From the polygraph operator's perspective, the rationale for the probable-lie "control" questions is to get the examinee to answer a question untruthfully, or at least to make the examinee have doubts as to whether his answer is completely truthful. The polygrapher then uses reactions to the control questions as a basis of comparison with any reactions to the relevant questions (the ones that are truly of interest).

"Did you ever cheat in school?" is an example of a commonly used control question. It is assumed that everyone has. (Not a safe assumption, I think.) But in any event, the polygrapher will try to convince the examinee that cheating in school is a very bad thing, and anyone who would do such a thing would not be a suitable candidate for hire. The idea is to pressure the examinee to answer that question "no."

If the examinee answers "yes," then the polygrapher will likely feign an attitude of deep concern, ask about precisely when and where the examinee cheated, and perhaps make a show of writing down the details. Then, the polygrapher may remind the examinee that his agency considers the honesty and integrity of its employees to be of paramount importance and ask, "Other than what you told me, did you ever cheat in school?" At this point, the examinee will likely answer "no." If the examinee still answers yes, the process of interrogation will be repeated until the examinee answers "no."

This final "no" will still be considered a probable-lie, and reactions to it will be compared with reactions to a relevant question such as, "Did you ever commit a major undetected crime?" The key to passing is to show a stronger reaction to the control question than to the relevant question, and countermeasures can help to achieve this result.

For more about control questions and countermeasures, see chapters 3 and 4 of The Lie Behind the Lie Detector:

https://antipolygraph.org/lie-behind-the-lie-detector.pdf

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And if the machine really scientifically detected deception, why the need for manipulative interrogation tricks IN BETWEEN chart readings?  Why not just run the required number of chart readings, making sure the applicant understands the questions, then be done with it?  After all, the machine DETECTS DECEPTION!  Doesn't it?  So run the charts (collect your ?scientific data samples), do the ?scientific? analysis, and come to a ?scientific? conclusion!

The answer of course is that it is NOT a test, but an interrogation cleverly disguised as a test.   The machine doesn't directly measure deception.  If it did, and after several chart readings there is a definite pattern of "reaction", they'd have the incriminating evidence they need (as in DNA testing), and that would be that.

But that is not that!  A pattern of reaction without the elicitation of self incriminating statements (goal of an interrogation) is worthless and will lead to an "inconclusive".  But why inconclusive?  I thought the machine can detect lies!  You have a pattern of "REACTIONS"!  They must be lying, right?   What is "Inconclusive" about that?


TC