David C. Raskin

Mental and Physical Countermeasures Reduce the Accuracy of Polygraph Tests

Effects of countermeasures on the control-question polygraph test were examined in an experiment with 120 Ss recruited from the general community. Ss were given polygraph tests by an examiner who used field techniques. Twenty Ss were innocent, and of the 100 guilty Ss, 80 were trained in the use of either a physical countermeasure (biting the tongue or pressing the toes to the floor) or a mental countermeasure (counting backward by 7) to be applied while control questions were being presented during their examinations. The mental and physical countermeasures were equally effective: Each enabled approximately 50% of the Ss to defeat the polygraph test. The strongest countermeasure effects were observed in the cardiovascular measures. Moreover, the countermeasures were difficult to detect either instrumentally or through observation.

Meta-analysis of Mock Crime Studies of the Control Question Polygraph Technique

A review of results obtained from standard guilty and innocent treatment conditions in 14 mock crime studies of the control question polygraph technique revealed accuracies ranging from chance to 100% correct. The present study examined several factors that may have contributed to the observed variability in detection rates across studies. Those included sampling error, differences in the populations from which subjects were drawn (Subjects), differences in the nature of incentives provided to subjects for passing the polygraph test (Incentives), and differences in the methods for diagnosing truth or deception (Decision Policy). A meta-analysis revealed that approximately 24% of the variance in detection rates could be attributed to sampling error, and detection rates were correlated with types of Subjects (r=.61). Incentives (r=.73), and Decision Policies (r=.67). The highest diagnostic accuracies were obtained from nonstudent subject samples, when both guilty and innocent subjects were offered monetary incentives to convince the examiner of their innocence, and when conventional field methods were used for interpreting the physiological recordings and diagnosing truth and deception. Together, differences in Subjects, Incentives, and Decision Policies may account for as much as 65% of the observed variance in detection rates. The present findings highlight the importance of conducting mock crime experiments that closely approximate field conditions.

Recent Laboratory and Field Research on Polygraph Techniques

This paper describes some of the major procedures and issues concerning uses of polygraph techniques in criminal investigation. The methods and aims of the control question test (CQT) are discussed, together with a brief review of the scientific literature and controversies concerning its validity. A major field research project on the validity of the CQT is described, which demonstrates that the accuracy of the CQT can exceed 90% when properly employed by skilled examiners. Some of the practical and psychometric problems of the CQT are discussed, together with techniques employed in the directed lie test (DLT). Laboratory and field research with the DLT are described, and the results indicate that it is at least as accurate as the CQT, produces fewer false positive errors, is simpler to construct and administer, and provides a good substitute for the CQT in criminal investigation. Finally, extensive analyses of data are presented to assess the generalizability of laboratory results to criminal investigative uses of the CQT. The results show substantial similarity between data sets obtained from laboratory subjects and criminal suspects when comparable procedures are used. The findings indicate that laboratory experiments can shed a great deal of light on the processes involved in the use of the CQT on criminal suspects, but adjustments in decision criteria should be made to reduce the false positive errors caused by overprediction of deceptive field outcomes using criteria derived from laboratory experiments. Finally, it is argued that available computer methods can be used effectively to further our scientific understanding of polygraph techniques and to increase the objectivity and accuracy of credibility assessment of criminal suspects.

Validity of Polygraph Techniques and Decision Methods

This chapter describes the current methods and uses of polygraph techniques for the detection of deception. Following a brief overview of the basic principles of polygraph tests, it provides a detailed description of the most widely applied technique for physiological detection of deception, the Comparison Question Test (CQT), and the various analytic methods for determining the outcomes of such tests. It analyzes the scientific research and validity of the CQT, and compares the diagnostic reliability and validity of polygraph tests to other commonly used psychological and medical tests and diagnostic procedures. The findings refute the misguided and disingenuous attack on the polygraph by the National Research Council. There is an extensive description and analysis of current methods for rendering decisions, and the chapter concludes with a discussion of some of the major issues concerning uses of polygraph tests, including its accuracy on psychopaths and victims of crimes, confidential tests for defense attorneys, and government uses of polygraph examinations.

Effects of socialization on the physiological detection of deception

Abstract Effects of socialization on the physiological detection of deception using the control question test (CQT) were explored in three mock crime experiments. Subjects were 168 volunteers from criminal, community, and college student populations. Socialization was measured by the Socialization (So) scale of the California Psychological Inventory. All subjects were given a CQT using standard field techniques. The physiological data were blindly evaluated by a semiobjective field scoring technique and previously developed discriminant function. There were no effects of socialization on the accuracy of classification by the semiobjective field scoring or the discriminant function. A modest negative relationship was found between socialization scores and differential reactivity in the CQT as indicated by correlations with the semiobjective ( r = −.22) and discriminant scores ( r = −.17). It was concluded that socialization is not an important variable for field applications of the CQT.