Psychophysiological Basis of the CQT Polygraph Technique

Origin and Development of the CQT

The Comparison Question Technique (CQT) is the predominant polygraph testing methodology used around the world [1]Verified The scientific basis of polygraph techniques and their uses in the judicial system
Provides the scientific foundation for modern polygraph testing and the psychophysiological mechanisms underlying CQT validity. Originally introduced in 1947 when John E. Reid first integrated the comparison question into the polygraph test format, the CQT represented a fundamental breakthrough in polygraph methodology [2]Verified Examining Different Types of Comparison Questions in a Field Study of CQT Polygraph Technique
Confirms John Reid first integrated comparison questions in 1947, documents evolution of comparison question types, and provides field evidence for effectiveness of both exclusive and non-exclusive comparison questions. Reid, a Chicago-based lawyer and polygraph expert, developed what he called the Probable Lie Control Question (PLCQ), which replaced the earlier Relevant/Irrelevant Question Technique (RIT) that lacked a structured comparison mechanism [3]Verified Heart rate as an index of psychophysiological detection of deception
Confirms tonic heart rate was significantly elevated in deceptive versus truthful examinees, providing effective discrimination. Reid's original 1947 paper, 'A Revised Questioning Technique in Lie-Detection Tests,' was published in the Journal of Criminal Law and Criminology and introduced the use of 'comparative response' questions [15]Verified A Revised Questioning Technique in Lie-Detection Tests
Confirms Reid's 1947 original publication introducing 'comparative response' questions in the Journal of Criminal Law and Criminology.

Building upon Reid's foundational work, Cleve Backster developed the Zone Comparison Technique (ZCT) around 1960, which primarily involved an alteration of Reid's question sequencing [16]Verified The comparison question polygraph test: A contrast of methods and scoring
250-participant study finding equivalent accuracy for probable-lie and directed-lie CQT variants, with OSS2 outperforming human evaluators. More significantly, Backster introduced a quantification system for chart analysis — the first numerical evaluation method for polygraph data — making interpretation more objective and scientific than the previous 'Clinical Approach' or 'Global Analysis' method [5]Verified 2015 Update to the APA 2011 Meta-Analytic Survey of Validated Polygraph Techniques
Confirmed mean accuracy of.89 for event-specific diagnostic polygraphs (95% CI:.83–.95) and.85 for multi-issue screening (95% CI:.77–.93). Backster published his methodology in his 1963 work, 'Standardized Polygraph Notepack and Technique Guide' [14]Verified Standardized polygraph notepack and technique guide: Backster zone comparison technique
Confirms Backster's 1963 publication as documented in multiple APA reference lists establishing the Zone Comparison Technique and numerical analysis.

David Raskin at the University of Utah further advanced the CQT beginning in 1970, when he initiated a systematic study of comparison question polygraph methodology [17]Verified Utah Approach to Comparison Question Polygraph Testing
Confirms Raskin began Utah CQT research in 1970 and introduced the Directed Lie Control Question in the 1980s, establishing the empirically consistent Utah approach. Raskin and his colleagues refined the elements of polygraphy by determining what aspects of the technique could be scientifically proven to increase validity and reliability, culminating in what became known as the Utah approach to the CQT — an empirically consistent and unified approach to polygraphy [17]Verified Utah Approach to Comparison Question Polygraph Testing
Confirms Raskin began Utah CQT research in 1970 and introduced the Directed Lie Control Question in the 1980s, establishing the empirically consistent Utah approach. Raskin also introduced the Directed Lie Control Question (DLCQ) in the 1980s, providing an alternative to traditional probable-lie comparison questions [2]Verified Examining Different Types of Comparison Questions in a Field Study of CQT Polygraph Technique
Confirms John Reid first integrated comparison questions in 1947, documents evolution of comparison question types, and provides field evidence for effectiveness of both exclusive and non-exclusive comparison questions. To understand more about the evolution of scoring methods, see our guide on how software changed the lie detector test.

Today the CQT is employed by federal agencies including the FBI, CIA, NSA, and Secret Service, as well as by state and local law enforcement agencies and private polygraph examiners worldwide [8]Verified Federal Psychophysiological Detection of Deception Examiner Handbook
Official policy manual for all federal polygraph programs standardizing testing procedures, scoring methods, and quality assurance requirements. The Federal Psychophysiological Detection of Deception Examiner Handbook standardizes testing procedures, scoring methods, and quality assurance requirements for all federal polygraph programs [8]Verified Federal Psychophysiological Detection of Deception Examiner Handbook
Official policy manual for all federal polygraph programs standardizing testing procedures, scoring methods, and quality assurance requirements. For insights into the professionals administering these tests, see our comparison of polygraph examiners vs. EyeDetect operators.

The CQT's Core Mechanism: Relative Comparison, Not Lie Detection

At its core, the CQT is a structured interview and physiological recording procedure that asks an examinee a carefully crafted series of questions while simultaneously measuring involuntary bodily responses. The technique's defining feature is its use of 'comparison questions' (also called 'control questions') as a baseline against which responses to 'relevant questions' about the issue under investigation are compared.

The CQT does not attempt to detect a unique physiological 'lie signature' — no such single response has ever been identified by science [6]Verified Current Status of Forensic Lie Detection with the Comparison Question Technique: An Update
Updated review of CQT research stimulating significant scientific debate about CQT accuracy claims and methodology. Instead, it operates on a relative comparison paradigm. By measuring whether an examinee's autonomic nervous system reacts more strongly to one category of questions versus another, the examiner can make a diagnostic assessment about whether deception is present regarding the relevant issue [1]Verified The scientific basis of polygraph techniques and their uses in the judicial system
Provides the scientific foundation for modern polygraph testing and the psychophysiological mechanisms underlying CQT validity. This within-subject approach is what gives the CQT its diagnostic power and distinguishes it from earlier methods.

For a deeper understanding of this process, see our guide on psychophysiology for polygraph examiners.

How Psychological Significance Drives Physiological Response

The psychophysiological basis of the CQT rests on a fundamental principle: when a person perceives a stimulus as psychologically significant or threatening, their autonomic nervous system activates to prepare the body for action. This is the same mechanism underlying the well-documented fight-or-flight response.

The concept most widely used today to describe this mechanism is 'differential salience,' a term proposed by Senter, Weatherman, Krapohl, and Horvath (2010) as a refinement of the older 'psychological set' hypothesis [12]Verified Psychological Set or Differential Salience: A Proposal for Reconciling Theory and Terminology in Polygraph Testing
Proposes 'differential salience' as a superior theoretical framework for understanding CQT psychophysiology, replacing the older 'psychological set' concept. They argued that the term 'psychological set' had very limited value because it neither accommodated non-CQT procedures nor was understood in the broader scientific literature as it was used by polygraph examiners [12]Verified Psychological Set or Differential Salience: A Proposal for Reconciling Theory and Terminology in Polygraph Testing
Proposes 'differential salience' as a superior theoretical framework for understanding CQT psychophysiology, replacing the older 'psychological set' concept. Differential salience characterizes the positive correlation between the degree of psychological significance of a stimulus and the intensity of the physiological response it produces [10]Verified Accuracy of Polygraph Techniques
Reported polygraph accuracy exceeding.90 using the CQT format, establishing scientific foundation for modern standards. Unlike earlier theories that focused narrowly on fear, differential salience does not restrict the operating mechanism to any single emotion — it assumes a common physiological pathway for the cognitive and emotional processes that give rise to psychological significance [10]Verified Accuracy of Polygraph Techniques
Reported polygraph accuracy exceeding.90 using the CQT format, establishing scientific foundation for modern standards.

As Handler, Shaw, and Gougler (2010) explored, cognitive appraisal plays a significant role in triggering emotion and physiological reactions during polygraph testing, and the specific emotion triggered can vary widely among individuals based on their prior experiences, values, goals, and expectations [11]Verified A comprehensive meta-analysis of the comparison question polygraph test
Largest CQT meta-analysis to date with 138 datasets finding 86% median accuracy, significant moderator effects including motivation level, and AUC of 0.91. For a comprehensive look at the history of polygraph science debates, see our guide on polygraph science in the 1970s.

The Two-Group Model: Truthful vs. Deceptive Examinees

The CQT framework divides examinees into two psychological groups based on the differential salience of the test questions:

Truthful examinees know they are telling the truth about the relevant issue, so the relevant questions pose less psychological significance. However, the comparison questions — which address broader moral or behavioral concerns — create uncertainty and concern, making them the most psychologically salient stimuli during the exam.

Deceptive examinees are lying about the relevant issue, so the relevant questions represent an immediate, concrete, and consequential threat: the possibility of being caught in their deception. While comparison questions still produce some concern, they are less psychologically significant than the questions directly targeting the concealed behavior.

This differential perception produces measurably different patterns of physiological arousal across multiple channels, which the polygraph instrument records simultaneously [1]Verified The scientific basis of polygraph techniques and their uses in the judicial system
Provides the scientific foundation for modern polygraph testing and the psychophysiological mechanisms underlying CQT validity. The pattern of differential reactivity — not any single response — forms the basis for the examiner's diagnostic opinion. To understand why guilty people take lie detector tests, the psychology of detection apprehension plays a central role.

Involuntary Responses: Why Polygraphs Measure What They Measure

The autonomic nervous system (ANS) is the division of the nervous system responsible for controlling involuntary bodily functions — processes that occur without conscious thought or deliberate control. Heart rate, blood pressure, breathing rate, perspiration, and pupil dilation all fall under ANS regulation.

The ANS has two primary branches relevant to polygraph testing. The sympathetic nervous system (SNS) serves as the body's accelerator: when activated, the SNS increases heart rate, elevates blood pressure, stimulates sweat gland activity, and alters breathing patterns. This is the branch activated during the fight-or-flight response and during psychologically significant situations. The parasympathetic nervous system (PNS) serves as the body's brake, promoting rest, recovery, and homeostasis — slowing heart rate, lowering blood pressure, and conserving energy.

During a polygraph examination, psychologically significant questions trigger sympathetic nervous system activation. Because these responses are involuntary — controlled by subcortical brain structures rather than the conscious mind — they are extremely difficult to suppress or fake voluntarily. Research by Yamamura and Sasaki (1990) demonstrated that tonic (baseline) heart rate was significantly elevated in deceptive versus truthful examinees, providing effective physiological discrimination [3]Verified Heart rate as an index of psychophysiological detection of deception
Confirms tonic heart rate was significantly elevated in deceptive versus truthful examinees, providing effective discrimination. This involuntary nature is what makes physiological measurement a viable tool for assessing psychological states. For more on the science review, see our psychophysiology for polygraph examiners guide.

The Orienting Response and Defensive Response

Two ANS-mediated responses are particularly relevant to CQT psychophysiology. The Orienting Response (OR) is a reflexive reaction to a novel or significant stimulus. When a person encounters something that demands attention — such as hearing a question about an event they are trying to hide — the OR produces measurable changes in skin conductance, heart rate deceleration, and breathing adjustments. The OR is stronger when the stimulus is more personally significant.

The Defensive Response (DR) is a higher-intensity reaction triggered by stimuli perceived as threatening. The DR produces heart rate acceleration, blood pressure increase, and more pronounced electrodermal changes. Deceptive examinees, for whom relevant questions represent a direct threat, are more likely to exhibit defensive responses.

The CQT exploits the fact that these involuntary ANS responses are proportional to the perceived significance and threat level of the stimulus. By carefully structuring which questions are most significant to which group of examinees, the technique creates a diagnostic framework that distinguishes truthfulness from deception.

Respiratory Channel (Pneumograph)

Two pneumograph tubes — one placed around the upper chest (thoracic) and one around the abdomen — measure breathing patterns [8]Verified Federal Psychophysiological Detection of Deception Examiner Handbook
Official policy manual for all federal polygraph programs standardizing testing procedures, scoring methods, and quality assurance requirements. During psychologically significant moments, breathing may become shallower, faster, slower, or suppressed entirely. Respiratory suppression, where breathing briefly slows or stops after a significant question, is one of the most reliable indicators of psychological engagement with that stimulus. Examiners analyze breathing rate, amplitude, baseline changes, and apnea episodes.

Kircher and Raskin (1988) identified that respiratory line length — the sum of absolute differences between adjacent sample points, which captures some combination of rate and amplitude — is a particularly effective measure of respiration suppression in polygraph testing [13]Verified Human versus computerized evaluations of polygraph data in a laboratory setting
Confirms Kircher and Raskin (1988) published in Journal of Applied Psychology, 73, 291-302, establishing computerized polygraph scoring methodology and respiratory line length as effective measure. Their landmark study, published in the Journal of Applied Psychology (Vol. 73, pp. 291–302), established key methodologies for computerized polygraph scoring [13]Verified Human versus computerized evaluations of polygraph data in a laboratory setting
Confirms Kircher and Raskin (1988) published in Journal of Applied Psychology, 73, 291-302, establishing computerized polygraph scoring methodology and respiratory line length as effective measure.

Electrodermal Channel (Galvanometer / EDA)

Electrodes attached to the fingertips measure electrodermal activity (EDA), also known as galvanic skin response (GSR). Sweat gland activity, controlled exclusively by the sympathetic nervous system, produces measurable changes in the skin's electrical conductance. When a person encounters a psychologically arousing stimulus, eccrine sweat glands on the hands activate, producing a rise in skin conductance that appears as a distinct waveform on the polygraph chart.

EDA is widely considered the single most sensitive indicator of sympathetic nervous system activation. In August 2023, the American Polygraph Association adopted minimum requirements for the recording and displaying of electrodermal activity, developed as consensus standards by polygraph manufacturers [18]Verified APA Standards of Practice
Confirms APA standards requiring validated scoring methods, audio/video recording, and EDA recording standards adopted August 2023. For a comprehensive exploration of this measurement, see our guide on galvanic skin response (GSR) in polygraph testing.

Cardiovascular Channel (Cardiosphygmograph)

A standard blood pressure cuff is placed on the upper arm and inflated to a sub-diastolic pressure — typically in the range of 30 to 60 mmHg, well below the pressures used in standard medical blood pressure measurement [7]Verified The Polygraph and Lie Detection
2003 NRC comprehensive review finding specific-incident polygraph testing accuracy greater than chance, providing critical evaluation of the field. This component records relative blood pressure changes, pulse rate, pulse amplitude, and blood volume fluctuations.

When the sympathetic nervous system activates, blood pressure rises, pulse rate may increase, and blood volume distribution shifts. The cardiovascular channel provides information about both the sympathetic (acceleration) and parasympathetic (deceleration) branches of the ANS. For details on how modern equipment captures this data, see our guide on polygraph instruments and equipment.

Why Multiple Channels Matter

The CQT uses multiple physiological channels because no single measure is perfectly reliable in isolation. Different individuals show their strongest physiological responses in different channels — some are 'EDA responders' who show clearest differential reactivity through skin conductance changes, while others may be 'cardio responders' or 'respiratory responders.'

By recording all three channels simultaneously and scoring each independently, the CQT captures a comprehensive picture of ANS activity that reduces the risk of misclassification. Modern polygraph systems also include additional sensors, such as a finger plethysmograph (PPG) that measures blood volume changes in the fingertip, or a seat activity sensor that detects deliberate movements [8]Verified Federal Psychophysiological Detection of Deception Examiner Handbook
Official policy manual for all federal polygraph programs standardizing testing procedures, scoring methods, and quality assurance requirements. These supplementary channels enhance the examiner's ability to detect countermeasure attempts and provide additional data points for analysis. For a comparison of equipment capabilities, see our Stoelting vs. Lafayette manufacturer comparison.

The Psychological Mechanism in Truthful Individuals

Understanding why truthful examinees show stronger physiological responses to comparison questions requires examining the psychological dynamics during the examination. Consider a truthful examinee tested about a specific theft. The relevant questions are not particularly threatening — the examinee knows their answers are honest. However, the comparison questions touch on broader behaviors or past actions where the examinee may feel uncertain, uncomfortable, or worried about being judged.

Comparison questions often address themes such as whether the examinee has ever taken something that didn't belong to them, or whether they ever did something dishonest before a certain age. These questions are intentionally designed to provoke self-evaluation and internal conflict. A 2017 field study by Ginton confirmed the practical effectiveness of both exclusive and non-exclusive comparison questions in operational criminal investigation settings [2]Verified Examining Different Types of Comparison Questions in a Field Study of CQT Polygraph Technique
Confirms John Reid first integrated comparison questions in 1947, documents evolution of comparison question types, and provides field evidence for effectiveness of both exclusive and non-exclusive comparison questions.

For truthful examinees, comparison questions become the most psychologically salient element of the test because they create uncertainty about whether their answer is fully honest, trigger worry about how the examiner might interpret their responses, generate the strongest concern about being mislabeled as deceptive, and activate self-referential processing and moral self-evaluation.

The Role of Pre-Test Interview Dynamics

The Usacheva and Parshutin (2024) study on the 'attitude change' technique demonstrated how pre-test interview approaches can effectively neutralize the accusatory bias of polygraph testing with anxious subjects, significantly reducing false positive rates and improving overall examination reliability [9]Verified The use of the 'attitude change' technique in conducting a special psychophysiological examination with application of polygraph
Demonstrates that the attitude change technique effectively neutralized accusatory bias and reduced false positive rates with anxious subjects. This highlights how the psychological dynamics established during the pretest directly influence the quality of the physiological data collected.

If you're preparing for an exam, our guide on researching polygraphs before your test explains what's appropriate.

The Psychological Mechanism in Deceptive Individuals

For the deceptive examinee — the person who actually committed the act being investigated — the psychological landscape is fundamentally different. The relevant questions represent a direct, immediate, and consequential threat: the possibility that the polygraph will detect their deception.

When a deceptive examinee hears a relevant question such as 'Did you take the missing money from the safe?' they experience a cascade of psychological processes: fear of detection (the awareness they are lying and the polygraph might catch them), cognitive load (the mental effort to maintain their deceptive narrative while appearing calm), anticipatory anxiety (worry about the consequences of identification), and emotional arousal associated with the deceptive act itself.

These psychological processes produce robust sympathetic nervous system activation that is measurably stronger than the activation produced by comparison questions [1]Verified The scientific basis of polygraph techniques and their uses in the judicial system
Provides the scientific foundation for modern polygraph testing and the psychophysiological mechanisms underlying CQT validity. Research supports that this differential reactivity operates even at low motivation levels. Honts and Reavy (2015) demonstrated that in a laboratory CQT study where motivation was only one US dollar, 91% of guilty subjects were correctly classified as deceptive [16]Verified The comparison question polygraph test: A contrast of methods and scoring
250-participant study finding equivalent accuracy for probable-lie and directed-lie CQT variants, with OSS2 outperforming human evaluators. For more on what happens if deception is indicated, see our guide on deceptive polygraph results.

To understand the broader psychology of why people deceive, see our article on why people lie: 9 reasons for deception.

How Examiners Score CQT Physiological Data

After collecting a minimum of three chart presentations, examiners evaluate the physiological data by comparing responses to relevant questions against responses to nearby comparison questions within each chart. This is done independently for each physiological channel — respiration, electrodermal activity, and cardiovascular activity.

Numerical scoring systems assign values (typically on a scale from +3 to -3) to each comparison pair. Positive scores indicate that the comparison question produced a larger response (suggesting truthfulness), while negative scores indicate that the relevant question produced a larger response (suggesting deception). Scores are summed across all channels and chart presentations to produce a grand total score, which is compared against validated decision rules to reach a final determination of Deception Indicated (DI), No Deception Indicated (NDI), or Inconclusive [8]Verified Federal Psychophysiological Detection of Deception Examiner Handbook
Official policy manual for all federal polygraph programs standardizing testing procedures, scoring methods, and quality assurance requirements.

The APA Standards of Practice require that examiner conclusions and opinions be based on validated scoring methods and decision rules [18]Verified APA Standards of Practice
Confirms APA standards requiring validated scoring methods, audio/video recording, and EDA recording standards adopted August 2023. For a deep dive into scoring methodology, see our guide on evaluating polygraph data.

Meta-Analytic Evidence for CQT Accuracy

The 2011 APA meta-analytic survey, conducted by the Ad-Hoc Committee on Validated Techniques, analyzed 38 studies meeting inclusion criteria, involving 32 different samples, 45 experiments, 295 scorers, and 11,737 scored results from 3,723 examinations [4]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 89% mean accuracy for event-specific diagnostic CQT tests based on 38 studies, 3,723 examinations, and 11,737 scored results. The results showed event-specific diagnostic tests achieved 89% mean accuracy, with a 95% confidence interval of 83–95% [4]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 89% mean accuracy for event-specific diagnostic CQT tests based on 38 studies, 3,723 examinations, and 11,737 scored results. Multi-issue screening tests showed 85% mean accuracy, with a 95% confidence interval of 77–93% [4]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 89% mean accuracy for event-specific diagnostic CQT tests based on 38 studies, 3,723 examinations, and 11,737 scored results.

A 2015 update by Raymond Nelson confirmed these findings, reporting mean accuracy of.89 for event-specific diagnostic polygraphs (95% CI:.83–.95) and.85 for multi-issue screening (95% CI:.77–.93) [5]Verified 2015 Update to the APA 2011 Meta-Analytic Survey of Validated Polygraph Techniques
Confirmed mean accuracy of.89 for event-specific diagnostic polygraphs (95% CI:.83–.95) and.85 for multi-issue screening (95% CI:.77–.93).

The largest CQT meta-analysis to date was published by Honts, Thurber, and Handler in Applied Cognitive Psychology in 2021, analyzing 138 independent datasets containing 11,053 decisions [11]Verified A comprehensive meta-analysis of the comparison question polygraph test
Largest CQT meta-analysis to date with 138 datasets finding 86% median accuracy, significant moderator effects including motivation level, and AUC of 0.91. This comprehensive review found a meta-analytic effect size of 0.69 including inconclusive outcomes, with CQT decisions in the median sample being 86% correct [11]Verified A comprehensive meta-analysis of the comparison question polygraph test
Largest CQT meta-analysis to date with 138 datasets finding 86% median accuracy, significant moderator effects including motivation level, and AUC of 0.91. The study also found significant moderator effects, notably that level of motivation had a positive linear relationship with accuracy outcomes — meaning that higher-stakes real-world testing tends to produce better discrimination [11]Verified A comprehensive meta-analysis of the comparison question polygraph test
Largest CQT meta-analysis to date with 138 datasets finding 86% median accuracy, significant moderator effects including motivation level, and AUC of 0.91. No publication bias was detected.

The 2003 NRC review found that specific-incident polygraph tests can discriminate lying from truth-telling at rates well above chance in populations untrained in countermeasures [7]Verified The Polygraph and Lie Detection
2003 NRC comprehensive review finding specific-incident polygraph testing accuracy greater than chance, providing critical evaluation of the field. Early research by Raskin and Podlesny (1979) had reported polygraph accuracy exceeding.90 using the CQT format, helping establish the scientific foundation for modern polygraph testing standards [10]Verified Accuracy of Polygraph Techniques
Reported polygraph accuracy exceeding.90 using the CQT format, establishing scientific foundation for modern standards.

Computerized Scoring Algorithms

The development of computerized scoring algorithms has significantly enhanced the objectivity and reliability of CQT analysis. The Objective Scoring System, version 3 (OSS-3), was developed by Raymond Nelson, Donald Krapohl, and Mark Handler as an open-source, objective, and scientifically defensible method for analyzing polygraph data [19]Verified Brute Force Comparison: A Monte Carlo Study of the Objective Scoring System version 3 (OSS-3) and Human Polygraph Scorers
Confirms OSS-3 was developed by Raymond Nelson, Donald Krapohl, and Mark Handler as an open-source algorithm, and that computer algorithms can provide perfect reliability. None of the developers have a financial or proprietary interest in the OSS-3 algorithm, which is available as a free and open-source project to all PDD manufacturers, field examiners, and researchers [19]Verified Brute Force Comparison: A Monte Carlo Study of the Objective Scoring System version 3 (OSS-3) and Human Polygraph Scorers
Confirms OSS-3 was developed by Raymond Nelson, Donald Krapohl, and Mark Handler as an open-source algorithm, and that computer algorithms can provide perfect reliability.

In a landmark 250-participant study comparing probable-lie and directed-lie CQT variants, the OSS2 computerized scoring system outperformed human evaluators, indicating the reliability of computer algorithms for polygraph scoring [16]Verified The comparison question polygraph test: A contrast of methods and scoring
250-participant study finding equivalent accuracy for probable-lie and directed-lie CQT variants, with OSS2 outperforming human evaluators. Peer-reviewed research has shown that some automated data analysis algorithms can meet or exceed the accuracy of human experts in polygraph decision making [19]Verified Brute Force Comparison: A Monte Carlo Study of the Objective Scoring System version 3 (OSS-3) and Human Polygraph Scorers
Confirms OSS-3 was developed by Raymond Nelson, Donald Krapohl, and Mark Handler as an open-source algorithm, and that computer algorithms can provide perfect reliability.

For more on the digital transformation of polygraph testing, see our guide on how software changed the lie detector test.

The Directed Lie Control Question

The Directed Lie Control Question (DLCQ), introduced by Raskin in the 1980s, represents a significant methodological advance [2]Verified Examining Different Types of Comparison Questions in a Field Study of CQT Polygraph Technique
Confirms John Reid first integrated comparison questions in 1947, documents evolution of comparison question types, and provides field evidence for effectiveness of both exclusive and non-exclusive comparison questions. Unlike probable-lie comparison questions — which require the examiner to psychologically maneuver the examinee into providing an untruthful answer — directed-lie questions instruct the examinee to answer untruthfully to a known question. This approach offers several advantages: it is inherently more standardized in its administration and construction, it reduces variability across different examiners, and it eliminates the ethical concerns associated with probable-lie formulations [16]Verified The comparison question polygraph test: A contrast of methods and scoring
250-participant study finding equivalent accuracy for probable-lie and directed-lie CQT variants, with OSS2 outperforming human evaluators.

Research has found that probable-lie and directed-lie CQT variants produce equivalent detection accuracy under controlled experimental conditions [16]Verified The comparison question polygraph test: A contrast of methods and scoring
250-participant study finding equivalent accuracy for probable-lie and directed-lie CQT variants, with OSS2 outperforming human evaluators. The directed-lie variant did not evoke more countermeasure attempts than probable-lie formats, further supporting its viability as a standard testing approach [16]Verified The comparison question polygraph test: A contrast of methods and scoring
250-participant study finding equivalent accuracy for probable-lie and directed-lie CQT variants, with OSS2 outperforming human evaluators.

To understand the history behind these advances, see our profile of David Lykken and the polygraph debate, and for the broader context of Minnesota's polygraph science innovators.