Can you nominate in order now the degrees of a lie?
-- SHAKESPEARE, As You Like It
It is manifest that man is . . . subject to much variability.
-- DARWIN, The Descent of Man
The polygraphic lie test most commonly used in criminal investigation is the method developed by John Reid and known in the trade as the Control Question Test. Backster's Zone of Comparison method is a popular variant of the CQT that differs slightly from Reid's in the arrangement of questions and the methods of scoring. The important difference between the modern CQT and Reid's method is that the CQT is scored relatively objectively and the diagnosis is based on that numerical scoring, eschewing behavior symptoms and clinical impressions.
The format of the CQT is illustrated in Table 8.1. The first question is the familiar irrelevant type. Question 2 is relevant in substance but is not used in scoring the charts; it is called a "sacrifice relevant." Question 3 is an "outside issue" question designed for the situation in which the subject might be afraid that the interrogation will stray into an area about which he has real concern. If he seems disturbed by this question, testing will be postponed until he can be convinced that the only questions asked will