Artifacts in Polygraph Testing: Examiner’s Guide

Defining the Artifact in Psychophysiology

In the context of psychophysiological detection of deception (PDD), an artifact is any observable change in the recorded physiological data that is not caused by the psychological or physiological response to the test questions being asked. Think of artifacts as noise in the signal — they contaminate the data stream and can make it difficult, or impossible, for an examiner to accurately interpret genuine autonomic nervous system (ANS) responses.

Polygraph instruments measure multiple physiological channels simultaneously, typically including thoracic and abdominal respiration, electrodermal activity (EDA or galvanic skin response), cardiovascular activity (blood pressure, pulse rate, and relative blood volume), and activity sensors [1]Verified APA Standards of Practice
Confirms APA requirements for audio/video recording, evidence-based techniques, data retention, activity sensors, and informed consent procedures. Each channel is vulnerable to different types of artifacts. The electrodermal channel, driven exclusively by sympathetic nervous system activity, is the most robust and informative signal in polygraph testing and provides the greatest contribution to diagnostic accuracy [2]Verified EDA Primer for Polygraph Examiners
Confirms electrodermal response is the most robust and informative signal in polygraph testing, driven exclusively by sympathetic nervous system activity. However, even this powerful channel can be contaminated by movement artifacts, temperature changes, and electrode contact issues.

Understanding how artifacts interact with each channel is fundamental to competent polygraph practice and accurate data analysis according to APA standards.

The Signal-to-Noise Challenge

The core challenge every polygraph examiner faces is distinguishing between signal (genuine physiological responses related to deception or truthfulness) and noise (artifacts unrelated to the stimulus questions). This signal-to-noise ratio problem exists across all biomedical measurement disciplines, from electrocardiography (EKG) to electroencephalography (EEG).

However, polygraph testing presents unique challenges because the examiner must make this distinction in a high-stakes environment where the consequences of error can be significant for the examinee. Unlike a hospital technician who can simply re-record a contaminated EKG strip, a polygraph examiner must consider that re-asking a question introduces its own variables. The examinee's psychological state may change, habituation effects may occur, and the overall testing dynamic shifts with each repeated question series [3]Verified Main Features of Polygraph Examiners Training
Confirms core elements essential for effective polygraph examiner training including artifact identification skills. Research has shown that prior expectations can create statistically significant bias in scoring inconclusive polygraph charts [4]Verified The effects of prior expectations and outcome knowledge on polygraph examiners' decisions
Confirms prior expectations created statistically significant bias in scoring inconclusive polygraph charts, making clean data all the more essential for objective decision-making.

This is why preventing artifacts in the first place is always preferable to managing them after they occur. Understanding what happens to the body during a polygraph helps examiners distinguish normal physiological reactions from artifact contamination.

Why Artifact Recognition Is an Ethical Obligation

Accurate artifact recognition is not merely a technical skill — it is an ethical obligation rooted in the professional standards governing polygraph practice. APA Standards of Practice require examiners to use evidence-based validated testing techniques [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements and to make data-driven decisions based on clean, interpretable physiological data. When an examiner fails to identify an artifact and scores contaminated data as a genuine response, the consequences can be severe:

False positive errors: An innocent person may be judged deceptive because an artifact mimicked a deceptive response pattern. False negative errors: A deceptive individual may pass the test because an artifact obscured a genuine deceptive response. Inconclusive results: Excessive artifacts may make the data uninterpretable, requiring retesting that adds time, cost, and psychological burden. Legal vulnerability: Poorly managed artifact data can be challenged in legal proceedings, undermining the credibility of the entire examination.

Research by Hunter and Ash (1973) demonstrated that structured scoring methods achieve examiner accuracy of 92.4% for deceptive subjects and 95.5% for truthful subjects [6]Verified The Accuracy and Consistency of Polygraph Examiners' Diagnoses
Confirms examiner accuracy of 92.4% for deceptive subjects and 95.5% for truthful subjects when using structured scoring methods — but these figures depend on the quality of the underlying physiological data. Artifact contamination degrades accuracy, which is why identification and management of artifacts remains a critical competency covered extensively in polygraph training programs [7]Verified Academy of Polygraph (Lie-Detector) Examiners, An
Confirms the historical importance of standardized training and professional credentialing for polygraph examiners and throughout an examiner's career.

Physical and Movement Artifacts

Physical movement is the most common source of artifacts in polygraph testing. Even minor body adjustments can produce significant changes across multiple physiological channels. Movement artifacts are particularly problematic because they can simultaneously affect respiration, electrodermal activity, and cardiovascular tracings, creating a pattern that may superficially resemble a genuine deceptive response.

Common movement artifacts include postural adjustments (shifting weight in the chair, crossing or uncrossing legs, adjusting arm or hand position), gross body movement (turning the head, leaning forward or backward, stretching), fine motor movements (clenching fists, pressing toes against shoes, tensing arm or leg muscles), facial movements (jaw clenching, grimacing, eye squinting), and swallowing, which produces a characteristic pattern in the cardiovascular channel and may affect respiration.

Movement artifacts are detectable through direct visual observation and through characteristic multi-channel disruption patterns on the polygraph chart. Modern instruments equipped with motion-sensing pads beneath the examinee provide additional detection capability [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements. APA standards call for the use of a seat activity sensor as standard polygraph instrumentation [8]Verified APA Standard for Polygraph Instrumentation
Confirms APA instrumentation standards including activity sensor requirements, minimum 25 samples per second data acquisition, and EDA recording standards. Understanding suppression responses in polygraph testing helps examiners distinguish between genuine respiratory suppression and movement-induced breathing disruptions.

Environmental Artifacts

The testing environment can introduce artifacts entirely outside the examinee's control. Environmental artifacts typically produce a startle or orienting response in the examinee, generating physiological changes the polygraph records.

Auditory disturbances are among the most common environmental artifacts: doors slamming, phones ringing, voices in adjacent rooms, traffic noise, sirens, or construction sounds. Temperature fluctuations from HVAC systems cycling on or off, drafts from doors or windows, or heater activation can alter electrodermal baselines. External factors such as temperature and humidity affect EDA measurements, which can lead to inconsistent results [9]Verified Electrodermal activity
Confirms electrodermal responses are delayed 1-3 seconds and that temperature and humidity affect EDA measurements. Visual disturbances such as sudden changes in lighting, someone entering the room, or movement visible through windows also produce orienting responses.

Vibratory stimuli from building equipment, elevators, or nearby construction, and olfactory stimuli from cleaning products or external sources, can also contaminate data. Environmental artifacts are particularly challenging because the examiner may not always be aware of subtle environmental changes occurring during testing. This underscores the critical importance of selecting and preparing an appropriate testing environment.

Physiological Artifacts

Certain involuntary physiological events produce data changes unrelated to the stimulus questions. These are among the most challenging artifacts to manage because they originate from the examinee's own body and may be difficult to distinguish from genuine responses.

Key physiological artifacts include Premature Ventricular Contractions (PVCs), which produce characteristic disruptions in the cardiovascular tracing appearing as a sudden, distinct spike followed by a compensatory pause. Coughing and sneezing produce dramatic, multi-channel disruptions involving respiration, cardiovascular, and potentially electrodermal channels [10]Verified A History of Polygraph Digitization
Confirms early digital polygraph systems enabled editing of anomalies from movements, deep breaths, coughing, and similar activity. Hiccups (diaphragmatic spasms) directly affect respiration tracings. Borborygmi (stomach growling) can produce subtle respiratory and abdominal movement changes.

Deep sighing or yawning disrupts respiratory patterns and may indicate fatigue, boredom, or an attempt at respiratory countermeasures. Perspiration surges unrelated to test stimuli can affect electrodermal baseline and responsivity. Internal factors such as medications and hydration can also change EDA measurements, demonstrating inconsistency with the same stimulus level [9]Verified Electrodermal activity
Confirms electrodermal responses are delayed 1-3 seconds and that temperature and humidity affect EDA measurements. Understanding how caffeine and other substances affect polygraph results helps examiners anticipate and manage physiological artifact sources.

Examiners working with individuals who have borderline personality disorder or other psychological conditions should be especially alert for physiological artifacts related to emotional dysregulation.

Equipment-Related Artifacts

The polygraph instrument itself can introduce artifacts when components malfunction or are improperly configured. Equipment artifacts include loose sensor connections (poorly attached EDA electrodes, loose blood pressure cuff, or displaced pneumograph tubes), electrical interference from nearby electronic devices or fluorescent lighting, calibration drift during prolonged testing sessions, and software glitches in computerized polygraph systems.

Blood pressure cuff issues are a common source: over-inflation causes discomfort and movement artifacts, while under-inflation produces weak cardiovascular tracings. The APA approved specific standards for polygraph instrumentation in August 2023, including minimum requirements for the recording and displaying of electrodermal activity [11]Verified APA Minimum Requirements for EDA Recording and Display
Confirms APA adopted minimum requirements for recording and displaying electrodermal activity in August 2023. APA standards require that data acquisition occur at not less than 25 samples per second [12]Verified APA Standard for Polygraph Instrumentation (Approved August 25, 2023)
Confirms data acquisition must occur at not less than 25 samples per second and details sensor technology requirements. Compliance with APA standards for polygraph calibration and maintenance is essential for minimizing equipment-related artifacts.

The Importance of Timing

The most critical factor determining an artifact's impact is when it occurs relative to the stimulus question. Polygraph scoring focuses on physiological changes that occur in the reaction window following each question. APA Standards of Practice require that questions used in the assessment of truth and deception be followed by time intervals of not less than 20 seconds from question onset to question onset [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements.

The physiological response windows vary by channel. According to the Utah Numerical Scoring System, respiratory and cardiograph reactions may be scored if they begin immediately after question onset, electrodermal reactions are scored only if they begin at least 0.5 seconds after question onset, and finger pulse reactions are scored only if they begin at least 2 seconds after question onset [13]Verified The Utah Numerical Scoring System
Confirms response window timing: EDA scored from 0.5s after onset, reactions must begin within 5 seconds of answer, and details respiratory scoring criteria. For all physiological measures, the reaction must begin no later than 5 seconds after the subject's answer [13]Verified The Utah Numerical Scoring System
Confirms response window timing: EDA scored from 0.5s after onset, reactions must begin within 5 seconds of answer, and details respiratory scoring criteria. The electrodermal response has an onset latency of 1-4 seconds after stimulus, with peak values typically achieved between 3 and 6 seconds post-stimulus [14]Verified Electrodermal Response - ScienceDirect Topics
Confirms SCR latency of 1-4 seconds after stimulus onset with peak values at 3-6 seconds post-stimulus.

An artifact that occurs during this critical response window is far more consequential than one occurring between questions or during the inter-question rest period. For example, an examinee who coughs immediately after a relevant question produces dramatic changes in respiration and cardiovascular activity. If the examiner fails to identify the cough as the cause, the data might be scored as a significant response — potentially contributing to a deceptive finding where no deception exists.

The Cascade Effect

Some artifacts do not just affect the immediate data point — they create a cascade effect that disrupts physiological baselines for subsequent questions. A sudden loud noise might startle the examinee, producing an immediate orienting response. The anxiety generated by that startle can elevate the examinee's overall arousal level for minutes afterward, affecting the baseline against which subsequent responses are compared.

Research in psychophysiology confirms that tonic skin conductance level (SCL) shifts can manifest within a few tens of seconds, while drift may take many tens of minutes to become apparent [15]Verified A Guide for Analysing Electrodermal Activity (EDA) & Skin Conductance Responses
Confirms tonic SCL shifts can manifest within tens of seconds and drift may take tens of minutes to become apparent. This cascade effect is one reason why examiners may need to discard an entire chart series rather than just excluding a single contaminated question. If the artifact has disrupted the examinee's physiological equilibrium for the remainder of the chart, all subsequent data points in that series may be unreliable.

The spontaneous fluctuation rate of an examinee's electrodermal activity also influences how artifacts interact with genuine response patterns, making a thorough understanding of baseline variability essential.

Impact on Scoring Accuracy

Artifacts can push results in either direction. A movement artifact coinciding with a relevant question can create the appearance of a significant response where none exists, contributing to a false positive (deceptive) finding. Conversely, an artifact coinciding with a comparison question can inflate the comparison score, potentially masking genuine deceptive responses and contributing to a false negative (non-deceptive) finding.

Research confirms that respiratory suppression was the most frequently cited criterion in examiner scoring decisions [16]Verified Numerical scoring of polygraph charts: What examiners really do
Confirms respiratory suppression was the most frequently cited scoring criterion, with examiners achieving 82% overall accuracy in blind chart review, which means respiratory artifacts have an outsized impact on final outcomes. The APA's 2011 meta-analytic survey found that validated PDD techniques produced a combined decision accuracy of 87% (confidence interval 80-94%) with an inconclusive rate of 13% [17]Verified Polygraph Validity Research - APA Meta-Analytic Survey
Confirms aggregated decision accuracy of 89% for single-issue testing and 87% combined accuracy across all validated PDD techniques. Single-issue diagnostic testing achieved 89% accuracy (CI 83-95%) [17]Verified Polygraph Validity Research - APA Meta-Analytic Survey
Confirms aggregated decision accuracy of 89% for single-issue testing and 87% combined accuracy across all validated PDD techniques. These accuracy figures assume clean, interpretable data — artifact contamination can significantly degrade performance.

Studies examining inter-rater reliability have found substantial agreement among experienced examiners (Fleiss kappa of.61 with mean decision agreement reaching 95.4% excluding inconclusives), but this reliability depends on chart quality and proper artifact exclusion [18]Verified Reliability of the Empirical Scoring System with expert examiners
Confirms Fleiss kappa of.61 indicating substantial inter-rater agreement and mean decision agreement of 95.4% excluding inconclusives. The Empirical Scoring System and seven-position evidentiary model showed no statistically significant differences across 13 dimensions of criterion accuracy when scored by experienced examiners [19]Verified Criterion Validity of the Empirical Scoring System with experienced examiners
Confirms no statistically significant differences between ESS and seven-position evidentiary model across 13 dimensions of criterion accuracy, further emphasizing that scoring systems perform optimally with clean data.

Real-Time Visual Observation

The examiner continuously monitors the examinee throughout the chart collection phase. Any observable movement, cough, sneeze, or adjustment is mentally noted and correlated with the polygraph tracings in real time. Examiners position themselves to maintain a clear line of sight to the examinee without being in the examinee's peripheral vision, which could itself create artifacts.

APA Standards of Practice require that an audio or audio-video recording of all phases of the exam be maintained as part of the examination files for a minimum of one year [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements. This video recording serves as an invaluable reference for post-test artifact identification, allowing examiners to review examinee behavior in conjunction with chart data. Thorough pre-test interview techniques help establish rapport and reduce anxiety-related artifacts before chart collection even begins.

Activity Logging and Chart Marking

Many examiners maintain a written or electronic activity log during chart collection. Each time an observable event occurs — movement, cough, external noise — the examiner marks the chart or timestamps the event. Standard chart marking symbols include M (moved/movements), N (noise), S (sighed), SN (sniffed), CT (cleared throat), C (coughed), Y (yawned), and OS (outside stimulus caused change of tracing) [20]Verified Polygraph Chart Markings and Interpretation
Confirms standard chart marking symbols for artifacts including M (movement), N (noise), C (cough), OS (outside stimulus), and others.

This contemporaneous record is invaluable during post-test analysis when the examiner reviews the charts and needs to determine whether a data anomaly was caused by an artifact. Modern computerized polygraph systems from manufacturers like Lafayette Instrument Company allow examiners to annotate charts digitally with customizable markers [21]Verified LXSoftware by Lafayette Instrument Company
Confirms LXSoftware is bundled with OSS-3 scoring algorithm and supports digital chart annotation capabilities, streamlining the documentation process.

Cross-Channel Correlation and Pattern Recognition

Genuine physiological responses to deception typically show specific patterns in individual channels. Artifacts, by contrast, often affect multiple channels simultaneously in a distinctive way. A body movement typically produces simultaneous disruptions across respiratory, cardiovascular, and EDA channels — a pattern that differs from the typical response to a psychologically meaningful stimulus [22]Verified The Scientific Basis for Polygraph Testing (NRC Chapter 3)
Confirms respiration must be monitored to determine whether cardiovascular and electrodermal responses are artifacts of respiratory changes. Respiration needs to be monitored specifically to determine whether cardiovascular and electrodermal responses to relevant and comparison questions are artifacts of respiratory changes [23]Verified The Polygraph and Lie Detection (NRC Chapter 3)
Confirms respiration is easily brought under voluntary control and that respiratory changes can affect other physiological channels.

Experienced examiners develop the ability to recognize characteristic artifact signatures. PVCs produce a distinctive cardiovascular pattern (a premature beat followed by a compensatory pause). Coughs create a sharp respiratory spike followed by recovery breathing. Movement artifacts typically show abrupt onset and resolution across multiple channels. These signature patterns become easier to identify with experience and continuing education [7]Verified Academy of Polygraph (Lie-Detector) Examiners, An
Confirms the historical importance of standardized training and professional credentialing for polygraph examiners.

Motion Sensor Data and Post-Test Review

Modern polygraph instruments include activity sensors — typically pads placed beneath the examinee or strain gauges attached to the chair — that detect body movement. APA standards specify that polygraph systems should include a seat activity sensor [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements, and instrumentation standards detail the sensor technology requirements (pneumatic or piezoelectric) [12]Verified APA Standard for Polygraph Instrumentation (Approved August 25, 2023)
Confirms data acquisition must occur at not less than 25 samples per second and details sensor technology requirements. The motion sensor channel provides objective evidence of movement that can be correlated with anomalies in the primary physiological channels, and is particularly valuable for detecting subtle movements the examiner may not have visually observed.

After chart collection is complete, the examiner conducts a thorough review of all recorded data, examining each question's response window for consistency across charts and cross-referencing activity log entries. Computer-scored analyses using algorithms such as the Objective Scoring System version 3 (OSS-3) and PolyScore provide additional objectivity [24]Verified Modern Algorithms in Polygraph Data Analysis
Confirms OSS-3 and PolyScore accuracy rates of 85-92% and their role as decision-support tools for examiners[25]Verified Appendix F: Computerized Scoring of Polygraph Data (NRC)
Confirms the two main scoring systems evaluated were CPS (University of Utah) and PolyScore (Johns Hopkins APL), with their statistical methodologies detailed. OSS-3, developed by Raymond Nelson, Mark Handler, and Donald Krapohl, is based on sound polygraph testing principles and has demonstrable validity with multiple validation samples [26]Verified Objective Scoring System – Version 3
Confirms OSS-3 has demonstrable validity with multiple validation samples including confirmed investigative polygraphs. PolyScore, developed at the Johns Hopkins University Applied Physics Laboratory, uses linear discriminant analysis and Bayesian probability [24]Verified Modern Algorithms in Polygraph Data Analysis
Confirms OSS-3 and PolyScore accuracy rates of 85-92% and their role as decision-support tools for examiners. Both algorithms have demonstrated accuracy rates between 85-92% under laboratory conditions [24]Verified Modern Algorithms in Polygraph Data Analysis
Confirms OSS-3 and PolyScore accuracy rates of 85-92% and their role as decision-support tools for examiners. The examiner retains final authority on artifact identification and data exclusion decisions.

Data Exclusion Rules

The primary method for handling artifact-contaminated data is exclusion — removing the affected question or response window from the numerical scoring analysis. The rules governing exclusion are defined by the scoring system being used, such as the Empirical Scoring System (ESS), Federal Zone Comparison Technique, or Utah scoring approach [13]Verified The Utah Numerical Scoring System
Confirms response window timing: EDA scored from 0.5s after onset, reactions must begin within 5 seconds of answer, and details respiratory scoring criteria, and by institutional or organizational policies.

General exclusion principles include: Mark before scoring — artifacts should be identified and marked on the chart before any numerical scoring begins to prevent bias. Research has shown that prior expectations can create bias in scoring, particularly with inconclusive charts [4]Verified The effects of prior expectations and outcome knowledge on polygraph examiners' decisions
Confirms prior expectations created statistically significant bias in scoring inconclusive polygraph charts, making pre-scoring artifact identification critical. Document the reason — every exclusion should be documented with a clear explanation of the artifact observed and the basis for the exclusion decision. Apply consistently — exclusion criteria must be applied uniformly across all question types (relevant, comparison, and irrelevant) to prevent systematic bias. Preserve the data — the original, unmodified chart data must be retained as part of the examination record for a minimum of three years or as otherwise required by law [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements, even when segments are excluded from scoring.

The NCCA Numerical Evaluation Scoring System specifies that when a recording channel is unable to be evaluated due to an artifact or excessive noise, a value of zero with a line through it (Ø) should be assigned to the respective analysis spot [27]Verified NCCA Numerical Evaluation Scoring System
Confirms artifact notation procedures including the Ø (zero with line through it) for contaminated analysis spots and RLL evaluation methodology.

Chart Re-Administration

When artifact contamination is extensive enough that one or more questions in a chart series cannot be scored, the examiner typically re-administers the entire chart. This approach ensures that each chart presents a complete set of scorable question comparisons. However, re-administration introduces its own considerations: additional charts increase total testing time and examinee fatigue, habituation effects may diminish response magnitude over repeated presentations, and the examinee may become aware that something went wrong, potentially increasing anxiety.

Most standard examinations involve three to five chart series with a series of 8 to 12 yes-or-no questions asked per chart [28]Verified Evaluating Polygraph Data
Confirms cardiovascular channel is most complex recorded measurement and standard examination structure of 8-12 questions per chart. Understanding the different types of polygraph examinations helps contextualize when re-administration is appropriate versus when termination and rescheduling is the better option.

Test Termination, Rescheduling, and Inconclusive Findings

In rare cases, artifact contamination is so severe or persistent that the examination cannot produce reliable results. This might occur when the examinee has an uncontrollable medical condition (persistent coughing, continuous PVCs, uncontrollable tremors), environmental conditions cannot be adequately controlled, the examinee is experiencing acute distress preventing normal physiological functioning, or equipment malfunction cannot be resolved.

In these situations, the examiner may terminate the examination and recommend rescheduling. The decision to terminate should be documented thoroughly, including all artifact data that supports the decision. This documentation protects both the examiner and the examinee and demonstrates professional judgment consistent with APA ethical standards. Understanding polygraph examination disqualification criteria helps examiners make appropriate termination decisions.

When artifacts contaminate enough data to prevent a definitive conclusion but insufficient grounds exist for complete termination, the examiner may render an inconclusive finding (No Opinion) [29]Verified PDD Terminology Reference for the Science of Psychophysiological Detection of Deception
Confirms the acquaintance test procedure and its role in gain adjustment, countermeasure detection, and anxiety reduction. An inconclusive result means the examination did not produce sufficient clean data to support either a truthful or deceptive determination. While not ideal, an inconclusive finding is far more defensible than a forced conclusion based on contaminated data.

The Ideal Testing Room

The most effective artifact management strategy is prevention. Careful environmental preparation eliminates many common artifact sources before testing begins. A properly configured polygraph testing room significantly reduces artifact risk.

The ideal room features sound isolation, located away from high-traffic areas, external noise sources, and mechanical equipment. Walls, doors, and windows should provide adequate sound attenuation, and white noise machines may be used to mask unavoidable background sounds. Climate control should maintain a consistent temperature (generally 68-72°F / 20-22°C) with minimal airflow variation, as the HVAC system should not cycle noticeably during testing. External factors such as temperature and humidity affect EDA measurements [9]Verified Electrodermal activity
Confirms electrodermal responses are delayed 1-3 seconds and that temperature and humidity affect EDA measurements, making environmental stability critical for the electrodermal channel.

Lighting should be consistent, non-flickering, and at a comfortable level. Fluorescent lights that buzz or flicker should be replaced with LED alternatives. Ideally, the room has no windows or windows with opaque coverings to eliminate visual distractions. Only essential furnishings should be present — a comfortable chair for the examinee, the examiner's workstation, and the polygraph instrument. The door should be closed during testing with a sign indicating that testing is in progress to prevent interruptions.

Examinee Preparation

Preparing the examinee before chart collection is a critical artifact prevention measure. The pre-test interview serves multiple functions: establishing rapport, explaining the process, reviewing test questions, and identifying potential medical or psychological conditions that may produce artifacts.

Research demonstrates that when examiners conducted complete examinations including pre-test interviews, prior expectations produced no discernible effect on test outcomes, suggesting that behavioral information from direct examiner-examinee interaction may counteract confirmation bias [30]Verified The role of prior expectations in polygraph examiners decisions
Confirms prior expectations produced no discernible effect on test outcomes when examiners conducted complete examinations with pre-test interviews. The acquaintance test, conducted as the first chart, assesses the examinee's capability to process information, permits adjustment of gain settings, and reduces excessive anxiety [31]Verified Polygraph Testing and Social Intolerance: A Warning to Examiners Outside of the United States
Foundational research relevant to examiner ethics and the boundaries of legitimate polygraph testing applications.

APA Standards of Practice require examiners to obtain informed consent after providing an overview of the polygraph process, including instrumentation and sensors, use of video/audio recording, issues to be discussed, and requirements for cooperating during testing [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements. This thorough preparation reduces anxiety-related physiological artifacts and helps the examinee understand why remaining still and cooperative during chart collection is essential for data quality.

Distinguishing Genuine Artifacts from Deliberate Manipulation

An important distinction exists between artifacts (unintentional data contamination) and countermeasures (deliberate attempts to manipulate test results). General state countermeasures attempt to alter the examinee's overall physiological or psychological state during the test, while specific point countermeasures target physiological responses at particular moments during the examination [32]Verified Polygraph - Wikipedia: Countermeasures
Confirms two major types of countermeasures: general state and specific point, with details on how they differ from genuine artifacts.

Physical countermeasures — such as biting the tongue, pressing toes against shoes, or flexing muscles — produce patterns similar to movement artifacts but differ in their timing. Countermeasures are typically timed to coincide with comparison questions (to inflate comparison responses and mask deceptive reactions), while genuine artifacts occur randomly. The motion sensor channel is particularly valuable for distinguishing these patterns.

Respiratory countermeasures involve deliberately altering breathing patterns. The suppression response in polygraph testing can sometimes be mimicked through controlled breathing. However, respiration is easily brought under voluntary control, so it is unlikely by itself to be a robust indicator of any psychological state an examinee is trying to conceal [23]Verified The Polygraph and Lie Detection (NRC Chapter 3)
Confirms respiration is easily brought under voluntary control and that respiratory changes can affect other physiological channels. Research confirms that changes in respiration can affect heart rate and electrodermal activity, which is precisely why respiration must be monitored to determine whether cardiovascular and electrodermal responses are artifacts of respiratory manipulation [23]Verified The Polygraph and Lie Detection (NRC Chapter 3)
Confirms respiration is easily brought under voluntary control and that respiratory changes can affect other physiological channels.

For examinees concerned about the process, understanding the role of the polygraph examiner helps clarify that trained professionals are specifically equipped to identify both artifacts and countermeasures.

Conditions Requiring Protocol Adaptation

Certain medical conditions increase the frequency and severity of physiological artifacts, requiring examiners to adapt their protocols accordingly. Cardiovascular conditions such as arrhythmias (including frequent PVCs), hypertension, and heart failure can produce irregular cardiovascular tracings that complicate scoring. Respiratory disorders including chronic obstructive pulmonary disease (COPD), asthma, and chronic cough generate frequent respiratory artifacts.

Chronic pain conditions cause involuntary movements and physiological stress responses unrelated to test stimuli. Neurological conditions such as essential tremor, Parkinson's disease, and peripheral neuropathy can affect multiple channels. Internal factors such as medications and hydration levels can change EDA measurements [9]Verified Electrodermal activity
Confirms electrodermal responses are delayed 1-3 seconds and that temperature and humidity affect EDA measurements, making a thorough medication review during the pre-test interview essential.

Psychological conditions also play a role. Research has indicated that innocent neurotics and particularly psychotics were more likely to be identified as deceptive in polygraph testing [33]Verified Scientific Validity of Polygraph Testing (OTA Chapter 6)
Confirms examiner training, examinee characteristics, and testing conditions affect polygraph accuracy, which underscores the importance of medical screening. Individuals with borderline personality disorder present particular challenges due to emotional instability that can produce artifact-like physiological fluctuations.

Examiners should document all medical conditions in the examination record and note any protocol modifications made to accommodate them. In some cases, medical conditions may render the examinee unsuitable for testing, in which case the examiner should terminate the examination and document the rationale.

Respiratory Channel Artifacts

The respiratory channels (thoracic and abdominal pneumographs) are highly susceptible to artifacts from coughing, sneezing, deep sighing, yawning, talking, and upper body movement. APA standards specify that thoracic and abdominal patterns should be recorded separately using two pneumograph components [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements. Respiratory suppression — the most frequently cited scoring criterion according to research by Capps and Ansley (1992) [16]Verified Numerical scoring of polygraph charts: What examiners really do
Confirms respiratory suppression was the most frequently cited scoring criterion, with examiners achieving 82% overall accuracy in blind chart review — can be mimicked by movement-induced breathing changes or voluntary respiratory manipulation.

The NCCA scoring system identifies five primary respiratory diagnostic features using the Reduced Line Length (RLL) evaluation methodology: apnea-blocking (suppression), decrease in amplitude (suppression), progressive decrease in amplitude (suppression), decrease in cyclic rate, and inhalation/exhalation ratio changes [27]Verified NCCA Numerical Evaluation Scoring System
Confirms artifact notation procedures including the Ø (zero with line through it) for contaminated analysis spots and RLL evaluation methodology. Artifacts must be distinguished from each of these genuine response patterns.

Electrodermal Channel Artifacts

The electrodermal channel measures skin conductance changes driven by eccrine sweat gland activity under sympathetic nervous system control [2]Verified EDA Primer for Polygraph Examiners
Confirms electrodermal response is the most robust and informative signal in polygraph testing, driven exclusively by sympathetic nervous system activity. Electrodermal response is considered the most informative signal in polygraph testing, contributing the greatest weight to diagnostic accuracy [2]Verified EDA Primer for Polygraph Examiners
Confirms electrodermal response is the most robust and informative signal in polygraph testing, driven exclusively by sympathetic nervous system activity. This makes EDA artifact management particularly critical.

EDA artifacts can result from loose electrode contact, excessive hand movement, temperature fluctuations, and electrical interference. Electrodermal responses are delayed 1-3 seconds after stimulus onset [9]Verified Electrodermal activity
Confirms electrodermal responses are delayed 1-3 seconds and that temperature and humidity affect EDA measurements[14]Verified Electrodermal Response - ScienceDirect Topics
Confirms SCR latency of 1-4 seconds after stimulus onset with peak values at 3-6 seconds post-stimulus, with skin conductance response characterized by a latency of 1-4 seconds and peak values at 3-6 seconds post-stimulus [14]Verified Electrodermal Response - ScienceDirect Topics
Confirms SCR latency of 1-4 seconds after stimulus onset with peak values at 3-6 seconds post-stimulus. Understanding these temporal characteristics helps examiners determine whether an EDA change falls within the expected response window for a given stimulus. Artifacts occurring outside these temporal parameters are more easily identified, while those occurring within the response window require careful cross-channel analysis.

Cardiovascular Channel Artifacts

The cardiovascular channel records blood pressure changes, heart rate, and relative blood volume using a sphygmomanometer cuff. As a hybrid signal of relative blood pressure and heart rate, it is the most complex of the recorded measurements [28]Verified Evaluating Polygraph Data
Confirms cardiovascular channel is most complex recorded measurement and standard examination structure of 8-12 questions per chart. The cardiovascular response is either coactivated or coinhibited by other physiological responses, making its evaluation more difficult.

PVCs, cuff pressure changes, arm movement, and deep breathing all produce cardiovascular artifacts. Blood pressure cuff inflation level is a common source of artifacts: too much pressure causes discomfort leading to movement artifacts, while too little produces weak tracings with poor signal quality. The finger plethysmograph (vasomotor sensor), when used, provides additional cardiovascular data but is sensitive to finger movement and temperature changes.

Computerized Scoring Algorithms

Modern computer-based scoring algorithms provide powerful tools for artifact detection and management. The two most widely validated systems are the Objective Scoring System version 3 (OSS-3) and PolyScore [24]Verified Modern Algorithms in Polygraph Data Analysis
Confirms OSS-3 and PolyScore accuracy rates of 85-92% and their role as decision-support tools for examiners[25]Verified Appendix F: Computerized Scoring of Polygraph Data (NRC)
Confirms the two main scoring systems evaluated were CPS (University of Utah) and PolyScore (Johns Hopkins APL), with their statistical methodologies detailed[26]Verified Objective Scoring System – Version 3
Confirms OSS-3 has demonstrable validity with multiple validation samples including confirmed investigative polygraphs.

OSS-3, developed by the U.S. Department of Defense Polygraph Institute (now NCCA), uses a logistic regression formula trained on large datasets of confirmed truth and deception outcomes [24]Verified Modern Algorithms in Polygraph Data Analysis
Confirms OSS-3 and PolyScore accuracy rates of 85-92% and their role as decision-support tools for examiners. It is bundled with Lafayette Instrument Company's LXSoftware platform [34]Verified LXSoftware Features - Lafayette Instrument Company
Confirms OSS-3 bundling with Lafayette LXSoftware and digital chart annotation capabilities. PolyScore, developed at the Johns Hopkins University Applied Physics Laboratory, uses logistic regression models incorporating features describing galvanic skin response, blood volume, pulse, and respiration [25]Verified Appendix F: Computerized Scoring of Polygraph Data (NRC)
Confirms the two main scoring systems evaluated were CPS (University of Utah) and PolyScore (Johns Hopkins APL), with their statistical methodologies detailed. The Computerized Polygraph System (CPS), developed at the University of Utah, automates what careful human scorers do and has focused on a relatively small set of data features [25]Verified Appendix F: Computerized Scoring of Polygraph Data (NRC)
Confirms the two main scoring systems evaluated were CPS (University of Utah) and PolyScore (Johns Hopkins APL), with their statistical methodologies detailed. The Polygraph Automated Scoring System (PASS), also from Johns Hopkins APL, represents another validated computer scoring approach [35]Verified POLYSCORE: A Comparison of Accuracy
Confirms the Polygraph Automated Scoring System (PASS) version 2.0 as a real prototype scoring algorithm from Johns Hopkins APL. Additional algorithms include ESS-M and CPS Elite [24]Verified Modern Algorithms in Polygraph Data Analysis
Confirms OSS-3 and PolyScore accuracy rates of 85-92% and their role as decision-support tools for examiners.

Early polygraph digitization enabled users to edit anomalies such as distortions resulting from movements, deep breaths, coughing, and similar activity, providing the capability to remove data segments or reconstruct test data minus the disruptive items [36]Verified A History of Polygraph Digitization
Confirms early digital polygraph capabilities for editing anomalies and reconstructing test data. Modern systems have expanded these capabilities significantly. Despite technological advancement, algorithms function as decision-support tools, enhancing but not substituting the expert's interpretation [24]Verified Modern Algorithms in Polygraph Data Analysis
Confirms OSS-3 and PolyScore accuracy rates of 85-92% and their role as decision-support tools for examiners. Examiners interested in modern reporting tools may find AI-powered report writing valuable for documenting artifact management decisions.

Video and Audio Recording

APA Standards of Practice require that an audio or audio-video recording of all phases of the exam be maintained as part of the examination files, consistent with agency policy, regulation, or law, for a minimum of one year [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements. Modern polygraph software such as Lafayette's LX platform supports the ability to integrate audio and video tracks right into the chart [37]Verified Lafayette LX 9.5 Polygraph Software Review
Confirms LX software supports audio and video integration into charts for comprehensive artifact documentation, allowing examiners to hear the subject's inflections and see their body language synchronized with physiological data.

Video recording is particularly valuable for artifact identification during post-test review. An examiner may not have observed a subtle movement during chart collection, but reviewing the synchronized video with the chart data can reveal the source of an unexplained data anomaly. This documentation also strengthens the defensibility of artifact exclusion decisions in quality assurance reviews and legal proceedings.

Maintaining proper confidentiality and data security protocols is essential when storing these audio and video recordings, as they contain sensitive examination data.

APA Standards Relevant to Artifact Management

The American Polygraph Association's Standards of Practice provide the professional framework within which artifact management operates. Key provisions relevant to artifacts include the requirement that examiners use evidence-based validated testing techniques with demonstrated accuracy rates of 80% or greater (excluding inconclusive results) for investigative examinations [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements. Polygraph techniques for evidentiary testing must demonstrate an unweighted average accuracy rate of 90% or greater [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements.

The standards mandate that where examinations deviate from the protocols of a validated polygraph technique, the deviations should be explained [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements. This includes artifact-related modifications such as re-administration of charts, exclusion of contaminated data, or termination of testing. Polygraph examiners should ensure that all reports, test questions, data, recordings, and documents are maintained for a minimum of three years or as otherwise required by law [5]Verified APA Standards of Practice (Amended 8-23-24)
Confirms specific APA requirements for validated techniques, minimum accuracy rates, question timing intervals, and recording requirements.

Understanding validity in polygraph testing provides essential context for how artifact management contributes to the overall validity of examination results. Research has consistently shown that examiner training, orientation, and experience — along with examinee characteristics and testing conditions — affect polygraph accuracy [33]Verified Scientific Validity of Polygraph Testing (OTA Chapter 6)
Confirms examiner training, examinee characteristics, and testing conditions affect polygraph accuracy, making standardized artifact management protocols a critical component of quality assurance.