Information gain of psychophysiological detection of deception in forensic and screening settings.

We adapted and applied the Wells and Olson's (2002) Information Gain Analyses to examine the relative usefulness of a common psycho-physiological deception detection (PDD) technique, the Comparison Question Test, in forensic and screening settings as compared to unassisted lay and professional persons. We found that in forensic settings PDD provided substantial improvements in information gain over unassisted laypersons across nearly the complete range of the base rate of guilt. This was true for accuracy estimates based on laboratory and field data. At p(guilt) = 0.9, a benchmark set by critics of PDD, PDD provided 27 times the information gain of credibility decisions made by unassisted lay persons. Analyses of a screening PDD indicated that only deceptive outcomes provide useful information gain at relevant low base rates of guilt. These results strongly support the use of PDD in forensic settings and have implications for how screening PDD results are used.