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Abstract

REED, S. D. Effect of demographic variables on psychophysiological detection of deception outcome accuracies. February 1993, Report No. DoDPI93-R-0007. Department of Defense Polygraph Institute, Fort McClellan, AL 36205.

This study was designed to assess whether or not demographic variables and individual differences, specifically, residence (urban/rural), income level (less or more than $20,000.), gender, age, education, and role (innocent or guilty) affected the outcome accuracies of Modified General Question Technique (MGQT) and Zone Comparison Test (ZCT) psychophysiological detection of deception (PDD) examinations. The study utilized 213 military and 168 civilian examinees. Two hundred and thirty-two examinees were male and 147 examinees were female. Examiners were 24 students enrolled in the Department of Defense Polygraph Institute (DoDPI) Basic Polygraph Examiners Training Course (91-1) and three Federally certified examiners on staff at the DoDPI. Examiners participated in the study during the 7th, 8th, 10th, and 11th weeks of the course. All examiners used standard field polygraph instruments. A variety of scenarios (rape, murder, robbery) were used to program examinees guilty or innocent. All examinations were conducted according to DoDPI standards and guidelines. Analyses of the data concerning income and residence was limited to data from the civilian examinees. Results suggest that these PDD techniques are relatively robust with respect to the examined demographic variables. in general, there were no significant results. The accuracies of the tested PDD techniques were not influenced by the examined demographic variables or individual differences.

Key-words: Psychophysiological detection of deception (PDD), modified question technique (MGQT), zone comparison test (ZCT), accuracy, demographics, urban, rural, income, gender, education

Director's Foreword

Anecdotal evidence suggests that demographic variables may impact on the results and therefore the accuracy of PDD examinations. If PDD truly produced different results on persons based solely on status, its usefulness would be questionable. this research is important in attempting to identify any single variable or variables that may have a negative impact on examiner diagnosis.

This is one of the few studies in the literature designed to address whether or not demographic variables and individual differences, specifically, residence (urban/rural), income level (less or more than $20,000.), gender, age, education, and role (innocent or guilty) affected the outcome accuracies of Modified General Question Technique (MGQT) and Zone Comparison Test (ZCT) psychophysiological detection of deception (PDD) examinations. Analysis of data did not result in any definitive finding reflecting the tested demographic variables or individual differences affect examination decision accuracy.

Michael H. Capps

Director