An evaluation of polygraphers' judgments: A review from a decision theoretic perspective

Reexamined data from 7 field studies to estimate the discriminability of the control questions technique (CQT) in real-life situations. A signal detection model was applied, and an attempt was made to derive the value system of the polygraphers who participated. It was demonstrated that under an assumption of rationality, the examiners tended to value the detection of guilty suspects highly, even in the presence of a high risk of falsely classifying innocent suspects as deceptive. An index of usefulness of the CQT-based evaluation system was defined, and the CQT's range of usefulness was examined as a function of operating costs, possible payoff ratios, and prior probabilities of guilt. It is unlikely that the CQT method of lie detection would be useful for determining guilt in a court of law or even for preemployment screening, although it might be useful for police investigative procedures. (30 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).