Polygraph "Lie Detector"
How It Works

The human body has various automatic functions which are controlled unconsciously by the lower brain. Some of these are responses to stimulus and fear. Others are for such things as temperature control and control of digestion, respiration, water balance, blood pressure, breathing, heart rate, heart blood volume and others.

It is well known that some experts can tell when someone is lying just by observing the person's eyes, breathing and other indications.

Sensitive instruments can detect far more than can trained experts. The most telling measurement is sweat (perspiration). Most people do not realize that the body has some moisture on the skin even when you cannot see it. This is measured by a lie detector instrument. The instrument also measures aspects of blood pressure and volume and respiration rates, volume and other aspects. Finally, the instrument also measures tell-tale characteristics of heart activity.

Fear or alertness or anxiety show up in all these readings even when at very low levels. The automatic functions simply cannot be controlled consciously. For example, you cannot detect moisture on your hand that is at so low a level that you would not be aware it was there.

Well trained polygraph examiners can even determine characteristics of the waves and oscillations on charts that together have additional meaning. Training to become a licensed examiner takes a long time and much study.

Not all examiners are equal. Choosing an examiner is not a place to shop for a $50 difference in price on a matter that could affect the rest of your life. We attempt to screen and know the examiners and have agreements that they meet certain standards.

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