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Abstract:
Investigations of regular and irregular morphology have been
central to the question of whether distinct systems subserve
grammar and lexicon. On a dual-system view, regular forms are
computed by the application of a suffixation rule, whereas
irregular forms are retrieved from lexical memory. On a
single-system view, regulars and irregulars are computed in an
associative memory. Clinical neurological double dissociations link
regulars to left frontal regions and irregulars to temporal-lobe
regions (Ullman et al., 1997). Event-Related Potential (ERP)
studies have linked syntactic violations to left anterior
negativities, and lexical/semantic violations to central/posterior
negativities. To compare the grammar/lexicon distinction assessed
by these methods, we recorded ERPs as subjects viewed sentences
with and without violations of phrase structure, lexical-semantics
(after Neville et al., 1991), and regular and irregular verb
morphology (after Newman et al., 1998). Violations of regular verbs
yielded a more anterior negativity than did violations of irregular
verbs. Similarly, the phrase structure violations elicited a
negativity which was more left and anterior than that elicited by
the lexical-semantic violations. The results converge with other
lines of evidence linking syntactic processing of regular verb
inflection to syntax and related brain regions, and irregular verb
inflection to lexical-semantic processing and more posterior
regions. NSERC PGS-B; Army DAM-17-93-V-3018; McDonnell-Pew grant;
NIH DC-00128.
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