The purpose of the polygraph in the CIA clearance process is to ellicit disqualifying admissions that the adjudicators could not have known based on the SF-86 and background investigation. The polygraphers want you to pull out the skeletons in your closet of your private life and tell them things you have done that no one knows about. They will use all kinds of manipulative techniques to get you to spill the details of all the things you have done in your private life. They will try to convince you that more likely than not its not going to disqualify you, but that's actually their goal - to ellicit admissions that will disqualify you. More posts to come...