title: Visual, auditory and tactile stimuli compete for early sensory processing capacities within but not between senses.
abstract: We investigated whether unattended visual, auditory and tactile stimuli compete for capacity-limited early sensory processing across senses. In three experiments, we probed competitive audio-visual, visuo-tactile and audio-tactile stimulus interactions. To this end, continuous visual, auditory and tactile stimulus streams ('reference' stimuli) were frequency-tagged to elicit steady-state responses (SSRs). These electrophysiological oscillatory brain responses indexed ongoing stimulus processing in corresponding senses. To induce competition, we introduced transient frequency-tagged stimuli in same and/or different senses ('competitors') during reference presentation. Participants performed a separate visual discrimination task at central fixation to control for attentional biases of sensory processing. A comparison of reference-driven SSR amplitudes between competitor-present and competitor-absent periods revealed reduced amplitudes when a competitor was presented in the same sensory modality as the reference. Reduced amplitudes indicated the competitor's suppressive influence on reference stimulus processing. Crucially, no such suppression was found when a competitor was presented in a different than the reference modality. These results strongly suggest that early sensory competition is exclusively modality-specific and does not extend across senses. We discuss consequences of these findings for modeling the neural mechanisms underlying intermodal attention.
authors.affiliation: Institut für Psychologie, Universität Leipzig, Neumarkt 9-19 04109 Leipzig, Germany.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Porcu
authors.affiliation: Institut für Psychologie, Universität Leipzig, Neumarkt 9-19 04109 Leipzig, Germany; Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, 58 Hillhead Street, G12 8QB Glasgow, UK.
authors.forename: Christian
authors.initials: C
authors.lastname: Keitel
authors.affiliation: Institut für Psychologie, Universität Leipzig, Neumarkt 9-19 04109 Leipzig, Germany. Electronic address: m.mueller@rz.uni-leipzig.de.
authors.forename: Matthias M
authors.initials: MM
authors.lastname: Müller
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D010812:Physical Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D014110:Touch / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Biased competition; Cross-modal; EEG; Inter-modal attention; Multisensory; Steady-state evoked potential