| |
Abstract:
The novelty P3 is most often elicited using environmental
sounds. The physical nature of these stimuli makes them sensory
"rich" relative to their single tone target counterparts.
Therefore, sensory as well as cognitive aspects of the stimuli may
contribute to novelty P3 amplitude. To assess this, the effect of
stimulus features on the novelty P3 was examined. 36 young adults
participated in a "novelty" oddball ERP paradigm. Auditory stimuli
were 50 unique tones and 48 unique environmental sounds presented
under 3 conditions. For all conditions, the standard stimulus was
either 1000 or 700 Hz. 48 environmental sounds served as
task-irrelevant stimuli in conditions 1 and 3, and targets in
condition 2. In condition 1, the target was either 1000 or 700 Hz.
The 48 unique tones served as task-irrelevant stimuli in condition
2, and as targets in condition 3. All target and task irrelevant
stimuli elicited P3s with a frontally oriented scalp topography
(novelty P3 or P3a). The anterior magnitude of the novelty P3 was
most affected by stimulus features, with a secondary effect of task
difficulty and task category. By contrast, the posterior aspect was
most affected by task category. These results support the view that
the frontal aspect of the novelty P3 is associated with the
evaluation of the stimulus per se while the posterior aspect is
associated with the evaluation of task relevance.
|
