title: The effects of accessory stimuli on information processing: evidence from electrophysiology and a diffusion model analysis.
abstract: People typically respond faster to a stimulus when it is accompanied by a task-irrelevant accessory stimulus presented in another perceptual modality. However, the mechanisms responsible for this accessory-stimulus effect are still poorly understood. We examined the effects of auditory accessory stimulation on the processing of visual stimuli using scalp electrophysiology (Experiment 1) and a diffusion model analysis (Experiment 2). In accordance with previous studies, lateralized readiness potentials indicated that accessory stimuli do not speed motor execution. Surface Laplacians over the motor cortex, however, revealed a bihemispheric increase in motor activation-an effect predicted by nonspecific arousal models. The diffusion model analysis suggested that accessory stimuli do not affect parameters of the decision process, but expedite only the nondecision component of information processing. Consequently, we conclude that accessory stimuli facilitate stimulus encoding. The visual P1 and N1 amplitudes on accessory-stimulus trials were modulated in a way that is consistent with multisensory energy integration, a possible mechanism for this facilitation.
authors.affiliation: Leiden University Institute for Psychological Research, and Leiden Institute for Brain and Cognition, the Netherlands. mjepma@fsw.leidenuniv.nl
authors.forename: Marieke
authors.initials: M
authors.lastname: Jepma
authors.forename: Eric-Jan
authors.initials: EJ
authors.lastname: Wagenmakers
authors.forename: Guido P H
authors.initials: GP
authors.lastname: Band
authors.forename: Sander
authors.initials: S
authors.lastname: Nieuwenhuis
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D004562:Electrocardiography / Q000379:methods; D004569:Electroencephalography / Q000379:methods; D004576:Electromyography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008606:Mental Processes / Q000502:physiology*; D008954:Models, Biological; D009483:Neuropsychological Tests; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D011930:Reaction Time / Q000502:physiology*; D014825:Vocabulary; D055815:Young Adult