Book Section: Essay and Review: The Polygraph and Lie Detection

This 2003 book review by forensic psychologist Gregory DeClue examines the landmark National Research Council report 'The Polygraph and Lie Detection,' which conducted the most comprehensive scientific evaluation of polygraph testing commissioned by the U.S. government. The NRC Committee reviewed 57 studies encompassing 3,681 examinations and concluded that while specific-incident polygraph tests discriminate lying from truth-telling at rates above chance, the evidence is scanty and scientifically weak, with accuracy well below perfection.

The NRC Committee conducted a systematic literature review of 57 studies (52 laboratory, 7 field) using signal detection theory and ROC curve analysis to evaluate polygraph validity, examining both basic psychophysiological science and applied accuracy research across criminal investigation, employment screening, and counterintelligence contexts.

Background & Context

This 2003 book review essay by forensic psychologist Gregory DeClue examines the landmark National Research Council report "The Polygraph and Lie Detection," published by the National Academies Press. The NRC report represented the most comprehensive scientific evaluation of polygraph testing commissioned by the U.S. government since the 1983 Office of Technology Assessment review.

The review came at a critical juncture when polygraph testing—often portrayed as a magic mind-reading machine—remained controversial among experts, and as the nation sought fresh approaches to enhancing security. The NRC Committee's goal was assessing polygraph validity for security uses, especially screening of substantial numbers of government employees, finding that "overall, the evidence is scanty and scientifically weak".

DeClue's review provides a critical evaluation of this influential report for the forensic psychiatry and psychology community, examining its implications for legal and clinical practice. The timing—shortly after 9/11—made questions about security screening technologies particularly urgent for policymakers.

Research Design & Methodology

The NRC Committee was chaired by Stephen E. Fienberg of Carnegie Mellon University and included experts from psychology, statistics, biostatistics, neuroscience, and law. The committee conducted a systematic literature review extracting 59 datasets from 57 studies (52 laboratory, 7 field) including 3,681 polygraph examinations.

The methodological approach included:

• Review of specific-event investigation studies, with evidence quality rated as "relatively low: the substantial majority of studies were below the quality level typically needed for funding by the National Science Foundation or NIH"
• Use of signal detection theory and ROC curve analysis—concepts little used in U.S. government-supported polygraph research despite decades of application elsewhere
• Analysis of polygraph use in criminal investigation, employment screening, and counter-intelligence, examining theory, empirical performance evidence, countermeasure success, and national security applications
• Evaluation of both theoretical foundations and field validity

The committee examined two main evidence sources: basic scientific knowledge about processes the polygraph measures and factors influencing them, and applied research assessing criterion validity in particular settings.

Results & Key Findings

The committee's central conclusion: "in populations of examinees such as those represented in the polygraph research literature, untrained in countermeasures, specific-incident polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection".

Key accuracy findings:

• Estimates from the 57 acceptable studies "are almost certainly higher than actual polygraph accuracy of specific-incident testing in the field"
• Almost a century of research in scientific psychology and physiology "provides little basis for the expectation that a polygraph test could have extremely high accuracy"
• Generalization from specific-incident studies to screening uses "is not justified" and "polygraph accuracy for screening purposes is almost certainly lower than what can be achieved by specific-incident polygraph tests"
• For security screening: "Its accuracy in distinguishing actual or potential security violators from innocent test takers is insufficient to justify reliance on its use in employee security screening in federal agencies"

The theoretical basis was judged "quite weak, especially in terms of differential fear, arousal, or other emotional states" with "no serious effort at construct validation" and research that "has not progressed over time in the manner of a typical scientific field".

Laboratory studies suffered from "lack of realism" and field studies had "major problems with identifying the truth against which test results should be judged" plus issues with "heterogeneity and lack of control of extraneous factors".

Discussion & Significance

The NAS report became a landmark document: it "found that 'overall, the evidence is scanty and scientifically weak', concluding that 57 of the approximately 80 research studies that the American Polygraph Association relied on were significantly flawed". This represented the most authoritative scientific assessment of polygraph validity to date.

The report's significance extended beyond polygraph testing itself. The committee offered questions and characteristics indicating "what kinds of scientific evaluation are needed for future claims of scientific detection of deception" and "characteristics of high-quality studies that address issues of accuracy"—establishing standards for evaluating any deception detection technology.

Fifteen years later, experts noted the NAS report "concluded that the scientific basis of the comparison question technique (CQT) was weak, the extant research was of low quality, the polygraph profession's claims for high accuracy were unfounded, and although the CQT has greater than chance accuracy, its error rate is unknown"—conclusions that continue to shape scientific consensus.

DeClue's review brought these findings to the attention of forensic mental health professionals, who frequently encounter polygraph evidence in legal proceedings and sex offender management contexts.

Limitations & Considerations

A critical limitation acknowledged by the committee: "extreme paucity of studies that directly address the validity of the polygraph for current or preemployment screening" with most research dealing with event-specific investigations, and "the relevance of such research for the screening context is not self-evident".

The committee noted "little knowledge about how much" extraneous factors "influence the outcomes of polygraph tests in field settings" including evidence that "truthful members of socially stigmatized groups and truthful examinees believed to be guilty may show emotional and physiological responses that mimic those expected of deceptive individuals".

The report recognized that "most polygraph testing procedures allow for uncontrolled variation in test administration (e.g., creation of emotional climate, selecting questions) that can be expected to result in variations in accuracy"—limiting the consistency of results achievable in practice.

Practical Applications

DeClue's review made the NRC report's conclusions accessible to forensic psychiatrists and psychologists who must evaluate polygraph evidence in clinical and legal settings. Forensic professionals are "advised to make use of multiple sources, and if possible extended observation, to detect deception" rather than relying on what is "probably the most quintessential approach to detecting lies—the polygraph".

The report recommended that federal agencies develop "methods of the highest possible scientific validity for protecting national security" and become "fully aware of the strengths and limitations of the techniques they use," suggesting that if government continues polygraph reliance, research should either "put the polygraph on a firmer scientific foundation or lead to its supplementation or replacement". This framing helped professionals understand polygraph testing as a tool requiring ongoing scientific scrutiny rather than an established, validated technique.