J. COMMUN. DISOKD. 23 (1990). 77-88

REPETITION DEFICITS IN THREE APHASIC SYNDROMES EDITH CHIN LI Cul[fornia

Stale

Unhzersity,

Fullerton

SARAH E. WILLIAMS Depurtment

of Veferuns

This study examined

Afftiirs.

Mediurl

the repetition

errors

Center.

of three aphasic

task. A total of 95 subjects, including 32 conduction. repeated phrases and sentences from the Repeating Aphusicr tempts,

Exuminution. word revisions,

more phonemic

Conduction

BN~ Pines,

aphasics Finally,

subgroups

38 Broca’s,

during a repetition

and 25 Wernicke’s

Phrases Subtest of the Bo.t/on

exhibited

a greater

and word and phrase repetitions.

errors and omissions.

Florida

Wernicke’s

Broca’s

number

aphasics, Dirrgnostic

of phonemic

aphasics

at-

demonstrated

aphasics showed more unrelated

words and jargon.

INTRODUCTION The ability to repeat verbal material is an elementary language mechanism acquired early in life. Repetition ability is routinely tested in aphasic patients as part of a complete diagnostic battery. The types, as well as the total number of errors made in repetition tasks, frequently provide information useful in the classification of aphasic patients into a particular syndrome. There are few formal studies which examine in depth the repetition errors made across various aphasic syndromes. Joanette et al. (1980) examined one specific type of verbal response-phonemic paraphasia sequences (conduites d’approche phonemiques)-produced by Broca’s conduction and Wernicke’s aphasics. Two repetition tests (word and sentence repetition; nonsense syllable repetition) and four additional tasks (spontaneous speech, naming, reading aloud, and automatized sequences) were included. Conduction aphasics differed from the other aphasic groups in that they tended to produce paraphasias with increasing phoAddress correspondence to Edith C. Li, Ph.D., Department of Speech Communication (EC-199), California State University, Fullerton, Fullerton, California 92634.

0 1990 by E. C. Li and S. E. Williams

77

78

EDITH CHIN LI and SARAH E. WILLIAMS

nemic resemblance to the target utterance during the course of the paraphasic sequence. This occurred for all tasks with the notable exception of the repetition tests. Gardner and Winner (1978) reported a more comprehensive investigation of repetition behaviors. A group of 17 anterior, 14 posterior, and 12 conduction aphasics completed a single-word repetition task under immediate and delayed recall conditions. Incorrect responses were coded as sound errors, meaning errors, and other errors. The anterior aphasics consisted of Broca’s, transcortical motor, and mixed anterior aphasics (patients characterized by anterior lesions and moderate comprehension loss); the posterior group was composed of Wernicke’s, anemic, and transcortical sensory aphasics. The results documented some significant differences among aphasic groups. The delayed recall condition aided the performance of the Broca’s aphasics and impeded that of the anemic aphasics. With regards to the analysis of error type, sound errors were more likely to be produced by Broca’s and mixed anterior aphasics. In contrast, conduction aphasics were prone to meaning errors. Gardner and Winner (1978) investigated a wider range of verbal behaviors than Joanette er al. (1980). However, their coding system (e.g., sound/meaning/other errors) did not allow a fine delineation of error types. Also, their test was limited to single-word responses. Frequently, clinical observations reveal that patients who exhibit virtually flawless repetition of single words will experience difficulty on multi-word repetition tasks. The current study was designed to examine the types of repetition errors during a phrase repetition task which best discriminate among three major aphasic subgroups-conduction, Broca’s, and Wernicke’s aphasics. The goal was to provide additional information which could prove useful in the diagnostic classification of aphasic patients. In addition, as a number of conflicting theories have been advanced to account for the repetition deficit in conduction aphasia, it was felt that comparisons among the three subgroups of aphasia might yield information regarding the mechanism underlying this deficit. Geschwind (1965) attributed the repetition deficit to an anatomical disconnection between Wernicke’s area and Broca’s area. Warrington and colleagues (1971, 1972) propose that the repetition problem arises from a disruption of auditory short-term memory. Finally, several researchers suggest that the inability to repeat results from a general deficit in phonemic or motor encoding (Kahn, 1984; Yamadori and Ikumura, 1975; Dubois et al., 1973). The majority of the evidence for these theories has been derived from single case studies or small group studies involving conduction aphasics exclusively. By utilizing a different approach and comparing repetition behaviors in several major aphasia syndromes, it was hoped that this study would shed additional light on the nature of conduction aphasia.

REPETITION

IN THREE APHASIC

SYNDROMES

79

The final goal of this project was to compare verbal behaviors during repetition versus naming tasks. Both of these tasks are considered to be “target-bound”; that is, the target word is determined by a given stimulus and the speaker cannot substitute an easy word for a word which is difficult to produce (Yamadori and Ikumura, 1975; Kohn, 1984). Published research comparing repetition and naming is lacking. Such a comparison might lend insight into the psycholinguistic processes underlying these two commonly utilized clinical tasks.

METHODOLOGY Subject Description A total of 95 subjects participated in this study. They included 32 conduction, 38 Broca’s, and 25 Wernicke’s aphasics. Subjects were native English speakers. The etiology of aphasia was a single, thrombo-embolic left hemisphere cerebrovascular accident in all cases. Only right-handed individuals with unilateral left hemisphere lesions were included in the study. Age of onset of aphasia ranged from 20 years to 84 years with a mean of 58.9 years. Duration of aphasia ranged from one month to 40 years with a mean of 2.8 years. Subjects were alert, cooperative, and medically stable at the time of testing. In addition, all patients had passed an audiometric screening test at frequencies of 500, 1000, and 2000 Hz. Screening level was set at 25 dB IS0 in the better ear. To determine type of aphasia, the guidelines provided by Goodglass and Kaplan (1983) were used. Specifically two clinical parameters, spontaneous speech and comprehension, were examined. With regards to spontaneous speech, fluency is one major characteristic that distinguishes between anterior and posterior patients. Criteria for classification as fluent/nonfluent were the six features of speech production used in the Boston Diagnostic Aphasia Examination (Goodglass and Kaplan, 1983) rating scale. The scales were applied to lo-minute samples of spontaneous speech. To assess comprehension, the Complex Ideational Materials (CIM) Subtest from the Boston examination was used. Since Wernicke’s patients score consistently lower on auditory comprehension subtests than patients with other aphasia syndromes included in the present study (Goodglass and Kaplan, 1983), subjects classified as demonstrating Wernicke’s aphasia had to have CIM Subtest scores at or below the 50th percentile. Subjects classitied as Broca’s and conduction aphasics all scored above the 50th percentile on this subtest.

x0

EDITH

Table I. Description I. Phonemic

of Repetition

CHIN

Error

error--appr~~ximalion~

L-1 and

SAKAH

E.

WILLIAMS

CategorA

tcr the target

words

M ith one or mar-c phoneme\

in

error tsmail/.\r~tri/l.

2. 3. 4. Neologism-utter;lnccs are neither get words t~toploggitlhic~~( I(,). >

Phonemic

attempt--phonemic

6. Semantic-phonemic

real words nor phonemic

or syllabic

error-rwl

attempt

word bear\

~lppro~im;ltion~

‘hic~vc~/r,).

at the target tiorcl Ihi

phonemic

resemhlancc

of the ta.-

to the target uord

(stair/c Ilc~irl. 7. Grammatical

error-responw

deviate\

from normal

only by alteration

of #I-ammatical

form tgirlsirrir-Il. 8. Persever~~tion-inappr~~pri~lte

t-epctition of pre\ iou\ whole word utterance\. Addition

9. Word

addition-add

a single v,ord within

IO. Phrase addition--add II.

Sound interjection--an

I?.

Word interjection-an fiord\

aw~ciated

two or more word\ extranew\

wund

extranew\

t’rro1-\ target sentence. within tht! target sentence. i\ added (r//r).

\VOI-d \uch a\ II,C// ix ad&d

which i\ distinct from the

with the fluent text.

extraneous. parenthetical rrmarh wch a\ >‘~,,r XI~CIII,i\ ddctl. 13. Phrase interjection-an which i$ distinct from the words a\\ociatetl with the fluent text. Omission 14. Word

omission-one

word i*l omitted

15. Phrase omiaion-two

or more word\

16. Word

transposition-one

word

error\

within

the target \entt‘nce.

are omitted

is \witched

Lvithin the twget

\vith another

sentence.

or out of order

in the tat-@

sentence. Kevislon 17. Word IX.

reviGon-correct

Phrase revision-the

19. Word

or incorrect content

repetition-repetitions

20. Phrase repetition-repetition\ 21.

error\

revision

of the phraw of \inglc

at the word level thirth:earth).

i? modified

(They

\aqThcy

heard him).

word5 (l-l-1).

of two or more word\. Jar-pan

(They

s~):‘Theq

sty).

Keal word jargon--string of uol-d\ which do not rewmble the target sentence 01 grammatical structure (makes him rnoney:~l~~~~~/~-~~~-~,~f~//~).

71. Neologistic

jargon-jargon

icI cornpod

primarily

of neolopi\m\

t\lin.qhorc\

in content forpim,

dol~~~?-ro-c~tr~tII ). Paraphrase 23. Paraphrase-the idly

altered.

content

(I left work and came home// Imdequate

24. Inadequate

error-

iy similar to the target hut the grammatical

response-the

wh.ject

refu\ed

YC/ /~o/~Ic fi~w

Ire\pon\e to rc\pond.

wrd.)

structure

i\ dra\t-

REPETITION

IN THREE APHASIC SYNDROMES

81

Procedures The Repeating Phrases Subtest of the Boston Diugnnstic Aphusiu Exuminution (Goodglass and Kaplan, 1983) was used to assess repetition ability. The subtest consists of eight high-probability and eight low-probability phrases and sentences, arranged in the order of increasing length and complexity. The high-probability sentences are more predictable than the low-probability sentences with respect to verbal content and vocabulary. To be included in the study, each subject had to complete at least four high-probability and four low-probability phrases from the subtest. All responses were tape-recorded for subsequent transcription. Errors produced during the repetition task were classified into 24 possible error categories (see Table I). The classification system was designed to include both a linguistic dimension (e.g., unrelated word and neologistic errors) as well as a fluency dimension (e.g., revision errors). A portion of the error categories (word substitution errors and inadequate response errors) has been utilized in previous studies (Williams and Canter, 1987, 1982). The percentage of errors made in each error category within each subject’s total test sample was determined. This constituted the subject’s repetition scores. To assess reliability, 257~ of the subject protocols were scored by an independent aphasiologist and compared to scores obtained by the principal investigator. Interjudge reliability for the classification of error responses was found to be 93%. In addition to the repetition task, a portion of the subjects (28 patients) also performed naming tests to provide a basis for comparing repetition to naming errors. Two naming tests were administered: confrontation naming and picture description. To elicit confrontation-naming responses, simple line drawing of 40 picturable nouns were used. These were depicted on individual cards 5 x 4 in. in size. The picture description task utilized IO 8 x 1 I in. composite drawings, each containing representations of four of the same nouns as the confrontation naming task within a pictorial context. During the course of the picture description task, the subject attempted to name the four key items depicted in each composite picture and to place these names in a syntactic context. A total of 80 responses (40 on each task) was obtained from each of the 28 subjects. Patient naming responses were scored from written transcriptions of the tape-recorded testing sessions. Observed errors were classified into 1I categories: phonemic attempts, related words, perseverations. extended circumlocutions, phonemic errors, inadequate responses, semantic-phonemic errors, unrelated words, indefinite terms, neologisms. and grammatical errors. The percentage of errors within each of these error categories was computed across both naming tests. These data were then compared to the percentage of errors within the I I error categories during

82

EDITH

Table 2. Univariate

F-values

Variable

CHIN

LI and SARAH

E. WlLLlAMS

for Significant

Discriminating

Variables

(p < .05)

Wilks’ lambda

F

Significance

Phonemic

error

,933

3.328

,040

Unrelated

word

.8Y7

5.270

,007

Phonemic

attempt

,925

3.712

,028

Word omission

,871

6.784

.002

Phrase omission

,848

x.257

.oo I

Word

revision

,874

6.612

,002

Word

repetition

.874

6.609

.OO?

Phrase repetition

,920

4.006

Real word jargon

,817

Neologistic

,917

jargon

10.28 4. I90

,021s .ooo I ,018

the repetition task. When 25% of these subject protocols were scored by an independent aphasiologist, interjudge reliability was found to be 95%.

RESULTS Discriminant Analysis A discriminant analysis was performed to determine whether the 24 error types significantly discriminated among the three aphasic syndromes with respect to errors made during the repetition task. The grouping variable consisted of the three aphasic groups: conduction, Broca’s, and Wernicke’s aphasics. The set of discriminating variables consisted of the 24 variables listed in Table 1. The discriminant analysis yielded two significant discriminant functions (p < .OOOl) indicating that the aphasic groups could be differentiated on the basis of the 24 error types. The proportion of total variance accounted for by both functions was 99.7%. To determine which error types were the best discriminators, univariate F-ratios were computed for the individual discriminating variables. Among the 24 variables, the following were significant (p < .05): phonemic error, unrelated word, phonemic attempt, word and phrase omission, word revision, word and phrase repetition, and real word and neologistic jergon. Table 2 lists the univariate F-values for the significant variables. Since three aphasic subgroups were involved in the analysis, it was necessary to employ a multiple comparisons test to interpret the significant univariate F-values. A Tukey’s HSD test (p < .OS) was performed for each significant variable. As Table 3 indicates, the conduction aphasics exhibited a greater number of phonemic attempts, word revisions. and word and phrase repetitions in comparison to one or both of the other

REPETITION

IN THREE APHASIC

SYNDROMES

83

Table 3. Results of the Tukey’s HSD Test Comparing Mean Scores Three Aphasic Groups on Individual Discriminating Variables*

error

Wernicke’s

Conduction

6.08

Unrelated

Phonemic

word

attempt

Word omission

Phrase omission

Conduction

Wernicke’s

Broca’s

Wernicke’s

Conduction

* The

same

line

from

underlining

13.89

3.94

Broca’s

Broca’s

Wernicke’s

more

than

Conduction

I .92

Wernicke’s 1.84

at the .05 level

Broca’s

Wernicke’s

Conduction

2.08

5.41 Conduction

I .48

2.09

Conduction

Wernicke’s

.9l

Broca’s

each other

14.45

6.44

9.32

Conduction

.26

signticantly

Broca’s

8.36

Broca’s

jargon

9.63

Wernicke’s

.50 Neologistic

Conduction

Conduction 7.53

.47

Real word jargon

6.16

7.00

1.oo

Phrase repetition

Wernicke’s

3.75

Broca’s

Word repetition

II.00

Broca’s 1.79

5.84 revision

Broca’s

8.72

3.76

Word

the

Percentage coriect

Variable Phonemic

for

Wernicke’s

.28

one

mean

score

indicates

3.24

that

these

means

did

not

differ

of significance.

The Broca’s aphasics demonstrated more phonemic errors and omissions than one or both of the remaining subgroups. Finally, the Wernicke’s aphasics showed more unrelated words and jargon when compared to other aphasics. A classification analysis was performed to determine the percentage of cases which could be classified correctly into their aphasic group based upon the error types that were significant discriminators. Table 4 indicates that the correct classification rate was at least 80% for each of the three aphasic subgroups. These results are substantially better than the percentage of cases which could be classified correctly by chance alone (33.3%). groups.

EDITH CHIN LI and SARAH E. WILLIAMS

84

Table 4. Predicted Group Membership

Based on the Discriminant Predicted

Functions

group membership

(percentage Number

Group Conduction Broca’s

aphasia

aphasia

Wernicke’s

aphasia

of cases

correctly

predicted)

32

X4.4%’

38

x4.257

35

XO.O’/r

Repeated Measures Analysis For 28 subjects in this study. I I conduction, 9 Broca’s, and 8 Wernicke’s aphasics, it was possible to perform an additional statistical analysis to provide a comparison between repetition and naming tasks. The percentage of errors within the I1 error categories utilized for both repetition and naming tasks was computed. An analysis of variance with repeated measures was performed with one between-factor (aphasic group) and two within-factors (condition and error type). The aphasic group factor consisted of three levels: conduction, Broca’s. and Wernicke’s aphasics. The condition factor was composed of two levels: naming and repetition. The error type factor consisted of I I levels: the I I verbal error categories. The raw scores for the analysis were the percentage of errors in each error category. Results of the analysis are given in Table 5. The main effect of error type was significant (p < .OOl). In addition, the error type X condition interaction (p < .OOl) and the error type X group interaction (p < ,016) were significant. The presence of the interactions indicates that the trends observed within error categories were dependent on the group and the condition variables. With regards to the error type X condition interaction, simple effects testing revealed a significantly greater percentage of indefinite terms, extended circumlocutions, and perseverations in the naming condition. On the other hand, a significantly greater percentage of semantic-phonemic errors was produced in the repetition condition. Table 6 lists the means. Simple effects testing following the error type X group interaction revealed discrepant performances among aphasic groups in two error categories. In the unrelated word category, Wernicke’s aphasics produced the greatest percentage of unrelated words (16%), followed by conduction (8.8%,) then Broca’s aphasics (I .O%). Multiple comparisons, utilizing the Tukey’s NSD procedure, indicated that all of the comparisons were staattempt category. tistically significant (p < .05). Within the phonemic conduction aphasics (74.8%) produced the largest percentage of these errors, followed by Broca’s (50.75%) and then Wernicke’s (30.9%) aphas-

REPETITION

IN THREE APHASIC

85

SYNDROMES

Table 5. Results of Analysis of Variance Comparing Across Three Aphasic Groups

Error

Type

and

Condition

Probability (Greenhouse Sum of Source

Degrees

,028

Group

5.10

Error

square

2

,014

,034

Condition

,642

F

Probability)

.07

.934

,034

.28

,604

,321

2.61

,094

,204

25

Condition

Geisser

Mean

of

freedom

squares

2

X group Error 4674

Error type

3.0x

2s

I ,608

IO

7427.032

Error type

.I23 4674.16 371.352

20

3 I .37

,001

2.49

,016

X group 149.015

IO

935.082

8.09

.oo

4330.822

20

216.541

1.87

,080

28887.958

250

115.552

9350.82

Error type

I I

250

37253.63

Error

I

X condition Condition X error type X group Error

HSD test revealed significant (p < .05).

its. The Tukey’s statistically

that

all of the comparisons

were

DISCUSSION sought to determine whether three aphasic subgroups could be differentiated on the basis of their repetition behaviors. The discriminant analysis revealed that specific verbal behaviors effectively discriminated among conduction, Broca’s, and Wernicke’s aphasics. Conduction aphasics exhibited a greater number of phonemic attempts, word revisions, and word and phrase repetitions in comparison to one or both of

This study

Table 6. Mean Percentage of Indefinite Term, Extended Circumlocution, Perseveration, and Semantic-Phonemic Errors During Naming and Repetition Conditions Error

types

Naming

condition

Indefinite

term

4.53

Extended

circumlocution

5.04

Perseveration Semantic-phonemic

error

Repetition

condition .32

0

6.50

.I0

8.40

29.07

86

EDITH CHIN LI and SARAH E. WILLIAMS

the other groups. The Broca’s aphasics demonstrated more phonemic errors and omissions than one or both of the remaining subgroups. Finally. Wernicke’s aphasics showed more unrelated words and jargon. In comparing the current study with Gardner and Winner’s 1978 study, similarities emerge in the Broca’s aphasic subgroup. Gardner and Winner (1978) found a predominance of sound errors, consisting of literal paraphasias, elaborations, simplifications, and articulation errors, in their Broca’s and mixed anterior aphasics. This is consistent with the phonemic errors and omissions found in the current study. Both sets of error patterns highlight the articulatory problems of the Broca’s aphasics. Among similar lines, Gardner and Winner (1978) found that Broca’s aphasics tended to be aided by the delayed recall condition, in which patients were required to wait 3 seconds before attempting to repeat the item. Their finding suggests that the 3-second interval allowed Broca’s aphasics time to prepare their articulatory gestures with greater precision. The results of this study for conduction aphasics differ somewhat from Gardner and Winner (1978). Their conduction aphasics were particularly prone to making meaning errors or verbal paraphasias. In the current study, phonemic attempts and revisions were prominent. The differences in findings across the two studies may be related to the type of repetition task used. Garnder and Winner (1978) used a single-word repetition task, while the current study utilized phrases and sentences. If the deficits of the conduction aphasic are within the realm of motor encoding or production processes (Kohn. 1984: Yamadori and Ikumura, 1975: Dubois et al., 1973). the increased formulation demands of the sentence task would emphasize these difficulties. According to Dubois et al. (1973). repeating items and sentences of increasing complexity tends to reveal the disorganized execution of the encoding program in the conduction aphasic. A task requiring only a single-word response might not be sufficiently taxing to reveal this disorganization. Aside from the conduction aphasics, the highest number of meaning errors in Gardner and Winner’s (1978) study was produced by the Wernicke’s aphasics. This is consistent with the findings of the present study in which Wernicke’s patients produced more linguistic errors (unrelated words and jargon) than the other two groups. The results of this study offers some support for the group of theories that attribute the difficulties of the conduction aphasic to motor encoding deficits (Kahn, 1984, Yamadori and Ikumura, 1975: Dubois et al., 1973). It is useful to consider Kohn’s (1984) model. Although this model was devised to examine single-word production, it also provides a useful paradigm for repetition, since a variety of stages in the production process are considered. To produce a word, the phonological representations are initially accessed from the lexicon and transmitted to working memory, which retains a trace of the representations while they are programmed

REPETITION

IN THREE

APHASIC

SYNDROMES

87

for production at later stages. The representations are then converted into a sequence of phonological targets at the prearticulatory programming stage. Finally, this output is converted at the articulatory programming stage into a sequence of motor commands. The earliest stage of Kohn’s model-access from the lexicon-does not pertain to the repetition process, since repetition initially requires recognition of the auditory stimulus rather than lexical retrieval. However, the remaining stages are directly applicable to repetition. Kohn suggests that the errors of the conduction aphasics in both naming and repetition tasks occur at the prearticulatory programming stage. This involves the selection and sequencing of phonemic targets into a form necessary for articulatory realization. The error types exhibited by the conduction aphasic in the current study support Kohn’s interpretation. Specifically, the prevalence of phonemic attempts, word revisions, and word repetitions suggests that the conduction aphasic is attempting to organize and sequence his output prior to production. Dubois et al. (1973) refer to this level of production as the “first articulation,” the ordering of sounds into words and phrases. In contrast, it is likely that the Broca’s aphasic, with a pattern of phonemic errors and omissions, is experiencing deficits at the articulatory programming stage. The deficits of the Wernicke’s aphasics are not readily explained by Kohn’s model, since the model does not incorporate the initial stage of repetition-recognition of the auditory stimulus. This initial stage is the likely locus of breakdown for the Wernicke’s aphasic. Goodglass and Kaplan (1983) suggest that the deficient repetition skills of this subgroup are based on poor comprehension ability. The Wernicke’s patient experiences a partial or complete distortion of auditory image. The predominance of jargon and unrelated word responses in the current study would support this interpretation. With regard to verbal behaviors during repetition and naming tasks, the error type X condition interaction reveals there are some basic differences related to task. Although both tasks are considered to be target-bound, the subject is less bound by the stimulus during the naming situation. He has more liberty to substitute a word or phrase for the target. This is manifested in the types of errors which predominated during naming performance. Subjects tended to exhibit significantly more indefinite terms, extended circumlocutions, and perseverations in the naming conditions. These behaviors could be viewed as verbal strategies to compensate for inability to produce the specific target word. These strategies were employed less during the repetition task, perhaps because aphasic subjects recognized they would not be useful in a situation which was more targetbound. The error type X group interaction indicated that the error categories of unrelated word and phonemic attempt elicited differential performances

88

EDITH

CHIN

LI and SARAH

E. WII.LIAMS

among the three aphasic groups. Wernicke’s aphasics displayed the greatest number of unrelated words on naming and repetition tasks. followed by conduction, and then Broca’s aphasics. On phonemic attempts. conduction aphasics were the top-ranking group, followed by Broca’s and then Wernicke’s aphasics. These error patterns are consistent with the clinical symptomatology of the three subgroups. In summary. this study revealed verbal behaviors which cffectivcly and Wernicke’s aphasics durdiscriminated among conduction, Broca’s, ing a repetition task. The results appeared to support the motor encoding theories of repetition deficit in the conduction aphasic. The behaviors exhibited during repetition differed from those shown during naming, another target-bound task. These findings help to illuminate the psychological mechanisms underlying repetition disturbances in a variety of aphasic syndromes. In addition, they indicate that a qualitative rather than strictly quantitative approach to repetition errors could contribute substantially to the diagnostic process.

REFERENCES Dubois.

J., Hecaen.

rolinguistic (eds.).

study

H..

Angelergues.

of conduction

K., Chatelier

aphasia.

Ps?~c,ho/in~:Ni.sti~,.s and Aphasirr.

In H.

A..

Marcie.

Goodglass

Baltimore:

Johns

P. (1973).

Neu-

and S. Blumxtein Hopkins

University

Press. Gardner,

H.

and Winner.

E. (197X).

A study

of repetition

in aphasic

patients.

Brrrin nnd Lang:rr~~~~ 6: 16% 178. Geschwind. N. 88:585-644. Goodglass,

Y..

E.

Philadelphia: Keller.

proximations Kohn,

Disconnexion

H. and Kaplan,

Disturbances. Joanette,

(1965).

E.,

in animals

( 1983). T/w A.s.sc~s.srne~~tof‘

and

Aphnsitr

man.

rrd

Hrtri11

Krlrrtctl

Lea and Febiger.

and Lecours.

A.

(1980).

of the phonological

LanRl4mgc 23:97-l

Sequences

of phonemic

ap-

I I :30-44.

Brtrin trnd Ltrngmgc

in aphasia.

S. (1984) The nature

Bruin cd

syndrome\

disorder

in conduction

aphasia.

IS.

Warrington. calization

E. K.. Logue. V., and Pratt. K. 1‘. c‘. (IY71). The anatomical loof selective impairment of auditory verbal short-term memory. Nellropsychologitr 9:377-387.

Warrington. E. K., and Shallice, T. (1972). Neuropsychological evidence of visual storage in short-term memory tasks. Qmrto.ly Journrrl of’ Exprrimc~r~tcll P.sv

chlog?, Williams,

24:30-40. S. and Canter,

of aphasia. Williams,

S.. and Canter.

performance Yamadori.

G.

performance

G. (1982). The influence

in aphasic

A. and Ikumura,

nese patient.

( 1987). Action-naming

in four syndrome\

Brclin and Lrrtz,qrtagc~ 32: 124- 136.

C‘ortm

syndromes. G. (1975).

I l:73-82.

ofsituational

Bruin rrnci Lar~g~cccg:r Central

(or conduction)

context

on naming

17:Y2- 106. aphasia

in a Japa-