Polygraph Basics:

The  term "polygraph" means "many writings" and refers to the various  tracings on a chart which are recording physiological data from an  examinee.

A polygraph instrument collects physiological data from an examinee through at least three and usually four sensors.

Two of These sensors are placed over the examinee's chest and abdominal area and record respiratory activity.

Two  small metal plates are attached to the fingers or palms and record  sweat and salt gland activity.

A blood pressure cuff records  cardiovascular activity. 

There is also a motion sensor which ensures  that the examinee is remaining still during the instrumental testing  phase.

A typical polygraph examination includes a pre-test interview, a chart/data collection phase and a test data analysis phase. The entire testing process may take from 1 1/2- 2 hours, typically.

During  the pre-test phase, the polygraph examiner will complete required  paperwork and discuss the test agenda with the examinee. 

During this  phase of the polygraph test, the examiner will discuss in detail the  questions to be asked and familiarize the examinee with the testing  procedure.

During  the instrumental testing phase, the examiner will administer the test  and collect a number of polygraph charts, usually three to five.

Following  this, the examiner will analyze the charts and render an opinion as to  the truthfulness of the person taking the test based on nationally  recognized scoring standards. When appropriate, the examiner will offer  the examinee an opportunity to explain physiological responses in  relation to one or more questions asked during the test. It is important  to note that ‘voice stress analysis’ tests have NOT been shown to be  effective and are not used.

When  the polygraph examination is complete, a formal report is prepared by  the examiner and delivered to the appropriate person(s).

POLYGRAPH TEST CHART ANALYSIS-

There are three basic results for a polygraph test. They are:

NO DECEPTION INDICATED

This  result occurs when an examinee’s physiological responses are indicative  of, and associated with, someone who is being truthful when answering  the questions on the test.

DECEPTION INDICATED

This  result occurs when an examinee’s physiological responses are indicative  of, and associated with, someone who is being untruthful when answering  the questions on the test. The examinee is likely to be deliberately  and intentionally withholding information relating to the subject of the  examination. When an examinee attempts to use counter¬measures in order  to “beat” a test, the examination will result in a deceptive outcome.

INCONCLUSIVE

When  a polygraph is found to be inconclusive, it means that the  physiological reactions did not meet nationally recognized scoring  standards to determine truthfulness or deceptiveness. Inconclusive  results can occur in 10-20% of all responses analyzed, and increase  proportionately with the number of relevant questions asked during the  instrumental phase of the examination.

Some common causes of inconclusive results are:

INSUFFICIENT REACTIONS

Reactions  of the examinee are too slight or distorted to produce results which  can be scored. This can be caused by fatigue, legal or illegal drugs,  lack of sleep, thirst, hunger and ambient room temperature.

INCONSISTENT REACTIONS

 Reactions of the examinee are inconsistent throughout the examination.  To come to a definitive decision, reactions must be significant,  specific and consistent throughout the test.

DISTORTIONS

 Distortions may be caused by the examinee’s voluntary or involuntary  actions and/or body movements. Such actions may be caused by medical  disorders, coughing, sneezing, sniffling, hyperventilation and other  respiratory issues, or muscle spasms and other nervous reactions.