pailryder wrote on Jun 7
th, 2008 at 2:39am:
Its not that I am so much concerned about countermeasures, but that I find the topic very interesting. For instance, if a subject answers truthfully and employes CM, and my call is NDI. Was my call correct?
That is a very interesting question indeed.
Obviously, the answer hinges on one's definition of what constitutes a correct decision in a polygraph exam. I think that question can be approached as follows.
First, there are four possible decisions (or "calls") that a polygrapher can make on an exam:
(1) Examinee is deceptive,
(2) Examinee is truthful,
(3) Examinee is using countermeasures, and
(4) No conclusion possible from the available data
Obviously, it is possible for examinees to tell the truth, to lie, and to use CM. But, in a well-constructed exam, it is not possible for an examinee to neither lie nor tell the truth. And, of course, the examinee can use CM while telling the truth or while lying.
I think that reaching no conclusion must be regarded as something of a failure of the polygraph, though not as large a failure as reaching a conclusion that is wrong. That is, it is better to say "I don't know" than to make a positive statement that is false. Similarly, if the examinee uses CM you can't tell if he or she was lying or telling the truth on the relevant questions; the polygraph has failed to determine what it is ultimately meant to determine.
This brings up my second major point: the
purpose of a polygraph exam is to determine if the examinee is telling the truth or lying vis-a-vis the relevant questions. The purpose of the polygraph is not to determine if someone is using CM; obviously, it is necessary to be able to tell if someone is using CM, but that is only so that it can be determined if he or she is lying on the relevant questions.
Now, to accomplish it's purpose, the polygraph community has devised various practices and techniques. Basically, you follow these practices, whose application varies case-by-case, and then other standards tell you how to interpret the resulting charts.
From all this, two possible answers present themselves to the question "What constitutes a correct decision in a polygraph exam?"
First, what we might call the teleological answer: A correct decision is one which says someone who is lying (on the relevant questions) is lying and that someone who tells the truth (on the relevant questions) is telling the truth.
Secondly, what, for lack of a better term, we might call the process-based answer: A correct decision is one which says an examinee who has produced charts consistent with what is expected from someone who lies (on the relevant questions) is lying; that an examinee who has produced charts consistent with what is expected from someone who tells the truth (on the relevant questions) is telling the truth; that an examinee who has produced charts consistent with what is expected from someone who uses CM is using CM; and that no conclusion is reached on an examinee who has produced charts inconsistent with any other determination.
The important thing to note is this:
neither of those two responses is incorrect.
Here is an analogy. Suppose you were visiting my house and saw a tea kettle on my stove that was boiling and you asked "why is the kettle boiling?" I could respond "the kettle is boiling because the heat released from the burning propane transfers energy to the water molecules in the pot which become excited and, at 100 degrees centigrade, begin to boil and go from a liquid to a gas." That answer would be correct in one sense. However, I could also say "the kettle is boiling because I want tea," and that response would also be correct, albeit in a different way.
I think polygraphers are mostly concerned with the process-based response: their decision is correct if it is in line with what polygraph doctrine tells them about a certain pattern on the charts. There are many reasons that they prefer this sort of answer.
First, they know all about polygraph doctrine and practice; they spend their careers learning and studying it and become good at applying the principles. Therefore, they attach great importance to correct practice and come to take pride in their ability to proficiently apply the doctrines.
Second, they really can't measure their success at finding liars and identifying truthful people because it is very rare to have independent confirmation of an obtained result (it can happen, but those cases are the exception). Since they can't tell how good they are at achieving the ultimate end of the polygraph (identifying who lies and who tells the truth on relevant questions) the must perforce measure their abilities and successes against how well they follow the means by which the end is most likely to be obtained.
Thirdly, polygraphers know that they will make bad calls which condemn the innocent and exonerate the guilty. If they measure success the teleological way, they'd have to consider these grave failures, which would be very uncomfortable. However, by defining success as correctly applied practice they can transfer much of the responsibility for these calls to the polygraph. "I did my job, my interpretation of the charts was correct; I succeeded at what I had to do, which was ask the questions in the correct way and interpret the results correctly"
However, my position is that the success of the polygraph must ultimately be measured in what I have called the teleological manner: every person who tells the truth on the control questions and is declared truthful is a success, every such person who is declared untruthful is a failure, and every person who lies on the relevant questions and is declared a liar is a success and every such person who is declared truthful is a failure.
Every person who uses CM also is a failure of the polygraph system, in my view, since we don't know (at least via the polygraph) if the person was telling the truth or lying on the relevant questions. I have discussed this with Sackett, who, of course, disagrees. But the purpose of the polygraph is to find out if someone did or didn't do the act described in the relevant questions, not if he did the things described in the control questions. Therefore, we don't care if someone tries to deceive us by lying on the control questions except insofar as it helps or hinders our quest to find out if they are lying on the relevants because, contrary to what the given instructions tell the examinee, lying on the control questions doesn't correlate with lying on the relevants. In precisely the same way, we don't care about if someone uses CM in and of itself except that it makes it impossible to determine if someone is lying on the relevant questions. Using CM is no more or less immoral than lying on the control questions.
This leads to a fourth reason why polygraphers generally prefer the process-based approach to measuring their correctness: it leads to a far, far higher success rate. An inconclusive result isn't a failure on their part to obtain the desired information after consuming significant societal resources, it is a success at correctly interpreting the data.