A modified, event-related potential-based guilty knowledge test.

Subjects chose and pretended to steal one object from a box of nine. They then watched a visual display of verbal representations of objects including their chosen object or one of eight novel objects on each trial. They were told to count one of the novel objects and that although they were welcome to try to beat our test, they would be unable to avoid noticing the chosen object. P3 responses were obtained only to counted and to chosen objects in 7 of 10 subjects not eliminated for artifact or noncooperation.