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Abstract:
The N400 was used to study the processing of coherence in
two-clause sentences in which the first clause ended with a
homographic word and the second began with a word related to one of
two meanings of the homograph (e.g., (1) The sandwich is better
with ham because bacon has more fat in it. or (2) The actor was a
ham because bacon has more fat it in.). In normal participants,
words opening the second clause (bacon) were predicted to show
larger N400s when semantically incongruent with the biasing context
of the first clause, even though the alternative (dominant) meaning
of the homograph primed the meaning of these items. This prediction
was confirmed in undergraduate participants (i.e., the N400 to
bacon in 2 was larger than in 1), supporting the hypothesis that,
in normal readers, sentence context can overcome the potentially
intrusive effects of the alternative meaning of a homograph. In a
currently running experiment, we predict that, due to the symptoms
of formal thought disorder, schizophrenic patients will have
difficulties inhibiting the irrelevant dominant meanings of
homographs in incoherent sentences (e.g., the meat meaning of ham
in 2). If correct, then the N400 effect observed in normal controls
in the current study should be attenuated in patients, showing that
schizophrenic thought disorder impairs the patients ability to
inhibit contextually inappropriate associations in language
comprehension.
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