Hey there. New here... Came across this site while googling polygraph tests.
I was reading thru the LAPD sticky and one of the control questions was:
"Prior to applying with LAPD, did you ever do anything bad in your life?"
How do you define "bad" in this question? Wouldn't the answer always be 'yes' since every person has done something "bad" as a kid growing up...whether it was throwing snowballs at a neighbors house or teasing other kids, etc...
The idea is that virtually everyone will be thinking of something "bad" that they've done in their life (even if every person defines "bad" differently.) The polygraph operator will assume everyone who answers that ultimately answers that question (likely to be some form of "Other than what we've discussed, have you ever done anything 'bad' in your life?") will be lying. The physiological reactions shown when you "lie" on that question will be compared to the reactions you show when you answer the relevant questions. If your reactions to the relevant questions are greater than your reactions to the exceptionally vague "control" question they will deem you a liar.