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Tuesday, 19 September 2017 19:08

Countermeasures Gone Bad..by NPA President Gary Davis

I recently saw a posting on LinkedIn by an Examiner showing a chart with an obvious manipulation by the subject on the Directed Lie Comparison.  The post heading was, “The reason not to use Directed Lie Comparison”. The inference was the use of Directed Lies allowed the Subject to use Countermeasures.  My response was that is a silly representation.

 

Anyone who takes the time to research polygraph with the intent to manipulate the outcome clearly knows the difference between a Relevant and Comparison question. Every publication for beating the test clearly defines the difference in question type and wording.

 

Countermeasures are a fact of life for today's examiner.  According to research, at least 50% of subjects research polygraph and will attempt some form of manipulation. Does that mean every attempt of manipulation will render charts unreadable or alter the outcome of the examination? ... NO. Does that mean every subject will attempt to manipulate the outcome of the test? ... NO.  It simply means we must be alert to outcome manipulations, Those manipulations occurring outside the scoring window will not impact the outcome of the test.

 

It is important to remember the manipulators create a false reaction to the comparison but generally do not try to suppress the reactions to the relevant questions. Abnormally large reactions to a comparison question are suspicions.  When you stack charts, if the reactions to the comparison questions look the same, that is of concern. Normal physiology will vary from question to question.  If it is not, that may be a clue.  ESS requires you to look at the data prior to stimulation to insure you are scoring stable data.  The answer to manipulation is if the data is not stable, don't score it. 

 

As we all should recognize, there are no perfect tests, and Polygraph is no exception. The important thing to remember there will be errors, some just happen, some are caused by subject manipulation and some are caused when we do something wrong. That is the real world.

 

All we can do use evidence based techniques, follow best practices and use statically validated scoring models. We need to remember this score is very subjective. Different examiners will arrive at different scores. And, in some occasions a different outcome.

 

It is also advisable to verify test outcome using a validated computer algorithm.  Computers will evaluate the chart the same way every time, generate the same score and outcome.  This outcome is completely objective.        

                                                                                            

As examiner's we must embrace research driven testing and evidence base practices. We must use instruments what that scientific standards. Should we decide to abandon what science has shown to be effective the Profession is doomed. It is a new world we are facing.

 

Disagree? Let's visit at the next NPA seminar.

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