I have read most of "behind the lie.." and Doug Williams' piece in preparation for a law enforcement pre-employment polygraph.  I admitted to having tried marijuana.  So if I am asked the following relevant question "have you ever used marijuana," should I treat this as a control question?(with a hightened response). 8)

G.W.,

If you have already admitted to having tried marijuana, then the question, "Have you ever used marijuana?" would not be a productive relevant question, as the answer is already known. Nor would the question be suitable as a probable-lie "control" question, as your answer to it will be a truthful "yes."

Instead, you are likely to be asked a relevant question about use of illegal drugs along the lines of, "Did you violate this agency's drug usage guidelines? (which have previously been explained to you)" or "Did you smoke marijuana more than X times?"

When employing countermeasures, it is important that one augment one's physiological responses only to those questions which one clearly recognizes as "control" questions. If one were to erroneously augment one's responses to a relevant question, then one would very likely fail. Thus, if one is not sure about a question, it would be safest to assume that it is not a "control" question. Review Chapter 3 of The Lie Behind the Lie Detector for more on how to distinguish relevant from "control" questions (but don't hesitate to post any further questions you may have).

After your pre-employment polygraph, consider posting a note to the Share Your Polygraph Experience forum.