A Psychophysical and EEG Investigation of Cross-Modal Amplitude Modulation
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1
University of Newcastle, Australia
It is well established that both auditory and tactile perceptual processing is dependent on the temporally dynamic features of sensory stimulation. Much less is known about how these temporal features are integrated across sensory modalities. According to the temporal principle of multisensory integration greater cross-modal temporal correspondence should enhance the integration of multisensory stimulation.
Aim: Investigate how cross-modal temporal correspondence of amplitude modulation (AM) rate of multimodal presentations of acoustic and vibrotactile AM stimuli influence perceptual sensitivity for both psychophysical and EEG steady state measures of multisensory integration.
Method: A psychophysical procedure was used to estimate auditory and vibrotactile AM detection thresholds for a 32 Hz AM target stimuli while the cross-modal modulation rate was varied across six conditions (0, 8, 16, 32, 64 and 128 Hz). In a separate session EEG activity was recorded while participants were presented with the same stimulus conditions. FFT was then used to measure EEG entrainment at the frequency corresponding to AM rate of stimulation.
Results: Cross-modal AM rate significantly influenced auditory thresholds with polynomial contrasts indicating a significant quadratic trend. Cross-modal AM rate also significantly influenced vibrotactile thresholds with polynomial contrasts revealing a significant linear trend. Analysis of the 32 Hz SSR activity revealed no significant effect of cross-modal AM rate on the magnitude of 32 Hz SSR activity.
Conclusions: Results of the psychophysical analysis suggest that perceptual sensitivity to AM stimuli varied with cross-modal AM rate. Contrary to prior literature, auditory sensitivity was worst when the cross-modal AM rates matched while sensitivity to vibrotactile AM stimuli decreased as the cross-modal AM rate increased. SSR activity was not influenced by cross-modal AM rate suggesting that the oscillatory activity as measured by the SSR may not reflect entrained activity involved in multisensory integration.
Keywords:
multisensory integration,
steady-state responses,
temporal processing,
amplitude modulation,
Temporal correspondence
Conference:
Australasian Society for Psychophysiology, Inc, Coffs Harbour, Australia, 26 Nov - 28 Nov, 2014.
Presentation Type:
Oral Presentation
Topic:
Psychophysiology
Citation:
Timora
JR and
Budd
TW
(2014). A Psychophysical and EEG Investigation of Cross-Modal Amplitude Modulation.
Conference Abstract:
Australasian Society for Psychophysiology, Inc.
doi: 10.3389/conf.fnhum.2014.216.00008
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Received:
20 Oct 2014;
Published Online:
02 Dec 2014.
*
Correspondence:
Mr. Justin R Timora, University of Newcastle, Newcastle, Australia, justin.timora@uon.edu.au