“Lie Detector” is the popular, but misleading name for polygraph. In Greek, the word polygraph means “many writings” and the instrument was so named because it made various ink recordings of a person’s physiology. Today, the polygraph is computerized and a person’s physiological responses are recorded on the computer screen.
The polygraph should be called the “Truth Verifier”, since statistics show that in the majority of instances, the examiner’s opinion is that the individual is truthful.
There are many misconceptions about the polygraph examination. Below, are some of the most frequently asked questions, answered in a forthright and simple manner. Each of the following questions have been asked many times by persons about to take an examination, as well as those merely interested in the subject.
What does a polygraph consist of?
A Polygraph examination consists of three separate and distinct phases: The “Pre-Test” interview, the “In-Test” phase and the “Post-Test” interview.
- PRE-TEST INTERVIEW: During the pre-test interview, the polygraph examiner will explain your legal rights and the voluntary nature of the examination. Also discussed is your medical, physical, and psychological background as well as your knowledge of the investigation and an explanation on how the instrument works.
- IN-TEST PHASE: at this point the polygraph examiner will review all the pertinent test questions with you and then conduct a “Demonstration Test” to help him/her assess your suitability for additional tests. Several tests will then be conducted which will include the reviewed questions. There will be no surprise questions on any of the tests. The polygraph examiner will then analyze the results of each test to arrive at an opinion.
- POST-TEST INTERVIEW: During the post-test interview, the polygraph examiner will discuss the results of the “In-Test” and provide you with his or her opinion.
What is I am telling the truth but I am nervous about taking the examination
It is normal for an innocent person to be nervous, the polygraph examiner is aware of this. Nervousness does not prevent the polygraph examiner from distinguishing between the truth and deception.
I have high blood pressure, won’t that look as though I’m lying?
No, while blood pressure is one of the recordings, high blood pressure does not invalidate the results of the test. If you are currently under a doctor’s care for a medical condition, be sure to tell the polygraph examiner about it.
Suppose the instrument says I’m lying when I’m not.
The polygraph cannot say anything. It merely records on the computer certain physiological reactions to the questions being asked. It is up to the polygraph examiner to read the information your body provides.
Can I be forced to take the examination?
No. The polygraph examination is voluntary. The polygraph examiner requires your cooperation throughout the test. As a result, it must remain voluntary. If, for any reason, you don’t wish to take the examination, you may decline.
How long does the examination take?
Most examinations require 2 – 3 hours. Some may be longer while others may be shorter, depending upon the issues involved.
Does the examination mean that the polygraph is infallible?
No. Most examinations readily reveal to the polygraph examiner whether or not the person is truthful. Possible outcomes of any polygraph examinations are: Truthful, Deceptive or Inconclusive. Inconclusive means that the examiner is unable to render an opinion of either truthful or deceptive in that particular case. The polygraph examiner may request a re-examination if the results are inconclusive. A re-examination is also voluntary.
The aim of the polygraph examiner is to determine the truth. S/he must give careful attention to every person s/he is examining. Every person has the right to be examined with dignity and impartiality.