"Norming" your responses to various questions is part of any interview.  It is common for police officers conducting an interview to ask some innocuous questions that are virtually guaranteed to elicit a truthful response in order to gauge how you respond when you are telling the truth.  "Is the wall painted white" is probably a bit too obvious to ask as part of this process, but you can be sure that other questions will be asked in order to get a sense of how you react when recalling truthful information.  If the interviewer is skilled, you probably won't even realize the interview has begun yet when he or she asks these questions.

As the polygraph examination progresses you will likely be steered into answers the polygraph operator will assume are lies, even if they are not.  For example, you might be asked something like, "Other than what you have told me, have you ever stolen from an employer?"  Generally, regardless of how you answer, the polygraph operator will assume there are a few instances of minor thefts from employers which you have decided not to share with him.  He will then assume that your reactions/lack of reactions during your answers to those questions are your baseline for how you react when telling a lie.  If you react in a similar fashion when answering relevant questions, it is likely he will believe you are lying.

The problems with such assumptions are obvious.

I have an upcoming test and I must say I am practically scared to death. Can anyone help? Here is my question.

Just a hypothetical scenario: 
if the polygrapher asks me a question that he and I both already know the correct answer to how are you supossed to control your response. 
For example, if he asks is the wall white and it is indeed white and I answer yes he will record that response. Then if he asks me to lie about the same question wouldn't he have a baseline of when im lying? 
Also what are the best countermeasures to use and when should I use them? 
Thanks