Stimulus characteristics and task category dissociate the anterior and posterior aspects of the novelty P3.

The novelty P3 is an event-related potential component that is most often elicited by environmental sounds within the "novelty oddball" paradigm. Within the context of this paradigm, it is not clear if the novelty P3 can be elicited by deviant stimuli regardless of whether they serve as target or nontarget deviants, or to what extent the physical characteristics of the stimulus contributes to the amplitude of the novelty P3. The current study examines this issue by systematically switching target and nontarget deviants between environmental sounds and tonal stimuli. Participants were 36 young adults. Auditory stimuli were 48 unique tones and 48 unique environmental sounds presented under three experimental conditions. The results showed that target and nontarget deviants elicited novelty P3s with anterior and posterior aspects. The major determinant of the extent of the anterior aspect was the degree of difference between the physical characteristics of the deviant stimuli and the standards. By contrast, the major determinant of the posterior aspect was the task relevance of the deviant stimuli.