What does the polygraph instrument record?
A standard polygraph instrument records changes in blood pressure, pulse rate, pulse strength, galvanic skin response (sweat gland activity), and upper and lower breathing patterns (movement). It does not matter if the subject is “nervous” during the examination process – that is to be expected. The polygraph instrument records significant changes from the subject’s “norm” when specific issue questions are asked. A person intending deception to a particular question will activate his/her Sympathetic Nervous System (SNS) as a “self defense” mechanism when that specific issue question (threat) is asked on the test. The SNS activation will cause recognizable changes in one or more of the physiological responses.
