LINGUIST List 18.2068
Mon Jul 09 2007
Diss: Neuroling/Psycholing/Cog Sci: Roehm: 'Waves and Words: Oscill...'
Editor for this issue: Hunter Lockwood
<hunterlinguistlist.org>
Directory
1. Dietmar
Roehm,
Waves and Words: Oscillatory activity and language processing
Message 1: Waves and Words: Oscillatory activity and language processing
Date: 06-Jul-2007
From: Dietmar Roehm <roehmcbs.mpg.de>
Subject: Waves and Words: Oscillatory activity and language processing
Institution: Philipps University Marburg
Program: Department of Germanic Linguistics
Dissertation Status: Completed
Degree Date: 2004
Author: Dietmar Roehm
Dissertation Title: Waves and Words: Oscillatory activity and language processing
Dissertation URL: http://archiv.ub.uni-marburg.de/diss/z2005/0110/pdf/ddr.pdf
Linguistic Field(s):
Cognitive Science
Neurolinguistics
Psycholinguistics
Dissertation Director:
Hubert Haider
Matthias Schlesewsky
Dissertation Abstract:
Successful language comprehension depends not only on the involvement ofdifferent domain-specific linguistic processes, but also on theirrespective time-courses. Both aspects of the comprehension process can beexamined by means of event-related brain potentials (ERPs), which not onlyprovide a direct reflection of human brain activity within the millisecondrange, but also allow for a qualitative dissociation between differentlanguage-related processing domains. However, recent ERP findings indicatethat the desired one-to-one mapping between ERP components and linguisticprocesses cannot be upheld, thus leading to an interpretative uncertainty.This thesis presents a fundamentally new analysis technique forlanguage-based ERP components, which aims to address the ambiguityassociated with traditional language-related ERP effects. It is argued thatthis new method, which supplements ERP measures with correspondingfrequency-based analyses, not only allows for a differentiation of ERPcomponents on the basis of activity in distinct frequency bands andunderlying dynamic behaviour (in terms of power changes and/or phaselocking), but also provides further insights into the functionalorganisation of the language comprehension system and its inherentcomplexity. On the basis of 5 EEG experiments, I show (1) that it ispossible to dissociate two superficially indistinguishable language-relatedERP components on the basis of their respective underlying frequencycharacteristics (Experiment 1), thereby resolving the vagueness ofinterpretation inherent to the ERP components themselves; (2) that theprocessing nature of the 'classical' semantic N400 effect can beunambiguously specified in terms of its underlying frequencycharacteristics, i.e. in terms of (evoked and whole) power andphase-locking differences in specific frequency bands, thereby allowing fora first interpretative categorisation of the N400 effect with respect toits underlying neuronal processing dynamics; and (3) that frequency-basedanalyses may be employed to distinguish the semantic N400 effect fromN400-like effects that appear in contexts which cannot readily becharacterised as semantic-interpretative processes. Depending on therespective task and stimulus manipulations, the N400 effect appears as aresult of the superposition of functionally different activities, which canbe clearly distinguished in terms of their underlying frequencycharacteristics. In this way, the proposed frequency-based methods directlybear upon the interpretation of language-related ERP effects and thus havestraightforward consequences for psycholinguistic theory. In view of thephenomenon that language-related processes have, in a number of cases, beendirectly attributed to the lexical-semantic processing domain on account ofthe observation of an N400, these results not only call for areinterpretation of previous findings but also for a reinterpretation oftheir theoretical consequences.
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