Thesis Title

Development of Grammatically Different Word Pairs and Series to Elicit the N400 Auditory Evoked Potential

Date of Graduation

Spring 2007

Degree

Master of Science in Communication Sciences and Disorders

Department

Communication Sciences and Disorders

Committee Chair

Thomas Franklin

Keywords

N400, P300, word pairs, word series, semantic processing

Subject Categories

Communication Sciences and Disorders

Abstract

Early auditory evoked potentials have been used to assess hearing sensitivity, as well as to explore the neurological processes of audition. Later auditory evoked potentials have been utilized as a means of exploring language processing and comprehension. The auditory evoked N400 response is an endogenous potential that requires the participant to actively attend to and cognitively process the stimulus. The auditory N400 response is typically elicited as a semantically unexpected word is positioned as the final word in a sentence and is thus thought to reflect semantic processing abilities. With previous studies, there has been little consistency of stimuli. The purpose of this study was to create sets of word pair and word series stimuli utilizing varying grammatical classes of the stimuli that would consistently and reliably elicit the auditory N400 response. The P300, an earlier endogenous auditory evoked potential, was also analyzed. An oddball paradigm of congruent and incongruent stimuli was used to construct nine word lists. Six of the word lists comparing adjectives, nouns, and mixed word pairs and word series were analyzed using the Neuroscan electrophysiological acquisition system. The auditory N400 and P300 response were consistently evoked with the adjective and noun word series and word pairs lists. This study has provided more evidence that the N400 can be elicited using non-sentential stimuli and supports the theory that differences in the N400 may be a result of varying grammatical classes of stimuli. This research will be valuable for reliable elicitation of the N400 and P300 responses in future studies that measure late auditory evoked potentials in reference to auditory processing abilities.

Copyright

© Heidi Jean Josenia Erickson

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