Science of Aphasia 5 Cross Linguistic Aspects of Aphasia ...

Verb retrieval in anomic aphasic speakers: the role of sentence context.
Roel Jonkers & Christien Prak
Department of Linguistics, University of Groningen (NL)
Introduction
In studies on verb processing in aphasic speakers, different patterns of performance have been found for verb
retrieval in isolation and in spontaneous speech. Williams and Canter (1987), Bastiaanse and Jonkers (1998), and
Pashek and Tompkins (2002) showed that there is no significant correlation between action naming scores and
the production or diversity of verbs in spontaneous speech or narrative discourse.
In action naming, a target verb has to be retrieved in isolation, whereas in spontaneous speech verbs are
produced within sentences and there is no target verb. A third possibility to study the production of verbs is the
investigation of verb retrieval in sentence context. In these cases, target verbs have to be produced within a
sentence. Williams & Canter (1987) showed that especially anomic speakers profit from sentence context in
order to find the intended verb. The relation between verb retrieval in isolation, sentence context and
spontaneous speech has, however, never been studied in a group of anomic aphasic speakers.
Methods and Materials
Subjects: 11 anomic speakers were tested (mean age 60, 7 male, 4 female). All aphasic subjects were righthanded
and suffered from aphasia due to a single stroke. Spontaneous speech data of 10 age-matched non-braindamaged
control subjects were used for comparison.
Materials and procedure: Action naming and verb retrieval in sentence context were tested with the tests
described by Jonkers (1998). Both tests contain 60 items. For action naming a picture was shown, after which the
subject was asked to tell in one word which action was depicted. For verb retrieval in sentence context a picture was
shown and the subject was asked to tell in one sentence what was happening in this picture. For both tests, an item
was scored as correct, if the target verb was produced.
A spontaneous speech sample was obtained by asking the subjects to tell about their speech problems, their work,
and their hobbies. The spontaneous speech was analysed with the method of Vermeulen, Bastiaanse, and Van
Wageningen (1989). 300 Words per sample were used for this analysis. The total number of verbs and the diversity
of the verbs, expressed by the type-token-ratio (number of different verbs divided by the total number of verbs), were
calculated.
Statistics: Verb retrieval in isolation and in sentence context were compared using a paired t-test. Comparisons
between the number of verbs and the type-token-ratio of the verbs produced by the anomic speakers and the
control subjects were made with an independent t-test. Correlations between verb retrieval scores in isolation,
sentence context and the type-token-ratio for verbs in spontaneous speech were calculated with the Pearson test.
Results
The scores for verb retrieval in isolation, sentence context, and in spontaneous speech are depicted in table 1.
Table 1:
A. Mean and standard deviation for the scores of the anomic speakers in verb retrieval in isolation and sentence
context (max.= maximum score)
B. Mean and standard deviation for the total number of verbs and the type-token-ratio for verbs in the
spontaneous speech of the anomic speakers (n=11) and the control subjects (n=10).
A. test results anomic speakers max.
verb retrieval in isolation 28.8 (12.3) 60
verb retrieval in sentence context 33.6 (12.0) 60
B. spontaneous speech anomic speakers control subjects
number of verbs 40.5 (4.5) 34.8 (5.6)
type-token-ratio 0.54 (0.15) 0.74 (0.10)
No significant difference was found between verb retrieval in isolation and in sentence context (t(10)=1.80,
p>0.05). A significant correlation was found between the scores for both tests (rho=0.73, p