Don’t bite your tongue.  Use it wisely.

Polygraph testing has no scientific basis.  While it is true that scientific instruments are used to record stress, in polygraph testing these instruments serve as the props of a con.  The stress measured does not correlate to truth or deception with any level of determinism.  You will be told it does verbally but that is just a ruse.

Q) Then why use countermeasures if you are honest and innocent?   
A) Simply because the polygraph prop con is used to plant false 'evidence'.  This false 'evidence' is then used as a platform for an intense interrogation.

Perhaps playing poker frequently with a bunch of con artists and crooks could help innocent people pass a polygraph.

Let them know before and after you take the test that you are not falling for their con.  When I was polygraph examined I was completely inexperienced and actually believed the test would be accurate and assist in the investigation of a crime my wife and I were the victims of.  They told me the measured stress meant I was lying.  I responded that they could not construe why I experienced stress.  They asked me how I reached that conclusion.  I pointed at the literature they gave me to read before the exam and told them I had read the truth there. 

If you take a polygraph exam, ask why you are being told different things in writing and verbally.  Ask why you should not be upset about that deception.  After all, if there were not a lot on the line you would not be forced to endure this prop con.

Don’t bite your tongue.  Use it wisely.

LP

user1982,

Tongue biting as a polygraph countermeasure should be applied hard enough to cause moderate pain, but not so hard as to injure oneself. See p. 149 of the 4th edition of The Lie Behind the Lie Detector for more on this. To effectively monitor changes in blood pressure associated with this or any other polygraph countermeasure, you need a blood pressure instrument that provides a continuous reading, rather than giving a one-time reading as yours does.

There is little one can do to prevent reactions to relevant questions. However, by maintaining your baseline breathing rate when the relevant questions are asked, you can ensure that you don't produce any scorable breathing reactions to them.

Yeeah, Suuurre 1904:

Ya saw George looking at ya, didn't ya Pal?

You good guy anyway 1904.

LP