Polygraphs

This passage discusses the use of polygraphs, which are also known as "lie detectors."

Lexile Level: 1060L

Categories: Science & Technology

Polygraphs are often referred to as "lie detectors." However, this nickname is a bit misleading. Polygraphs do not directly identify lies. They track a subject's heart rate, breathing rate, and perspiration levels. Changes in these measurements often occur when a person tells a lie. It is up to the examiner to determine whether the information collected signifies an action of deceit. One difficulty in using a polygraph to detect lies is that any type of stress can lead to changes in our basic bodily functions. However, polygraph operators are well-trained and can usually identify which metabolic changes are results of stress not associated with acts of deception. For instance, for many people, being hooked up to a polygraph would be an unusual experience. This, in itself, might cause a certain level of change in heart rate, breathing rate, or perspiration levels. Examiners factor this in when evaluating a subject's metabolic reactions during questioning.