Detection of guilty knowledge with event-related potentials.

The N400 component of the event-related potential (ERP) is elicited by words that complete sentences falsely. The utility of the N400 in discriminating subjects who have knowledge about a crime from those who do not was examined in this study. Subjects viewed a videotape of either an enacted burglary (guilty condition) or scenes from the city of New York (innocent condition). They then read crime-relevant phrases that had true or false completions but were not required to make any overt response as to the statements' truth. Post hoc analyses indicated that 78% of subjects could be correctly classified as guilty or innocent. Applying the same classifier to two other samples resulted in a correct classification rate of 73.2%. With further development, ERPs may become useful auxiliaries to current lie-detection techniques.