Fonetica Inglesa

Brain and Language 89 (2004) 484–498
www.elsevier.com/locate/b&l

Semantic, lexical, and phonological influences on the production
of verb inflections in agrammatic aphasia
Yasmeen Faroqi-Shah* and Cynthia K. Thompson
Department of Communication Sciences and Disorders, Northwestern University, 2240 Campus Drive, Evanston, IL 60208, USA
Accepted 23 December 2003

Abstract
Verb inflectionerrors, often seen in agrammatic aphasic speech, have been attributed to either impaired encoding of
diacritical features that specify tense and aspect, or to impaired affixation during phonological encoding. In this study we
examined the effect of semantic markedness, word form frequency and affix frequency, as well as accuracy and error patterns,
in an attempt to evaluate whether diacritical oraffixation operations are impaired. Verb inflections (V þ ing, V þ ed , V þ s,
and V stem in present progressive, past, present 3rd person singular, and future tense contexts, respectively) were elicited in
eight mild-moderate agrammatic aphasic individuals in a sentence context using a picture description task. Results revealed
that the majority of verbs produced were affixed (75%) although accuracy waslow (36%). Word form frequency was found to
be a significant predictor of the accuracy with which verb inflections were produced; while affix frequency and semantic
markedness were not found to influence accuracy. These results suggest that a diacritical deficit is more likely to undermine
the production of verb inflections than a affixation deficit, and indicate that when diacritical processes arecompromised, word
form frequency is likely to influence production of verb inflections in agrammatic aphasia.
Ó 2004 Elsevier Inc. All rights reserved.
Keywords: Agrammatism; Aphasia; Inflection; Verb production; Frequency

1. Introduction
An impairment in the production of inflectional
morphology is one of the characteristic features of
agrammatic BrocaÕs aphasia and this has been the
focus ofmuch research in the past two decades. In
English speaking individuals with agrammatic aphasia, a deficit in producing inflectional morphology is
manifested as verb inflection errors, frequently in the
form of omissions of inflectional affixes and overuse
of the ing form of the verb (V þ ing as in kicking
and smiling) (De Villiers, 1974; Goodglass, 1976).
Across most languages studied, difficulty withverb
inflections is largely restricted to features of tense and

*

Corresponding author. Present address: 24W503, Seabrook Ct.,
Naperville, IL 60540, USA. Fax: 1-847-467-2776.
E-mail address: y-faroqi@northwestern.edu (Y. Faroqi-Shah).
0093-934X/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved.
doi:10.1016/j.bandl.2003.12.006

aspect with relative sparing of subject verbagreement
(Benedet, Christiansen, & Goodglass, 1998; Friedmann & Grodzinsky, 1997; Goodglass, Christiansen,
& Gallagher, 1993). However, the underlying source
of tense/aspect errors is unclear.
The mental operations involved in the production
of inflected verbs are generally believed to include two
crucial processes: selection of diacritical features and
concatenation of verb stems with affixes(Levelt, 1989;
Levelt, Roelofs, & Meyer, 1999). The term diacritics
was used by Levelt (1989) to refer to segments of the
speakerÕs message that are typically conveyed by inflectional affixes (e.g., tense, aspect, mood, person, and
number). For the production of inflected verbs in
English, conceptual and semantic information is used
to specify diacritical features that indicate tense andaspect, such as +PAST or +PROGRESSIVE.
According to Levelt, selection of diacritical features
determines which verbal affix is retrieved from the
mental lexicon (ed for +PAST and ing for

Y. Faroqi-Shah, C.K. Thompson / Brain and Language 89 (2004) 484–498

+PROGRESSIVE and so on).1 Thus, production of
regular verbs is believed to proceed by locating the
lexical entries of the verb stem and...