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Abstract

INGRAM, E. M. Test of a mock theft scenario for use in the psychophysiological detection of deception: III. October 1996, Report No. DoDPI97-R-0003, Department of Defense Polygraph Institute, Ft. McClellan, AL 36205.

The Zone Comparison Test (ZCT), a psychophysiological detection of deception (PDD) test, was administered to 30 healthy male and female paid volunteers recruited by a local employment agency. The subjects were programmed to be either deceptive or non-deceptive regarding the mock theft of a valuable coin. This pilot study was designed to determine the effectiveness of the coin theft as a mock crime scenario for laboratory tests when a live pretest is used with the ZCT, with videotaped instructions, and with the digitized voice presentation of test questions. PDD tests were blind- evaluated by three independent scorers using the three position scale, scoring method. The frequencies of accurate determinations made were compared using proportionality tests. The overall accuracy rate was 60% when inconclusive examiner decisions were included. When inconclusive examiner decisions were excluded the overall accuracy rate increased to 87%. A significant interrater agreement among the blind scorers was found using the kappa statistic for multiple raters (p <.05). However, a proportionality test indicated that the level of unanimous agreement was not significantly different from a chance level (p> .05). It was concluded that this mock scenario did not meet the accuracy requirements for a standard scenario.

Key Words: psychophysiological detection of deception, mock crime scenarios, Zone Comparison Test

Director's Foreword

This report describes the third in a series of studies designed to develop laboratory tools to be used during psychophysiological detection of deception (PDD) research. In a typical deception detection laboratory study subjects participate in a procedure, usually called a mock crime, and then attempt to deceive the PDD examiner concerning their participation. The mock crime procedures used vary among reports, as do the reported accuracy rates of the subsequent PDD examinations. Differences among mock crime procedures may contribute significantly to these result differences. Use of the same, standard, mock crime procedures in multiple studies would reduce the possibility that inconsistent results among studies are due to differences among mock crime procedures. Such a standard procedure should be developed to have both validity and reliability. This report describes a third step toward development of such standard procedures. The procedure is intended exclusively for laboratory use. It is, consequently, more important that the procedure produces valid reliable decisions than it is that the procedure emulates real life situations.

Michael H. Capps

Director