Today again I had a client
regarding a truth
verification test that was done by an “expert” and the
client doubted the
The examiner tested 22 people (in
day) and found 18 to
show deception. The client
wanted to know how if they can rely on the results.
As a rule of thumb, a screening
should take at least 90
min (1h30m). An incident investigation, (zone) test will take between
minutes longer than a screening as there are issues to discuss before
can be done. A zone test should only test for a single issue. If there
than one issue to be tested, a separate zone test should be conducted
adding about an hour to the testing time.
Polygraph testing should take
than voice stress
testing as the polygraph examiner have
to unpack and set up a lot more equipment. The polygraph testing
also significant longer than voice stress and therefor the higher price
We very seldom test less than 2
on any type of test.
Our longest test to date was 21 hours over a period of 3 days (murder
investigation) and consisted of 27 tests ranging from screenings, zone
WET and POT tests to get the final result.
As the client, you should first
at the test duration of
about 2 hours per person to get an accurate and reliable test result
work with. If anything less, you could sit with a red face in the CCMA
labour court and spend a lot of unnecessary money on legal issues that
have been avoided. The duration of the pre-test phase and the in-test
determined by the examiner and should not take less than 90 minutes but
duration of the discussion of the incident is determined by the person
tested this can vary depending on how much they want to talk.
If a person test DI (Deception
Indicated), the examiner is
supposed to try to get a reason for the fail and if possible at all a
confession to go with his/her DI result.
The quality of an examiner is measured by their confession rate on the
and not by the quantity of tests they can do in one day. If they have a
confession rate, you can be assured that they followed the correct
Some Security Companies want
“quick and cheap” tests on
their staff and the result of all these results should state “NDI
indicated)” as they want to show this to their clients in an
attempt to avoid
responsibility in case of an incident.
This is called window dressing and degrades the Truth Verification
All examiners doing this should be reported and the client should
insist on an
external examiner .
Be careful of “cheap”
tests and examiners that can test the
same day or the next day as this is an indicator that they have no work
booked. In principal, the more expensive
the tests are and the longer you need to wait for the examiner the
is if you want an accurate result).
I trust this will assist in
examiner to test for you.
APAVSA Instructor on Voice stress, Polygraph and Poly-Stress (Africa