Directed Lie Comparison Questions in Polygraph Testing

Laboratory comparison of directed lie versus probable lie formats, finding DLC produced fewer false positives.

Controlled experiment comparing accuracy and error profiles of directed lie and probable lie CQT formats.

Published in 1987 in Psychophysiology (Conference Proceedings), this work by Driscoll and colleagues examined directed lie comparison questions in polygraph testing. Key findings include: Laboratory comparison of directed lie vs. probable lie formats. Found DLC produced fewer false positives while maintaining detection of deception, supporting its adoption as standard practice. The controlled laboratory conditions ensure known ground truth, enabling precise accuracy measurement.

The false positive advantage of directed-lie questions was confirmed in subsequent field studies, supporting the format's widespread adoption.

Background & Context

The late 1980s represented a pivotal period in polygraph methodology, marked by growing scrutiny of traditional probable-lie comparison question techniques. The Comparison Question Test (CQT) had dominated polygraph practice since John Reid's 1947 innovations, but concerns persisted about false positive errors—truthful examinees incorrectly identified as deceptive. This accuracy limitation carried significant implications for criminal justice and security screening applications.

The directed lie comparison (DLC) approach emerged as a potential solution to these methodological challenges. Unlike traditional probable-lie questions that rely on examiner skill to develop ambiguous questions examinees would likely lie about, directed lie questions explicitly instruct examinees to lie to known trivial questions. This standardization promised reduced examiner variability, simpler test construction, and theoretically, fewer false positive errors among innocent examinees.

Research in this era by the University of Utah laboratory, including work by Honts, Raskin, Driscoll, and colleagues, systematically evaluated whether this newer approach could match or exceed the accuracy of established techniques while offering practical advantages for field applications.

Research Design & Methodology

The 1987 research program appears to have involved controlled laboratory studies comparing directed lie and probable lie comparison question formats under experimental conditions with known ground truth. The design enabled precise measurement of accuracy metrics including correct detections, false positives, and false negatives for both question formats.

Key methodological features likely included:

• Within-subjects or between-subjects comparisons of the two CQT formats using standardized polygraph protocols
• Mock crime scenarios establishing known guilty and innocent participants to calculate accuracy rates
• Standard physiological measures including respiration, electrodermal activity, and cardiovascular responses
• Blind chart evaluation using numerical scoring systems to minimize examiner bias

The laboratory environment provided experimental control while the research team's parallel field validations (published in 1988) extended findings to real-world criminal investigations. This multi-study approach strengthened confidence in the generalizability of results across both analog and applied settings.

Results & Key Findings

The directed lie comparison format produced fewer false positive errors while maintaining equivalent detection of guilty examinees, representing a meaningful improvement in the balance between sensitivity and specificity. This finding addressed one of the most significant criticisms of traditional polygraph testing—the risk of falsely accusing innocent individuals.

Based on the research program from this period, key outcomes included:

• Equivalent or superior overall accuracy for DLC compared to probable-lie formats in detecting deception
• Reduced false positive rates among innocent examinees, the study's most practically significant finding
• Maintained sensitivity to deception with no compromise in detecting guilty examinees
• Greater standardization with less variability across examiners due to simplified question construction

These laboratory findings, combined with subsequent field validation by Honts and Raskin (1988) showing similar patterns in actual criminal cases, provided converging evidence for the directed lie approach's validity. The field study involved 25 confirmed criminal cases where both question types were tested within subjects, demonstrating real-world applicability.

Discussion & Significance

This research fundamentally challenged assumptions about optimal comparison question design that had dominated polygraph practice for four decades. The demonstration that explicitly directing examinees to lie could produce equal or better discrimination than the psychologically manipulative probable-lie approach represented both theoretical and practical advances.

From a theoretical standpoint, the success of directed lies suggested that what matters most is creating sufficient physiological arousal to comparison questions among truthful examinees, regardless of whether this arousal stems from actual deception or instructed falsehoods. This insight informed subsequent psychological models of polygraph responding, including attention-based and cognitive load theories.

Practically, the findings supported widespread adoption of directed lie questions in federal screening programs. The Test for Espionage and Sabotage (TES) and Directed Lie Screening Test (DLST) both incorporated these innovations, becoming standard tools for security clearance evaluations. The reduced false positive advantage was particularly important in screening contexts where base rates of actual deception are low and false accusations carry severe consequences for innocent examinees' careers and reputations.

Limitations & Considerations

As with all laboratory analog studies, questions remained about ecological validity and generalizability to high-stakes field settings. Laboratory participants face limited consequences compared to actual criminal suspects or security clearance applicants, potentially affecting the magnitude and quality of physiological responses. However, the research team's concurrent field validation work helped address these concerns.

Additional limitations include:

• Limited sample sizes typical of polygraph research, constraining statistical power for detecting small effects
• Potential for experimenter effects given the research team's known advocacy for the directed lie approach
• Uncertainty about whether advantages would persist across diverse examinee populations and testing contexts
• The inherent challenge that even "ground truth" in field settings involves some uncertainty

Subsequent meta-analyses and reviews have shown that while directed lie and probable lie formats demonstrate broadly similar validity, the literature remains equivocal on whether one consistently outperforms the other across all settings and populations.

Practical Applications

This research provided empirical justification for polygraph professionals to adopt directed lie comparison questions, particularly in government security screening where standardization and false positive reduction were priorities. The simpler question construction reduced training requirements and examiner-to-examiner variability, making the technique accessible to a broader range of practitioners while maintaining quality control.

For consumers of polygraph services, the reduced false positive profile of directed lie tests theoretically decreases the risk that truthful individuals will face adverse consequences from testing. However, this advantage must be balanced against recognition that no polygraph technique achieves perfect accuracy, and all comparison question approaches remain controversial within the scientific community regarding their fundamental validity and appropriate applications in legal and employment contexts.