Glossary of Terms

Glossary of Terms
Extracted from the Terminology Reference for the Science of Psychophysiological Detection of Deception (PDD)
American Polygraph Association (2012)


acquaintance test

Generic term for stimulation test. The acquaintance test serves several purposes: to familiarize the examinee with the test procedures; to properly set the gains and centerings; to help detect countermeasures; and to assess the range of responsiveness of the examinee.

analog instrument

Device that records data in a continuous form. An analog polygraph registers waveforms as continuous lines on a strip chart, whereas a digital instrument records them as discrete points. While many analog instruments are currently in use, the trend has been toward computerized instrumentation.


An American manufactured computer polygraph, developed and marketed by Bruce White of Houston, Texas.

blind chart analysis

Evaluation of PDD recordings without the benefit of extrapolygraphic information, such as subject behavior, case facts, pretest admissions, base rates of deception, etc. Studies employ various degrees of “blindness.” It is a popular research approach to gauge interrater reliability. Assessments of the accuracy of PDD test evaluation techniques also use blind chart analysis.

Benussi, Vittorio

One of the first researchers to examine respiration tracings for detecting deceptions. Though Italian, Benussi did most of his work in Austria at the University of Graz. See: Benussi (1914).


General term for any recording of heart activity. In PDD the use of a blood pressure cuff to monitor relative arterial blood pressure changes and pulse wave is more precisely described as sphygmography (recording of the arterial pulse) or occlusion plethysmography (partial blockage of circulation to measure volume changes in a body part). While cardiograph is not incorrect in this context, it lacks precision in denoting the actual phenomenon being recorded in PDD. The term cardiograph in the psychophysiological and medical literature most often refers to the electrocardiograph.

community safety examinations

A broad category of examinations that serve to detect and deter illegal behaviors that jeopardize the safety of communities. Types of community safety examinations include Post-Conviction Sex Offender Testing (PCSOT), Intoxicated Drivers on Probation (IDOP), and Domestic Violence Offender Testing (DVOT).

Concealed Information Test (CIT)

Otherwise known as the Guilty Knowledge Test. The CIT is actually a series of tests, perhaps as many as 10, in which there is only one critical item in each series, much like the better-known Peak of Tension tests. The tests are constructed so that the order of the item presentations is randomly selected, except the first item which is used as a buffer. The theoretical operating mechanism of the CIT is there is greater signal value in the critical item for guilty examinees than in the irrelevant items. The CIT is believed to rely on cognitive processes, and is therefore not subject to false positives from nervous examinees. CIT tests could be used in a small proportion of all criminal cases where sufficient details were available to construct it, however in most crimes such details are lacking or would be already known to innocent persons via the media or investigating officers. Despite assertions of theoretical superiority of the CIT over the CQT, the CIT has practical limitations that have hindered its broad acceptance among field practitioners. Moreover, the preponderance of independent research suggests that false negatives may be a problem with the CIT. See Lykken (1959); MacLaren (2001); Podlesny (1993).

confirmatory testing

PDD examination used to verify the statements of suspects, witnesses, and victims.

Deception Indicated (DI)

Along with NDI (No Deception Indicated) and Inconclusive, a conventional term for a polygraph outcome. A decision of DI in PDD means that (1) the physiological data are stable and interpretable, and (2) the evaluation criteria used by the examiner led him to conclude that the examinee is not wholly truthful to the relevant issue under investigation. The DI and NDI decision options are used primarily in single-issue testing, and they correspond with SR (Significant Response) or SPR (Significant Physiological Responses) and NSR (No Significant Response) or NSPR (No Significant Physiological Responses) in multiple-issue, or screening, examinations with the US Government.

electrodermal activity (EDA)

All exosomatic and endosomatic changes in the electrical properties of the skin. See: Handler et al. (2010).

electrodermal response (EDR)

Reaction of skin measured by changes in its electrical properties, including skin resistance (SR), skin conductance (SC), and skin potential (SP).  See: Handler et al. (2010).

false negative

The failure to detect the presence of a particular event or item. A false negative in PDD refers to the incorrect decision that deception was not practiced by the examinee. Also called a Type-2 error.

false positive

The false detection of something that is not actually present. In PDD, it is the incorrect decision that deception was practiced by the examinee. Also called a Type-1 error.

“friendly polygrapher” hypothesis

A hypothesis proposed by Martin Orne that a deceptive examinee would not be as detectible by an examiner who conducts a polygraph examination on behalf of the examinee’s attorney because the examinee has no fear of adverse consequences. There are no studies supporting this hypothesis with the CQT, and all field studies that have investigated it have failed to find the effect. See: Honts (1997); Ishida & Sevilla (1981); Matte & Reuss (1990); Orne (1973); Raskin (1976).

Galvanic Skin Response (GSR)

A superseded term for the electrodermal response measured exosomatically by the change in the electrical resistance of skin. GSR is sometimes erroneously called Galvanic Skin Resistance or Galvanic Skin Reflex. The modern term is electrodermal response (EDR).

guilt complex reactor

Hypothetical personality trait that causes innocent examinees to physiologically respond to any question that they consider accusatory. Guilt complex questions have been used in many of the contemporary formats at one time or another in an attempt to identify those examinees who would produce a false positive outcome because of this tendency. No empirical support exists for the existence of guilt complex examinees nor for the benefit of using a test question aimed at identifying them.


PDD outcome where testing was completed, but neither deception nor truthfulness can be diagnosed because the physiological data are inconsistent, inadequate, artifacted, or contaminated. There is disagreement whether an inconclusive outcome should be considered an error when computing validity of PDD. Some argue that examinees are either truthful or deceptive, but never inconclusive; therefore, such an outcome is necessarily in error. Conversely, in the forensic sciences it has been asserted that the inconclusive outcome is used to assess utility, but not validity, because samples in forensic disciplines are often inadequate, or contaminated. For example, fingerprint data is more frequently inadequate than adequate, though fingerprint analysis is considered highly accurate in spite of the relatively modest percentage of cases that it can render a positive identification. Because of this controversy, PDD validity studies report accuracies both with and without inconclusive results and should report inconclusive rates for each category of test subject. In practice, inconclusive outcomes are the default results when the criteria for deception or not-deception decisions are not satisfied and are a matter of the decision thresholds employed. Alternate term is indefinite, or no opinion.

irrelevant question

A question designed to be emotionally neutral to examinees. Irrelevant questions are most often placed in the first position of a question list because an orienting response usually follows the presentation of the first question and is of no diagnostic value. In CQT formats it is also used after a relevant or comparison question that has elicited a strong response so as to permit physiologic arousal levels to return to baseline before presenting another question. Irrelevant questions are used in nearly every type of PDD test. Also called norms or neutrals.

Karpman’s classification of lying

Classification of lies and their underlying motives. They are benign lies (for social conventions), hysterical lies (to attract attention), defensive lies (to avoid an adverse situation), compensatory lies (to impress another), malicious lies (for gain), gossip (exaggeration), implied lies (deceive with partial truths), “love intoxication” lies (idealistic exaggeration), and pathological lies (self-destructive or maladaptive). See: Karpman (1949).

Keeler, Leonarde

Student of John Larson and influential PDD pioneer. Among Keeler’s accomplishments are: the addition of the electrodermal channel to the polygraph, establishing the first PDD school, devising the Keeler Technique, and popularizing the polygraph field.

Lafayette Instrument Company

An American manufacturer of polygraphs, both analog and computerized, founded by Max Wastl. Headquarters is located in Lafayette, Indiana.

Limestone Technologies

A Canadian manufacturer of computerized polygraph instruments. Headquartered in Odessa, Ontario, Canada.

Lombroso, Cesare

Italian physician biologist who first employed instrumentation in an effort to detect deception in suspects in live criminal investigations. He reported in 1885 in the second edition of his book, L’Homme Criminel the use of the “hydrosphygmograph,” a mechanical arrangement invented for medical purposes, to detect blood pressure changes during interrogation. One of his students, Angelo Mosso, also went on to perform instrumental deception detection experiments.

Marston, William

Psychologist, inventor of the discontinuous blood pressure method deception test, and author of the 1938 book The Lie Detector Test. Marston was the first to attempt to have instrumental deception test evidence entered into evidence in court, for which resulted the Frye decision of 1923. Marston’s test entailed the use of a conventional blood pressure cuff and sphygmomanometer with which he manually plotted the examinees blood pressure during questioning at several points during the interview. He taught his technique to the U.S. Army, and he used his method to resolve espionage cases during World War I. Marston had several interests, and he was also the co-creator of the Wonder Woman comic book character. Both William Marston and his wife, Elizabeth, were lawyers and worked together to perform deception testing.

Munsterberg, Hugo

Chairman of the Psychology Department at Harvard who, in his 1908 book On the Witness Stand, suggested the possibility of devising deception tests using blood pressure, respiration, and electrodermal activity. In his book Munsterberg also described the Concealed Information Test. He had as a student William Marston, who later went on to develop the discontinuous blood pressure method deception test.

No Deception Indicated (NDI)

In conventional PDD, NDI signifies that (1) the polygraph test recordings are stable and interpretable and (2) the evaluation criteria used by the examiner led him to conclude that the examinee was truthful to the relevant issue. The NDI and DI (Deception Indicated) decision options are used in specific-issue testing and correspond to NSPR (No Significant Physiological Responses) and SPR (Significant Physiological Responses) in multiple-issue, or screening, examinations.

numerical analysis

Systematic assignment of numbers to physiologic responses, along with decision rules, so that PDD data analysis is more objective and standardized. The first such system was published by Dr. John Winter in 1936. Contemporary numerical analytic methods include the Rank Order Scoring System, Horizontal Scoring System, 3-position scoring system, 7-position scoring system, Lykken Scoring. Sometimes referred to as semi-objective analysis.

photoplethysmograph (PPG)

The PPG uses the reflection of a red light emitted into the skin to detect changes in the volume of blood in the upper layers of skin, typically recorded at the finger when using a polygraph. Physiological arousal is marked by a constriction in the pulse amplitude as blood is shunted from the extremity during activation of the sympathetic nervous system. See: Geddes (1974); Hander & Krapohl (2007); Kircher & Raskin (1988).


A device that records respiration, and one of the three traditional channels of the modern polygraph used in PDD. Most contemporary polygraphs use two pneumograph recordings: abdominal and thoracic. The types of sensors include the traditional corrugated rubber tube, the mercury strain gauge, or the newer piezoelectric.


By definition, an instrument that simultaneously records two or more channels of data. The term now most commonly signifies the instrument and techniques used in the psychophysiological detection of deception, though polygraphs are also used in research in other sciences. In PDD the polygraph traditionally records physiologic activity with four sensors: blood pressure cuff, electrodermal sensors, and two respiration sensors. Some instruments also record finger pulse amplitude using a PPG.

Post-Conviction Sex Offender Testing (PCSOT)

Specialized application of polygraphy which aids in the management of the convicted sex offender who has been released into the community, though sometimes is employed as part of treatment of offenders who are incarcerated. There are four principal types of PCSOT examinations: instant offense examination, sexual history/disclosure examination, maintenance examination and monitoring examination. See: Dutton (2000).

Reid, John

One of the first modern PDD examiners, Reid developed many techniques still in use today. Reid is credited with bringing the probable-lie comparison question into common practice in the field. He also developed the Reid Technique, which includes the Yes Test and the Guilt Complex Test. Reid helped bring about the first state licensure for PDD practitioners in Illinois in 1963. Reid instructed hundreds of students at his school and offered the first accredited Masters program in PDD. The Reid Technique, which emphasizes global evaluation, is used by some PDD examiners today.

Stoelting Instruments

C.H. Stoelting of Chicago, Illinois. An American manufacturer of analog and computer polygraphs.


All practices taking place in a polygraph examination, including pretest procedures, question formulation, format, number of tests, test sequencing, and scoring and decision rules.

test data analysis (TDA)

Newer expression for polygraph chart interpretation, a change prompted by digital polygraphs where physiological data are displayed on computer screens rather than paper strip charts.

true negative

Correct decision that the variable of interest is not present (i.e., an accurate PDD outcome of innocence).

true positive

Correct decision that the variable of interest is present (i.e., an accurate PDD outcome of guilt).

United States v Frye

James Alphonzo Frye was administered a deception test by Dr. William M. Marston in 1923 using Marston’s discontinuous blood pressure method. Marston’s opinion was that Frye was truthful in his recanting of a murder confession for the killing of a prominent Washington, DC, doctor. At Frye’s trial his defense attorneys attempted to have the results entered into evidence, but were unsuccessful (United States v Frye 54 App D.C.46, 293 F 1013). The Frye Rule, as it came to be known, stated that “expert testimony based on a scientific technique is inadmissible unless the technique is generally accepted as reliable in the relevant scientific community.” The Frye Rule was invoked thereafter in many jurisdictions to bar PDD evidence from admissibility. The Frye Rule has been superseded by Federal Rule 702, cited in Daubert v Merrell Dow Pharmaceuticals, Inc (1993), except in those states that do not follow the Federal Rules of Evidence. See: Daubert v Merrell Dow Pharmaceuticals, Inc (1993): Stern & Krapohl (2003).

voice stress analysis

Any analytical technique implemented to determine whether changes in the vocal signal are indicative of changing levels of stress. Most techniques assess the frequency or amplitude modulation of the vocal signal in one or more frequency bandwidths. Emphasis is often placed on modulation in the 8-10 Hz frequency bandwidth, otherwise known as microtremors. Numerous voice stress analysis devices have been introduced since the first was made available in 1971. All purport the ability to detect deception. Today, this genre of credibility assessment devices enjoys a wide distribution, possibly due to their low cost and brief training requirements relative to the polygraph. However, no independent scientific assessment has validated the use of voice stress analysis for credibility assessment. Because of this, these devices are prohibited from use by the US Department of Defense. Brand names include Computer Voice Stress Analyzer (CVSA), Lantern, Psychological Stress Evaluator (PSE), TiPi, VSA Mark, Vericator, and Layered Voice Analysis (LVA).


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