Two questions regarding polygraph tests

[Infinite_finiteness]

1.  Can alcohol-use before a test help a reaction-prone testee suppress reactions to relevant questions?

2.  When a testee is to take multiple tests, is it common practice to have the polygrapher (or scoring algorithm) refer back to the first/second /etc. tests to help establish a baseline, or compare reactions between the current & previous tests' relevant/control questions?

[George W. Maschke]

1.  Can alcohol-use before a test help a reaction-prone testee suppress reactions to relevant questions?

There is no evidence that alcohol consumption helps to suppress reactions to relevant questions.

2.  When a testee is to take multiple tests, is it common practice to have the polygrapher (or scoring algorithm) refer back to the first/second /etc. tests to help establish a baseline, or compare reactions between the current & previous tests' relevant/control questions?

The common practice when scoring polygraph charts is to only compare adjacent relevant and "control" questions on the same chart. The scoring of the individual charts is then tallied to arrive at an overall score.

[Infinite_finiteness]

Thanks for the response.

As for alcohol-use and false positives...  is it just possible, or moreso probable to cause a false negative?  And why?

[George W. Maschke]

Thanks for the response.

As for alcohol-use and false positives...  is it just possible, or moreso probable to cause a false negative?  And why?

I am not aware of any research that would support any conclusion regarding the questions you ask here. The 2002 National Academy of Sciences report notes at p. 142:

It is difficult to draw firm conclusions from research on the effects of drugs and alcohol on polygraph examinations for two reasons: there are relatively few studies that provide data, and these studies share a central weakness that is endemic in most of the polygraph research we have reviewed—a failure to articulate and test specific theories or hypotheses about how and why drugs might influence polygraph outcomes. These studies have rarely stated or tested predictions about the effects of specific classes of drugs on specific physiological readings obtained using the polygraph, on the examiner's interpretations of those readings, or of other behaviors observed during a polygraph examination. Different classes of drugs are likely to affect different physiological responses, and the effects of one class of drugs (e.g., benzodiazepines used to treat anxiety) might be qualitatively different from the effects of alcohol or some other drug. Research on drug and alcohol effects has not yet examined the processes by which these substances might influence polygraph outcomes, making it difficult to interpret any studies showing that particular drug-based countermeasures either work or fail to work.

To my knowledge, no research on such questions has been published since that time.

In any event, if the polygraph operator smells alcohol on the subject's breath, no good (for the subject) will come of that.