Lie detector test accuracy

Jul 1, 2022 | News & Science, Polygraph Examiner

How Accurate is a Lie Detector Test?

A lie detector test, or polygraph, is only as good as the examiner.

Look at it this way – you could take driving lessons in a top of the range Mercedes, with all the bells and whistles, but if the instructor is rubbish then you’re never going to pass your test!

It’s the same with a polygraph – anyone can buy the equipment, but without a fully-trained, ethical, honest examiner it’s about as much good as an empty box.

Surely it’s just a case of asking questions?

No! Not at all. In fact, the name ‘lie detector’ is a bit of a misnomer in itself – it doesn’t detect a lie so much as a deception. When we are being deceitful our bodies give out certain signals, and it is these signals which the polygraph picks up. And that is where the quality of the examiner comes into play.

In the UK there is no regulatory body governing the quality of polygraph examiners, therefore, in theory, anyone can buy second hand equipment and set themselves up as lie detector experts. In those cases, the success rate will probably be around 50/50 – no better or worse than if the questions had been asked with no equipment whatsoever.

Why? Because the examiner will have had no training, no screening, and really no idea what they are doing! Of course they could read a few books and call themselves experts, and charge hundreds of pounds for what is, essentially, a quick chat.

We, however, have no desire to cheat people out of money. Our only concern is obtaining accurate results, ethically and honestly, and because of this our levels of accuracy are 95% – 98%, every time.

As you can read in our other pages, our examinations will usually take 2 – 3 hours. This is because we are thorough. We never rush a test – it is essential to the efficacy of the examination that the subject thoroughly understands the process, and has asked, and had answered, any questions they may have. Our examiners will take the time (however long it takes) to explain everything, to put the subject at ease, and to make sure the examinee is as comfortable with the process as possible. This is all done before the actual testing even begins.

Once this stage is complete, the examiner will then attach the equipment to the subject, once again explaining everything as he or she goes along.

At every stage, our examiners make sure the subject fully understands what is happening, and why.
It is only then that the actual testing part of the process begins, and this is where the magic (otherwise known as 95% – 98% accuracy) happens.

We only employ what is known as the Single Issue Test. This means that, as the name suggests, only one single issue is raised during the test. Many other companies will use multi-issue tests, which is massively detrimental to the outcome and leads to much lower success rates. By using the Single Issue Test, we keep the questions to a minimum, focusing only on the issue we have been asked to look into. When multi-issue tests are used, the entire process becomes complicated and blurred. Truth isn’t complicated!

Why are our examiners different?

As we’ve said before, anyone can set themselves up as a polygraph expert. This is why we have such stringent criteria when it comes to our examiners.

To start with, all of our examiners have gained qualification through the American Polygraph Association – the world’s leading professional polygraph organisation. Without that training they will not be accepted by us (we refuse 70-80% of all applicants because they do not meet our exceptionally high standards).

Our examiners also undertake regular CPD (Continuing Professional Development) in order to keep up with the latest techniques and advances in the field of lie detection, and undergo annual checks to ensure this is being complied with.
Each and every one of our examiners will have their skills and knowledge regularly checked by other examiners, and background checks are also routinely carried out at intervals.

Thorough training also ensures that all of our examiners are able to handle any situation with which they are presented. They are masters at remaining calm and inspire the same in their clients.

Client confidentiality is paramount – any information regarding the situation is between the subject and the examiner, and will only be disclosed to a third party if expressly requested by the examinee. All of our examiners also only use the most advanced equipment available, so not only are you getting world class examiners, but also world class equipment.

Of course, having said all of that there will still be people who believe that they can cheat a lie detector test. And that is certainly possible – IF they are using sub-standard, old, outdated equipment and poorly trained examiners. The likelihood of being able to cheat one of our tests and/or examiners is negligible. Not only are there safeguards in place with the equipment itself, our examiners are highly trained to detect and deal with attempts at manipulation.

Research has shown that the accuracy of the latest computerised polygraph testing techniques is 98%. There are several key qualities that are important in order to achieve this level of accuracy. That is why all polygraph examiners working for adhere to the following criteria:

  1. Each examiner must be fully qualified, having gained their qualification from facilities accredited by the British Polygraph Society and/or the American Polygraph Association.
  2. The examiner must use the latest techniques and methods.
  3. The examiner must use the latest computerised equipment.
  4. Each examiner must be a current member of the British Polygraph Society and/or the American Polygraph Association, which is the largest association of polygraph examiners in the world
  5. Each examiner must undertake continual professional development courses on a regular basis.
  6. Each examiner must submit work for quality checks as part of a commitment to maintaining the highest standards of testing possible.

It really does come down to that old saying, you get what you pay for. We offer the absolute best and most accurate service you can get in the UK.

Accuracy and Validity of Polygraph Testing

Scientific research has shown polygraph examinations to be highly accurate, making them very useful in the criminal justice system. The American Polygraph Association (APA) requires the following to be met before an examination can be considered valid.

  1. The polygraph examiner must be properly trained and must use an accepted procedure and scoring system.
  2. The polygraph equipment must record, at a minimum, cardiovascular, respiratory, and electrodermal activity.

The following summarizes research data collected by the APA

Research Quantity Average Accuracy
Field examinations 12 studies
2,174 examinations


Field examinations
(Independent analyses)
11 studies
1,609 examinations


Laboratory simulations 41 studies
1,787 lab simulations


Laboratory simulations
(Independent analyses)
16 studies
810 lab simulations


[source: The British Polygraph Society ]

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