Defined Terms

Document: Defined Terms
Status: Adopted and in force
Version: 1.0
Adopted by: The Management Committee
Effective date: 1 January 2020
Last reviewed: January 2026 (reaffirmed without amendment)
Next review due: January 2027
Review cycle: Annually, or on material amendment of another governing document

1. Purpose and Use

1.1 This document is the Society’s glossary of defined terms. It collects, in one place, the formal meanings given to terms used across the Society’s governing documents (the Constitution, the Code of Ethics, the Standards of Practice, the Complaints, Discipline and Appeals Procedure, the Membership Regulations, and related policies).

1.2 Where a term defined in this document appears in another governing document, the meaning given here applies unless the other document expressly provides a different meaning. This document does not create new obligations; it only records definitions.

1.3 Cross-references are indicative: they point to the governing document or section from which the definition is drawn or in which the term is most heavily used. They are not exhaustive.

1.4 Where this document and the cited source document conflict on the meaning of a term, the source document prevails. This document is updated annually to absorb such differences.

2. Precedence and Interpretation

2.1 The order of precedence among the Society’s governing documents is:

1. the Constitution;
2. the Code of Ethics and the Standards of Practice (equal rank; see paragraph 2.2);
3. the Complaints, Discipline and Appeals Procedure;
4. the Membership Regulations;
5. the Committee and Officer Terms of Reference;
6. all other policies of the Society, including the CPD and Accreditation Policy, the Conflict of Interest Policy, the Privacy and Confidentiality Policy, the Membership Criteria and Grades, and the Corporate Supporter Scheme.

2.2 Where the Code of Ethics and the Standards of Practice both apply to a matter, both apply cumulatively. In the unlikely event of conflict, the stricter requirement applies.

2.3 Singular includes plural and vice versa. References to statutes include the statute as amended from time to time. References to “he”, “she”, or “they” are gender-neutral.

3. The Defined Terms

Terms are listed alphabetically. Each definition is followed, in parentheses, by the governing document from which it is drawn or in which it is principally used.

Test">Acquaintance test

A preliminary test conducted during the pretest phase to orient the examinee to the testing procedure, verify instrumentation function, and permit the examinee to practise compliance with behavioural instructions. Also referred to as a practice test. (Standards of Practice §8.6.)

Activity sensor

A component sensor designed to record somatic and behavioural movement activity during a polygraph examination, primarily to detect overt or covert countermeasure attempts. Required on all polygraph instruments used by members. (Standards of Practice §4.1(d).)

Affiliate Member

A class of membership open to practising professionals in roles adjacent to polygraph examination (including treatment providers, probation and HMPPS staff, barristers and solicitors, HR and corporate investigators, forensic psychologists, and clinicians). Affiliate Members are bound by the Code of Ethics in respect of their engagement with polygraph practice but do not conduct polygraph examinations as BPS-listed examiners and do not appear in the examiner directory. (Constitution cl. 5.2(e); Membership Regulations §6A.)

Affiliates directory

The register of Affiliate Members maintained by the Society, separate from the examiner directory. (Membership Regulations §9; Constitution cl. 5.2.3.)

American Polygraph Association (APA)

The international membership body for polygraph examiners based in the United States. Current APA certification (or a qualification recognised by the Management Committee as equivalent) is an admission criterion for Intern Member, Member, and Senior Member classes of the Society. The BPS is not an affiliate, chapter, or subsidiary of the APA. (Constitution cl. 5.1(a); Membership Regulations §§3–5.)

Annual General Meeting (AGM)

The yearly meeting of the members of the Society at which the Chair’s report, accounts, elections, and subscription rates are considered. Held not more than fifteen months after the preceding AGM. (Constitution cl. 8.1.)

Appeals Panel

A panel of three persons appointed to hear appeals from decisions of a Complaints Panel under the Complaints, Discipline and Appeals Procedure. None of the Appeals Panel may have sat on the original Complaints Panel, and none may be members of the Management Committee. (Complaints, Discipline and Appeals Procedure §10.4.)

Cardiovascular activity

Physiological activity recorded by cardiovascular sensors during a polygraph examination, including relative blood pressure, pulse rate, Amplitude">pulse amplitude, and (in primary scoring) the amplitude of vertical increase in relative blood pressure in response to test stimuli. (Standards of Practice §4.1(c).)

Chair

The officer who presides at meetings of the Management Committee and at general meetings of the Society, and who is the principal public representative of the Society. Has a casting vote in the event of a tie. (Committee and Officer Terms of Reference §3.)

Code of Ethics

The governing document that sets out the minimum standards of professional conduct required of members. Binding on every member on admission. (Published at /standards-ethics/code-of-ethics/.)

Comparison Question (CQ)

A question used in a comparison question test format that provides a within-subject reference against which responses to relevant questions are evaluated. May take the form of a Probable-Lie Comparison or a Directed-Lie Comparison. (Standards of Practice §8.)

Comparison Question Technique (CQT)

The family of polygraph testing formats that uses comparison questions alongside relevant questions and applies numerical scoring to the resulting data. The most exhaustively researched family of polygraph techniques in use today. (Standards of Practice §2.8.)

Complainant

A person who makes a complaint against a member under the Complaints, Discipline and Appeals Procedure. (Complaints, Discipline and Appeals Procedure §2.)

Complaints Panel

A panel of three persons appointed by the Management Committee to investigate and determine a complaint against a member. At least one must be a Senior Member; at least one must be independent of the Management Committee; none may have a personal, financial, or professional interest in the subject matter of the complaint. (Complaints, Discipline and Appeals Procedure §6.)

Complaints, Discipline and Appeals Procedure

The governing document that sets out how complaints against members are received, investigated, and determined, the sanctions available to the Society, and the route of appeal. (Published at /standards-ethics/complaints-discipline-appeals/.)

Constitution

The constituting document of the Society. Defines the Society’s legal status, objects, powers, membership classes, management, general meetings, finance, amendment, and dissolution. (Published at /standards-ethics/constitution/.)

Continuing Professional Development (CPD)

The ongoing professional learning required of members. The Society’s requirement is a minimum of 30 hours of CPD in polygraphy-related coursework every two years, of which at least 10 hours must be interactive and at least 5 hours must relate to ethics, professional standards, or UK law as it affects polygraph practice. (CPD and Accreditation Policy §2.)

Corporate Supporter

An eligible commercial organisation admitted under the Corporate Supporter Scheme. Corporate Supporter status is not a class of membership. Corporate Supporters have no vote, no role in Society policy or disciplinary proceedings, and acquire no rights over the Society’s standards. (Corporate Supporter Scheme §1.)

Correspondence address

The postal address of the Society for receipt of documents, membership applications, formal complaints, service of process, and postal enquiries: British Polygraph Society, Oxford Centre for Innovation, Blue Boar Court, Alfred Street, Oxford OX1 4EH, United Kingdom. (Contact page; site footer.)

Cutscore

A numerical threshold, derived from statistical reference distributions or validated performance curves, used to classify a polygraph test result. A cutscore corresponds to a stated probability of error (commonly alpha = .05 for a 95% confidence level). (Standards of Practice §10.)

Deception Indicated">Deception Indicated (DI)

A diagnostic opinion, arising from a validated deception test, that the recorded data indicate deception in response to the relevant test questions. (Standards of Practice §2.7.1.)

Diagnostic examination

An event-specific evidentiary or investigative polygraph examination conducted to assist in determining the veracity of an examinee regarding their knowledge of or involvement in a reported issue or allegation. (Standards of Practice §2.5.)

Directed-Lie Comparison (DLC)

A form of comparison question in which the examinee is instructed in advance to answer untruthfully. DLC techniques are transparent and do not require the examiner to manipulate the examinee. DLC techniques have been shown to perform with equivalent efficiency to probable-lie comparison techniques. (Standards of Practice §8; BPS summary of Nelson 2015.)

Directory

The public register of Intern Members, Members, and Senior Members of the Society in good standing, published at /find-an-examiner/. Also called the examiner directory. See also Affiliates directory. (Constitution cl. 5.2.3; Membership Regulations §9.)

Domestic Abuse Act 2021

An Act of the United Kingdom Parliament. Section 76 extended mandatory polygraph testing — previously applicable to specified sex offenders under the Offender Management Act 2007 — to specified domestic abuse perpetrators released on licence in England and Wales. Administered by HMPPS. (UK Legal Framework.)

Electrodermal Activity (EDA)

Physiological activity of the skin reflecting relative changes in conductance or resistance of electrical current in the epidermal tissue. Recorded by electrodermal sensors on the palmar or distal regions. The single most robust and reliable contributor to the final score and classification in comparison question polygraph tests. (Standards of Practice §4.1(b); Nelson 2015 p.39.)

Evidentiary Examination

A polygraph examination in which the written and stated purpose agreed by the parties is to provide a diagnostic opinion as evidence in a pending judicial proceeding. Must use a technique for which there exist at least two published empirical studies demonstrating an unweighted average accuracy of 90% or greater, excluding inconclusive results not exceeding 20%. (Standards of Practice §§2.2, 2.8.1.)

Examinee

The person undergoing a polygraph examination. (Code of Ethics; Standards of Practice.)

Examiner

The person conducting a polygraph examination. In Society documents, “examiner” means a member of the Society unless the context requires otherwise. (Code of Ethics; Standards of Practice.)

Extraordinary General Meeting (EGM)

A general meeting of the members called outside the AGM cycle. May be called by the Management Committee and must be called on the written request of not fewer than ten per cent of the voting members. (Constitution cl. 8.3.)

HMPPS (His Majesty’s Prison and Probation Service)

The executive agency of the Ministry of Justice that administers prisons and probation services in England and Wales, including the statutory polygraph testing regime under the Offender Management Act 2007 and the Domestic Abuse Act 2021. The BPS has no statutory or regulatory role in the HMPPS regime. (UK Legal Framework.)

Honorary Member

A class of membership admitted by resolution of the members in general meeting, on the recommendation of the Management Committee, in recognition of distinguished service. Honorary Members have no voting rights unless they also hold Member or Senior Member status. (Constitution cl. 5.2(d); Membership Regulations §6.)

Inconclusive (INC)

A result category used when the test data do not meet the threshold for either a deceptive or truthful categorical conclusion. Properly reported as “Inconclusive” or “No Opinion” and not suppressed. (Standards of Practice §10.2; Code of Ethics §4.3.)

Informed consent

The examinee’s voluntary, informed agreement in writing to undergo a polygraph examination, given after an explanation of the polygraph process, the instrumentation and sensors to be used, the fact of any audio or video recording, the issues to be discussed, the persons or bodies to whom information and results will be reported, and the examinee’s right to terminate at any time. (Standards of Practice §7.2; Code of Ethics §6.)

In good standing

Status of a member who (a) has paid all subscriptions falling due; (b) is not subject to a current suspension under the Complaints, Discipline and Appeals Procedure; (c) holds current APA certification (or recognised equivalent), where applicable to the class of membership; and (d) is otherwise compliant with the Society’s governing documents. (Membership Regulations §8.2; Membership Criteria and Grades.)

Intern Member

A class of membership open to examiners who have completed basic polygraph training and are engaged in supervised practice. No vote; appears in the examiner directory marked as Intern with supervisor named. (Constitution cl. 5.2(a); Membership Regulations §3.)

Investigative Examination

A polygraph examination intended to supplement or assist an investigation and for which the examiner has not been informed, and does not reasonably believe, that the result will be tendered as evidence in a court proceeding. Must use a technique for which there exist at least two published empirical studies demonstrating an unweighted average accuracy of 80% or greater, excluding inconclusive results not exceeding 20%. (Standards of Practice §§2.4, 2.8.3.)

Management Committee

The governing body of the Society, elected by the members, comprising between three and nine members including the Chair, the Secretary, and the Treasurer. Manages the Society’s affairs subject to the Constitution. (Constitution cl. 7; Committee and Officer Terms of Reference.)

MBPS

The post-nominal designation used by Members in good standing. (Membership Criteria and Grades §7.)

Member

A class of membership open to examiners holding current APA certification (or recognised equivalent) who have met the threshold of supervised examinations, references, disclosure, and insurance requirements in the Membership Regulations. Members vote at general meetings and may use the post-nominal “MBPS”. (Constitution cl. 5.2(b); Membership Regulations §4.)

Member Undertaking

The signed declaration by which an applicant, on admission, becomes contractually bound to observe the Society’s Constitution, Code of Ethics, Standards of Practice, and other policies. Recorded at Schedule 1 to the Membership Regulations. (Membership Regulations Schedule 1.)

Membership Regulations

The governing document that sets out the rules for admission to, continuation of, and termination of each class of membership. (Published at /standards-ethics/membership-regulations/.)

No Deception Indicated (NDI)

A diagnostic opinion, arising from a validated deception test, that the recorded data do not indicate deception in response to the relevant test questions. (Standards of Practice §2.7.1.)

No Opinion (NO)

A result category indicating that the examiner has suspended judgment due to countervailing information or external factors that reduce confidence in a decision that would otherwise be based on the polygraph data. (Standards of Practice §10.1.1.)

No Significant Response (NSR)

A screening opinion, arising from a validated screening test, that the recorded data do not indicate a significant response in relation to the screening issues. (Standards of Practice §2.7.2.)

Offender Management Act 2007

An Act of the United Kingdom Parliament. Sections 28–30 authorise the Secretary of State to impose a polygraph condition on the licence of specified sex offenders and (following amendment by the Domestic Abuse Act 2021 s.76) specified domestic abuse perpetrators released from custody in England and Wales. Section 30 excludes statements made during a licence-condition polygraph from use in criminal proceedings against the offender. Administered by HMPPS. Often referred to colloquially as “the Polygraph Act 2007”; the colloquial name is not a statutory title. (UK Legal Framework.)

Paired Testing Examination

Polygraph examinations conducted in tandem on two or more individuals by different examiners who are mutually blind to the other test result, regarding a single central contested fact. Used by voluntary stipulation between the parties. Must use a technique for which there exist at least two published empirical studies demonstrating an unweighted average accuracy of 86% or greater, excluding inconclusive results not exceeding 20%. (Standards of Practice §§2.3, 2.8.2.)

Pneumograph

The component sensor used to record respiration during a polygraph examination. Members’ instruments must have two pneumograph sensors (thoracic and abdominal) recording separately. (Standards of Practice §4.1(a).)

Polygraph examination

A psychophysiological test of deception or recognition comprising an interview phase, a data acquisition phase during which physiological responses to test stimuli are permanently recorded, and an analysis phase during which the recorded data are numerically quantified to produce a categorical test result. Sometimes referred to colloquially as a “lie detector test”; the colloquial term is not accurate to the science. (Standards of Practice §2.1; Code of Ethics §4.)

Positive Predictive Value (PPV) / Negative Predictive Value (NPV)

The probability that a positive (or negative) test result is correct, given the base-rate of the condition being tested. PPV and NPV vary with base-rate; sensitivity and specificity do not. (Standards of Practice §10; Nelson 2015 p.45.)

Sex Offender Testing">Post-Conviction Sex Offender Testing (PCSOT)

Polygraph testing of persons managed as sex offenders as a condition of treatment, probation, licence, or supervised release. Members conducting PCSOT examinations must have earned a certificate of training for a minimum of 40 hours of specialised PCSOT instruction consistent with APA standards. (Standards of Practice §§2.9, 8.11.)

Pretest interview

The first phase of a polygraph examination, during which the examiner establishes identification, obtains informed consent, develops and reviews the test questions with the examinee, and conducts the acquaintance test. (Standards of Practice §7.)

Probable-Lie Comparison (PLC)

A traditional form of comparison question in which the examinee is manoeuvred into denying a common behavioural issue that is not the target of the examination. Has been the subject of methodological criticism; remains widely used and has been shown to perform with equivalent efficiency to directed-lie comparison techniques. (Standards of Practice §8; BPS summary of Nelson 2015.)

Relevant Question (RQ)

A question used in a polygraph examination that describes the behaviour under investigation. Relevant questions are the primary stimuli against which the examinee’s physiological responses are evaluated. Each must address a single behavioural issue and avoid ambiguous or technical terminology. (Standards of Practice §§2.7, 8.)

Research Member

A class of membership open to researchers and scientists with a postgraduate qualification (or demonstrable research track record) in a field relevant to polygraphy. No vote; eligible to sit on the Research and Standards Sub-Committee on invitation. (Constitution cl. 5.2(f); Membership Regulations §6B.)

Research and Standards Sub-Committee

An advisory sub-committee of the Management Committee, drawing on Research Members and invited external experts. Its role is advisory only; it does not determine the content of the Standards of Practice or of any other binding policy. (Committee and Officer Terms of Reference §7.)

Retaining party

The person or body instructing a polygraph examination, with whom the examiner agrees the scope of work and fee. Distinct from the examinee, except in private examinations where the examinee may also be the retaining party. (Code of Ethics; Standards of Practice §9.2.)

Screening examination

A polygraph examination conducted in the absence of a known incident, known allegation, or known problem. Intended to add incremental validity to risk-management decisions. Must use a technique for which there exist at least two published empirical studies demonstrating an unweighted accuracy rate significantly greater than chance; used in a successive-hurdles approach. Should not be used alone as the basis for action affecting an individual’s rights, liberties, or health. (Standards of Practice §§2.6, 2.8.4.)

Secretary

The officer responsible for convening meetings, taking minutes, maintaining the Register of Members and the Register of Interests, acting as the point of first contact for applications and complaints, and maintaining the Society’s policies. (Committee and Officer Terms of Reference §4.)

Senior Member

A class of membership open to existing Members who meet the length-of-service, examination volume, CPD, and contribution criteria in the Membership Regulations. Senior Members vote at general meetings and may use the post-nominal “SMBPS”. (Constitution cl. 5.2(c); Membership Regulations §5.)

Sensitivity

The proportion of truly deceptive examinees correctly classified by the test as deceptive. Resistant to differences in base-rate. (Standards of Practice §10; Nelson 2015 p.45.)

Significant Response (SR)

A screening opinion, arising from a validated screening test, that the recorded data indicate a significant response in relation to the screening issues. (Standards of Practice §2.7.2.)

SMBPS

The post-nominal designation used by Senior Members in good standing. (Membership Criteria and Grades §7.)

Specificity

The proportion of truly truthful examinees correctly classified by the test as truthful. Resistant to differences in base-rate. (Standards of Practice §10; Nelson 2015 p.45.)

Standards of Practice

The governing document that sets out the technical standards for polygraph examinations conducted by members, including instrumentation, test conditions, pretest practices, validated techniques, data analysis, record retention, and quality control. (Published at /standards-ethics/standards-of-practice/.)

Student Member

A class of membership open to persons in training towards examiner certification, or in postgraduate study in a relevant field. Reduced subscription; no vote; not publicly listed save with consent. Auto-converts to Intern, Affiliate, or Research Member on qualification. (Constitution cl. 5.2(g); Membership Regulations §6C.)

Subtotal score

The numerical score for an individual relevant question within a multi-question test series, obtained by summing numerical scores across the question’s presentations. Used in multi-issue screening (under the Subtotal-Score Rule) and, with statistical correction, in diagnostic testing (under the Two-Stage Rule). (Standards of Practice §10.)

Treasurer

The officer responsible for keeping the Society’s accounts, collecting subscriptions and fees, authorising payments, and presenting the annual statement to the members. (Committee and Officer Terms of Reference §5.)

Unincorporated association

The legal form of the British Polygraph Society. An unincorporated association has no separate legal personality; contracts are entered into by officers acting on behalf of the members. The Society is established under the law of England and Wales and is not registered at Companies House. (Constitution cl. 2.)

Validated technique

A polygraph testing technique for which there exist at least two published empirical studies (original and replicated) meeting the accuracy thresholds set out in paragraph 2.8 of the Standards of Practice for the relevant examination type. Non-validated techniques are experimental and must not be used in isolation to render a screening or diagnostic decision. (Standards of Practice §§2.8, 8.)

4. Amendment

4.1 This document is reviewed annually by the Management Committee and may be amended by resolution of the Committee to reflect amendments to other governing documents, the adoption of new policies, or clarifications of terminology. Substantive amendments are communicated to the membership.

4.2 Where another governing document is amended in a way that changes the meaning of a term defined in this document, this document is to be updated at the earliest opportunity. In the interval, the amended source document prevails.