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Abstract:
The elements of sentence structure (phrasal
dependencies, grammatical agreement, etc.) are inherently local
in their formal character, and yet processing such dependencies
requires tracking across unbounded amounts of lexical and
structural planning. Evidence of how this information is
tracked can be found in a familiar performance error: Agreement
Attraction (Bock & Miller, 1991; Bock, et al., 2001).
On some recent accounts, the syntactic contribution to agreement
attraction is explained by positing a feature percolation
mechanism: Attraction arises whenever the features of a local
noun (e.g., plural number) migrate erroneously from a lexical
source to the root node of the Subject phrase. Once an
errant feature finds its way to this root node, the mistake is
accommodated by subsequent feature copying (or checking)
procedures (Vigliocco et al., 1996; Hartsuiker et al.,
2001). I will present cross-linguistic experimental
evidence (Slovak and English) indicating that the features that
participate in agreement attraction remain part of their lexical
source. E.g., Gender attraction depends on
Nominative/Accusative indeterminacy in both the head and local
noun, even though this morpho-syntactic ambiguity should be
eliminated if the case feature percolates to an intermediate node
that requires one or the other feature value.
Putative effects for syntactic distance
(Hartsuiker et al, 2001; Frank et al., 1997) have also been
offered as evidence for the percolation based production
model. Results from our own studies and from Nicol (1995)
show that the apparent effect derives from competition within
planning increments.
I present an alternative model in which the
agreement calculation respects the lexical integrity of
sources. Lexical (and phrasal) agreement sources are
flagged by activation-based tracking mechanisms, but this give
rise to a recurrent weakness: Activation can only distinguish an
element against a background of comparative dormancy. Other
sources of activation for local nouns may cause them to intrude
on the agreement calculation. In addition to effects for
morpho-syntactic indeterminacy, this model predicts another
finding: Attraction is more likely when a lexical element in a
conjoined local NP is itself plural (as in "the report of the
explosion(s) and the fire") since it adds an additional source of
distracting plural activation. This lexical source
contributes over and above that of the conjoined NP. In
contrast, in percolation-based theories, conjoined NPs will
affect the agreement calculation in a uniform manner, showing
plural features externally, regardless of their internal
content.
Percolation fails to capture these and other
properties of agreement attraction, while the activation based
model of tracking provides a natural explanation.
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