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The Polygraph and Lie Detection
Alternatives and Enhancements to the Polygraph
Alternative Techniques Some potential alternatives to the polygraph show promise, but none has yet been shown to outperform the polygraph. None shows any promise of supplanting the polygraph for screening purposes in the near term. Some potential alternatives may be useful as supplements, though the necessary research to explore that potential has not been done. Some, particularly techniques based on measurement of brain activity through electrical and imaging studies, have good potential on grounds of basic theory. However, research is at a very early stage with the most promising techniques, and many methodological, theoretical, and practical problems would have to be solved for these techniques to yield improvements on the polygraph. Not enough is known to tell whether it will ever be possible in practice to identify deception in real time through brain measurements.
Computerized Analysis Computerized analysis of polygraph records may be able, in theory, to improve test accuracy. This potential has not yet been demonstrated, however, either in research or in practice, and it is likely to be only modest. There have been major developments in computerized acquisition, summarization, display, and scoring of polygraph data, and further advances are likely. Computerized polygraph scoring procedures have the theoretical potential to increase the accuracy of polygraph interpretation because they allow analysis to use more information from the polygraph record and to weight different polygraph features more appropriately than do traditional scoring methods. Despite considerable government investment in computerized polygraph scoring methods, however, the existing approaches have at best an empirical base and are only loosely justified in terms of the features they extract from the polygraph record. These methods have a problematic statistical basis and have not been tested widely enough to generate confidence that their accuracy is any greater than that of traditional scoring methods. The difficulties that exist with computerized scoring of polygraph tests also exist, and may be multiplied, with possible expert systems for combining polygraph results with other forms of data.
Combining Information Sources It may be possible to improve the ability to identify major security risks by combining polygraph information with information from other screening techniques, for example, in serial screening protocols such as those used in medical diagnosis. We found no serious investigations of such multicomponent screening approaches.