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Abstract:
According to some theories of discourse comprehension,
incoming information consistent with prior context is mapped onto
an existing mental representation of a discourse, but separate
sub-representations are built for inconsistent information. The
present study examined the relative importance of syntactic and
semantic cues on representation-building choices by recording N400
and P600 ERP components elicited by semantically congruent and
incongruent target words in complex sentences (e.g., 'Diving was
forbidden from the bridge because the river had rocks/cracks in
it.' or 'Guests played bridge because the river ...'). Crucially,
the syntactic context either weakly ('river') or strongly
('rocks'/'cracks') suggested that these targets were congruent with
the context. We predicted that semantic incongruity would be more
likely to cause a switch to a new sub-representation when the
syntactic cues are weak, and that this would be reflected in a more
anterior N400 congruity effect for targets preceded by a weak
rather than strong syntactic context (because anterior N400s were
previously observed in random word lists where mapping is
unlikely). The weak syntactic context was also hypothesized to lead
to a larger P600 effect between congruent and incongruent targets
because switching to a new sub-representation would involve
syntactic re-analysis. The results confirmed only our predictions
for the N400. The P600 effect was larger to targets preceded by a
strong syntactic context, suggesting that semantic information
overrides even strong syntactic cues in defining the structure of
the discourse representation.
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