The "breakdown test" is documented in Section C12.4.3.5 at p. 41 of the 2 October 2006 Federal Psychophysiological Detection of Deception Examiner Handbook (https://antipolygraph.org/documents/federal-polygraph-handbook-02-10-2006.pdf) (p. 58 of the PDF):
QuoteC12.4.3.5. Breakdown Test. A breakdown test is conducted to verify an examinee's statements regarding an issue after specific responses to one question have been observed during an R/I screening examination. The issue is separated from the remaining test questions, and a breakdown test is conducted. To devise appropriate breakdown questions, divide the issue into its logical components and design a question to cover each key area. The breakdown test can be conducted using an R/I format or a comparison question format.
If a comparison ("control") question format is used, then countermeasures are straightforward: target the comparison or "control" questions.
If a relevant/irrelevant (R/I) format is used, then countermeasures are not so straightforward. One could target a different pair of relevant questions during each chart collection (question series) in an effort to ensure that no single relevant question stands out. But R/I scoring is particularly arbitrary, and it's far from certain that such an approach will be successful.
A possible countermeasure to the R/I technique that we don't address in
The Lie Behind the Lie Detector is scopalamine (https://en.wikipedia.org/wiki/Scopolamine), which is the active ingredient in transdermal (https://en.wikipedia.org/wiki/Transdermal_patch) anti-nausea patches. It inhibits palmar sweating and may reduce the likelihood of a strong electro-dermal reaction being shown to any relevant question. A doctor's prescription may be required.
The behavioral countermeasures outlined in Chapter 4 of
The Lie Behind the Lie Detector may be especially important in the context of the R/I technique (because the latter is such an arbitrary and capricious methodology).
In addition, as discussed at pp. 151-153 of the 4th ed. of
TLBTLD, it would be helpful to have a "throw-away" explanation prepared in advance for any alleged reaction to a relevant question.