The Polygraph records physiological (biological) changes that occur in the human body. These changes are evaluated based upon changes that occur when specific questions are asked. Most of us can remember a time when we lied to our parents or another significant person. We could feel the changes in our bodies. Often we can feel our heart racing, palms sweating, and other symptoms of apprehension (being afraid of being caught out lying).
When we evaluate the polygraph charts, we can see up to 32 different physiological changes indicative of lying. Knowing that we are lying makes us feel completely different from just being nervous. Simply put, the process of lying is more complex than that of telling the truth and also always holds risk. The body’s functionality changes as a result of this increased activity and these changes can be measured; much in the same way as a change in core temperature can be measured using a thermometer.