Trout,

Answers you provide during the polygraph interrogation will no doubt be compared with what you wrote in the questionnaire. If, during the polygraph interrogation, you disclose information that you withheld when completing the questionnaire, you may well be disqualified.

I've never heard of questions about drug use being used as "control" questions in a pre-employment setting. While many applicants may admit to having smoked marijuana a several times (if you have such an admission to make, it is best to state a specific number of times, e.g., "I smoked marijuana four times; the last time was in June of my junior year in highschool.") The polygrapher may then ask, as a relevant question, "Other than what you told me, did you use any illegal drug?"

With regard to being asked about drinking while under the influence of alcohol, although this is a commonly used probable-lie "control" question, substantive admissions in this regard could be disqualifying (e.g., if the applicant admits to habitual drunk driving).

Note also that no admissions are necessary for a question to be used as a "control" question. If you drink and have a driver's license, even if you've never driven under the influence of alcohol and say so, you may still be asked "Did you drive while under the influence of alcohol?" as a probable-lie "control" question.