Polygraphs – Fact or Fantasy
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Polygraphs – Fact or Fantasy

Polygraphs – Fact or Fantasy

Polygraphs operate on the principle that there is a physical side to emotion. The classic fight or flight response increases blood pressure and sugar levels, for stronger muscles and more endurance. Something similar happens during an interview, especially one with a police officer.

What Polygraphs Measure

A polygraph provides online reports concerning more subtle changes to the subject’s physiology. These include:

*  Blood Pressure – This increases when we are feeling stressed.

*  Pulse – That racing feeling as we anticipate an event like a job interview

*  Rate of Breathing – This commonly speeds up when we are excited

*  Skin Conductivity – Increased ability to conduct electricity caused by sweating

With a normative pattern established a skilled polygraph operator is able to infer emotions such as nervousness and fear.

Not an Exact Science

In the purest sense of the word polygraphs are pseudoscience, because everybody has a subtly different biological makeup, and a fallible human being interprets the readings. That said, polygraphs are useful indicators of the subject’s state of mind, with outcomes considerably greater that chance.

Testing Procedure

This begins with a pre-test interview to obtain preliminary information and get the testee into a relaxed state. The tester may explain how polygraphs work and emphasise how important it is to tell the truth, so as not to cause a false reading.

The interview proper kicks off with routine questions like ‘so your name is Fred’ and ‘are you okay to continue with this’. This sets the bottom line of the individual’s reaction scale. From then on, the interviewer alternates between investigative ‘relevant’ questions and neutral ones to highlight the differences in readings.

If polygraph scores remain on an even keel then the interviewee is more likely to be telling the truth (although this is not pure science).

Polygraphs and Private Detective Work

There have been remarkable breakthroughs in the Australian justice system thanks to polygraphs. Notorious criminals have gone to jail and innocent prisoners have been set free – although in neither case have the readings been admitted as direct evidence.

Hence polygraphs function more as indicators of possible states of mind, and signposts along an investigative trail suggesting which avenues to explore.

May We Assist?

If you are reading this because you believe you are unfairly accused of something – for example marital infidelity, partner fraud and employee misdemeanour – speak to QLD Covert Investigations about how a polygraph test could help you. You can call us now on 1300 553 788 or post a confidential message on our website.  

The results remain your property and that’s a promise, unless you choose to disclose them in your interests.

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