theories, various hypotheses can be offered about the effect of increased stakes on detection accuracy that are consistent with orienting theory (Ben-Shakhar and Elaad, 2002). Thus, theory and basic research give no clear guidance about whether laboratory conditions underestimate or overestimate the accuracy that can be expected in realistic settings.

Available data are inadequate to test these hypotheses. Two meta-analyses suggest that strength of motivation is positively associated with polygraph accuracy in comparison question (Kircher et al., 1988) and concealed information (Ben-Shakhar and Elaad, 2003) tests, but there are limitations to both analyses that preclude drawing any definite conclusions.3 In the papers we reviewed, only one of the laboratory models under which specific-incident polygraph testing was evaluated included stakes that were significant to the subjects’ future outside the polygraph room and so similar to those in field applications (Ginton et al., 1982). Unfortunately, that study was too small to be useful in evaluating polygraph accuracy.

Evidence from Medical Diagnostic Testing. Substantial experience with clinical diagnostic and screening tests suggests that laboratory models, as well as observational field studies of the type found in the polygraph literature, are likely to overstate true polygraph accuracy. Much information has been obtained by comparing observed accuracy when clinical medical tests are evaluated during development with subsequent accuracy when they become accepted and are widely applied in the field. An important lesson is that medical tests seldom perform as well in general field use as their performance in initial evaluations seems to promise (Ransohoff and Feinstein, 1978; Nierenberg and Feinstein, 1988; Reid, Lachs, and Feinstein, 1995; Fletcher, Fletcher, and Wagner, 1996; Lijmer et al., 1999).

The reasons for the falloff from laboratory and field research settings to performance in general field use are fairly well understood. Initial evaluations are typically conducted on examinees whose true disease status is definitive and uncomplicated by other conditions that might interfere with test accuracy. Samples are drawn, tests conducted, and results analyzed under optimal conditions, including adherence to optimal procedures of sample collection and preservation, use of fresh reagents, and evaluation by expert technicians in laboratories that participated in test development. In contrast, in general field use the test is used in a wide variety of patients, often with many concomitant disease conditions, possibly taking interfering medications, and often with earlier or milder cases of a disease than was the case for the patients during developmental testing. Sample handling, processing, and interpretation are also more variable.



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