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Abstract:
Recent research shows that verb-specific structural biases
have rapid effects in on-line sentence comprehension, but it
remains controversial whether verb bias affects the initial parse.
This question is often addressed by manipulating the semantic
plausibility of potential direct objects after verbs with differing
biases. For example, in an ERP study, Garnsey et al. (1998) found
that implausible DOs following NP-biased verbs elicited an N400
effect (associated with semantic anomalies), while those following
clause-biased verbs did not. This suggests that implausible DOs
following the two classes of verbs are processed differentially on
line.
In an independent ERP study, we addressed this same question
using only clause-biased verbs. Unlike earlier studies, our design
interposed a prepositional phrase with ambiguous attachment options
between the postverbal NP and the disambiguation point (the
embedded auxiliary), to isolate effects at these two points of
interest:
The priest believed the
doctrine/car
despite its problems
was
still fundamentally sound.
This manipulation allowed us to determine that the results differed
in interesting ways from those of earlier studies.
First, the implausible DOs
(car)
elicited a pronounced symmetric slow negative potential over
anterior regions of scalp relative to plausible DOs
(doctrine).
In addition, contrary to earlier results, implausible DOs showed
an N400 effect relative to plausible DOs. In this second respect
they resemble implausible DOs following NP-biased verbs in the
Garnsey et al. (1998) study.
The presence of these two concurrent effects suggests that
subjects entertained two interpretations of the implausible NP in
parallel: while the anterior negativity suggests that subjects are
projecting this NP as the subject of a new clause, the existence of
the N400 argues that they simultaneously hold out the possibility
that it was the DO of the main verb.
Second, at the disambiguating auxiliary of the verb phrase, both
conditions elicited a late positivity that continued through the
end of the sentence. However, this effect was much larger in the
plausible condition
(doctrine...was).
The late positivity to both conditions suggests that at this point
in the sentence subjects were forced to reanalyze a possible verb +
DO interpretation. However, reanalysis was more difficult following
plausible DOs, as indexed by the greater amplitude of this
positivity. This indicates a greater initial commitment to the verb
+ DO interpretation in the case of plausible DOs.
Overall, our results strongly suggest that our subjects
simultaneously entertain both a DO and a embedded subject
interpretation of the implausible DO, and consequently argue
strongly for a parallel or constraint satisfaction account of
ambiguity resolution.
References
Garnsey, S., Atchley, R., Wilson, M., Kennison, S., &
Pearlmutter, N. (1998). An event-related brain potential study of
verb bias and plausibility in the comprehension of temporarily
ambiguous sentences. Talk given at the 11th Annual CUNY Conference
on Human Sentence Processing, Rutgers University, New Brunswick,
NJ.
Pickering, M., & Traxler, M. (1998). Plausibility and recovery
from garden paths.
Journal of Experimental Psychology: Learning, Memory, and
Cognition,
24(4), 940-961.
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