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Abstract:
We examined the extent to which attention affects
grammatical, semantic, and discourse processing of function words
and content words in the auditory domain. Using 31 electrode sites,
ERPs were recorded to the words "the" and "cats", which were
presented in naturally spoken discourse. Critical words occurred
either at the onset of meaningful utterances or at the onset of
nonsense syllable strings. In one task, subjects listened for
meaning and then answered comprehension questions. In a second
task, subjects ignored the auditory stimuli, watched a silent film,
and then answered content questions about the film. When subjects
attended to the auditory stimuli, ERPs to "the" in meaningful
utterances showed sustained anterior bilateral foci from 200-800
ms. In the ignore condition, this positivity was attenuated only
over the right anterior sites. However, the attend and ignore tasks
showed a different pattern of results to the word "cats" at left
and right anterior sites. When subjects attended to the stimuli,
greater negativity was observed from 450-650 ms to "cats" at the
onset of nonsense versus meaningful syllables. When subjects
ignored the stimuli, this negativity was attenuated at both left
and right sites. These results suggest that the left and right
hemispheres are engaged to different degrees, depending on
attention and linguistic content.
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