Forensic Finals

Cardio - Sphygmograph
Galvanograph
Pneumograph
Kymograph

The major components of a polygraphmachine are:

Cardio-Sphygmograph

It was designed to detect changes in the blood pressure and pulse rate of the subject.

Blood Pressure Cuff

is attached to the upper right arm of the subject, slightly above the brachial artery.

Pump bulb assembly

which inflates air into the system, also known as air pump it has a hose connecting the blood pressure cuff through which the blood pressure changes and passed into the recording pen.

resonance control

is used for reducing or increasing the amount o air pressure to reach the brass bellows (tambour) and thus reduce or increase the amplitude of pen excursions.

centering control

is used to provide adjustment of the tracing so that the composite records patterns would be on the guideline.

Pneumograph

It is designed to detect changes in respiration of the subject. Its major components are the pneumograph chest assembly and the recording unit.

Rubber convoluted tube

which is ten inches in length corrugated rubber attached to the chest and abdominal area of the subject. One end of the tube is sealed and the other end is connected to the instrument by a rather thick walled rubber tube considerably larger in diameter than the pneumograph tube itself, it expands and contracts as the subject breathes.

beaded chain

another component of the pnuemograph assembly is used to fix in place the rubber convoluted tube.

pneumograph recording unit

is made up of brass bellows, a frame, crankshaft, countershaft, adjustable fulcrum, bearing with adjusting screw pen, vent limiting screws, pen cradle and pen centering control. Volume changes of the chest caused by breathing are transmitted to the chest assembly to the recording unit.

Galvanograph

Its primary function is to detect changes or alterations in skin resistance of the subject.

Finger electrode assembly

which has a finger electrode and retainer bond attached to the left index and ring finger of the subject. And a connecting plug designed to fasten the system to the polygraph machine.

Recording pen unit

which is usually 7 inches in length. Amplifier unit which is made to support the galvanometer in converting electrical to mechanical current.

Kymograph

Its primarily serves as the paper feed mechanism of the polygraph machine. It is the device that records the different tracings by driving the paper out under a recording pen unit. It pulls or drives the chart paper under a recording pen unit. It pulls or drives the chart paper under a recording pen simultaneously at the rate of 6 to 12 inches per minute. The chart must travel at a uniform speed to facilitate valid interpretations.

Chart Paper

is driven past the recodingpen shaft at a uniformspeed six (6) inches per minute. Chart rolls are approximately 100 ft. Holes spaced ½ inch apart. The paper is imprintedwith horizontal lines at ¼ inch interval twenty divisions and vertical lines at 1/10 inch intervals with heavy lines at ½ inch divisions acrossthe paper which represents five (5)seconds of time.

Rubber roller

which pulls the paper out of the machine.

POLYGRAPH CHART OR POLYGRAMS

This refers to the composite records of Pneumograph, Galvanograph, and Cardiosphymograph tracing recorded from a series of questions

CHART MARKING

It is the process of using symbols on the polygraph chart to denote the subject reactions and other circumstances that occur during the actual polygraph test.

Primary Markings

which indicate the beginning and end of examination as well as the questions and answers of the subject.

Secondary Markings

markings which are placed only if the examinee does something which will cause the physiological tracings to distort. These markings are usually placed below the affected tracing.

Phase I. Initial Interview

In order to conduct a satisfactory polygraph examination, it is necessary for the examiner to obtain accurate information regarding all the available facts and circumstances that form the basis for the suspicion or accusation directed against the person to be examined.

Phase II. Pre-Test

is the preparatory stage for polygraph examination. This includesall consideration bearing on polygraph examination up to the time of actual activation of the examination. The examiner pre-test interview with the subject prior to the test is considerable importance both for the purpose of conditioning the subject for the examination and also to provoke and observe indications of guilt or innocence.

Phase II

before the actual testingis done, the examiner must first make an informal interview of the subjectwhich may last fro to 20 minutesto 30 minutes.

Phase III. Test Execution

the actual questioning to the subjectin polygraph examination. These include all consideration bearingon polygraph examination from the time the instrumental attachments are placed on the subjectuntil the time the instrument is deactivated.

Phase IV. Post-Test

the consideration that bear polygraph examination from the time the instrument is deactivated following final polygraph examination until the diagnostic opinion is reported and the case is concluded. If the polygraph test result indicates deception the examiner will then proceed to conduct short interrogation. The purpose of which is to obtain confession.

Post-Test Interview

is conducted when the reactionsindicate truthful response and the subject is very cooperative to the examiner.

Post-Test Interrogation

the examinerwill conduct interrogation if there is a presenceof significant reactions on the relevant questions indicative of deception.

truthfulness
Deception
Inconclusive

Three Diagnostic Opinions in Polygraph Examination