The Polygraph

The polygraph is based on physiological science. When a person lies, they experience physiological changes in their body that can be measured and recorded. These automatic changes reflect a heightened state of stress or anxiety that occurs when someone is being deceptive or trying to conceal information.

The polygraph instrument measures several physiological responses which are used to determine whether someone is lying or telling the truth. The most commonly measured responses are blood pressure, heart rate, respiration rate, and skin conductivity, among others. These responses reflect changes in the autonomic nervous system, which controls bodily functions such as heart rate, blood pressure, and breathing.

During a polygraph examination, the subject is typically asked a series of questions, some designed to elicit a physiological response in the event of deception. The examiner then analyzes the physiological data to determine whether the subject is telling the truth or lying.

The polygraph is based on the scientific knowledge that the body’s physiological responses are involuntary and cannot be easily controlled, even by someone attempting to deceive.