What is a Lie Detector Test?2018-03-08T12:48:40+00:00

A lie detector test is also known or commonly referred to as a polygraph test or polygraph examination. It is one of the most powerful, robust and useful scientific tools in truth verification or the detection of deception regarding a specific issue, incident or event.

The term “polygraph” derives from the Greek words poly (many) and graph (writing) “many writings”.

A polygraph examination involves an in-depth procedure, using state of the art, computerised equipment and validated test techniques. During an examination, manifestations of a person’s nervous system are recorded from at least three systems in the body.

Two convoluted tubes are placed around the upper chest and abdomen of a person to record respiratory activity. Two metal plates or disposable adhesive electrodes are attached to a person’s fingers to record sweat gland activity and a blood pressure cuff will record cardiovascular activity. A motion sensor will monitor general movements throughout the examination.  A finger plethysmograph may also be used to monitor blood volume.

Voice stress tests should not be confused with a Polygraph Test. The two are completely different tests with voice stress testing working no better that pure chance (i.e. the accuracy of such voice stress instruments are similar to making a decision based on a flip of a coin). We therefore do not use it in our examinations.

An examination should only be conducted by an experienced and trained polygraph examiner.

How does a Lie Detector Test work?2018-03-08T13:43:36+00:00

How does a lie detector test work is one of the main questions our clients ask, so here we have given a brief synopsis as to how it works and an insight as to each of the four phases which form a Lie Detector Test.

The lie detector test records manifestations of a person’s nervous system from at least three systems in the body whilst questioned about concerns of a specific issue, incident or event. The examiner will analyse the charts collected and render an opinion as to the persons truthfulness.

A polygraph examination consists of four phases and will typically take between 2 to 3 hours to complete.

The four phases of a polygraph examination are known as the pre-test, chart collection, test data analysis and finally the post-test phase.

Pre-test phase.

During the pre-test, the examinee is required to complete a consent form and medical form.

The examiner will provide the subject with an overview of the examination and testing process and conduct a pre-test interview. The interview will provide the examinee with an opportunity to discuss their circumstance with the examiner in greater detail and to assist with test question construction. It is imperative to be truthful, open and honest with the examiner as any undisclosed information may affect the outcome of the test results.

Chart collection phase.

Sensors will be attached to the subject and the test questions reviewed.  The examiner will go onto administer and collect a number of charts. The number of questions asked and charts collected will vary depending on the format of the test used and the test technique.

Test data analysis phase.

On completion of the chart collection phase, the examiner will review the data collected and analyse the charts. An opinion of the examinee’s truthfulness regarding the specific issue, incident or event will then be rendered.

Post-Test phase.

The examiner will provide the examinee with a verbal result and where appropriate the examiner will offer the examinee an opportunity to explain physiological responses to the questions presented during the test.

How accurate is a Lie Detector Test?2018-03-08T13:46:49+00:00

How accurate is a Lie Detector Test? This is another frequently asked question and therefore we have provided you with the findings of statistical research gathered by The American Polygraph Association, along with access to the validated polygraph techniques.

Although no forensic testing of any kind can be guaranteed to be 100% accurate, research gathered by The American Polygraph Association has suggested that qualified polygraph examiners can achieve an accuracy of 95% to 98% when an examination is conducted in an accurate manner, with issue-specific questions and using validated polygraph techniques.

Through our robust policies and the application of best practices, Lie Detector Investigations can fulfill and satisfy these conditions by operating to the key conditions, listed below.

  1. Our examiners are fully qualified, experienced and accredited.
  2. We only use up-to-date, computerised polygraph equipment and validated test techniques.
  3. A pre-examination checklist is completed at the time of booking to ensure the examinee is a suitable candidate for testing.
  4. An examination is conducted in an environment which is void of distraction and disturbance, and therefore we do not conduct tests at a person’s home.
  5. We adhere to The American Polygraph Association’s continuing education policy, by undertaking updated polygraph training, every two years.

Important notes and references: 

Before choosing and committing to a Polygraph examiner or Polygraph company it is important to ensure you are choosing a qualified and accredited examiner. A quick and easy check to carry out is to refer to The American Polygraph Association and/or The British Polygraph Association.

Further details of studies gathered by The American Polygraph Association (APA) can be viewed on their website.

Lie Detector Investigations only use the latest and validated techniques which are listed on The American Polygraph Associations website,  “Meta-Analytic Survey of Criterion Accuracy of Validated Polygraph Techniques”, can be viewed and downloaded here.

Cost of a Lie Detector Test?2018-07-18T12:48:05+00:00

The cost of a Lie Detector Test can vary depending on several factors.

Lie detector test prices vary throughout the UK with the cost of a Lie Detector Test ranging from £395 to £695 for a specific issue test with an average test costing of around £550.

Lie Detector Test Costs can vary due to the test location, examiner experience, third-party providers, and the number of tests required. Therefore, it is imperative you check the credentials of the polygraph examiner and company before committing and ensure you are asking the correct questions.

  • The vast majority of UK polygraph examiners are based in a particular region of the UK and will therefore need to travel to you, or vice versa. Whilst it is reasonable to expect additional costs to be added to cover travel and meeting rooms, these costs should not be exorbitant.
  • In all professions, the cost of services can vary from one company to the next. Often you will find a “cheap” rate which may seem too good to pass up. However, you should always way up the cost against the experience of the examiner. It is unlikely you will find an experienced examiner offering the “cheapest rate: or introductory offers. Always, always, always check the credentials of the examiner and company, before you book.
  • It is advisable to book directly with an examiner and through their own website to avoid paying a higher cost as there are companies offering lie detector tests who will charge more, only to sub-contract examiners who you can book directly with.
  • Ensure the company you choose are using appropriate and verified polygraph equipment and not voice stress analysis toys or substandard equipment bought over the internet.
  • A qualified examiner will be happy to provide their findings in a written report and at no additional cost. An additional charge for a written report should be questioned and if the examiner is unwilling at all, to provide you with a written report.
  • The test techniques used for specific issue, incident or event examinations such as infidelity, may differ from the test techniques used in corporate matters for pre-employment screening of a large pool of prospective employees. Therefore, the type and circumstance of the examination may warrant a variance in test costs.

To obtain the cost of a lie detector test, you can contact our head office by telephone or by completing our contact form. One of our polygraph examiners will be happy to provide you with a fixed cost, inclusive of VAT.


How do I choose a Polygraph Examiner?2018-03-08T15:39:14+00:00

There are several factors to consider before you choose a Polygraph Examiner. These include primary training, overall experience, continuing education and the use of the latest computerised equipment & validated test techniques. In each section below, we have provided a brief outline as to what checks and credentials should be undertaken or verified.

Primary Training: It is paramount to ensure your chosen Polygraph Examiner has attended and graduated from an accredited polygraph training academy. To verify the accreditation of a Polygraph Examiner, this can be confirmed by visiting The American Polygraph Association website.

Overall Experience: A Polygraph Examiner should be comfortable in using a variety of test techniques and should only use the latest in computerised equipment. As with all businesses & trades, there are those who have more experience than others. The experience of a Polygraph Examiner can be measured by the number of tests conducted or the number of years they have conducted tests. Any Polygraph Examiner should be happy to discuss their experience and credentials with you.

Professional Associations: Qualified Polygraph Examiners must first and foremost be registered members of The American Polygraph Association. It is recommended you choose a Polygraph Examiner who is registered with a second and credible association such as The British Polygraph Association.  Our Polygraph Examiners are registered members of both associations as well as The International Society of Polygraph Examiners.

Continuing Education: Guidelines set out by The American Polygraph Association require Polygraph Examiners to complete training every two years as part of their Continuing Education Policy. These guidelines are set out to ensure examiners keep up with the advancements in polygraph science, research, and technology.

Equipment & Validated Test Techniques: Polygraph Examiners should be using complete and fully operational equipment which is maintained to the highest standards and the latest software versions.  Only the latest and validated testing techniques which have been approved by The American Polygraph Association should be used.

Countermeasure Detection: A qualified & quality examiner should have training and experience in identifying countermeasures, (attempts to “beat” the test).

Written Reports: A written report should be provided willingly, upon request and at no additional charge. A qualified and reputable Polygraph Examiner will be happy to put his/her opinions in writing.

How to book a Lie Detector Test?2017-12-22T14:24:56+00:00


If you are wondering how to book a Lie Detector Test, this can be achieved by simply completing our contact form or by calling our head office directly.

Should you choose to complete the contact form, we ask you to kindly provide us with the reason for the test, your location, along with your contact details. It is also advantageous to provide us with two dates which are convenient for the test to be conducted. One of our polygraph examiners will respond to your inquiry usually within the same day of you making the inquiry.

Alternatively, if your inquiry is urgent in nature you can call our head office. The date and time of your appointment can usually be confirmed at the time you call, should you choose to contact us by telephone.

A card payment is required to confirm your appointment. All payments are non-refundable should you cancel your appointment.

Once your booking is confirmed you will receive an appointment letter along with our Terms & Conditions of Service. The appointment letter will confirm the date, time and location of your appointment.



If you have a question, you can simply complete our inquiry form with your question(s) and one of our examiners will respond usually within the same day. Or you can call our head office direct where an examiner will be happy to answer your question(s) and provide you with any information you need.



An appointment can be arranged Monday through Friday.

Weekend appointments are available upon request.

We can also accommodate evening appointments.



  • Appointments are always necessary.
  • We do not accept walk-ins nor do we conduct tests without a confirmed appointment.
  • We are PCI DSS compliant.
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