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  Narrowed expectancies under degraded speech: Revisiting the N400

Strauss, A., Kotz, S. A., & Obleser, J. (2013). Narrowed expectancies under degraded speech: Revisiting the N400. Journal of Cognitive Neuroscience, 25(8), 1383-1395. doi:10.1162/jocn_a_00389.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-000E-B68C-C Version Permalink: http://hdl.handle.net/21.11116/0000-0003-ACD1-F
Genre: Journal Article

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 Creators:
Strauss, Antje1, Author              
Kotz, Sonja A.2, Author              
Obleser, Jonas1, Author              
Affiliations:
1Max Planck Research Group Auditory Cognition, MPI for Human Cognitive and Brain Sciences, Max Planck Society, ou_751545              
2Department Neuropsychology, MPI for Human Cognitive and Brain Sciences, Max Planck Society, ou_634551              

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Free keywords: N400, EEG, event related potentials, Auditory Processing, Semantic context, Adverse listening
 Abstract: Under adverse listening conditions, speech comprehension profits from the expectancies that listeners derive from the semantic context. However, the neurocognitive mechanisms of this semantic benefit are unclear: How are expectancies formed from context and adjusted as a sentence unfolds over time under various degrees of acoustic degradation? In an electroencephalography (EEG) study, we modified auditory signal degradation by applying noise-vocoding (severely degraded: 4-band, moderately degraded: 8-band, and clear speech). Orthogonal to that, we manipulated the extent of expectancy: strong or weak semantic context (±con) and context-based typicality of the sentence-last word (high or low: ±typ). This allowed calculation of two distinct effects of expectancy on the N400 component of the evoked potential. The sentence-final N400 effect was taken as an index of the neural effort of automatic word-into-context integration; it varied in peak amplitude and latency with signal degradation and was not reliably observed in response to severely degraded speech. Under clear-speech conditions in a strong context, typical and untypical sentence completions seem to fulfill the neural prediction, as indicated by N400 reductions. In response to moderately degraded signal quality, however, the formed expectancies appeared more specific: Only typical (+con +typ), but not the less typical (+con –typ) context–word combinations lead to a decrease in the N400 amplitude. The results show that adverse listening “narrows”, rather than broadens, the expectancies about the perceived speech signal: limiting the perceptual evidence forces the neural system to rely on signal-driven expectancies, rather than more abstract expectancies, while a sentence unfolds over time.

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Language(s): eng - English
 Dates: 2013-02-192013-08
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: DOI: 10.1162/jocn_a_00389
PMID: 23489145
Other: Epub 2013
 Degree: -

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Title: Journal of Cognitive Neuroscience
Source Genre: Journal
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Publ. Info: Cambridge, MA : MIT Press Journals
Pages: - Volume / Issue: 25 (8) Sequence Number: - Start / End Page: 1383 - 1395 Identifier: ISSN: 0898-929X
CoNE: /journals/resource/991042752752726