[unishark]

> You're wrong, they do not magically start working if you believe in them. If you're nervous for ANY reason it will give off a false positive. Not only if you're nervous of the machine itself.

If you're just as nervous during control questions as lies then it would be a false negative. The "tack in shoe" tactic is supposed to make yourself uncomfortable during control questions by stepping on the tack and raising the baseline.