Polygraph Test Results: How to Read & Understand Your Report

What Are the Three Possible Polygraph Results?

Every polygraph examination concludes with one of three possible outcomes. These outcomes represent the examiner's professional opinion based on the examinee's physiological responses to the relevant questions asked during the test. Understanding these three categories is the most fundamental step in reading your polygraph report.

The three outcomes are standardized across the profession and recognized by organizations including the American Polygraph Association (APA), the American Association of Police Polygraphists (AAPP), and the National Center for Credibility Assessment (NCCA). According to the APA Standards of Practice (amended August 2024), test results are formally reported using the terms Deceptive Indicated or Non-Deceptive Indicated, Inconclusive, and No Opinion (DI or NDI, INC, or NO) [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements. Regardless of the testing technique used — whether it's a Federal Zone Comparison Test (FZCT), a Matte Quadri-Track (MQTZCT), or a Utah ZCT — the final result will always be classified into one of these three categories.

Non-Deceptive Indicated (NDI) — "Passed"

A Non-Deceptive Indicated result means the examinee's physiological responses did not show significant reactions to the relevant (crime-relevant or issue-relevant) questions compared to the comparison questions. In simple terms, the data suggests you were being truthful.

The examiner's numerical scores for each relevant question met or exceeded the positive threshold established by the test technique's decision rules. An NDI result is the outcome most examinees hope for, and it is generally treated as confirmation of truthfulness by the requesting party — whether that's an employer, attorney, therapist, or family member.

Research from the APA's 2011 meta-analytic survey found that event-specific diagnostic polygraph techniques produced an aggregated decision accuracy of 89% (confidence interval of 83%–95%) [2]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 87% overall decision accuracy (CI 80%-94%), 89% for event-specific diagnostic testing, 85% for multiple-issue testing, and 13% inconclusive rate across 38 studies and 3,723 examinations, meaning that the vast majority of NDI results reflect genuine truthfulness.

Deceptive Indicated (DI) — "Failed"

A Deceptive Indicated result means the examiner observed significant physiological responses to one or more relevant questions. These reactions — typically measured through respiratory changes, electrodermal (skin conductance) activity, and cardiovascular response — were stronger during the relevant questions than during the comparison questions.

The numerical scores totaled a negative value that crossed the deceptive threshold according to the scoring system in use. A DI result does not automatically mean the person is guilty of anything; it indicates that the physiological data suggests deception regarding the specific issues tested. Understanding this distinction is essential, especially when results carry legal or personal consequences.

As Widacki (2014) has noted, polygraph results are classified as circumstantial evidence requiring logical inference rather than direct evidence, which helps explain judicial caution around their use [6]Verified Results of Polygraph Examinations: Direct or Circumstantial Evidence?
Confirms polygraph results are classified as circumstantial evidence requiring logical inference rather than direct evidence. A DI result warrants careful consideration of context, including whether to pursue a retest or independent review.

Inconclusive (INC) — "No Opinion Rendered"

An Inconclusive result means the physiological data did not clearly indicate either truthfulness or deception. The total numerical scores fell within the inconclusive range — between the positive (non-deceptive) and negative (deceptive) cut scores.

This can happen for several reasons, including elevated general physiological arousal, inconsistent responding between chart repetitions, medical conditions, medications, or an examinee's heightened anxiety that affected all question types equally. Conditions affecting the autonomic nervous system — from hypertension to certain medications like beta blockers — can impact physiological readings [14]Verified Beyond the Polygraph: Deception Detection and the Autonomic Nervous System
Confirms that medical conditions (cardiovascular disease, diabetes, rheumatoid arthritis) and medications (beta blockers, antihistamines, sympathomimetics) can affect autonomic nervous system responses during polygraph testing. Learn more about how these factors interact in our guide on schizophrenia and lie detector tests.

The APA's 2011 meta-analysis found an average inconclusive rate of approximately 13% across all validated techniques [2]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 87% overall decision accuracy (CI 80%-94%), 89% for event-specific diagnostic testing, 85% for multiple-issue testing, and 13% inconclusive rate across 38 studies and 3,723 examinations. An inconclusive result is neither a pass nor a fail; it simply means the test could not produce a reliable determination, and the examiner may recommend retesting. For more on your options in this situation, see our article on retaking a polygraph after an inconclusive result.

What Does "Significant Reaction" Actually Mean?

When polygraph examiners talk about a "significant reaction," they are referring to measurable changes in the examinee's autonomic nervous system responses. The polygraph instrument monitors three primary physiological channels simultaneously:

Respiratory activity: Two pneumograph tubes placed around the upper chest and abdomen record breathing rate, depth, and regularity. A deceptive response may involve breathing suppression, apnea (holding breath), or a baseline change in breathing rate following a relevant question. The APA Standards of Practice require thoracic and abdominal patterns to be recorded separately [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements. Learn more about suppression responses in polygraph testing.

Electrodermal activity (EDA): Finger plates or electrodes attached to the fingertips measure changes in skin conductance caused by sweat gland activity. Research by Handler, Nelson, Krapohl, and Honts (2010) confirmed that the electrodermal response is "the most robust and informative" of all signals collected during polygraph testing [3]Verified An EDA Primer for Polygraph Examiners
Confirms the electrodermal response is the most robust and informative signal in polygraph testing, and provides the greatest contribution to diagnostic accuracy. Several studies indicate the electrodermal component provides the greatest contribution to diagnostic accuracy in the comparison question test [3]Verified An EDA Primer for Polygraph Examiners
Confirms the electrodermal response is the most robust and informative signal in polygraph testing, and provides the greatest contribution to diagnostic accuracy.

Cardiovascular activity: A blood pressure cuff records changes in relative blood pressure, heart rate, and pulse amplitude. Deceptive responses may appear as increases in blood pressure (an upward shift in the baseline), changes in heart rate, or alterations in pulse amplitude.

The examiner evaluates each channel independently for each relevant question and assigns numerical scores based on the magnitude and consistency of responses compared to nearby comparison questions. A "significant reaction" is one where the response to the relevant question is notably larger, more pronounced, or more consistent than the response to the comparison question across multiple chart presentations. To learn what a polygraph actually measures, visit our guide on what a polygraph machine looks for.

How Numerical Scoring Works

Modern polygraph testing relies on a numerical scoring system to convert physiological data into objective, quantifiable results. This system was developed to standardize decision-making and reduce the subjective element of chart interpretation.

In a typical Zone Comparison Test, the examiner compares each relevant question against its paired comparison question across every physiological channel. Each comparison produces a score, typically ranging from -3 to +3 on a seven-point scale [4]Verified The Utah Numerical Scoring System
Confirms the seven-point scoring scale (+3 to -3) for each physiological channel per question presentation, and describes scoring criteria for respiration, EDA, blood pressure, and plethysmograph:

+3: A very clear, strong response to the comparison question relative to the relevant question (strongly suggests non-deception) +2: A clear response to the comparison question relative to the relevant question +1: A slight but noticeable response difference favoring the comparison question 0: No meaningful difference between the two responses (indeterminate) -1: A slight but noticeable response difference favoring the relevant question (slight deceptive indication) -2: A clear response to the relevant question relative to the comparison question -3: A very clear, strong response to the relevant question (strongly suggests deception)

These scores are assigned for each physiological channel (typically three or more) for each relevant question, and then summed across all charts. For a three-chart test examining two relevant questions across three channels, you could have up to 18 individual spot scores contributing to the grand total.

Cut Scores and Decision Rules

The "cut score" is the threshold value that determines whether the total numerical score indicates NDI, DI, or INC. Different test techniques use different cut scores. For example:

Federal ZCT and You-Phase formats: Typically use a three-chart minimum with a grand total of +6 or higher for Non-Deceptive, -6 or lower for Deceptive, and anything in between (-5 to +5) as Inconclusive [5]Verified Evaluating Polygraph Data
Confirms Federal ZCT cut scores of +6 for non-deceptive and -6 for deceptive, and reviews computerized scoring algorithms including CPS and PolyScore. For a detailed look at the Federal ZCT, see our complete guide to the Federal Zone Comparison Test.

Empirical Scoring System (ESS): Uses optimized cut scores derived from normative data. ESS decision cut scores are recommended at +2 for truthful subjects and -4 for deceptive subjects for single-issue tests [7]Verified Empirical Scoring System: A Cross-Cultural Replication and Extension Study of Manual Scoring and Decision Policies
Confirms ESS mean accuracy rate of 90.1% (95% CI = 83.8%-95.8%), ESS cut scores, and decision rules for single-issue and multiple-issue testing. For multiple-issue tests, any -3 score on a single relevant question results in a deceptive classification [7]Verified Empirical Scoring System: A Cross-Cultural Replication and Extension Study of Manual Scoring and Decision Policies
Confirms ESS mean accuracy rate of 90.1% (95% CI = 83.8%-95.8%), ESS cut scores, and decision rules for single-issue and multiple-issue testing.

Objective Scoring System version 3 (OSS-3): A computer algorithm that outputs a probability score indicating the likelihood of deception, calibrated to empirical accuracy thresholds [8]Verified Modern Algorithms in Polygraph Data Analysis
Confirms OSS-3 outputs probability scores calibrated to empirical accuracy thresholds, and that OSS-3 and PolyScore demonstrated accuracy rates between 85-92% under laboratory conditions. The OSS-3 uses a Gaussian-Gaussian decision model and was tested against 292 known single-issue exams [9]Verified Brute-Force Comparison: A Monte Carlo Study of the Objective Scoring System version 3 (OSS-3) and Human Polygraph Scorers
Confirms OSS-3 demonstrated balanced sensitivity and specificity, exceeded accuracy of 10 human scorers, and that computer algorithms provide perfect reliability (k = perfect vs k =.58 for experienced humans).

Your polygraph report should identify which technique and scoring system was used, and the cut scores applied to reach the final determination. If this information is missing, that's a significant quality concern — something we cover in detail in our article on fake polygraph results and how to verify them.

The 2011 APA meta-analytic survey established new mandatory standards requiring only scientifically validated techniques, effectively raising the bar for testing methodology [10]Verified Validated Techniques and Scoring Models for PDD Test Data Analysis – Conclusions from the 2011 APA Report
Confirms the 2011 APA meta-analysis established new mandatory standards requiring only scientifically validated techniques.

Understanding Per-Question Scores

In many professional-grade polygraph reports, you'll see a scoring table or matrix that breaks down the numerical scores for each relevant question, per channel, per chart. Here's a simplified example:

Example Scoring Matrix (3 charts, 2 relevant questions, 3 channels): Relevant Question 1 (R1): "Did you take the missing $5,000?" Relevant Question 2 (R2): "Do you know who took the missing money?"

Chart 1: R1 (EDA: +2, Respiration: +1, Cardio: +1) = +4 | R2 (EDA: +1, Respiration: +2, Cardio: +1) = +4 Chart 2: R1 (EDA: +2, Respiration: +1, Cardio: +2) = +5 | R2 (EDA: +1, Respiration: +1, Cardio: +2) = +4 Chart 3: R1 (EDA: +2, Respiration: +2, Cardio: +1) = +5 | R2 (EDA: +2, Respiration: +1, Cardio: +1) = +4

Grand Total: R1 = +14, R2 = +12 | Overall = +26 | Result: Non-Deceptive Indicated (NDI)

This level of detail allows attorneys, quality assurance reviewers, and other examiners to verify the call independently. Not all polygraph providers include this level of transparency in their reports, but it is considered best practice. If your report only states a conclusion without showing the scoring data, consider requesting the full documentation. For information about what to look for in your documentation, see our guide to polygraph test data sheets.

What Should Be in Your Polygraph Report?

A professional polygraph report is much more than a single-page letter stating "passed" or "failed." A comprehensive report serves as a forensic document that can be reviewed, evaluated, and, if necessary, challenged by qualified third parties. According to the APA's Standards of Practice (amended August 2024), a test result shall not be final until it is documented in the examination report and issued to the referring professional [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements. The APA also requires that all polygraph reports, test questions, data, recordings, and related documents be maintained for a minimum of three years [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements.

A complete polygraph report should contain the following components:

Examiner Identification and Credentials

The report should clearly identify the polygraph examiner by name and include their professional credentials, licensing information (if applicable in the state), APA membership status, and training school attended. The APA requires graduation from an APA-accredited or AAPP-recognized school as a minimum education standard [15]Verified Polygraph Standards: What We Should Be Doing for the Sake of the Profession
Confirms APA and AAPP are the two largest professional polygraph organizations providing standards based on research, case law, and best practices. This establishes the examiner's authority to conduct the examination and lends credibility to the findings.

Examinee Identification

The full legal name of the examinee, date of birth, and any case reference or file number should appear in the report. Some reports also include government-issued identification verification to confirm the examinee's identity.

Date, Time, Location, and Purpose

The report should specify exactly when and where the test took place, including the date, approximate start and end times, and the physical address of the testing location. The APA Standards of Practice specify that examinations shall be scheduled for not less than 90 minutes [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements. A clear statement explaining why the test was requested, who authorized it, and what specific issues were being examined should also be included.

Pre-Test Interview Summary

A summary of the pre-test interview, including background information gathered, the examinee's version of events, any disclosures made, medical or psychological conditions reported, and medications being taken. This section also documents that the examinee was informed of their rights, the voluntary nature of the test, and that they signed a consent form. The APA Standards require that informed consent be obtained after an overview of the polygraph process [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements. For tips on what to expect during this phase, see our complete pre-polygraph preparation guide.

Test Technique, Questions, and Physiological Data

The specific polygraph technique used must be named and referenced to its published validation research. The APA requires examiners to use evidence-based validated testing techniques, with evidentiary techniques requiring at least two published empirical studies demonstrating an unweighted average accuracy rate of 90% or greater [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements.

Every question asked during the examination should be listed in the exact order and exact wording used during the test, including relevant questions, comparison questions, irrelevant questions, and any sacrifice relevant questions. You may also request a specific polygraph technique before your test.

The actual polygraph tracings — either as printed charts or digital data files — should be available for review. While the raw charts may not always be included in the written report, they should be retained and available upon request.

Scoring Data, Examiner Opinion, and Post-Test Notes

The numerical scores for each relevant question, broken down by physiological channel and chart presentation, should be documented. If computerized scoring was also used, the algorithm and its output should be noted.

The final professional opinion — Non-Deceptive Indicated, Deceptive Indicated, or Inconclusive — along with a brief narrative explanation of the basis for the conclusion should reference the scoring data. If a post-test interview was conducted (particularly relevant in DI outcomes where the examiner may discuss reactions), the substance of those discussions should be summarized, including any admissions or additional disclosures.

Instrument Identification

The make, model, and software version of the polygraph instrument used should be recorded. Modern digital instruments from manufacturers such as Lafayette, Limestone, and Stoelting now incorporate built-in software for computerized scoring. Identifying the equipment allows for proper evaluation of the data quality and ensures the instrument meets current standards.

What the Polygraph Charts Actually Show

The physiological data recorded during a polygraph examination is displayed as continuous tracings — lines that rise and fall with changes in the examinee's autonomic nervous system activity. In a modern computerized polygraph, these tracings are captured digitally and can be viewed on screen, printed, or exported for review. Understanding how software changed the lie detector test helps you appreciate the evolution of chart analysis.

Each chart (also called a "presentation") records the same question sequence from start to finish. A standard examination includes a minimum of three chart presentations, though some techniques require four or five. The purpose of multiple presentations is to ensure that responses are consistent and not simply random fluctuations.

The Three Primary Channels

Pneumograph (Respiration): Typically displayed as two tracings — one for upper (thoracic) breathing and one for lower (abdominal) breathing. Normal breathing appears as a rhythmic wave pattern. Deceptive responses may manifest as breathing suppression (a sudden reduction in amplitude), apnea (holding breath), or a baseline change in breathing rate following a relevant question. The APA Standards require that thoracic and abdominal patterns be recorded separately [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements.

Electrodermal Activity (EDA): Displayed as a single tracing that shows changes in the skin's electrical conductance. When the sympathetic nervous system is activated, sweat glands increase activity, raising skin conductance, which appears on the chart as an upward deflection. Handler et al. (2010) describe the EDR as easily collected and simple to measure, with several studies confirming it provides the greatest contribution to diagnostic accuracy [3]Verified An EDA Primer for Polygraph Examiners
Confirms the electrodermal response is the most robust and informative signal in polygraph testing, and provides the greatest contribution to diagnostic accuracy. The spontaneous fluctuation rate of EDA is an important consideration for examiners in assessing data quality.

Cardiovascular: Displayed as a pulsating waveform showing individual heartbeats, overlaid on a baseline that reflects relative blood pressure. Deceptive responses may appear as increases in blood pressure, changes in heart rate, or alterations in pulse amplitude. Research using fMRI has explored the neural mechanisms underlying these polygraph responses, potentially providing construct validation for traditional measures [11]Verified Functional Magnetic Resonance Imaging May Promote Theoretical Understanding of the Polygraph Test
Explores how fMRI research can advance understanding of the neural mechanisms underlying polygraph responses and provide construct validation for traditional measures.

Additional Channels and Modern Instrumentation

Modern polygraph instruments may include additional channels beyond the traditional three:

Plethysmograph: A finger pulse sensor providing a secondary cardiovascular measure, recording peripheral vasomotor activity (blood volume changes in the fingertip). The Utah numerical scoring system includes finger plethysmograph as a scored channel, with scores from +3 to -3 assigned per presentation [4]Verified The Utah Numerical Scoring System
Confirms the seven-point scoring scale (+3 to -3) for each physiological channel per question presentation, and describes scoring criteria for respiration, EDA, blood pressure, and plethysmograph.

Movement sensor: A sensor placed on the seat or attached to the examinee that detects physical movement. The APA Standards of Practice require a seat activity sensor [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements. This helps identify countermeasure attempts and movement artifacts that might contaminate the physiological data.

Activity sensor: Some modern systems include additional sensors on the feet or legs to detect deliberate physical countermeasures like toe-pressing or muscle tensing.

The data from all these channels is recorded simultaneously and displayed in a synchronized timeline, allowing the examiner to evaluate the full physiological picture during each question. Understanding these channels connects to the broader science behind what a polygraph machine looks for in a liar.

Manual (Hand) Scoring

Manual scoring is the traditional method where a trained examiner visually evaluates the physiological tracings and assigns numerical values based on their professional judgment and the specific scoring rules of the technique being used. The examiner compares the magnitude and characteristics of the response to each relevant question against the response to the adjacent comparison question, channel by channel, chart by chart.

Manual scoring requires significant training and experience. Examiners learn to recognize different types of physiological responses — phasic EDA responses, respiratory baseline changes, blood pressure increases — and to distinguish genuine autonomic responses from artifacts (movement, coughing, deep breaths, equipment malfunction).

One advantage of manual scoring is that an experienced examiner can account for contextual factors that an algorithm might miss — for example, recognizing that a respiratory change was caused by the examinee clearing their throat rather than a deceptive response. The disadvantage is that it introduces a subjective element. Research has shown inter-scorer reliability for experienced examiners using Fleiss' kappa at approximately k =.58, while the Empirical Scoring System has helped inexperienced examiners achieve comparable accuracy to experienced scorers [9]Verified Brute-Force Comparison: A Monte Carlo Study of the Objective Scoring System version 3 (OSS-3) and Human Polygraph Scorers
Confirms OSS-3 demonstrated balanced sensitivity and specificity, exceeded accuracy of 10 human scorers, and that computer algorithms provide perfect reliability (k = perfect vs k =.58 for experienced humans).

Computerized Scoring Systems

To reduce examiner bias and increase objectivity, several computerized scoring algorithms have been developed and validated:

The Empirical Scoring System (ESS): An evidence-based normative system for manual test data analysis of comparison question test formats, developed by Nelson, Krapohl, and Handler. Validation data covers 5,192 scored results of 732 confirmed Federal and Utah three-question ZCT examinations from six samples scored by 140 scorers [7]Verified Empirical Scoring System: A Cross-Cultural Replication and Extension Study of Manual Scoring and Decision Policies
Confirms ESS mean accuracy rate of 90.1% (95% CI = 83.8%-95.8%), ESS cut scores, and decision rules for single-issue and multiple-issue testing. The ESS uses three-position scoring, electrodermal weighting, two-stage decision rules, and optimal cut-scores derived from normative data [7]Verified Empirical Scoring System: A Cross-Cultural Replication and Extension Study of Manual Scoring and Decision Policies
Confirms ESS mean accuracy rate of 90.1% (95% CI = 83.8%-95.8%), ESS cut scores, and decision rules for single-issue and multiple-issue testing. A mean accuracy rate of 90.1% (95% CI = 83.8%–95.8%) has been demonstrated with the ESS [7]Verified Empirical Scoring System: A Cross-Cultural Replication and Extension Study of Manual Scoring and Decision Policies
Confirms ESS mean accuracy rate of 90.1% (95% CI = 83.8%-95.8%), ESS cut scores, and decision rules for single-issue and multiple-issue testing.

The Objective Scoring System version 3 (OSS-3): Developed by Nelson, Krapohl, and Handler as an open-source, objective method for analyzing polygraph data [9]Verified Brute-Force Comparison: A Monte Carlo Study of the Objective Scoring System version 3 (OSS-3) and Human Polygraph Scorers
Confirms OSS-3 demonstrated balanced sensitivity and specificity, exceeded accuracy of 10 human scorers, and that computer algorithms provide perfect reliability (k = perfect vs k =.58 for experienced humans). OSS-3 uses a Gaussian-Gaussian decision model and outputs a probability score indicating the likelihood of deception [8]Verified Modern Algorithms in Polygraph Data Analysis
Confirms OSS-3 outputs probability scores calibrated to empirical accuracy thresholds, and that OSS-3 and PolyScore demonstrated accuracy rates between 85-92% under laboratory conditions. OSS-3 demonstrated balanced sensitivity and specificity and exceeded the average accuracy of ten human scorers [9]Verified Brute-Force Comparison: A Monte Carlo Study of the Objective Scoring System version 3 (OSS-3) and Human Polygraph Scorers
Confirms OSS-3 demonstrated balanced sensitivity and specificity, exceeded accuracy of 10 human scorers, and that computer algorithms provide perfect reliability (k = perfect vs k =.58 for experienced humans). It is bundled with Lafayette's LXSoftware [16]Verified LXSoftware with OSS-3 Scoring Algorithm
Confirms OSS-3 algorithm is bundled with Lafayette's LXSoftware and includes a report generator with categorical result, statistical classifier (p-value, confidence level, or odds ratio), and manual scores.

PolyScore: Developed by the Johns Hopkins University Applied Physics Laboratory (JHU-APL), it employs logistic regression for its classification model and is used with Axciton and Lafayette polygraph instruments [17]Verified Development of a Deep-Learning-Based Computerized Scoring Algorithm
Confirms PolyScore uses logistic regression and was developed by JHU-APL; CPS uses Naive Bayesian probability from University of Utah; documents multiple conventional and advanced computerized scoring systems. The Computerized Polygraph System (CPS) from the University of Utah utilizes Naive Bayesian probability to calculate scores based on a linear combination of weighted features [17]Verified Development of a Deep-Learning-Based Computerized Scoring Algorithm
Confirms PolyScore uses logistic regression and was developed by JHU-APL; CPS uses Naive Bayesian probability from University of Utah; documents multiple conventional and advanced computerized scoring systems.

A key advantage of computerized algorithms is perfect reliability — they produce the same result every time for the same data [9]Verified Brute-Force Comparison: A Monte Carlo Study of the Objective Scoring System version 3 (OSS-3) and Human Polygraph Scorers
Confirms OSS-3 demonstrated balanced sensitivity and specificity, exceeded accuracy of 10 human scorers, and that computer algorithms provide perfect reliability (k = perfect vs k =.58 for experienced humans). Most examiners now use a hybrid approach, combining manual scoring with computer algorithm validation for maximum accuracy [18]Verified Effective Policing: Understanding How Polygraph Tests Work and Are Used
Examines how polygraph tests function in real law enforcement contexts, noting the polygraph's value in eliciting confessions and admissions.

Key Quality Indicators

When reviewing your polygraph report, look for these quality indicators:

Examiner credentials clearly listed, including APA or AAPP membership and training school. The APA and AAPP are the two largest professional polygraph organizations and serve as the primary reference for professional standards [15]Verified Polygraph Standards: What We Should Be Doing for the Sake of the Profession
Confirms APA and AAPP are the two largest professional polygraph organizations providing standards based on research, case law, and best practices.

A named, validated test technique with reference to its published validation research. The APA Standards require that evidentiary testing techniques demonstrate at least 90% accuracy through at least two published empirical studies [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements.

Numerical scoring data shown for each relevant question, broken down by channel and chart. If your report only states "passed" or "failed" without supporting data, this is a significant red flag. Learn more about spotting fake polygraph results.

Computerized scoring used alongside manual scoring as a validation tool. This dual approach is now considered best practice in the profession [18]Verified Effective Policing: Understanding How Polygraph Tests Work and Are Used
Examines how polygraph tests function in real law enforcement contexts, noting the polygraph's value in eliciting confessions and admissions.

All test questions listed verbatim. This allows independent evaluation of question clarity, fairness, and relevance.

A clear statement of the purpose, scope, and context of the examination.

Red Flags in a Polygraph Report

Watch out for these warning signs:

No examiner credentials listed or examiner is not APA/AAPP affiliated. No technique identified or an unvalidated technique used. No scoring data provided — only a conclusory statement. Missing or incomplete question lists. No mention of informed consent or pre-test interview. Charts or physiological data unavailable for review. Examination lasted less than 90 minutes (below APA minimum standards) [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements. More than five examinations conducted by the same examiner in one day (also below APA standards) [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements.

A report missing these critical elements may not meet professional standards and could be challenged on quality grounds. If you suspect issues with your report, consult our guide on common misconceptions about polygraph exams.

Common Causes of Inconclusive Results

Inconclusive results occur when the physiological data falls within the range between the non-deceptive and deceptive cut scores. This happens more often than most examinees expect — the APA meta-analysis reported an average inconclusive rate of approximately 13% across validated techniques [2]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 87% overall decision accuracy (CI 80%-94%), 89% for event-specific diagnostic testing, 85% for multiple-issue testing, and 13% inconclusive rate across 38 studies and 3,723 examinations.

Common contributing factors include: elevated baseline arousal that makes it difficult to distinguish responses to relevant vs. comparison questions; inconsistent responding across chart presentations; certain medical conditions affecting the autonomic nervous system (cardiovascular disease, respiratory conditions, neurological disorders); medications such as beta blockers, anxiolytics, or antihistamines that affect ANS function [14]Verified Beyond the Polygraph: Deception Detection and the Autonomic Nervous System
Confirms that medical conditions (cardiovascular disease, diabetes, rheumatoid arthritis) and medications (beta blockers, antihistamines, sympathomimetics) can affect autonomic nervous system responses during polygraph testing; extreme test anxiety affecting all physiological channels equally; and environmental factors like noise, temperature discomfort, or equipment issues.

An inconclusive result is not a failure — it simply means the data could not reliably differentiate between truthfulness and deception. In many contexts, this leads to a recommendation for retesting under better conditions.

Polygraph Admissibility and Legal Weight

Polygraph admissibility varies significantly by jurisdiction. Some states ban polygraph evidence completely; others allow results by stipulation of both parties; and some allow polygraph evidence over objection [2]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 87% overall decision accuracy (CI 80%-94%), 89% for event-specific diagnostic testing, 85% for multiple-issue testing, and 13% inconclusive rate across 38 studies and 3,723 examinations. In the 1998 U.S. Supreme Court case United States v. Scheffer, the Court ruled on the admissibility of polygraph results, reinforcing that there is no consensus on polygraph reliability.

Widacki (2014) analyzed the evidentiary status of polygraph results and concluded they are classified as circumstantial evidence requiring logical inference, rather than direct evidence [6]Verified Results of Polygraph Examinations: Direct or Circumstantial Evidence?
Confirms polygraph results are classified as circumstantial evidence requiring logical inference rather than direct evidence. This classification helps explain why many courts exercise caution when considering polygraph evidence.

In PCSOT (Post-Conviction Sex Offender Testing) settings, polygraph results serve as a decision-support tool. Under approved judiciary procedures, polygraph results may be used to increase the level of supervision or modify treatment plans, but a polygraph result may not be used as the sole basis to revoke supervision [19]Verified Chapter 3: Polygraph for Sex Offender Management (Probation and Supervised Release Conditions)
Confirms polygraph results may not be used as sole basis to revoke supervision; maintenance examinations administered every six months; details approved judiciary procedures for polygraph use in PCSOT. The APA publishes a Model Policy for PCSOT (most recently updated September 2021) that provides best-practice guidelines for this specialized testing context [20]Verified APA Model Policy for Post-Conviction Sex Offender Testing
Provides comprehensive best-practice guidelines for PCSOT programs including examination types, multidisciplinary collaboration, ethical roles, and evidence-based approach requirements. Research by Kokish, Levenson, and Blasingame (2005) found that the majority of surveyed sex offenders reported the polygraph motivated them to be more honest in treatment and supervision [12]Verified Post-Conviction Sex Offender Polygraph Examination: Client-Reported Perceptions of Utility and Accuracy
Confirms majority of surveyed sex offenders reported the polygraph motivated them to be more honest in treatment and supervision, with high rate of agreement with test results.

The Employee Polygraph Protection Act of 1988 (EPPA) prohibits most private-sector employers from using polygraph tests, though exemptions exist for government agencies, security-related positions, and certain investigations involving economic loss [2]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 87% overall decision accuracy (CI 80%-94%), 89% for event-specific diagnostic testing, 85% for multiple-issue testing, and 13% inconclusive rate across 38 studies and 3,723 examinations.

Steps to Take Based on Your Outcome

Non-Deceptive Indicated (Passed): Obtain your full report and retain it for your records. If the test was ordered by an attorney, employer, or therapist, ensure the report is delivered to the appropriate party. Your NDI result provides strong evidence of truthfulness on the specific issues tested.

Deceptive Indicated (Failed): Do not panic. Request a copy of the full report including all scoring data. Review the report carefully or have it reviewed by a qualified independent examiner. Consider whether external factors may have influenced your results. Consult with an attorney before taking any further action, especially if the test has legal implications. You have the right to request a quality assurance review or schedule a retest with a different examiner.

Inconclusive: This is the most common scenario for scheduling a retest. The APA Model Policy recognizes that retesting may be appropriate when initial results are inconclusive. The timing of a retest varies by context — for general private testing, a waiting period of approximately 7 to 30 days allows the nervous system to return to baseline [21]Verified 5 Best Times to Retake a Polygraph (Based on Data)
Suggests 7-14 day waiting period for inconclusive results and 14-30 days when health conditions or medication affected the test. For federal agencies like U.S. Customs and Border Protection, polygraph examination results are valid for a two-year period, after which applicants are eligible to retest [22]Verified U.S. Customs and Border Protection — Polygraph Information
Confirms polygraph examination results are valid for a two-year period at CBP, and applicants are eligible to retake after that period. In PCSOT settings, maintenance examinations are typically administered every six months [19]Verified Chapter 3: Polygraph for Sex Offender Management (Probation and Supervised Release Conditions)
Confirms polygraph results may not be used as sole basis to revoke supervision; maintenance examinations administered every six months; details approved judiciary procedures for polygraph use in PCSOT. Consult our article on retaking a polygraph after an inconclusive result for detailed guidance.

Options for Challenging a Result

If you believe your polygraph results are inaccurate, you have several options:

Request an independent quality assurance (QA) review. A qualified examiner who was not involved in the original test can review the charts, scoring data, and report to verify the accuracy of the call. Any discrepancies in scoring or technique application can be documented.

Schedule a retest with a different examiner. Seeking a second opinion from an independent examiner is a legitimate and accepted practice. Ensure the new examiner is APA-affiliated and uses a validated technique.

Consult with an attorney. If the polygraph results carry legal consequences, an attorney experienced in forensic psychophysiology can advise you on the best course of action. Some defense attorneys retain polygraph experts to evaluate prosecution-obtained polygraph evidence.

File a complaint with the APA. If you believe the examiner violated professional standards, the APA has a complaint process for addressing ethical and procedural violations.

The Aldrich Ames case illustrates how polygraph results — in this case false negatives — can have significant consequences, and underscores the importance of quality assurance in every examination.

APA Meta-Analysis and Validated Technique Accuracy

The most comprehensive review of polygraph accuracy was conducted by the APA in 2011. Their meta-analytic survey examined 38 studies involving 32 different samples and 45 experiments, with 295 scorers providing 11,737 scored results from 3,723 examinations [2]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 87% overall decision accuracy (CI 80%-94%), 89% for event-specific diagnostic testing, 85% for multiple-issue testing, and 13% inconclusive rate across 38 studies and 3,723 examinations. The key findings were:

Event-specific (single issue) diagnostic techniques produced an aggregated decision accuracy of 89% (confidence interval 83%–95%) with an inconclusive rate of 11% [2]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 87% overall decision accuracy (CI 80%-94%), 89% for event-specific diagnostic testing, 85% for multiple-issue testing, and 13% inconclusive rate across 38 studies and 3,723 examinations.

Multiple-issue techniques produced an aggregated decision accuracy of 85% (confidence interval 77%–93%) with an inconclusive rate of 13% [2]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 87% overall decision accuracy (CI 80%-94%), 89% for event-specific diagnostic testing, 85% for multiple-issue testing, and 13% inconclusive rate across 38 studies and 3,723 examinations.

The combination of all validated PDD techniques, excluding outlier results, produced a decision accuracy of 87% (confidence interval 80%–94%) with an inconclusive rate of 13% [2]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 87% overall decision accuracy (CI 80%-94%), 89% for event-specific diagnostic testing, 85% for multiple-issue testing, and 13% inconclusive rate across 38 studies and 3,723 examinations.

Some individual validated techniques have shown even higher accuracy. The event-specific Zone Comparison Technique with ESS scoring has demonstrated accuracy rates exceeding 90% [7]Verified Empirical Scoring System: A Cross-Cultural Replication and Extension Study of Manual Scoring and Decision Policies
Confirms ESS mean accuracy rate of 90.1% (95% CI = 83.8%-95.8%), ESS cut scores, and decision rules for single-issue and multiple-issue testing. The 2021 comprehensive meta-analysis by Honts examined 138 datasets and confirmed that the CQT can be accurate and that experimental studies are generalizable [23]Verified A Comprehensive Meta-Analysis of the Comparison Question Polygraph Test
Meta-analysis of 138 datasets confirming CQT can be accurate, experimental studies are generalizable, and no publication bias was detected.

The APA requires that evidentiary-grade techniques must demonstrate at least 90% accuracy through peer-reviewed research, while investigative techniques must show at least 80% accuracy [1]Verified APA Standards of Practice (Amended August 23, 2024)
Confirms APA standards for validated techniques, report documentation requirements, minimum examination length of 90 minutes, and data retention requirements. These stringent validation requirements ensure that only the most reliable techniques are used for high-stakes testing.

The NRC 2003 Report and Ongoing Research

The National Research Council's 2003 report, "The Polygraph and Lie Detection," remains an important reference in the field. The NRC 2003 report reviewed the scientific evidence on polygraph testing and acknowledged that polygraph accuracy is above chance for naïve examinees untrained in countermeasures [24]Verified The Polygraph and Lie Detection (NRC 2003)
Confirms polygraph accuracy above chance for naïve examinees; interquartile range of accuracy indexes 0.81 to 0.91 across 59 datasets; discusses computerized scoring potential to improve accuracy. The report's interquartile range of accuracy indexes across 59 datasets was 0.81 to 0.91 [24]Verified The Polygraph and Lie Detection (NRC 2003)
Confirms polygraph accuracy above chance for naïve examinees; interquartile range of accuracy indexes 0.81 to 0.91 across 59 datasets; discusses computerized scoring potential to improve accuracy.

Notably, the APA's 2011 meta-analysis findings were described as "consistent with those of the National Research Council's (2003) conclusions regarding polygraph accuracy" [2]Verified Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques
Confirms 87% overall decision accuracy (CI 80%-94%), 89% for event-specific diagnostic testing, 85% for multiple-issue testing, and 13% inconclusive rate across 38 studies and 3,723 examinations, providing additional support for the validity of polygraph testing when conducted in accordance with APA Standards of Practice. Research continues to advance the field, including explorations of fMRI-based deception detection and eye-tracking technologies that may complement traditional polygraph testing in the future.