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Inattentional Deafness: Visual Load Leads to Time-Specific Suppression of Auditory Evoked Responses
Journal article   Open access   Peer reviewed

Inattentional Deafness: Visual Load Leads to Time-Specific Suppression of Auditory Evoked Responses

Katharine Molloy, Timothy D Griffiths, Maria Chait and Nilli Lavie
The Journal of neuroscience, Vol.35(49), pp.16046-16054
12/09/2015
DOI: 10.1523/jneurosci.2931-15.2015
PMCID: PMC4682776
PMID: 26658858
url
https://doi.org/10.1523/jneurosci.2931-15.2015View
Published (Version of record) Open Access

Abstract

Due to capacity limits on perception, conditions of high perceptual load lead to reduced processing of unattended stimuli (Lavie et al., 2014). Accumulating work demonstrates the effects of visual perceptual load on visual cortex responses, but the effects on auditory processing remain poorly understood. Here we establish the neural mechanisms underlying "inattentional deafness"--the failure to perceive auditory stimuli under high visual perceptual load. Participants performed a visual search task of low (target dissimilar to nontarget items) or high (target similar to nontarget items) load. On a random subset (50%) of trials, irrelevant tones were presented concurrently with the visual stimuli. Brain activity was recorded with magnetoencephalography, and time-locked responses to the visual search array and to the incidental presence of unattended tones were assessed. High, compared to low, perceptual load led to increased early visual evoked responses (within 100 ms from onset). This was accompanied by reduced early (∼ 100 ms from tone onset) auditory evoked activity in superior temporal sulcus and posterior middle temporal gyrus. A later suppression of the P3 "awareness" response to the tones was also observed under high load. A behavioral experiment revealed reduced tone detection sensitivity under high visual load, indicating that the reduction in neural responses was indeed associated with reduced awareness of the sounds. These findings support a neural account of shared audiovisual resources, which, when depleted under load, leads to failures of sensory perception and awareness. The present work clarifies the neural underpinning of inattentional deafness under high visual load. The findings of near-simultaneous load effects on both visual and auditory evoked responses suggest shared audiovisual processing capacity. Temporary depletion of shared capacity in perceptually demanding visual tasks leads to a momentary reduction in sensory processing of auditory stimuli, resulting in inattentional deafness. The dynamic "push-pull" pattern of load effects on visual and auditory processing furthers our understanding of both the neural mechanisms of attention and of cross-modal effects across visual and auditory processing. These results also offer an explanation for many previous failures to find cross-modal effects in experiments where the visual load effects may not have coincided directly with auditory sensory processing.
Acoustic Stimulation Adolescent Adult Attention Auditory Perception - physiology Auditory Perceptual Disorders - physiopathology Brain Mapping Electroencephalography Evoked Potentials, Auditory - physiology Evoked Potentials, Visual - physiology Female Humans Magnetoencephalography Male Psychophysics Reaction Time Time Factors Visual Perception - physiology Young Adult

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