title: Stimulus complexity effects on the event-related potentials to task-irrelevant stimuli.
abstract: The effects of irrelevant stimuli complexity on event-related potentials were investigated in 3 conditions using both auditory and visual oddball tasks. In Conditions 1 and 2, simple standard and target stimuli were presented in series with complex, identical (Condition 1) or variable (Condition 2), task-irrelevant stimuli. In Condition 3, complex standards and targets were presented with simple, identical, task-irrelevant stimuli. In Conditions 1 and 2, but not Condition 3, the irrelevant stimuli elicited the P3a component in both auditory and visual modalities and the N2b component in the visual modality. While we found that variable, irrelevant stimuli evoked larger P3a in the auditory modality compared with identical irrelevant stimuli, we observed the opposite effect in the visual modality. These results suggest that stimuli rareness and irrelevance are not sufficient for eliciting P3a. This component is only elicited by irrelevant stimuli that are at least as complex as the task-related stimuli.
authors.affiliation: Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary. barkaszi.iren@ttk.mta.hu
authors.forename: Irén
authors.initials: I
authors.lastname: Barkaszi
authors.forename: István
authors.initials: I
authors.lastname: Czigler
authors.forename: László
authors.initials: L
authors.lastname: Balázs
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Event-related potential (ERP); N2b; Novelty; P3a; Stimulus complexity; Task-irrelevant stimuli