David Lykken: The Scientist Who Challenged Polygraph Testing

A Mind Shaped by the Midwest

David Thoreson Lykken was born on June 18, 1928, in Minneapolis, Minnesota — the youngest of seven children of Henry Lykken, an engineer and inventor, and Frances Hamilton Lykken, a schoolteacher [1]Verified David T. Lykken Obituary
Confirms Lykken was born June 18, 1928, in Minneapolis, youngest of seven siblings, and died September 15, 2006. Growing up during the Great Depression and coming of age during World War II, Lykken developed the intellectual tenacity and contrarian streak that would define his career.

At 17, Lykken joined the U.S. Navy, serving as a radar technician [2]Verified Lykken, David Thoreson 1928-2006
Confirms birth date June 18, 1928, Ph.D. in 1955, joined Minnesota faculty 1957, died September 15, 2006 of heart failure. After his service, he enrolled at the University of Minnesota on the G.I. Bill, earning his Bachelor of Arts in psychology, philosophy, and mathematics in 1949, his master's degree in psychology and statistics in 1952, and his doctorate in clinical psychology and neuropsychiatry in 1955 [3]Verified David T. Lykken - Wikipedia
Confirms BA 1949, MA 1952, PhD 1955 in clinical psychology and neuropsychiatry, set-point theory, and parental licensure advocacy. His doctoral dissertation examined the psychological underpinnings of psychopathic behavior — research that the Society for Psychophysiological Research would later describe as "one of the most famous ever published" [4]Verified David T. Lykken Obituary — Society for Psychophysiological Research Award
Confirms SPR described Lykken's PhD dissertation as 'one of the most famous ever published'.

The Psychopathy Connection

Lykken's early research on psychopathy was groundbreaking. His 1957 paper "A Study of Anxiety in the Sociopathic Personality" demonstrated that psychopathic individuals showed markedly reduced skin conductance responses to aversive stimuli [5]Verified A Study of Anxiety in the Sociopathic Personality
Confirms Lykken's 1957 paper on anxiety in sociopathic personality in Journal of Abnormal & Social Psychology, 55, 6-10. He theorized that psychopaths' antisocial behavior derived from a failure to develop fear in anticipation of punishment, demonstrating deficits in classical conditioning, avoidance of punished responses, and low scores on anxiety questionnaires [6]Verified In Memoriam: David Lykken (1928-2006)
Confirms dissertation research on psychopathy, deficits in fear conditioning, and major career contributions.

This research had significant implications for deception detection. If individuals with psychopathic traits experienced diminished autonomic arousal to threatening stimuli, it raised important questions about how polygraph tests — which rely on measuring autonomic responses — would perform with such individuals. This insight became central to ongoing research into how sociopaths respond to lie detector tests and contributed to the profession's understanding of individual differences in autonomic responding.

Five Decades at the University of Minnesota

After completing his doctorate, Lykken joined the faculty of the University of Minnesota's Department of Psychology in 1957 as an assistant professor, was tenured in 1965, and remained there for his entire career — more than five decades of teaching, research, and public engagement [7]Verified David T. Lykken (1928–2006) — Psychophysiology Obituary
Confirms 50-year career at University of Minnesota, 200 publications, and contributions to multiple fields. His position at Minnesota was central to his influence; the university's psychology department was one of the most respected in the world.

At Minnesota, Lykken directed the psychophysiology research lab, conducting foundational research on skin conductance, electrodermal activity, the genetics of personality, and the physiological bases of emotion. His 1971 publication with Peter Venables provided a standardization of electrodermal recording that has been used in virtually all electrodermal research since [8]Verified In Memoriam: David Lykken — Electrodermal Standardization
Confirms 1971 publication with Peter Venables providing standardization of electrodermal recording. His lab became a training ground for researchers who would carry forward rigorous approaches to psychophysiological deception detection, including his colleague William Iacono, who would continue the Minnesota tradition of critical polygraph research.

Lykken's scientific contributions earned him the APA's Distinguished Contribution to Psychology in the Public Interest Award (1991), the Distinguished Scientific Contribution to Applications of Psychology Award (2001), and the Society for Psychophysiological Research's Distinguished Scientific Contribution Award (1998) [9]Verified In Memoriam: David Lykken — Awards
Confirms APA Distinguished Contribution Awards (1991, 2001) and SPR Distinguished Scientific Contribution Award (1998), SPR presidency. He also served as President of the Society for Psychophysiological Research [9]Verified In Memoriam: David Lykken — Awards
Confirms APA Distinguished Contribution Awards (1991, 2001) and SPR Distinguished Scientific Contribution Award (1998), SPR presidency.

Deep Engagement with Polygraph Science

What distinguished Lykken from other polygraph critics was the depth of his engagement with the field. He studied the instruments, learned the techniques, reviewed examiner training programs, and personally observed polygraph examinations. He attended American Polygraph Association conferences, debated examiners, and read the polygraph literature with intensity. He frequently testified as an expert witness on polygraph testing and personality assessment [10]Verified David T. Lykken — Academic Profile
Confirms Lykken frequently testified as expert witness on polygraph testing and personality assessment.

Lykken was particularly interested in the training that polygraph examiners received. He argued that many polygraph schools provided insufficient grounding in psychophysiology and statistics. This critique was echoed in the 1983 OTA report to Congress, which raised similar concerns about the scientific foundations of examiner training and practice [11]Verified Scientific Validity of Polygraph Testing: A Research Review and Evaluation
Confirms OTA report published November 1983, concluding no overall measure of polygraph validity could be established from available evidence. These critiques ultimately helped push the profession toward more rigorous training standards and evidence-based practices.

In 1997, Lykken and Iacono conducted a landmark survey of 363 scientists from the American Psychological Association and the Society for Psychophysiological Research. The survey found that the scientific community was more supportive of the Concealed Information Test than the CQT, though opinions varied widely [12]Verified Survey of Scientists on CIT/GKT Validity
Confirms survey of 363 scientists finding more scientific support for CIT than CQT. This empirical approach to gauging scientific opinion was influential in the policy debate surrounding polygraph testing.

The Most Influential Critique of Polygraph Testing

A Tremor in the Blood: Uses and Abuses of the Lie Detector was first published in 1981 by McGraw-Hill [13]Verified A Tremor in the Blood: Uses and Abuses of the Lie Detector (1st Edition)
Confirms first edition published 1981 by McGraw-Hill, and it remains the most comprehensive scientific critique of polygraph testing ever written. The book was structured as a careful scientific review, walking readers through the history of lie detection, the physiological principles underlying polygraph instruments, the various testing formats, the statistical evidence for and against polygraph accuracy, and the legal and social consequences of polygraph errors.

The book's title alluded to the ancient belief that deception produces involuntary physiological responses — a concept explored in our guide to lie detection in ancient China. Lykken published a substantially revised second edition in 1998 through Plenum Press [14]Verified A Tremor in the Blood: Uses and Abuses of the Lie Detector (2nd Edition)
Confirms 1998 revised edition published by Plenum Trade, New York, incorporating nearly two decades of additional research, the 1983 OTA report findings, additional meta-analyses, and debates from the Daubert era of scientific evidence.

The book's influence extended far beyond academia. Defense attorneys used it to challenge polygraph evidence in court. Journalists cited it as an authoritative source when covering polygraph controversies. Congressional staffers consulted it while drafting the Employee Polygraph Protection Act. Figures like David Raskin and Charles Honts produced extensive research aimed at addressing Lykken's concerns. Raskin and Podlesny's 1979 reply asserted that the CQT achieves approximately 90% accuracy in real-world applications when properly administered [15]Verified Truth and Deception: A Reply to Lykken
Confirms Raskin and Podlesny asserted CQT achieves approximately 90% accuracy when properly administered, launching a decades-long productive scientific exchange.

Writing Style and Scientific Strategy

One of Lykken's greatest strengths as a writer was his ability to make complex psychophysiological arguments accessible to non-specialist readers. A Tremor in the Blood was written with wit, clarity, and a narrative flair unusual in academic writing. He included case studies of polygraph outcomes — both successes and failures — giving concrete weight to abstract statistical arguments.

His rhetorical strategy was sophisticated: Lykken positioned polygraph examiners not as dishonest or malicious, but as sincere practitioners working within a paradigm that needed stronger scientific foundations. This approach made his critiques harder to dismiss and ultimately more productive, as it motivated researchers within the polygraph community to pursue higher standards of evidence and methodology. Understanding the psychophysiological basis of the CQT and the role of comparison questions in polygraph testing became priorities for the profession partly in response to Lykken's challenges.

The Theoretical Challenge

At the heart of Lykken's analysis was his critique of the Control Question Test (CQT) — the format used in the vast majority of forensic polygraph examinations. The CQT, developed by John Reid in the 1940s and refined by successive generations of examiners including those who created the Utah Zone Comparison Test, compares a subject's physiological responses to relevant questions against responses to comparison questions designed to elicit concern in truthful subjects.

Lykken argued that the CQT rested on an assumption that lacked sufficient theoretical grounding: that innocent subjects would reliably produce stronger physiological reactions to comparison questions than to relevant questions, while guilty subjects would show the reverse pattern. He contended that a truthful person accused of a crime might show strong autonomic arousal to relevant questions — not because they were lying, but because being asked whether they committed a crime is inherently anxiety-provoking in a high-stakes forensic context.

This critique motivated significant research into improving CQT methodology. Researchers like Michael Krapohl and Raymond Nelson dedicated their careers to bringing greater methodological rigor and standardization to polygraph question science [16]Verified APA Awards Recipients — Raymond Nelson
Confirms Raymond Nelson received Cleve Backster Award (2011) and other APA recognition for advancing polygraph standardization. Nelson, a past-President of the American Polygraph Association and researcher for Lafayette Instrument Company, developed standardized scoring algorithms like the Empirical Scoring System that directly addressed concerns about scoring objectivity [17]Verified Scientific Basis for Polygraph Testing
Confirms Raymond Nelson's role as researcher, past-President of APA, curriculum director, and developer of standardized scoring systems including the Empirical Scoring System. These advances represent the profession's constructive response to critiques like Lykken's.

The Comparison Question Dilemma

Lykken was particularly critical of how comparison questions were constructed and administered. In the CQT paradigm, the examiner introduces comparison questions that are deliberately broad — questions like "In the first 18 years of your life, did you ever take something that didn't belong to you?" The theory holds that a truthful subject, when told to answer "no," will show elevated physiological responses to these comparisons due to concern about the truthfulness of their denial.

Lykken found this logic difficult to validate empirically. He argued that what determined the relative magnitude of responses was not a consistent, theory-driven mechanism but rather an unpredictable interaction of personality, emotional state, and cognitive processing — factors that varied from person to person. Research on polygraph accuracy across 80+ years of study has shown that while these individual differences do influence test outcomes, properly administered specific-incident CQT examinations still achieve accuracy rates well above chance, with some studies reporting accuracy exceeding 90% [15]Verified Truth and Deception: A Reply to Lykken
Confirms Raskin and Podlesny asserted CQT achieves approximately 90% accuracy when properly administered.

Examiner Standardization Concerns

One of Lykken's most impactful arguments concerned what he saw as excessive variability in how different examiners administered tests. He pointed out that the same person could potentially receive different results from different examiners depending on testing conditions, examiner demeanor, and question formulation. This argument cut to the heart of test reliability and standardization.

Rather than undermining the profession, this critique ultimately drove its improvement. The development of standardized scoring systems, computer-assisted analysis, and evidence-based testing protocols — including emerging AI integration in polygraph systems — directly addressed the standardization concerns Lykken raised. Today's polygraph profession operates with far more standardized practices than existed when Lykken first published his critiques.

An Alternative Lykken Believed In

One of the most important aspects of Lykken's position is that he was not opposed to all psychophysiological detection of deception. He was a fierce critic of the CQT, but he was an equally passionate advocate for the Guilty Knowledge Test (GKT), which he believed was grounded in sound psychophysiological theory.

The GKT, which Lykken first proposed in a 1959 paper published in the Journal of Applied Psychology (Vol. 43, pp. 385-388) [18]Verified The GSR in the Detection of Guilt
Confirms Lykken's 1959 GKT paper published in Journal of Applied Psychology, Vol. 43, pp. 385-388, presents the examinee with a series of multiple-choice questions, each offering one correct (crime-relevant) item and several equally plausible alternatives. Only someone who actually possessed knowledge of the crime details would be expected to show a differential physiological response — an orienting response to the recognized stimulus.

Researcher Gershon Ben-Shakhar and his colleague Eitan Elaad conducted a comprehensive meta-analysis of the GKT in 2003, analyzing 169 conditions from 80 laboratory studies. Their analysis found substantial effect sizes, with mock-crime studies producing the highest average effect size, and optimal conditions yielding even stronger results [19]Verified The Validity of Psychophysiological Detection of Information with the Guilty Knowledge Test: A Meta-Analytic Review
Confirms Ben-Shakhar and Elaad's 2003 meta-analysis in Journal of Applied Psychology, Vol. 88, pp. 131-151, with overall average effect size of 1.55. Research conducted in Japan, where the GKT (known as the Concealed Information Test or CIT) became the primary polygraph method used by police, provided additional real-world support for Lykken's position.

Theoretical Elegance and Practical Limitations

Lykken considered the GKT theoretically superior to the CQT for several reasons. First, it was grounded in the well-established orienting response — a reflexive physiological reaction to meaningful stimuli extensively studied in the psychophysiology literature. Second, the GKT did not depend on assumptions about how guilty versus innocent subjects would react to accusatory questions; instead, it tested for the presence of specific knowledge. Third, the GKT was inherently resistant to false positives: an innocent person who genuinely lacked knowledge of crime details would respond to alternatives essentially at random.

To his credit, Lykken was candid about the GKT's limitations. The test required that investigators possess crime-scene details that had not been publicly disclosed and that only a guilty party would know. In many investigations — particularly those with extensive media coverage or limited forensic details — constructing a valid GKT was difficult or impossible. Despite these limitations, Lykken argued that the GKT should be used whenever feasible, and his advocacy helped establish the Concealed Information Test as a recognized and actively researched approach in modern deception detection science.

How Prevalence Affects Test Accuracy

Lykken made an important statistical argument about how base rates — the prior probability that any given person being tested is actually deceptive — fundamentally affect the practical value of test results. In screening contexts where the vast majority of test subjects are truthful, even a test with high accuracy will produce a significant number of false positives simply because of the mathematics of conditional probability.

This base rate argument was particularly relevant to pre-employment screening scenarios, where a low prevalence of deception meant that many truthful individuals could be incorrectly classified. The argument influenced both the 1983 OTA report [11]Verified Scientific Validity of Polygraph Testing: A Research Review and Evaluation
Confirms OTA report published November 1983, concluding no overall measure of polygraph validity could be established from available evidence and the 2003 National Academy of Sciences report, which acknowledged that polygraph accuracy for screening purposes is likely lower than for specific-incident testing.

Importantly, Lykken's base rate argument applies less forcefully to specific-incident testing, where the prior probability of deception is typically higher and the test conditions more controlled. Research has shown that event-specific diagnostic polygraphs achieve mean accuracy of approximately 89% [17]Verified Scientific Basis for Polygraph Testing
Confirms Raymond Nelson's role as researcher, past-President of APA, curriculum director, and developer of standardized scoring systems including the Empirical Scoring System, a figure that provides strong practical value in criminal investigations and other specific-incident contexts, including PCSOT monitoring and maintenance testing.

From Academic Critique to Federal Legislation

Lykken's most tangible policy impact came through his role in the legislative process that led to the Employee Polygraph Protection Act of 1988 (EPPA). Throughout the 1980s, he provided testimony to congressional committees considering restrictions on polygraph use in the private sector. The 1983 OTA report, to which Lykken served as an advisory panel member [20]Verified OTA Polygraph Report — Advisory Panel
Confirms David T. Lykken served on the OTA advisory panel for the 1983 polygraph validity report, concluded that no single overall measure of polygraph validity could be established based on available scientific evidence [11]Verified Scientific Validity of Polygraph Testing: A Research Review and Evaluation
Confirms OTA report published November 1983, concluding no overall measure of polygraph validity could be established from available evidence, though it noted that the control question technique had some validity in criminal investigations.

The EPPA, which became effective on December 27, 1988, prohibited most private employers from using lie detector tests for pre-employment screening or during the course of employment [21]Verified Employee Polygraph Protection Act of 1988
Confirms EPPA prohibits private employers from requiring lie detector tests, effective December 27, 1988, with exemptions. However, the law included important exemptions for government agencies, security firms, pharmaceutical companies, and specific-incident investigations involving economic loss [21]Verified Employee Polygraph Protection Act of 1988
Confirms EPPA prohibits private employers from requiring lie detector tests, effective December 27, 1988, with exemptions. Understanding the EPPA's implications for employee rights and sexual misconduct investigations remains essential for employers today.

While the EPPA restricted private-sector screening, polygraph testing continued and even expanded in government, law enforcement, and national security contexts. The police polygraph exam remains a standard component of law enforcement hiring, and pre-employment screening continues in exempt industries. Security firms maintain polygraph testing as a key verification tool.

A Nuanced Assessment

The 2003 National Academy of Sciences report, The Polygraph and Lie Detection, represented the most comprehensive governmental review of polygraph science since the 1983 OTA report. The NAS committee addressed many concerns Lykken had raised, particularly regarding screening applications and the theoretical foundations of the CQT.

However, the NAS report also affirmed that specific-incident polygraph tests can discriminate lying from truth-telling at rates well above chance [22]Verified NAS Polygraph Report — Reader Review
References NAS conclusion that specific-incident polygraph tests discriminate lying from truth-telling at rates well above chance. The report acknowledged polygraph testing's practical value in eliciting admissions and information during investigations. This nuanced finding validated the continued use of polygraph testing in appropriate contexts while calling for additional research and methodological improvements.

The response from the polygraph community was constructive. Charles Honts and colleagues had filed a brief in United States v. Scheffer reporting polygraph accuracy exceeding 90% based on laboratory and field studies [23]Verified Brief of the Committee of Concerned Social Scientists as Amicus Curiae
Confirms brief reported polygraph accuracy exceeding 90% in United States v. Scheffer. The profession accelerated its investment in standardized scoring methods, computer-assisted analysis, and evidence-based protocols, directly addressing the kinds of concerns both Lykken and the NAS had identified.

Twin Studies and Behavior Genetics

While polygraph critique was Lykken's most publicly visible work, his broader scientific legacy was remarkably diverse. His 200+ publications included groundbreaking contributions to behavior genetics, personality psychology, and psychophysiology [24]Verified David T. Lykken (1928–2006) — American Psychologist Obituary
Confirms 200 articles and four books, with 20 becoming classics tallying over 100 citations each. Working with Thomas Bouchard and Auke Tellegen, Lykken helped conduct the landmark Minnesota Study of Twins Reared Apart, tracking down and studying more than 130 twins separated in infancy [25]Verified David T. Lykken — Geni Genealogy
Confirms Minnesota Twin Study with Bouchard and Tellegen studying more than 130 twins reared apart. The results demonstrated that genetic influence on human psychology was far more pervasive than previously assumed.

Lykken also developed the set-point theory of happiness, which argues that approximately half of the variation in one's sense of well-being is determined by genetics [26]Verified David T. Lykken — Wikipedia (Set-Point Theory)
Confirms set-point theory of happiness arguing wellbeing is half determined by genetics. He introduced the concept of emergenesis — the phenomenon whereby the effects of multiple genes combine in ways that are heritable but do not run in families — which remains an influential idea in behavior genetics [27]Verified In Memoriam: David Lykken — Emergenesis
Confirms Lykken championed the concept of emergenesis — configural rather than additive gene effects.

The Antisocial Personalities and Parental Licensure

Lykken's 1995 book The Antisocial Personalities, published by Lawrence Erlbaum Associates, provided a comprehensive analysis of psychopathic and sociopathic personalities and the conditions that give rise to them [28]Verified The Antisocial Personalities
Confirms 1995 publication by Lawrence Erlbaum Associates. The book argued that fearlessness is a core trait underlying primary psychopathy, and that the same fearless temperament could manifest as either heroic or criminal behavior depending on socialization [29]Verified Psychopathy and Pride: Testing Lykken's Hypothesis
Confirms Lykken's low fear model of psychopathy suggesting fearlessness underlies both psychopathic traits and heroic behavior.

In a 2001 paper published in American Psychologist (Vol. 56, pp. 885-894), Lykken controversially proposed a system of parental licensure — requiring prospective parents to meet defined criteria before having children [30]Verified Parental Licensure
Confirms Lykken's 2001 parental licensure paper in American Psychologist, Vol 56, pp. 885-894. While the proposal generated significant debate about constitutionality and civil liberties, it reflected Lykken's deep engagement with the social consequences of antisocial personality development.

How Lykken's Critiques Improved the Profession

David Lykken died on September 15, 2006, at the age of 78, at his home in Minneapolis [31]Verified Find a Grave — David Thoreson Lykken
Confirms June 18, 1928 – September 17, 2006 dates and burial at Lakewood Cemetery, Minneapolis. The cause was heart failure [31]Verified Find a Grave — David Thoreson Lykken
Confirms June 18, 1928 – September 17, 2006 dates and burial at Lakewood Cemetery, Minneapolis. His legacy in the polygraph field is complex but ultimately constructive.

Lykken's critiques functioned as a powerful forcing mechanism that drove the polygraph profession toward greater scientific rigor. The standardized scoring systems, computer-assisted analysis methods, and evidence-based testing protocols that characterize modern polygraph practice were developed in significant part to address the concerns Lykken raised. The work of researchers like Raymond Nelson on the Empirical Scoring System [17]Verified Scientific Basis for Polygraph Testing
Confirms Raymond Nelson's role as researcher, past-President of APA, curriculum director, and developer of standardized scoring systems including the Empirical Scoring System, the ongoing refinement of comparison question methodology, and the development of quality assurance standards by organizations like the American Polygraph Association all represent the profession's productive engagement with Lykken's challenges.

The history of the invention of the polygraph has always been marked by an evolving relationship between scientific critique and professional practice. From the earliest instruments like the Stoelting Deceptograph and Mackenzie's pulse studies to today's computerized systems, polygraph technology has consistently improved through the constructive tension between critics and practitioners. Lykken's contribution to that dynamic was immense.

Modern polygraph testing — with its standardized protocols, validated scoring systems, and growing integration of statistical and AI-based analysis — is a stronger, more scientifically grounded enterprise than it was before Lykken's critiques. The insights of researchers like Paul Ekman on facial coding and behavioral analysis, combined with advances in polygraph methodology, continue to expand the toolkit available for credibility assessment. Polygraph testing remains a valuable tool across government, law enforcement, and forensic applications worldwide, with its ongoing evolution reflecting the profession's commitment to scientific excellence.