Recent Laboratory and Field Research on Polygraph Techniques

Comprehensive review of DLT laboratory and field research demonstrating directed-lie testing is at least as accurate as CQT with fewer false positive errors.

Review of directed-lie testing research from both laboratory and field settings.

Raskin, Kircher, Horowitz, and Honts provided a comprehensive review of directed-lie testing research showing it is at least as accurate as the traditional CQT with the added benefit of fewer false positive errors. The directed-lie format is simpler to construct and provides a good substitute in criminal investigations, making it more accessible to less experienced examiners while maintaining or improving accuracy.

The DLT's combination of equivalent or superior accuracy, simpler construction, and fewer false positives makes it an ideal format for widespread professional adoption.

Background & Context

This 1989 chapter emerged during a critical period of debate over polygraph validity, when the technique faced intense scrutiny following the 1983 Office of Technology Assessment report questioning its scientific foundations. The work provided a comprehensive response by examining both the traditional Control Question Test (CQT) and introducing the Directed Lie Test (DLT) as a methodologically superior alternative. The chapter was presented at the NATO Advanced Study Institute on Credibility Assessment in 1988, reflecting international recognition of the Utah laboratory's leadership in polygraph science.

The research was particularly significant because it drew upon a major field research project funded by the National Institute of Justice (Grant No. 85-IJ-CX-0040), which represented one of the most rigorous field studies of polygraph validity conducted to that point. The DLT addressed long-standing psychometric problems inherent in the traditional CQT, particularly the difficulty of constructing effective probable-lie comparison questions that would reliably elicit stronger responses from innocent examinees.

Research Design & Methodology

This chapter presented a comprehensive review rather than a single experimental study, synthesizing findings from extensive analyses comparing laboratory and field data to assess the generalizability of laboratory results to criminal investigative uses of the CQT. The authors described a major field research project demonstrating that the accuracy of the CQT can exceed 90% when properly employed by skilled examiners.

Key research components reviewed included:

• A field study by Honts and Raskin (1988) published in the Journal of Police Science and Administration evaluating the validity of the directed lie control question
• Horowitz's 1988 unpublished doctoral dissertation from the University of Utah examining the role of the control question in physiological detection of deception
• A meta-analysis by Kircher, Horowitz, and Raskin (1988) of 14 mock crime studies of the control question polygraph technique

The laboratory research involved 60 "guilty" and 60 "innocent" participants in mock crime experiments, testing different types of comparison questions including relevant-irrelevant, trivial directed lie, personal directed lie, and probable lie conditions, with respiration, cardiovascular, vasomotor, and electrodermal activity recorded.

Results & Key Findings

Laboratory and field research with the DLT indicated 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. This represented a major advancement in polygraph methodology with direct practical implications.

Key empirical findings included:

• The accuracy of the CQT can exceed 90% when properly employed by skilled examiners
• Manipulation of comparison questions produced different patterns of physiological responses for innocent but not for guilty participants
• The relevant-irrelevant test without comparison questions produced an unacceptable rate of false positive decisions
• Substantial similarity was found between data sets obtained from laboratory subjects and criminal suspects when comparable procedures were used, though adjustments in decision criteria should be made to reduce false positive errors

The 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), providing critical insights into factors affecting polygraph accuracy.

Discussion & Significance

This work represented a watershed moment in polygraph science by offering the DLT as simpler to construct and administer than traditional probable-lie comparison questions. The DLT eliminated the ambiguity inherent in constructing probable-lie questions that must be emotionally arousing yet purposefully vague—a challenging balance that required considerable examiner skill and experience. By instructing examinees explicitly to lie to certain questions, the DLT provided a standardized, reproducible comparison stimulus.

The research addressed fundamental theoretical questions about how comparison questions function. Finding that manipulation of comparison questions produced different patterns for innocent but not guilty participants supported the underlying theoretical model: innocent examinees focus psychological arousal on comparison questions they know they're lying to, while guilty examinees remain focused on the relevant questions about the crime.

The authors argued that available computer methods could be used effectively to further scientific understanding of polygraph techniques and to increase the objectivity and accuracy of credibility assessment of criminal suspects. This presaged the development of computerized polygraph systems that would become standard in subsequent decades.

Limitations & Considerations

The findings indicated that 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. This acknowledged an important limitation in generalizing from controlled laboratory settings to real-world criminal investigations where base rates of guilt, psychological stakes, and examiner-examinee dynamics differ substantially.

While the chapter synthesized multiple studies, the field research necessarily lacked the experimental control of laboratory studies, making it difficult to isolate specific variables contributing to accuracy. Additionally, only approximately 24% of variance in detection rates could be attributed to sampling error, suggesting other unmeasured factors significantly influenced outcomes. The reliance on retrospective analysis of field cases, despite using confirmed outcomes, raised potential concerns about case selection bias.

Practical Applications

The DLT's practical advantages were immediately apparent to the polygraph profession. Being simpler to construct and administer, it reduced training requirements and made high-quality testing more accessible to examiners with varying experience levels. The standardized nature of directed-lie questions—asking examinees to lie to questions like "Have you ever told a lie?"—eliminated much of the art and uncertainty involved in crafting effective probable-lie comparison questions.

For consumers and agencies using polygraph services, the research suggested that the DLT produces fewer false positive errors, meaning reduced risk of truthful individuals being incorrectly classified as deceptive. This made the technique particularly valuable in criminal investigations where protecting innocent suspects is paramount. The work laid the foundation for widespread adoption of directed-lie testing, which continues to be used extensively in both law enforcement and security screening contexts today.