A polygraph examination is
a helpful tool in any investigation or in a case
where there is no other way of establishing facts.
Our aim is to provide professional, experienced and
accredited polygraph services that are based on
validated techniques that are in accordance with
internationally accepted standards.
Some new users of the
polygraph technique refer to this technique as "lie
detection". The polygraph is not a lie detector!
Polygraph refers to two things namely: "poly"
meaning many and "graph" meaning to write. It
therefore refers to the many writings the instrument
makes that indicate whether or not someone is
telling the truth.
"Polygraph" in the sense
in which it is normally used refers to mainly two
things namely the technique applied and secondly the
instrument used for such purpose. As the majority of
lie detector examinations performed in South Africa
yield results of non-deception it should rather be
called a "truth detector" instead of "lie detector".
"Graph" in the word means
the graphical display of tracings representing
functions of the body when someone is answering a
question. This means it is an instrument that is
used to measure and record certain responses coming
from the body when someone is asked questions to
indicate whether or not he or she is telling the
These physical reactions
happen whether or not the instrument is attached or
used. Whenever there is a measure of fear created by
the question to which a person is responding, the
responses that are recorded are produced in the
examinee. Such fear may relate to imprisonment and
loss of position etc. The fact that it is a forensic
technique means it may be used as scientific
evidence in hearings or in court trials.
polygraph is an instrument that simultaneously
measures thoracic and abdominal breathing patterns,
relative changes in blood volume and the resistance
of electricity in sweating. During the polygraph
examination, the examinee is connected to the
instrument and then monitored to see how that
personís body reacts based on those parameters when
being asked questions.
It is important to
understand what a polygraph examination entails. A
polygraph instrument will collect physiological data
from at least three systems in the human body.
Convoluted rubber tubes that are placed over the
examinee's chest and abdominal area will record
respiratory activity. Two small metal plates,
attached to the fingers, will record sweat gland
activity, and a blood pressure cuff, or similar
device will record cardiovascular activity.
It is better to refer to
this technique as forensic psycho-physiological
detection of deception. Basically it is the same
technique that has been in use since 1896. It has
been refined and now uses a sophisticated
instrument, question techniques and a trained and
experienced Examiner determining the truth reliably.
The name refers to the
manner in which selected physiological activities
are simultaneously recorded. Polygraph examiners may
use conventional instruments, sometimes referred to
as analogue instruments, or computerized polygraph
A typical polygraph
examination will include a period referred to as a
pre-test, a chart collection phase and a test data
In the pre-test, the
polygraph examiner will complete required paperwork
and talk with the examinee about the test. During
this period, the examiner will discuss the questions
to be asked and familiarize the examinee with the
During the chart
collection phase, the examiner will conduct and
collect a number of polygraph charts. Following
this, the examiner will analyze the charts and
render an opinion as to the truthfulness of the
person taking the test.
The examiner, when
appropriate, will offer the examinee an opportunity
to explain physiological responses in relation to
one or more questions asked during the test.
important to note that a polygraph does not include
the analysis of physiology associated with the
voice. Instruments that claim to record voice stress
are not polygraphs and have not been shown to have
scientific support. The video below is a prime
example of the difference between a polygraph and
voice stress instrument.