Polygraph Examinations & International Credibility Assessment

The first step is to contact Dr Ashcroft or submit a confidential enquiry. Your matter will then be reviewed to determine whether the requested service is suitable and within scope.

Where appropriate, an introductory or suitability call will be arranged to discuss the nature of the issue, consent, question scope, timing, location, fees and next steps.

A polygraph examination is not confirmed until the matter has been accepted as suitable, the scope and terms have been agreed, and any required retainer has been received.

No. Polygraph examinations are not arranged as instant bookings. The matter must first be reviewed for suitability, consent, ethics, question scope, timing, location and testing conditions.

This protects the client, the examinee, any referring professional and the integrity of the examination process.

No. Some matters may be unsuitable for polygraph examination or may fall outside the Centre's professional scope. Enquiries may be declined where there are concerns about coercion, consent, medical or psychological suitability, unclear question scope, safeguarding issues, legal complexity or the intended use of the result.

Where appropriate, these issues can be discussed during the enquiry or suitability-call process.

We operate within a suitability-led and ethics-led framework. Not every enquiry is accepted. Before any examination is arranged, the matter is reviewed for suitability, consent, scope, testing conditions, location, potential conflicts and professional limitations.

We do not accept instructions where there is evidence of coercion, intimidation, unlawful purpose, punitive intent or circumstances that would undermine the integrity of the process. We reserve the right to decline instructions where a matter is unsuitable or falls outside our professional scope.

No. All polygraph examinations must be undertaken voluntarily. In the private sector, no person can be forced to take a lie detector test. No individual should be intimidated, pressured or coerced into taking a polygraph examination.

If there is evidence of coercion, threats or improper pressure, this may undermine the process and the instruction may be declined.

Yes. In a professional polygraph examination, the relevant questions are reviewed and clarified with the examinee before testing begins. The examinee must understand the questions and be able to answer them clearly with 'yes' or 'no'.

Surprise questions are not used.

A polygraph examination should not be treated as an instant online purchase. Before an appointment is confirmed, the issue must be reviewed for suitability, consent, scope, testing conditions, location and professional limitations.

A direct conversation helps prevent the wrong type of examination being booked, ensures that the process is properly explained, and protects the confidentiality and integrity of the assessment.

The presence of a medical, psychological or temporary condition does not always mean a person is automatically unsuitable. However, these issues must be disclosed and reviewed before any examination is confirmed.

Relevant factors may include significant cardiovascular, respiratory, neurological, psychological, cognitive, pain-related, medication-related, fatigue-related, intoxication-related or cooperation-related concerns.

Polygraph examinations are usually conducted in a suitable neutral testing environment. For therapeutic services, clinic settings may be used.

Home or domestic testing is not usually appropriate because it is rarely possible to control the environment to a satisfactory degree. A controlled setting helps protect the reliability and integrity of the examination.

Polygraph examination fees in the UK vary depending on the nature of the issue to be investigated, the complexity of the case, the location of the appointment, travel requirements, meeting room or venue costs, and the professional time required.

At the Centre for Forensic Neuroscience, fees are quoted individually so that the cost reflects the actual work involved. A straightforward private examination may differ from a legally instructed matter, a therapeutic disclosure examination, a post-conviction sex offender assessment, or a workplace investigation.

Where possible, the fee will be confirmed in advance after a short discussion about the circumstances of the case. The quotation may take account of preparation time, travel, venue arrangements, examination time, reporting requirements and any necessary professional follow-up.

For solicitors, barristers, therapists, employers and organisations, fees may be quoted on a case-by-case basis or on a professional day-rate basis, depending on the nature of the instruction.

To receive an accurate fee estimate, please contact us with a brief outline of the matter, the preferred location, and any relevant timescales.

Claims that polygraphs are a specific percentage accurate can be misleading, because a single figure does not capture how a test performs in practice. To understand the real-world usefulness of any diagnostic procedure, including polygraph testing, it is necessary to consider not only sensitivity (the ability to detect deception) and specificity (the ability to correctly identify truthfulness), but also the base rate—that is, how common deception actually is within the population being tested.

Even when a polygraph examination has good sensitivity and specificity, the practical meaning of the result changes depending on the base rate of deception. In a population where deception is rare, a larger proportion of positive results will be false positives, meaning that truthful individuals may be incorrectly identified as deceptive. Conversely, in a population where deception is common, the same test parameters may produce relatively fewer false positives but more false negatives. This principle applies to all diagnostic tests, not only polygraph examinations.

Properly conducted single-issue polygraph examinations can provide useful credibility-assessment information when administered by a suitably trained examiner using validated procedures. However, polygraph results should not be treated as definitive proof of truthfulness or deception, nor should they be used as a standalone basis for important decisions.

Before any significant decision is made, results should always be considered alongside the wider evidential and contextual picture, including investigation findings, clinical judgement, legal advice, and relevant safeguarding information.

Yes, in some circumstances. A polygraph examination may be administered with the assistance of a suitably qualified interpreter. The questions must be clearly understood by the examinee and must be reviewed before testing begins.

The position of The Centre for Forensic Neuroscience on EyeDetect is one of cautious consideration. While EyeDetect is frequently promoted with reported accuracy rates of 86–88%, such headline figures should not be interpreted as a simple measure of reliability. The practical evidential value of any credibility assessment method depends on its sensitivity, specificity, and the base rate of deception within the population being tested.

In practical application, even a test demonstrating apparently strong overall accuracy can produce misleading outcomes if deployed in unsuitable populations or interpreted without regard to prevalence rates and the consequences of false positive and false negative decisions. For this reason, EyeDetect is not regarded as a stand-alone method for determining truthfulness.

EyeDetect may have utility as an investigative or screening instrument, particularly where rapid assessment is required. However, any significant findings should be considered preliminary and interpreted within the wider evidential context.

Where the outcome of an assessment is important, The Centre for Forensic Neuroscience recommends that EyeDetect findings are validated through a formal polygraph examination conducted by a suitably trained examiner using a recognised and validated testing protocol. A comprehensive polygraph examination allows for assessment of examinee suitability, detailed case review, structured question formulation, quality-control procedures, and professional interpretation of results—elements that are not available through a predominantly automated assessment process.

Accordingly, EyeDetect may provide useful screening information, but important decisions should not be based upon EyeDetect results alone. Any findings should be corroborated through a formal polygraph examination and considered alongside all other available evidence.

P300-based EEG testing may have value for detecting recognition of specific information, but it is not a general replacement for a polygraph examination.

Its limitations include narrow scope, vulnerability to countermeasures, limited real-world field validation and the possibility that a positive result may indicate recognition rather than deception. It should be viewed as a specialised investigative tool, not a comprehensive lie detector.

You will be sent preparation information before the appointment. In general, you should attend in a normal, rested condition; avoid alcohol or recreational drugs; take prescribed medication as normal unless advised otherwise by a medical professional; eat normally; stay hydrated; and raise any health, medication or anxiety-related concerns in advance.

You should also be ready to discuss the relevant issue clearly during the pre-test interview.

A polygraph examination is a valuable investigative tool, but it is important to understand its limitations:

• Polygraph findings are not conclusive proof of truthfulness or deception; they represent a professional opinion
• Results must be interpreted in context and should be considered alongside other available information before any decisions are made
• The suitability of the examinee — including medical, psychological, and temporary factors — may affect the validity of the examination
• The clarity and specificity of the issue under examination affects the reliability of the findings
• Question formulation is critical; poorly defined or ambiguous questions may reduce validity
• Not everyone is suitable for testing due to physiological and psychological differences
• The number of issues being tested within a single examination affects accuracy

Polygraph findings should be considered as one element within a broader assessment, not as a standalone substitute for evidence, investigation, clinical judgement, or legal advice.

Our examiners do not re-examine the work of other polygraph examiners as a matter of company policy and professional ethics unless there is a clear violation of the American Polygraph Association standards of practice.

In most cases the results are given during the examination process, or soon thereafter if a peer review is necessary. Our examiners will at all times ensure complete confidentiality and discretion.

The examinee must provide government identification (Photo ID Card, Passport, Driving Licence) on arrival for verification purposes.

A polygraph test typically takes around two hours or more to complete. The process involves a full pre-test interview to establish the facts, followed by the polygraph instrument data collection phase. Only one issue is addressed per examination to ensure accuracy.

Single-Issue and Specific-Issue Polygraph Examinations have proven the most accurate. In formal, valid credibility assessment, only one issue is addressed within the examination to ensure accuracy.

Furthermore, the answer to each question is limited to 'yes' or 'no'. You cannot mix issues within the same polygraph interview.

Question wording is reviewed before testing begins. Learn more about professional polygraph question formulation and how questions are scoped, clarified, and understood before the examination.

A polygraph measures physiological responses including blood pressure, pulse rate, respiration and skin conductivity. Modern polygraph science analyses the orienting response to novel or important stimuli, rather than relying on outdated notions of fight, freeze or flight.

Current understanding refers to what is known as the 'orienting response' to novel or important stimuli, which are intrinsically related to experiences in autobiographical memory, emotional salience and the act of lying requiring increased cognitive processing.

Specifically, research suggests it takes more cognitive activity to lie than to tell the truth because you need to construct a narrative. Thus, essentially, we are analysing the strength of attention as determined by autonomic arousal.

For a more detailed discussion of the science behind these processes, see our article on Preliminary Process Theory and the scientific basis of polygraph testing.

Only the examiner and the examinee can be present when the actual polygraph interview and examination takes place. As recommended by the American Polygraph Association, which ensures the whole process can be conducted in a controlled environment.

Professional polygraph instruments include Movement Monitoring Systems with multiple channels specifically designed to detect countermeasures. Attempts to manipulate physiological responses during a professionally administered examination are monitored for and may be identified and recorded. All of our instruments use the latest monitoring technology to ensure examination integrity.

When choosing a polygraph examiner, clients should look for clear professional accountability, including the name of the examiner, relevant training, suitability screening, informed consent procedures and a controlled testing environment. Domestic or home-based testing is not usually appropriate where the environment cannot be properly controlled.