I was just wondering since I am one of the few that can control their tensor tympani muscle (located inside your head near the ear) would tensing that be a good countermeasure or like the sphincter could it throw off the readings too much?
To be effective as a countermeasure, such muscle tensing would have to produce physiological responses measurable by the polygraph. I don't know whether such would be the case, and to the best of my knowledge, there is no peer-reviewed research on this matter. Under the circumstances, I think it would be safer to choose a tested countermeasure such as mental arithmetic or tongue biting.