Pneumograph
Breathing
Two tubes rest across the chest and abdomen and record the depth and rhythm of each breath. People hold their breath without noticing; the chart notices.
Straight answers
The questions people actually ask us
Every answer is on the page — no accordions to click, no form to fill in first. Where the honest answer is “that depends” or “ask a solicitor”, it says so. These are the questions Lie Detector UK is actually asked, answered without the hedging that usually surrounds them.
£495
All inclusive
£150
Deposit to reserve
95–98%
Accuracy of a validated test
24–48 hrs
Written report
Jump to
Section 1 of 8
What a polygraph is, and what it can settle
Worth reading before anything else: most disappointment with a polygraph comes from asking it a question it was never able to answer.
What does the instrument actually measure?
Three channels, recorded continuously. Two tubes across the chest and abdomen record the depth and rhythm of your breathing. A cuff on the upper arm tracks pulse rate and relative blood pressure. Two fingerplates measure the response of the sweat glands. That is the whole of what the instrument does — it records physiology.
So it does not detect lies?
Nothing detects a lie directly, and no instrument ever has. What a polygraph produces is a record of how your body reacted to specific questions. The examiner scores the pattern of those reactions across all three channels, comparing your responses with each other. The conclusion comes from the scoring, not from a machine deciding anything.
What can an examination actually establish?
A small number of specific, factual questions about things that have already happened. “Did you have physical contact with that person between June and August?” is testable. “Is my partner trustworthy?” is not — it is an opinion about the future, and there is no chart for it. Narrow and factual is what makes a question scoreable.
What can it not establish?
Feelings, intentions, opinions, or what someone will do next. It cannot date an event, cannot tell you how many times something happened, and cannot identify which member of a group did something by testing one of them. If a question cannot be answered yes or no about a specific past fact, it does not belong in an examination.
How accurate is a lie detector test?
A validated technique, run properly by an accredited examiner, sits at 95–98%. Anyone quoting 100% is selling you something else.
Does being nervous affect the result?
No. Nervousness is expected and shows up on every chart. The analysis compares your responses against each other, not against a calm stranger.
What is actually recorded
A polygraph is a recorder, not a lie meter.
Four channels run continuously for the whole examination. No single reading decides anything — the examiner scores the pattern across all of them, against your own baseline answers.
Cardiovascular
Pulse and blood pressure
A cuff on the upper arm tracks pulse rate and relative blood pressure through the examination, not just at the moment a question is asked.
Electrodermal
Skin conductance
Two fingerplates measure the sweat glands’ response, which shifts within seconds of a relevant question and is not something a person can consciously hold still.
Activity sensor
Movement and countermeasures
A pad in the seat records movement, including the small deliberate kind — pressing the toes into the floor, tensing a muscle, altering the breath on purpose. Attempts to influence a chart show up here as steps that belong to none of the other channels, which is exactly why the channel exists.
Each examination is limited to three relevant questions, agreed with you before the instrument is attached. You will not be asked anything you have not already seen.
Section 2 of 8
What it costs, and how booking works
One price, quoted in full. The examination, the consultation before it and the written report after it are the same fee.
How much does a lie detector test cost in the UK?
£495 all inclusive for one person and £695 for a couple, covering the consultation, the examination and a written report. A £150 deposit reserves the appointment.
Is anything charged on top?
No. £495 covers the pre-test consultation, the examination itself and the written report. The £150 deposit is part of that price rather than an addition to it — it is a booking fee that comes off the total, not a surcharge.
When is the balance due?
Not on the day. The £150 deposit is paid when you book, and the balance is payable 48 hours before the appointment. That deadline is set out in our terms of service, and we will contact you before it falls due.
Is the deposit refundable if I cancel?
No. The deposit is a retainer and is non-refundable, which is stated at the point of booking rather than buried afterwards. Our terms also treat the full fee as non-refundable for a cancellation, a missed appointment or an arrival after the scheduled start time — so if a date is uncertain, say so before you book rather than after.
Is the price different in Scotland?
Yes. Scottish appointments are £695 for one person and £850 for a couple, against £495 and £695 in England and Wales. The difference is travel and office cost, not a different examination — the format, the equipment and the report are identical.
Can more than one person be tested?
Yes. Two people are £695 in England and Wales, and groups of three or more are £295 per examination. Each person is still tested individually and privately: a couple booking is two separate examinations, not one test with two people in the room.
Do you offer home or on-site tests?
Tests are normally conducted at our private office in the UK, where the environment can be controlled. Alternative locations may be possible subject to pre-approval.
Section 3 of 8
The appointment itself
Around two hours, and the part with the instrument attached is the shortest of them.
What actually happens on the day?
You give your name at reception — no more than that. The examiner checks identification, you sign a consent form, and the examination is video and sound recorded for analysis. Then the pre-test interview, the instrument phase with nobody else in the room, and the scoring.
How long does the test take?
Around two hours in total. Most of that is the consultation and question review; the instrument phase is the shortest part.
What questions will be asked?
Up to three relevant questions, agreed with you in the pre-test consultation. Nothing is asked on the day that you have not already seen.
Why only three questions?
Because the validated formats are built around that number and the research behind them assumes it. A test with eight relevant questions is not a longer version of a good test — it is a different procedure with no validation behind it, and its accuracy figure would be unknown. Fewer questions, properly tested, is the whole method.
Which test format do you use?
One of two formats recognised by the American Polygraph Association: the UTAH, a single-question test, or the AF/MGQT, a three-question test. Both are validated and heavily researched, which is precisely why we cannot deviate from them or add extra questions on request.
Who decides how the questions are worded?
You bring the issue; the examiner words it. Wording is technical work — a question has to be answerable yes or no, cover one fact rather than several, and contain nothing ambiguous. You see and agree the final wording in the pre-test interview, before the instrument is attached.
Do I need to bring anything?
Photo identification, which the examiner checks before starting. Bring details of any medication you take if you have not already told us when booking. Nothing else is needed — there is no paperwork to prepare and nothing to write in advance.
Can I attend someone else’s test?
No — a third party in the room invalidates the examination. You are welcome to wait in reception and to see the written report if the examinee consents.
Section 4 of 8
Accuracy, nerves and countermeasures
The honest version, including the outcome nobody advertises: sometimes a chart cannot be scored either way.
What does 95–98% actually mean?
It is a research figure for the technique — how often validated formats reach the correct decision when run by accredited examiners under proper conditions. It is not a promise about your particular chart, and it is not a guarantee. Anyone who quotes you 100% is describing something that does not exist.
Can the test be cheated?
Countermeasures are what examiners are trained to spot. Attempting them typically produces an inconclusive result, not a pass.
What is an inconclusive result?
A chart that does not produce a large enough difference between your responses to be scored either way. It is not a pass, it is not a fail, and it is not the examiner hedging — it is the honest outcome when the data does not support a conclusion. Your examiner will explain what produced it and what the options are.
Can a medical condition produce a wrong result?
A condition that changes how your heart, breathing or sweat response behaves can make a chart harder to score, which is exactly why suitability is assessed before you are tested rather than after. Declare anything relevant when you book. Where a condition means the examination should not go ahead, we will say so before you pay the balance.
Section 5 of 8
Whether you can be tested, and how to prepare
The criteria below are the American Polygraph Association’s, not ours. Source: APA Model Policy for Examinee Suitability, 9 September 2021.
How should I prepare?
Get a good night’s sleep, avoid stimulants such as caffeine beforehand, be honest during the pre-test interview, and ask the examiner about anything you do not follow. Source: APA Model Policy for Examinee Suitability, 9 September 2021.
Is there anything I have to avoid before the test?
Abstain from alcohol and recreational drugs for 24 hours beforehand. Tell us about any medication when you book so we can advise — prescribed medication should be taken at its normal dosage, not skipped for the appointment.
Do medications affect the results?
Tell your examiner what you take. Most prescriptions are fine; a few are not, and your examiner will say so before you pay the balance.
Who is not suitable for a polygraph examination?
The APA lists active psychosis or an unmanaged psychotic condition, functional maturity below the equivalent of twelve years old on psychometric testing, severe intellectual disability with an IQ below 55, acute severe mental health conditions or a need for continuous assistance, and observable impairment through alcohol or drugs.
I have anxiety or a diagnosed mental health condition. Am I excluded?
Not automatically, and most people asking this are not. The criteria above describe acute or unmanaged conditions, not a diagnosis on your record or a condition you are managing. Tell us when you book, so the examiner assesses it properly rather than discovering it in the room.
What is the examiner assessing in the screening?
That you can think in the abstract and follow why the test is being run, have insight into your own and others’ motivations, understand right and wrong and the consequences involved, and can tell the difference between a truth and a lie with clear examples of each.
Do you test under 18s?
Only in limited circumstances, with the written consent of a parent or guardian, and at the examiner’s discretion. Please call to discuss before booking.
Section 6 of 8
The result and the report
What you are told, when you are told it, and who else ever sees it.
How do I receive the result?
Verbally at the end of the appointment, so you do not leave without knowing. The full written report, with the examiner’s detailed conclusions, follows within 24 to 48 hours. It goes only to the person who made the booking unless you instruct otherwise. If someone needs to verify the test is genuine, we can issue a pass code for third-party confirmation.
Why is the written report not handed over on the day?
Because scoring a set of charts properly takes longer than an appointment allows, and a report written in the ten minutes after an examination would be worth less than one written carefully. You get the conclusion verbally before you leave; the document that sets out the reasoning follows in 24 to 48 hours.
Who else gets to see it?
Nobody, unless the person who booked says so. The report goes to the booker. We do not send results to partners, employers, family members or solicitors on our own initiative, and we do not confirm to a third party that an appointment happened at all.
What does the written report contain?
The questions as they were finally worded, the format used, the examiner’s scoring and the conclusion drawn from it. It is a technical document rather than a certificate — the reasoning is set out so that someone else can follow how the conclusion was reached.
What if I disagree with the result?
Raise it in the post-test interview, which exists for exactly that. The examiner will walk you through the scoring rather than simply assert it, and if you believe something affected the examination — a condition, a medication, the wording of a question — say so then, because it is a substantive point. Note that the recordings are deleted within 24 hours unless you ask in the pre-test for them to be kept.
Section 7 of 8
Consent, the law and your privacy
What we can tell you is how we operate. What a court or an employer will do with a result is a question for a solicitor.
Can I refuse to take the test?
Yes, at any point, including once you are in the room. An examination in the UK cannot proceed without your written consent.
Is a polygraph examination legal in the UK?
Yes, privately and with consent. There is no law preventing an adult from choosing to take one. What the law does not do is make anyone submit to one: consent is given in writing before the examination and can be withdrawn at any point, including once it has started.
Will a result be accepted by a UK court?
Not automatically. A polygraph result is not admissible evidence by right in this country, and what weight — if any — is given to one is entirely a matter for the court. People do commission examinations in connection with family proceedings, but we sell an examination and a report, not evidence. If a case is live, ask your solicitor before you book.
Can an employer require me to take one?
They cannot make us test you without your written consent, and we will not proceed without it. Whether refusing has consequences inside your employment is an employment-law question and not one we can answer — take advice from a solicitor or your union before agreeing to anything.
What happens to my data and the recording?
The examination is video and sound recorded so the charts can be analysed, and our terms commit to deleting those recordings within 24 hours of the test unless you ask us in the pre-test interview to keep them. We are registered with the Information Commissioner’s Office under ZB150442, which is a public register you can check.
Section 8 of 8
Telling a real examination from a fake one
This is the section we would most like people to read before paying anybody, including us.
How do I check an examiner is genuine?
Ask which body they are registered with, then check the register yourself. The British Polygraph Society and the American Polygraph Association both maintain public ones. A real examiner will expect the question and will tell you where to look; anyone who is evasive about it has answered you already.
Is a voice-stress or eye-tracking test the same thing?
No. Voice stress analysis, camera and eye-tracking systems and phone apps are different instruments measuring different things, and they are not validated techniques. They are frequently sold using the words “lie detector”, which is exactly why the distinction is worth knowing before you pay.
Why are some tests so much cheaper?
Usually because they are not a polygraph examination, are not run in a validated format, or are not run by an accredited examiner. A validated examination takes around two hours of an accredited examiner’s time plus the scoring and the report afterwards. If a price does not cover that, something has been left out — and it is normally the part that makes the result mean anything.
Can a phone app detect lies?
No. There is no validated method of detecting deception through a phone camera or microphone, and no app has one. They are entertainment products, and treating one as a test of something that matters is how people end up making irreversible decisions on nothing at all.
Before you pay anyone
A real examination uses a validated instrument
Camera-based and voice-stress “tests” are unvalidated and carry no standing in the UK. Check that whoever you hire is registered with the British Polygraph Society or the American Polygraph Association — both keep public registers.
Something not answered here? 020 8058 6848 — a specialist will tell you whether an examination can answer your question before you book one.
