies don’t replicate “real life” and that people who are “programmed” as guilty or innocent don’t display the same emotions or reactions as “real life” people. Well these researchers did a number of things to quell that argument. First they let the participants chose whether they wanted to be the criminals or the innocent suspects. After all that’s what people in “real life” do. They then gave the guilty subjects two weeks to go about committing the crime, thereby allowing them to choose the most appropriate time to do the deed while unobserved. The guilty subjects had to steal a money voucher from a box on a desk in an office area accessible to all the participants. This method again replicates the manner in which a “real crime” would occur. Next, they conducted the polygraph examinations between one week and five months of the “crime” again replicating “real life” in much the same way one might become a suspect in a criminal case at some point during the investigation. Their questions to be answered were: 1. Is it possible to achieve significantly higher than chance identification rates in a mock crime study under more realistic conditions of subjects deciding for themselves, whether they participate as guilty or innocent? 2. Does explanation of the comparison questions (CQ) in the pre-test interview affect the identification rates as expected? 3. Does discussion of the comparison questions between tests – based on the concept of “delicate balance” affect identification rates? 4. Is the subjectively felt stress imposed by questions related to test results based on physiological measures? 5. Does the subjective uncertainty about the truthfulness of negating the CQ contribute to the significance of these questions. Rewards were offered to motivate the participants. The guilty were offered double the reward should they be later identified as non-deceptive and half for those innocent participants who successfully pass the polygraph. The results were very telling. The subjects were divided into 4 groups with Group 1 receiving an explanation of the CQ both during the pre-test and between test charts. Group 2 received explanation of the CQ only during the pre-test interview. Group 3 received no CQ explanation during the pre-test but did receive discussion of the questions between test charts. Group 4 received neither explanation of the CQ during the pre-test nor discussion of those questions between test charts. To further explain the term “explanation” and “discussion”, explanation is the totality of what we as polygraph examiners do when we explain the comparison questions and their relative importance to the overall outcome of the test during the pre-instrument phase. “Discussion” as used here, means that the QC were discussed between charts during the data collection phase. An example of discussion might be “Now, Georgina, are any of those questions about your past honesty causing you any problems?”. This type of discussion would occur between each chart. When explanation of the CQ was accomplished during the pre-test and between test charts, the results were 88.9% for both conditions being correctly identified. When explanation of the CQ was accomplished during the pre-test but with no discussion between test charts, the identification rates were 93.3%. Group 3 participants who received only between chart discussion of the CQ were identified correctly at a rate of 80.0%. Group 4 participants who received no explanation or discussion were correctly identified by condition at a rate of 58.8% Questionnaires completed by all participants after their polygraph examinations, revealed that both guilty and innocent participants subjectively “felt” that the relevant questions were the most important of the questions answered on the test. The guilty, however “felt” that they reacted stronger to the relevant questions and the innocent “felt” they responded stronger to the comparison questions. This test has confirmed, yet again that when performing the CQT under normal conditions in mock crime studies rates of 90% or better can be obtained even when the participants chose their condition. Innocent subjects subjectively felt the relevant questions were the most important yet they felt they responded stronger to the CQ. Guilty subjects actually were identified at lower rates when the explanation of the CQ was not given and innocent subjects were correctly classified at a higher rate when explanation of the CQ was provided. In other words, it helped them pass the test at higher rates. To answer Mr. Maschke’s usual & obvious questions: 1. Yes the examiners were blind to conditions of the participants. 2. Even with inconclusive results included in the study, the resulting identification rates differed only slightly and were not significant. 3. The “delicate balance” argument made by many polygraph opponents (lykke, Iacono) did not play out. Discussion of the CQ between the test charts did not increase or decrease identification rates. This test shows, in the words of the authors “that the differential significance of questions is essentially achieved through the different significance of the relevant questions for guilty and innocent participants, but not through a difference in significance of CQ.” In other words, the CQT works just as it is designed to do and it works well.