addresses the implications of observed accuracy for large security screening programs with very low base rates of the target transgressions, such as those now being conducted by major government agencies.
The so-called screening studies in the literature report accuracy levels that are better than chance for detecting deceptive examinees, but they show inconsistent results with regard to the ability of the test to detect the specific issue on which the examinee is attempting to deceive. These results indicate the need for caution in adopting screening protocols that encourage investigators to follow up on some issues and ignore others on the basis of physiological responses to specific questions on polygraph charts.
There are no studies that provide even indirect evidence of the validity of the polygraph for making judgments of future undesirable behavior from preemployment screening tests. The theory and logic of the polygraph, which emphasizes the detection of deception about past acts, is not consistent with the typical process by which forecasts of future security-related performance are made.
The variability in empirical estimates of polygraph accuracy is greater than can be explained by random processes. However, we have mainly been unable to determine the sources of systematic variability from examination of the data. Polygraph test performance in the data we reviewed did not vary markedly with several objective and subjective features coded by the reviewers: setting (field, laboratory); type of test (comparison question, concealed information); funding source; date of publication of the research; or our ratings of the quality of the data analysis, the internal validity of the research, or the overall salience of the study to the field. Other reviews suggest that, in laboratory settings, accuracy may be higher in situations involving incentives than in ones without incentives, but the evidence is not definitive and its relevance to field practice is uncertain.
The available research provides little information on the possibility that accuracy is dependent on individual differences among examinees in physiology or personality, examinees’ sociocultural group identity, social interaction variables in the polygraph examination, or drug use by the examinee. There is evidence in basic psychophysiology to support an expectation that some of these factors, including social stigmas attached to examiners or examinees and expectancies, may affect polygraph accuracy. Although the available research does not convincingly demonstrate any such effects, replications are very few and the studies lack sufficient statistical power to support negative conclusions.