i recently took a polygraph exam.  I was asked to give only yes or no responses and was asked is your name xxx?  do you live in the US? then straight to relevent questions.  there were no obvious control questions; however once durring the exam i was asked to provide an answer to a mathmatical question this time that plus the other = what?

all questions in the exam were repeated three times, though the questions were not presented in the same order.  the mathmatical question was only presented once durring the first grouping of the questions asked.  Could this have been the control question? ???