Once instructed, the examiner will be briefed on various background information and other case facts for which the examination can be based upon. An appointment for the test itself will then be made which is mutually acceptable to both the instructing party and the examinees.
A typical polygraph test usually takes approximately two to three hours. The process is divided into three discrete phases: The Pre-test phase, In-test and Post-test Phase.
Prior to the in-test phase all the respective sensors will be placed on the examinee which will collect physiological data via a computerised polygraph system. The so-called components are divided into: Cardiovascular (i.e. heart rate, changes in blood pressure and blood volume. including changes in peripheral blood flow using a Nonin finger pulse oximeter); Respiratory (changes in thoracic and diaphragmatic breathing); and Electrodermal activity (changes in the skin conductance as a result of sweat glands on the finger extremities opening).
The polygraph instrument will then be calibrated to ensure that all of the various data collection sensors other electronic components are functioning effectively.
This by far the shortest part of the examination wherein a minimum of three distinct tests (charts) will be administered, each lasting approximately 5 minutes. During this phase physiological data will be continuously recorded as the examinee responds to the previously formulated and reviewed questions.
Once this process has been completed to the satisfaction of the examiner, professional opinion will be set forth: No-Deception indicated, Deception indicated, Inconclusive, or, Purposeful Non-Cooperation. In screening situations, the opinions are Significant Reactions, No Significant Reactions.
Every opportunity will be given to the examinee to explain his or her reactions to the relevant questions that were asked. The instructing party will then be given a summary of the results verbally on the day, once the examiner has had time to analyse the charts, followed up by a written report containing all the information gathered from the interview, as well at the opinion based upon the analysis and interpretation of the physiological data.
Each examination is recorded in both audio and video, according to the American Polygraph Association standards, and conducted in confidence.
Copyright 2017 - Centre for Forensic Neuroscience Limited