Visual and auditory stimuli capture attention in a cross-modal oddball paradigm irrespective of the attended modality E Friedel1, M Bach2, S Heinrich1 |
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1Dept. of Ophthalmology, University of Freiburg, Germany |
| Does attending to one stimulus modality affect attentive processing in a different modality? Using the P300 of the event-related potential as an index of attentional allocation, we assessed the role of unimodal attention in a crossmodal auditory-visual oddball paradigm with a 2x2 design (stimuli x tasks). Stimuli were either auditory oddballs embedded among frequent visual stimuli, or vice versa. The task was either to attend to auditory stimuli or to attend to visual stimuli (whether oddball or not). Additionally, in a third stimulus sequence, oddballs were conjoint auditory-visual stimuli among randomly alternating unimodal visual and auditory stimuli. Again, the task was to either attend visual or auditory stimuli (whether unimodal or part of a conjoint stimulus). P300s to both visual and auditory oddballs were nearly independent of the task modality. This suggests that oddballs captured sufficient attention even when disattended. With either task, responses to conjoint oddballs in the third stimulus sequence were absent. Thus, despite unimodal oddballs being unaffected by a crossmodal diversion of attention, oddballs defined by conjointness of modalities are inefficient in eliciting a P300 response with either task. Both findings are symmetric with respect to the task, suggesting a common underlying principle of stimulus processing. |
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