EEG Correlates of Hemispheric Word Recognition.
In: Brain Research in Language; 2008, p225-245, 21p
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In several experiments, we compared behavioral and electrophysiological correlates of hemifield tachistoscopic presentations of single words and nonwords for lexical decision in English and in Hebrew. The English task showed an overall right visual field advantage for latency and accuracy, which was larger for target words than for nonwords, suggesting independent processing in each hemisphere. The right hemisphere was more sensitive to word frequency than the left, and the left hemisphere was more sensitive to orthographic regularity than the right. All lexical variables (Wordness, Frequency, Regularity, and Word Pronounceability) had physiological correlates, and those correlates were often different in the two hemispheres. Occasionally, the behavioral and physiological measures conflicted and some lexical variables had physiological but no behavioral correlates. The physiological variables can reflect early stages of information processing that are not available to conscious decision. Moreover, different cognitive phenomena may have the same EEG correlates. Thus, gamma changes as a function of Lexicality (Wordness), semantic (Word Frequency), orthographic (Word Regularity), and phonological (Nonword Pronounceability) variables. The Hebrew lexical decision task showed an overall right visual field advantage, but not the same for target word and nonword, suggesting exclusive specialization in the left hemisphere. The EEG at rest was predictive of subsequent hemispheric specialization for lexical decision. We also studied hemispheric error monitoring in the English task. We found that while the left hemisphere was superior for lexical decision, the right hemisphere better monitored errors and adapted to them by slowing down and becoming more accurate. Further, error correction in a given trial was negatively correlated with left asymmetry in the alpha amplitude over mid and posterior electrodes. Thus, effective error monitoring seems to require interhemispheric cooperation. We conclude that the EEG, as currently measured, differentiate all the relevant dimensions of the lateralized lexical decision task, but that it taps different stages of processing. The EEG response in the gamma band multiply determines so that different cognitive states have the same EEG signature. Consequently, a more refined, wider range, and more theoretically informed partitioning of the EEG spectra is now due. [ABSTRACT FROM AUTHOR]
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Titel: |
EEG Correlates of Hemispheric Word Recognition.
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Autor/in / Beteiligte Person: | Joshi, R. Malatesha ; Breznitz, Zvia ; Zaidel, Eran ; Hill, Andrew ; Weems, Scott |
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Quelle: | Brain Research in Language; 2008, p225-245, 21p |
Veröffentlichung: | 2008 |
Medientyp: | Buch |
ISBN: | 978-0-387-74979-2 (print) |
DOI: | 10.1007/978-0-387-74980-8_9 |
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