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Abstract

SHULL, K. W. and CROWE, M. Effects of two methods of comparing relevant and control questions on the accuracy of psychophysiological detection of deception. April 1993, Report No. DoDPI93-R-0002. Department of Defense Polygraph Institute, Ft. McClellan, AL 36205.

This study was designed to examine the effectiveness of using two methods of comparing relevant and control questions. A mock homicide scenario was set up using a female mannequin sleeping, while a thief burglarized the room. During the robbery, the female victim woke up, causing the thief to kill her. A total of 120 subjects were used for training, piloting and data collection. Tests were analyzed by instructors who were blind to the programmed condition. The first comparison involved comparing the relevant questions to the overall strongest control question. The second comparison consisted of comparing the relevant questions to the strongest and closest control question. The study results showed the evaluation of the tests using the strongest control and the strongest and closest control were not significantly different.

Key-words: psychophysiological detection of deception (PDD), chart interpretation, decision criteria, question comparisons

Director's Foreword

The Department of Defense Polygraph Institute (DoDPI) has been encouraging psychophysiological detection of deception (PDD) examiners, who are practitioners in the field, to participate in research which will advance the knowledge base of forensic psychophysiology. The approach requires that the examiner have a research idea; that the idea be approved by the Institute's research staff; that they have the complete support of their agency; that when necessary the data collection be accomplished at DoDPI; and, that the examiner serves as the principle investigator (PI). The Institute provides financial and logistical support.

This study is the first study, in what is anticipated to be a series of studies, that fits the above requirements. In this instance an experienced forensic psychophysiologist from the Federal Bureau of Investigation (FBI) served as the PI. The purpose of the study was to compare the accuracy of two systems for scoring physiologic data collected during PDD tests. The results, which show no significant difference between the two scoring systems, are presented along with the details of the study in the following report.

Michael H. Capps

Director