Lie Detection – A Series of articles on credibility (4 Last)

Do they work?

The credibility of the lie detecting was challenged almost as soon as it was invented, and there is much debate about its accuracy.

The fundamental premise that lie detecting tests measure deception, is incorrect.

Lie Detection methodologies measure responses to questions and compares the responses to control questions with responses to relevant questions. Theoretically liars will show increase arousal when answering the relevant questions, whereas truth tellers will not. Unfortunately, there is no sound theory to back this up.

There are several different reasons why a test may be inaccurate. These include the questions being poorly formulated and the interviewer misreading the results.

If the examiner is well-trained, if the test is properly carried out, and if there’s proper quality controls, the accuracy is estimated between 80%-90%. This being higher than the average person’s ability to tell if someone is lying.

Lie Detection – A Series of articles on credibility (3)

Can you cheat?

The short answer is Yes!

You can beat the test, BUT you need to know HOW and WHEN.

You may find websites telling you how to, but the reality is if you just go in and take a lie detecting test while hoping to beat it, you’re in for a surprise.

To cheat successfully requires sitting down and practicing with a trained examiner. But for those who don’t have a qualified questioner to assist – what else can they do?

There is the classic ‘tack in your shoe’ to cause yourself pain which will result in for example, a big increase in your sweating response. However, the natural response to causing yourself pain is for your body to move away from it and this will simply activate the movement sensor, indicating you are applying a counter measure.

So, be cautions as most examiners will be able to spot any covert attempt to beat the test.

Then of course, I’m not going to tell how to do it!

Lie Detection – A Series of articles on credibility (2)

How are they carried out?

Lie Detecting is used around the world, in countries such as Japan, Russia and China, and the technology remains much the same.

The test will begin with a pre-test interview that can last up to an hour, this introduces the examinee to the process, the questions to be asked and the examiner collects all necessary information about the examinee. There are never any surprise questions as they may in fact trigger a response. What is going to be asked is known.

The equipment is then attached, and it usually includes either a headset with microphone or a blood pressure monitor, electrodes which are placed on an index finger, and two tubes which are wrapped around the chest and stomach. The individual may also sit on a movement sensor pad. The examiner will ask several control questions during the test which have all been presented to the examinee earlier. And then compare those responses to the responses of the questions relevant to the issue.

Lie Detection – A Series of articles on credibility

How credible are lie detector tests?

Being in the industry for over 25 years and a professional examiner since 2006, I consider my opinion on the credibility of both Polygraph and Voice Stress Analysis, valid.

In this series of short articles, you will hear first-hand, from the horse’s mouth so to speak, the truth.

Read on to learn what such a test is, how they are done, the answer to the most asked question “Can you cheat?”, and the answer to the second most asked question, “Do they work?”

What is a Lie Detecting Test?

In short, lie detector tests record several different bodily responses which can then be used to determine whether someone is telling the truth.

They measure things like voice frequency, blood pressure, heart rate, changes in a person’s breathing, and in the electrical resistance of the skin. All lie detection techniques, measure an indirect effect of lying, that of an increase in physiological stress when responding to questions.

So, Lie Detecting tests do not measure deception or lying directly, but rather possible signs that a person could be deceiving the examiner.

This information is then used in conjunction with everything else that is known about the person to form a clearer picture of whether they are being truthful.

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