for understanding basic brain processes, it is antithetical to the use of imaging for detecting deception in individuals. Some recent fMRI studies on individual differences do suggest the possibility of a future role for brain imaging in detecting deception, but much additional research must be done to move that prospect beyond mere possibility.

Measurement of event-related potentials has shown some promise as a way to assess orienting responses that are believed to signal the presentation of material that is familiar to the examinee. If this theory is accurate, they would be appropriate for lie detection in settings when questions can be asked about concealed information. The mechanisms linking deception to event-related potentials have not been clearly elucidated. In fact, it will be difficult to establish the mechanisms because measurement of the potentials is too diffuse to localize the underlying brain activity. Nevertheless, the basis for the orienting response is plausible and the very limited data on accuracy suggest a level similar to that of the polygraph. It seems plausible that event-related potentials tap different underlying phenomena than the polygraph measures, so that combining the two techniques might provide some added validity. This possibility is worth investigating. Some believe that event-related potentials are less vulnerable to countermeasures than the polygraph, which, if true, would make them useful as a substitute for the polygraph when questions about concealed information can be asked. The basic science, however, is unclear on whether or not people can learn to manipulate event-related potentials. There are as yet no empirical data on countermeasures and event-related potentials. In sum, the limited available knowledge justifies further research investigation of measurement of event-related potentials as an alternative or supplement to the polygraph.

Detection of Deception from Demeanor

Although there is considerable research on cues to deception in demeanor, there is relatively little on any one cue and much less on finding combinations of cues that might accurately discriminate lying from truth-telling. Most of the research on deception and demeanor has not been seriously applied to criminal or security investigation contexts. The evidence indicates that the right measure or measures might achieve a useful level of accuracy in those contexts, even though some techniques on the market, such as voice stress analysis, have not demonstrated such accuracy. It is unclear whether accurate demeanor measures would provide information different from the polygraph in terms of the underlying processes assessed: the theory of demeanor indicators is not well enough developed to judge.

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