A language impairment that affects the production of inflected and/or
derived words may result from a deficit that specifically affects morp
hological processing mechanisms. but it might also arise from whole-wo
rd processing failures as well (Badecker & Caramazza, 1987: Funnell, 1
987). However, to motivate a true morphological impairment, the defici
t must be understood in terms of one or more different levels of morph
ological structure. Minimally, we can distinguish a word's morphosynta
ctic representation from its morphophonological representation. In the
single-case study reported here a deficit affecting the representatio
n or processing of morphosyntactic representations is motivated. A cri
tical part of the argument is that the deficit affects both regular an
d irregular inflection, and that no whole-word processing deficit can
account for the particular pattern observed in this patient. (C) 1997
Academic Press.