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Abstract:
This study uses ERP measures to investigate the time-course
of processing demands in sentence comprehension. The study focuses
on the processing of sentences involving long-distance
wh-dependencies. It is known that longer structural dependencies
between words and phrases entail increased processing demands, but
the cause of the length effect is unclear. The length effect may be
due to increased difficulty in storing long incomplete structural
dependencies; alternatively, it may be due to increased difficulty
in the integration of material at the completion of long structural
dependencies. Existing behavioral results do not clearly
distinguish these alternatives (Gibson, 1998). These competing
accounts make different predictions about the time course of
resource demands, and can be distinguished using ERPs. The
experiment tested 4 conditions: a long wh-dependency condition
(2-clause extraction), a short wh-dependency condition (1-clause
extraction), and control conditions which lacked wh-dependencies.
28 participants read 40 sentences from each condition, interspersed
with 320 filler sentences. ERPs were collected for each word, in
order to track the temporal evolution of the dependency-length
effect. The study shows the contribution to the dependency-length
effect of both (i) the Left Anterior Negativity, an ERP component
associated with storage of structural dependencies (e.g. King &
Kutas, 1995), and (ii) the P600, an ERP component associated with
integration of words at the completion of syntactic dependencies
(Kaan et al. 2000).
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