Answer to Question 1
The primary reason for using deception is to increase the chances of observing normal behavior. If participants know the true purpose for a research study, they may modify their natural behavior in order to make themselves look better, to avoid embarrassment, or even to help the success of the study. In each case the validity of the study is seriously threatened. The solution to this problem is to conceal the true purpose of the study.
Answer to Question 2
a