A polygraph examination can be used as a technical aid during the course of an investigation. It can help verify the statements of the complainants, establish the credibility of the witnesses, or assess the suspect's honesty.
The term "polygraph examination" refers to the entire questioning process, as well as the choice of one chart from a series of questions, or the entire test's charts and question sheets. The examination is conducted in the following stages: preliminary preparation, conduct of pre-test interview with the persons to be examined, conduct of the actual instrumental test, and post-test interrogation.
Here are some useful related terms:
polygraph chart also known as polygrams, a permanent chart or graph that records all emotional patterns based on a series of questions
polygraphist also called a polygraph examiner or forensic psychophysiologist, the person who conducts the actual polygraph test or examination
subject anyone who is undergoing a polygraph examination or test, regardless of whether they are the victim, witness, or suspect in the crime
The findings of the investigation must be used to accomplish the following objectives:
Obtain additional investigation leads to the facts of the case/offenses
Ascertain if the person is telling the truth
Locate the fruits or tools of the crime and whereabouts of wanted persons
Identify other persons involved (e.g. accomplices)
Obtain valuable information from reluctant witnesses
Eliminate innocent suspects
Just like all other allied sciences under Criminalistics, polygraphy has specific primary purposes for which it is used:
Aid in investigating criminal incidents and issues
Speed up the process of investigation
Eliminate innocent suspects
Screen job applicants
Check the honesty and/or loyalty of members of specific groups
As already mentioned in the previous section, polygraph examinations can be used beyond criminal investigations. It can be used in any type of investigation involving interview and interrogation. These are why the polygraph examination is important in the field of investigation:
It enables faster and more accurate detection of deception
It has been shown to have a decided psychological effect in inducing confession from a guilty subject
It helps innocent people be spared from fear, embarrassment, and inconvenience
It minimizes the use of THIRD DEGREE practices particularly upon innocent subjects
It aids investigators in getting all the facts regarding the offense under investigation
When conducting a polygraph examination, the examiner must be careful to consider the following setup so as not to affect or hinder the success of the examination:
A room that is free from vehicular and human traffic and preferably on the ground floor
Must be conveniently ventilated or air-conditioned
Must be conveniently-sized with an adjoining observer room equipped with a one-way mirror, microphone, tape recorder, and amplifier
Must be soundproof and acoustic
Must have an outlet of 110 volts to 60 cycles
Color must not be glaring to the eyes, blue or plain white will do
Must not possess any telephone, decorated picture frames, ornamentals, etc.
Must have a system to indicate whether a room is occupied
Must only have one door
As mentioned in previous lessons, the polygraph instrument is not an absolute tool. Instead, it is but an investigative tool. A good investigator would do well to remember the following limitations of this machine:
It is an investigative aid, never a substitute for an investigation.
It is not a lie detector, but a scientific diagnostic instrument.
It does not determine facts, only diagnostic reactions.
It only records responses, not determines the truth.
The test must not be given until enough facts of the case have been established to permit an examiner to prepare a complete set of suitable questions. The test should not be given without voluntary consent of the subject nor should it be given before the accusations could be explained to the subject. No indication to any person or place in any report that a person will be considered guilty because he refused to take the test.
Additionally, the test should not be conducted on any unfit subject nor should it be used for the mental or physical evaluation of any person.
All empirical methods or scientific investigative methods are acknowledged and considered by the court during trial. As such, all experts doing any matter of lab work should be very careful to ensure that no data is contaminated.
The following are some of the factors that could influence the success or failure of a polygraph examination:
Adequate examination facilities Before conducting an examination, the examiner should ensure that the instrument is in good working order, according to the manufacturer's specifications, and will perform well during questioning. The attachments must be spotlessly clean and the examiner must properly explain how the instrument works and how it is used during the examination.
Privacy must be assured The best ambiance for a polygraph examination would be a room that is away from noise or any form of disturbance. The examiner should make sure that no distractions will crop up during the conduct of the examination. This is to ensure that the subject is able to maintain their focus towards the test and to make sure that the subject could not make any disturbances an alibi or reason why there was a sudden change in their physiological reactions.
Establishment of proper rapport between examiner and subject An effective examiner is one who can gain the subject's trust and confidence, which can only be accomplished by establishing a good rapport or relationship between the examiner and the subject. Being a polygraph examiner is akin to being a psychologist in that you can direct the conversation and allow the subject to recognize you as an individual without any personal gain from the questioning. The examiner should make certain that the subject understands why the examination is being conducted.
Reaching of the subject's level of understanding There are various types of people who will be subjected to a polygraph examination. These different types of people will have their own level of understanding and perception on diverse topics. In order to better communicate and avoid offending the subject's ego, the polygraph examiner should determine the type of personality and understanding that the subject possesses. The choice of words is crucial in ensuring that your point of view is not misunderstood by your audience.
Permitting the subject to tell his side of the story The subject has the opportunity to speak and tell his own perception during the preliminary phase of the polygraph examination. During this time, the examiner should allow the subject to speak and share his side of the story or version of the story in order to boost the subject's confidence and reduce their anxiety. Examinees who are intimidated by the examiner are more jittery and reactive. Allowing them to speak has an advantage for the examiner in that the subject's statements can be used as a basis for question formulation, especially in preparation for the main polygraph examination phase.
The subject of the examination Physical and mental capabilities, past associations, economic and educational status, employment, background, sensitivity to right or wrong, and the subject's personal projection should all be taken into account by the polygraph examiner when formulating the questions to be asked during the examination.
Chart interpretation The ability of the polygraph examiner to interpret polygrams following the examination is another factor to consider. He must be able to distinguish between responses that contain or do not contain deception criteria. He must be completely familiar with the chart markings of guilty potentials and collusion potentials, as well as consequences that will befall the guilty subject.
The examiner Among all the variables that could influence the test results, the polygraph examiner, or the person who administers the test, must be given careful consideration. The examiner must be in good physical and mental health, as well as being a professional examiner. He must be familiar with the examiner's techniques and approaches to the examination process. If the examiner is ineffective in his work, the results may be contaminated or no accurate results will be obtained.