As we note at p. 147 of the 4th edition of The Lie Behind the Lie Detector, blocking should be done after exhaling.

Thanks George! So do I hold my breath on the inhale? Or after I exhale?

Fly Guy,

Any of the breathing "scoreable" reactions mentioned in Chapter 4 of The Lie Behind the Lie Detector would be okay. It's not necessary that all reactons be the same. Blocking is not only the easiest, it is also the most commonly observed reaction, so it's a good choice.

If choosing blocking, I would avoid exhaling "hard," that is, I wouldn't make an effort to exhale more than I normally might while, for example, pausing breathing to listen carefully. It would also be prudent not to exhale for a certain number count for each control question. If every breathing reaction looks the same (for example, has a close to identical duration), countermeasure use may be inferred. One of the countermeasure "indicators" sometimes mentioned in polygrapher training sessions is so-called "cookie-cutter reactions."

I've read several posts about the breathing CM and also read about different types. I apologize if I have missed it or something but should I remember one breathing CM and stick to it? Of course I was thinking about doing the blocking CM because it's the easiest. 

Should I use one or mix it up? Also wouldn't it appear suspicious to the polygrapher that CM are being used if I did the blocking on every control question? 

Thanks!