what does this mean?

[john (Guest)]

You maintain that polygraphs are biased against the truthful. How can this be?

A. Applicants who explain all their past indiscretions to the polygrapher during the pre-"test" interview and actually give honest answers to the "control" questions are destined to fail the "test."

can someone elaborate on this?

[George W. Maschke]

john,

You'll find this explained at length in Chapter 3 of The Lie Behind the Lie Detector.