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Effects of acoustic distortion and semantic context on event-related potentials to spoken words

Authors

  • Jennifer Aydelott,

    1. Center for Research in Language, University of California, San Diego, San Diego, California, USA
    2. School of Psychology, Birkbeck College, University of London, London, UK
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  • Frederic Dick,

    1. Center for Research in Language, University of California, San Diego, San Diego, California, USA
    2. School of Psychology, Birkbeck College, University of London, London, UK
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  • Debra L. Mills

    1. Center for Research in Language, University of California, San Diego, San Diego, California, USA
    2. Department of Psychology, Emory University, Atlanta, Georgia, USA
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  • The research was supported by grants from the National Institute of Child Heath and Human Development (P50) HD3313O1A to Ursula Bellugi and the National Institute of Deafness and Communication Disorders, DCO1289, to Elizabeth Bates. We thank Kara Federmeier for her extremely helpful advice and remarks, Chantel Prat for her assistance in data collection, and Liz Lewis Sheehan for her help in data analysis. We especially thank the participants in the study.

Address reprint requests to: Dr. Jennifer Aydelott, School of Psychology, Birkbeck College, University of London, Malet Street, London WC1E 7HX, UK. E-mail: j.aydelott@bbk.ac.uk.

Abstract

This study examined the neurophysiological effects of acoustic degradation on auditory semantic processing. Event-related potentials were recorded to target words presented in a sentence context. Targets were semantically congruent or incongruent with the context, which was acoustically intact or low-pass filtered. In unaltered contexts, N400 amplitude was significantly greater for incongruent than congruent words. Filtering significantly reduced this effect, even though participants were highly accurate in interpreting the degraded stimuli, as shown by an anomaly detection task. This reduction in the N400 effect appeared to be driven by decreased N400 amplitudes over posterior electrode sites for incongruent targets. These results demonstrate that acoustic degradation influences the neural response to words in context by reducing the availability of semantic information in on-line sentence comprehension.

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