dercak,
Be aware that you've probably posted enough information for the NSA polygraph unit to identify you. (Polygraphers from various federal agencies read the posts here, and there are presumably not many high school students applying for work-study programs who were polygraphed in October, December, and February and have been scheduled for a fourth polygraph.)
I cannot predict how your fourth polygraph "test" will go, but I can give you some background information that may be helpful.
It is not unusual for NSA applicants to be polygraphed as many as three times; indeed, multiple polygraph interrogations seems to be the rule rather than the exception. A fourth polygraph examination is less common. According to the
NSA polygraph regulation, it requires the decision of the Director of Security. Any additional polygraph examinations require the approval of the Deputy Director for Administration.
If you haven't already done so, you might download
The Lie Behind the Lie Detector and peruse Chapter 3, which includes a description of the Relevant/Irrelevant polygraph technique used by the NSA for screening purposes.
The Relevant/Irrelevant technique, by the way, has no scientific basis whatsoever and is completely invalid as a diagnostic test for truth versus deception. It is based on wildly implausible assumptions and has long been discredited even amongst the polygraph community itself. It is a national embarrassment that our country's most high tech intelligence-gathering agency is relying on such quackery to make decisions about the honesty and integrity of applicants and employees.
Chapter 4 of
The Lie Behind the Lie Detector includes tips on how to protect yourself against a false positive outcome. If I were you, I would adopt the "complete honesty" approach described in Chapter 4. That is, when you go for your fourth polygraph examination, be candid with your polygrapher regarding what you've learned about polygraphy, including the fact that you've visited AntiPolygraph.org, and hope for the best.
I think your post here presents the NSA polygraph unit an ethical dilemma: do you fail a high school student simply for having educated him/herself about polygraphy and posted on this website?