BRAIN

AND

LANGUAGE

39, 14-32 (1990)

Retrieval of Nouns and Verbs in Agrammatism and Anomia LOUISE

B. ZINGESER AND RITA SLOAN BERNM

University of Maryland School of Medicine The ability of five agrammatic and five anemic aphasic patients to produce nouns and verbs was assessed in four tasks. Target words were form class unambiguous, frequency and length matched nouns and verbs, elicited as single words in picture naming and naming-to-definition tasks. The same unambiguous verbs were targets in an action description task. Narrative speech was obtained from each patient using a story elicitation procedure. Agrammatic aphasics produced significantly fewer verbs than nouns, relative to other groups, in all tasks. Anemic aphasics reliably produced more verbs than nouns in naming to definition. These results replicate previous findings for Italian-speaking patient groups, and for several individual cases. In addition, these results extend the relative verb deficit among agrammatic patients to connected speech tasks. Results are interpreted in light of current models of lexical and sentence production. e 1990 Academic

Press, Inc.

Word retrieval difficulties are a frequent consequence of both focal and diffuse brain damage. These difficulties may be noted in spontaneous speech as well as in structured language tasks. Recent studies of word retrieval have attempted to characterize the nature of aphasic naming deficits in light of current models of lexical retrieval. This research has revealed that there are different varieties of naming disorder, with diverse sources of underlying linguistic impairment (Howard & Orchard-Lisle, 1984; Kay 8z Ellis, 1987; Zingeser & Berndt, 1988). Since word-retrieval is a complex cognitive operation (Ellis, 1987), it may be expected that damage to any of the component processes that are required for word This research was carried out by the first author in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Hearing and Speech Sciences, University of Maryland. Support for this project was provided by Grant Number NS21054 from the National Institutes of Health to the University of Maryland School of Medicine. The authors are grateful to the patients and control subjects for their participation, to Charlotte Mitchum for helpful comments on an early version of the paper, and to Maryne C. Glowacki for preparing the manuscript. Reprint requests should be addressed to Rita Sloan Bemdt, Department of Neurology, University of Maryland Medical School, 22 South Greene Street, Baltimore, MD 21201. 14 0093-934x/90 $3.00 Copyright AU rights

0 1990 by Academic Press, Inc. of reproduction in any form reserved.

NOUN

AND VERB RETRIEVAL

15

retrieval may lead to naming difficulties. Examination of the pattern of preserved and impaired language functions in aphasic patients, as well as analysis of error responses, have helped to determine the various functional sources of damage to the word retrieval system (Kohn & Goodglass, 1985; Kay & Ellis, 1987). Detailed studies of naming deficits have led to the identification of a number of factors that may affect the ease and accuracy with which aphasic patients are able to retrieve words. These factors can be characterized as either contextual or lexical/semantic in nature. Contextual factors relate to the circumstances of elicitation of target items. One such factor is the modality of presentation of stimuli, that is, whether items to be named are presented through visual, auditory, or tactile input channels (Spreen, Benton, & Van Allen, 1968; Goodglass & Stuss, 1979). Another contextual variable shown to affect some patients’ naming efforts is the means of elicitation of the target words. Dissociations have been reported between aphasic patients’ production of single word targets and of the same targets in connected speech (Williams & Canter, 1982; Zingeser & Bemdt, 1988). Lexical/semantic factors affecting word retrieval are those that are inherent in the target item itself. For example, frequency of usage of a word has been shown to be a powerful determinant of whether it will be reproduced by aphasic patients (Howes, 1964; Rochford & Williams, 1965). Other lexical/semantic factors affecting word retrieval in some patients include phonological variables, such as word length (Howard, Patterson, Franklin & Orchard-Lisle, 1984), and the semantic category or words (Hart, Berndt, & Caramazza, 1985; Warrington & Shallice, 1984). One important lexical/semantic factor that has been less carefully examined in studies or word retrieval is the syntactic form class of words. Preliminary research has indicated that in one aphasic syndrome, agrammatism, retrieval of grammatical function words may be disproportionately impaired in relation to access to content word vocabulary (de Villiers, 1978; Goodglass, 1976). Within the class of content words, however, dissociations have been reported in the ability of patients to produce nouns and verbs. Agrammatic patients have been noted to demonstrate relatively preserved retrieval of nouns in contrast to markedly impaired verb retrieval for both single word production (McCarthy & Warrington, 1985; Miceli, Silveri, Villa, & Caramazza, 1984) and sentence production (Myerson & Goodglass, 1972; Saffran, Schwartz, & Marin, 1980). In contrast, anemic patients have been occasionally reported to demonstrate the opposite pattern, that of superior verb compared to noun retrieval in naming (Miceli et al., 1984; Zingeser & Bemdt, 1988). The finding that agrammatic aphasic patients have particular difficulty producing verbs has a number of implications. First, it suggests that

16

ZINGESER

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BERNDT

agrammatism, assuming that it can be considered to be a coherent clinical entity, is not adequately characterized as a disorder that arises solely because of difficulties in the processing or representation of grammatical morphemes (Bradley, Garrett, & Zurif, 1980; Kean, 1978). Some other (or additional) deficit must be postulated to account for a limitation in the production of verbs, as well as for other types of structural deficits that occur in patients’ speech (Berndt, 1987; Saffran, Berndt, & Schwartz, 1989; Saffran et al., 1980). A second implication of poor verb retrieval among agrammatic aphasics involves the possibility that this deficit is causally linked to the poor sentence production abilities that characterize this patient group. Saffran and colleagues (1980; see also Saffran, 1982) suggested some time ago that some aspects of the structural problems found in agrammatism might relate to their poor retrieval of verbs and other predicates. Models of sentence production (e.g., Garrett, 1975; Bock, 1987) emphasize the role that the verb plays in the assignment of retrieved lexical items to positions in the syntactic frame; poor access to verbs could cause widespread disruption of the specification of sentence structure during production (see Berndt, in press, for discussion). The notion of a causal link between verb retrieval problems and sentence formulation deficits is supported by the finding that anemic aphasics, who do not typically demonstrate sentence production problems, are facile in the production of verbs (Miceli et al., 1984). Moreover, the finding of better verb than noun retrieval among anomies suggests that the agrammatic patients’ problems do not simply reflect the greater conceptual difficulty of verbs. It might be argued that verbs are more difficult to retrieve, especially in confrontation naming tasks that depict dynamic actions in static pictures, and are thus more susceptible to disruption when the brain is damaged. For this reason, the double dissociation of noun and verb retrieval by agrammatic and anemic patients is an important element in the interpretation of the selective deficit for verbs among agrammatic patients. There are a number of experimental variables that must be controlled in studies of this question. First, many words in English are syntactically ambiguous; that is, they may occur in more than one form class (e.g., “hammer” may be a noun and a verb). Without careful control of this variable, it is impossible to determine actual levels of noun and verb production in tasks that elicit single words. This probem was not encountered in the previous group study on this topic, since that work tested speakers of Italian, a language in which grammatical class is unambiguously marked by an inflection (Miceli et al., 1984). Another variable that must be controlled is frequency of occurrence, which has been shown to have strong effects on lexical retrieval in aphasic patients (e.g., Howes, 1964). Lack of appropriate matching of frequency for nouns and

NOUN AND VERB RETRIEVAL

17

verbs could lead to an erroneous conclusion regarding differences that occur in their production. Finally, previous research has not investigated the effect of contextual factors on patients’ ability to produce nouns and verbs. Although dissociations have been reported in production of the two form classes for spontaneous speech, and for picture naming, no comparison has been made to date of the noun and verb naming abilities of the same patients in different elicitation contexts. Similarly, the effect of visual and auditory presentation modes on noun and verb naming has not been assessed. In the current study, investigation of the relative levels of noun and verb production in agrammatic and anemic aphasic patients was carried out using stimuli controlled for the variables of syntactic ambiguity and frequency of usage. Production was assessedin single word and sentential contexts, and for targets elicited through visual and auditory channels of presentation. METHODS Stimulus Materials Single word elicitafion. Two tasks were developed to assess patients’ ability to produce single noun and verb targets outside a sentence context. For both tasks, form-class unambiguous nouns and verbs were selected from frequency norms (Francis & Kucera, 1982) such that each target had no listing of an alternative form class whose frequency of use was greater than 12% of the target form class. Thirty verb targets were selected, 27 of which had no listed noun usage. Sixty noun targets were identified, 49 of which had no verb usage. For each verb target, one noun was selected to match the verb’s cumulative frequency, and a second noun was selected to match the verb’s base frequency. Members of each triad were also matched for number of syllables. A complete listing of single-word targets, with frequencies, is found in Appendix A. I. Picture Naming. Black and white line drawings were prepared freehand by a professional graphic artist on 9 x I1 paper. Norms for labeling the pictures were obtained from a group of 40 undergraduates at the University of Maryland, College Park, who were tested individually. Pictures were pseudo-randomized within form class blocks, with the two noun sets combined and presented separately from the verbs. Half the control subjects named verbs first, half named nouns first. For noun targets the control subjects were instructed to “tell me what this is.” For verb targets they were instructed to “tell me what action is shown.” For both nouns and verbs, two sample items were presented to establish that subjects understood instructions. No attempt was made to elicit a particular form of the verb; however, most subjects produced the present progressive “-ing” form for all responses. If subjects produced an acceptable but nontarget response they were cued to “tell me another word for it,” and were allowed two further attempts. Acceptable nontargets followed by this cueing included responses that were either approximately synonymous with targets (e.g., “stove” for “oven”), or which were accurate, but nontarget, descriptions of the picture (e.g., “envelope” for “letter”). All pictures elicited targets from more than 90% of subjects. 2. Naming to DQintion. Definitions were formulated for the same verb and noun targets using simplified dictionary entries. Norms were obtained from a different group of 40 students, who were tested as a group with written definitions. All items but two yielded consistent targets (greater than 90%). The two definitions with lower agreement (85%)

18

ZINGESER AND BERNDT

elicited labels that were judged to be unlikely responses from non-student subjects (“study” for “read”), and were retained. Connected speech rusks. Two tasks were administered to allow assessment of relative levels of noun and verb production in connected speech. I. Action description. Four scenarios were identified that would be likely to involve some of the actions and objects described by the target nouns and verbs. These included (1) preparing a birthday cake; (2) going to church or synagogue; (3) getting the house ready for Christmas or other holiday); and (4) attending a concert. For example, description of the “cake” scenario was thought likely to yield the items “read,” “follow,” “melt,” Norms were obtained from “sit, ” “write, ” “decorate,” “bake,” “add,” and/or “buy.” a new group of 20 students, who were tested individually. Subjects were asked to tell how they would carry out each of the activities. All descriptions were tape recorded and transcribed. Number of subjects producing each of the target verb items was calculated for each activity. Seventeen verbs of the total 30 target verbs selected for the single word tasks were produced by more than one subject in the normative group. All four scenarios yielded high levels of consistent target production, with 7 to 13 targets for each scenario produced by more than one subject, and 4 to 7 items for each scenario produced by 2090% of subjects. 2. Story-narration tusk. To obtain a larger sample of cohesive narrative, subjects were asked to recount a well-known fairy tale. The elicitation procedures developed by Saffran et al. (1989) were followed. That is, subject’s memories of the story were refreshed as needed by looking at a picture book of the fairy tale with the words obliterated, but the elicitation occurred without pictures present. Examiner comments were kept to a minimum.

Procedures Testing on all tasks was completed in three sessions, lasting approximately 1 hr for aphasic patients and half an hour for controls. Testing sessions were held 7-10 days apart, with no more than 3 weeks elapsing for administration of the entire test battery for any individual. Order of presentation of tasks was the same for all subjects, and was designed to minimize the effects of repeated exposure to the same stimuli. Since the Picture Naming task and the Naming to Definitions task employed the same verb and noun targets, task blocking was designed to ensure that no stimulus was elicited more than once in a single session. Thus, all presentations of a partiuclar target item were separated by at least one session. Verb elicitation for Pictures and Definitions was separated by two sessions. In cases where nouns were to be elicited for both Pictures and Definitions in a single session, different split-halves (odd vs. even numbered items) of the noun list were used. Thus, the order of tasks used was as follows: Session 1: (a) Story Narration (b) One-Half Noun Definitions-Even items (c) Verb Pictures Session 2: (a) One-Half Noun Pictures-Even items (b) One-Half Noun Definitions-Odd items (c) Elicitation of Action Description Session 3: (a) One-Half Noun Pictures--Odd items (b) Verb Definitions Order of presentation of items within tasks was constant across patients. No time limits were imposed.

Subjects Ten aphasic patients and five normal control subjects were tested. Patients ranged in age from 45 to 79 years of age and had a minimum of 10 years of education. None had a history of drug or alcohol abuse, or of hospitalization for psychiatric disorder. All had

NOUN AND VERB RETRIEVAL

19

adequate vision for picture analysis, as assessed by self-report and administration of a standard naming test and of the Raven’s Coloured Progressive Matrices (Raven, 1962). No subject had a hearing disorder severe enough to interfere with comprehension of conversation. All subjects were native speakers of English, and showed no functional signs of a generalized dementia. Aphasic patients were at least 3 months postonset. All were either in-patients at a rehabilitation hospital or living at home. They had received varying amounts of speech therapy. None presented with a severe articulation deficit, defined here as production of more than 1 unintelligible word out of 10 produced. Functionally good auditory comprehension was assured for all patients by their aphasia classification (see below), and by clinically adequate understanding of conversation. Further information concerning patients and controls is found in Table I. Patients were classified through administration of the Boston Diagnostic Aphasia Examination (BDAE; Goodglass & Kaplan, 1972)and the Boston Naming Test (BNT; Kaplan, Goodglass, & Weintraub, 1978). All patients were tested on standard tests less than 1 month prior to initiation of experimental testing. Five agrammatic patients were initially classified as Broca’s aphasics on the BDAE, and all showed at least some of the following symptoms of agrammatism in their spontaneous speech: restricted use of grammatical morphemes, including verb inflections, noun determiners, pronouns, prepositions, auxiliary and modal verbs; restricted sentence length; and/or structural syntactic problems. No attempt was made to select patients according to specific patterns or degrees of agrammatism. The five anemic patients were so classified by the BDAE, and they also scored less than 48/60 on the Boston Naming Test (3 standard deviations below the mean for adults aged 50-55). Five normal controls were matched to the age and education levels of patients by the group means and ranges. All controls were in good health with no history of central nervous system disease. The Raven’s Coloured Progressive Matrices were administered to all patients and controls to assure that no significant differences existed between aphasic groups in nonverbal cognitive performance, or in visual analysis and reasoning abilities. Scores for the patient groups show similar means and ranges (agrammatic group mean = 20.4/36, range 15-31; anemic group mean = 21.4/36, range 17-27; means for both groups are at the 25th percentile for subjects 65 years old). Normal subjects obtained a mean score of 31.6/36 (90th percentile).

RESULTS Scoring Criteria Single word elicitation tasks. Final responses were used for scoring when produced spontaneously as a single response or through self-correction, or after cuing (“is there another word?“). The final response was also used for scoring if the subject produced a sequence of more than one response. The single exception to scoring the final response occurred when the subject produced the target item as a nonterminal element in a sequence ending with an acceptable alternate (e.g., “buy . . . pay”); this type of production was not cued, and the response was scored as correct. If the subject produced the target as a nonterminal element in a string ending with an incorrect word (e.g., “buy . . . sell”), the response was scored as incorrect. Connected speech tasks. After transcription of each subject’s samples

?/73

Keypunch operator

11

3/42

F

AT

2169

Government analyst

18

12/08

M

JS

a/73

Secretary

14

7/29

F

LR

7185

Government loan officer

Onset

18

l/34

M

TM

12

Occupation 10/81

M

Agrammatic FM

Education Truck driver

11143

Sex

Group

Date of birth

TABLE 1 PATIENT/SUBJECT INFORMATION

CT: L. internal carotid occlusion; posterior inferior frontal and temporal/parietal involvement (occlusive CVA) Neurological exam: L. middle cerebral artery infarction (occlusive CVA) Neurological exam: L. middle cerebral artery infarction (occlusive CVA) Brain scan: Decreased activity in L. middle cerebral artery distribution (occlusive CVA) CT; Large area of involvement, L. frontal, temporal, parietal lobes (intracerebral hemorrhage)

Localizing information

15136

21/36

26/36

28136

31136

Raven’s Matrices Score

E

%

i

8 si

fz

M

M

M

M

F

Anemic HY

Jst

GW

RS

KH

10120

2/37

3/24

9/29

l/15

Store manager

Real estate sales

12

Architect

Security guard

16

12

Businessman

l/87

12119

10/87

7/86

12/81

MRI: Posterior cerebral artery; involvement of L. temporal occipital lobes and part of inferior parietal lobule (intracerebral hemorrhage) CT: Large area of involvement; L. frontotemporal areas, possibly into putamen (intracerebral hemorrhage) Angiogram: L. anterior communicating artery aneurysm CT: periventricular L. involvement; small R. mesial-frontal infarct (L. intracerebral hemorrhage) CT: Bullet entered R. occipital area; lodged behind frontal inner table near midline (gunshot wound) CT: deep L. temporal lobe lucency 3-4 cm. large; ill-defined temporo-parietal lucency (occlusive CVA) 22136

17/36

22136

z

Sex

F F F F F

Group

Controls EC FL EH PK MD

1913 1937 1936 1928 1931

Date of birth 12 12 18 16 12

Education Housewife Bookkeeper Social worker Sales person Secretary

Occupation

TABLE l-Continued

-

Onset

-

Localizing information

30136 33136 32136 34136 29136

Raven’s Matrices Score

E

E E 3

8

5 g g

23

NOUN AND VERB RETRIEVAL

for each task, occurrences of all nouns and verbs (targets and all others) were counted. In the case of ambiguous form class (for example, “run” occurring alone), the form class of the first listing in the dictionary (American Heritage, 1978 edition), was taken as the intended form class. Two calculations were made from these counts for the Action Description task-noun/verb ratio and number of target verbs/total verbs. Noun/verb ratio was also calculated for the Story Narration task. Single Word Tasks

Two nouns had been frequency-matched to each verb (to cumulative and to base frequencies) to ensure that any noun/verb differences obtained were not attributable to frequency of use. An inspection of the mean number correct for the two noun lists revealed nearly identical values for the two lists, and t tests confirmed that the difference between the two noun list means was not statistically significant (I = 1.63, p = .178 for pictures; t = -.53, p = .621 for definitions). For all subsequent analyses, therefore, the mean of the two noun lists was used as the score for noun stimuli. Table 2 shows the mean proportion of nouns and verbs that was correctly produced by the patient groups in the two single word elicitation tasks. Control subjects performed near ceiling levels. Raw scores for individual subjects are contained in Appendix B. A three-factor mixed analysis of variance was carried out with patient group as a between subjects factor, and form class and modality of presentation as repeated measures factors. There was no main effect of group (nl, 81 = 3.31, p = .l l), but there were reliable effects for both form class (E;11, 81 = 9.62, p = .Ol) and presentation modality (fll, 81 = 180.72, p < .OOl). These results indicate that, overall, verbs were more difficult than nouns, and naming pictures was easier than producing names to definition. In addition, all two-way interactions were significant (group x form class, fll, 8] = 59.59, p < .OOl; group x modality, fll, 81 = 48.87, p < .OOl; form class x modality, F[l, 81 = 13.94, p = TABLE 2 F’ROP~RTION OF NOUNS AND VERBS CORRECTLY PRODUCED IN Two SINGLE ELICITATION TASKS BY ACRAMMATIC AND ANOMIC APHASICS

Picture naming Group” Agrammatic Anemic a N = S/group.

WORO

Naming from definition

Nouns (N = 60)

Verbs (N = 30)

Nouns (N = 60)

Verbs (N = 30)

35 30

.57 30

.63 .67

.41 35

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.006). The interaction of group x form class x modality did not reach significance (F[l, 81 = 4.39, p = .07). Planned comparisons (using t tests) showed that there was no difference between the groups in the number of nouns produced either to pictures or to definitions (both ps > S), but agrammatic patients produced significantly fewer verbs than did anemic patients in response to both pictures (p = .03) and definitions (p = .0004). The difference between the number of nouns and verbs produced by agrammatic patients was significant both for pictures @ = .002) and definitions (p = .002), while the difference for anemic aphasics (favoring verbs) was significant only for definitions (p = .OOOl). In summary, results of the single word elicitation tasks for carefully matched noun and verb targets replicate results previously reported for Italian-speaking agrammatic aphasics (Miceli et al., 1984): verb production is significantly impaired relative to noun production. This finding holds to some extent for all patients in the group regardless of whether targets are elicited through picture naming or by definitions (see Appendix B). Further, anemic aphasics produced an opposite result: they are significantly more facile in producing verbs than nouns, at least in the more difficult (for them) naming to definitions task. All anemic patients produced more verbs than nouns in that task, although two patients produced more nouns than verbs to pictures. Thus, although results for anemic aphasics are not entirely uniform, they are generally consistent with the findings of previous studies. Noun/Verb Production, Connected Speech Tasks Two indices were calculated for the Action Description task, using the scoring criteria set out above. The ratio of nouns to verbs produced was tabulated for comparison to the noun/verb differences found in the single word tasks. The ratio of target verbs to total verbs was also calculated as an index of the variety of verbs that was elicited beyond those that had been target items in the single word task. Group means for both measures are shown in Table 3; individual subject data can be found in Appendix C. Transcriptions of a sample of each aphasic patients’ productions are in Appendix D. A log transformation was carried out on each of these measures, which were then subjected to a one-way ANOVA, followed by t tests to deTABLE GROUP MEANS (AND STANDARD

DEVIATIONS)

Group

Noun/Verb

Agrammatic Anemic Control

2.08 (1.36) .74 ( .12) .93 ( .12)

3 ON THE ACTION

DESCRIFIION

TASK

Target verbs/Total .21 (.15) .08 (.05) .08 (.03)

verbs

NOUN

25

AND VERB RETRIEVAL

termine group constrasts. The control group data were included in this analysis, since ceiling effects were not an issue for these measures. The groups differed significantly on noun/verb ratio (F[2, 121 = 6.22, p = .014), with agrammatic patients differing significantly from each of the other two groups @ < .05). There was no reliable difference between anemic aphasics and control subjects on this measure @ > .05). Although there was a trend in the direction of agrammatic aphasics’ verb productions containing a larger proportion of target verbs than did the other groups’, this difference was only marginally significant (F[2, 121 = 3.81, p = .0524). It can be noted in the individual subject data in Appendix C that one patient in the agrammatic group (LR) produced four times as many nouns as verbs in this task, while almost half the verbs she did produce were target verbs. Noun/verb ratios were also calculated for the Story Narration task. Scores for individual subjects on this measure, which demonstrate some variability, are also shown in Appendix C. One-way analysis of variance documented a significant group effect (E;12,121 = 9.10, p = .0039), with planned comparisons showing reliable differences between agrammatics and each of the other two groups @ < .05), but no difference between anomies and controls (p > .05). DISCUSSION

These results replicate and extend to English-speaking patients the findings of Miceli et al. (1984) that agrammatic and anemic aphasics demonstrate different patterns of relatively selective difficulty with retrieval of nouns and verbs. When frequency and length are controlled, agrammatic patients find it more difficult to name actions than objects, while anemic patients under some conditions show an opposite effect. All individual agrammatic patients showed the pattern of superior noun to verb production when naming from pictures and definitions. For the

PICTURE

NAMING

NAMING

TO DEFINTTION

ACTION DEBCRIPTION

0

2

1 NOUN/VERB

RATIO

FIG. 1. Comparison of noun/verb ratios for agrammatic patients, anemic patients, and normal controls on four production tasks.

26

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anemic group, the pattern was somewhat less clear. All anon-tic patients except JSt showed either a superiority of verbs relative to nouns or a lack of marked difference between nouns and verbs. The lack of difference between form classes noted for several of the anemic patients for picture naming (GW, RS, KH) may be attributable to their performance at near-ceiling levels for both noun and verb lists. For Definitions, where overall performance did not approach ceiling, all anemic patients showed a superiority of verb over noun production. Most importantly, however, was the absence of any trend for anemic aphasic patients to find verbs more difficult than nouns (see Fig. 1). This finding indicates that the result for agrammatic patients does not reflect the greater conceptual difficulty of retrieving verb labels in the tasks employed. Pictures were, in general, easier to name than definitions, for both actions and objects. This was true for each individual aphasic patient, as well as for the patient groups overall, while the control subjects were at ceiling in both modalities. The strength of this effect demonstrates the importance of examining production of words in both modalities for all patients. This finding also supports results of earlier studies by Barton, Maruszewski, and Urrea (1971) and by Goodglass and Stuss (1979) that, in general, naming of pictures is easier for aphasic patients than naming aurally presented descriptions. However, this has not until now been shown to be true for pictures of actions, which might be conceptually more difficult to interpret than pictures of objects. The consistency of agrammatic patients’ action naming impairment across pictures and definitions suggest that relative difficulty retrieving verbs is not caused by difficulty interpreting static pictures of dynamic events. The findings of this study that reliable differences in noun and verb retrieval exist in the naming performance of agrammatic and anemic aphasic patients suggest that the selective involvement in aphasia of words within a particular grammatical class extend beyond the rough division between content and function words. Models of lexical representation typically include form class information as a basic component of each entry’s listing; it may be that such representational distinctions within the lexicon are honored by the neural architecture. Another possibility is that the processes required to gain access to nouns and verbs in the lexicon may differ in principled ways. For example, the important role of the verb in sentence formulation and interpretation might require that some syntactic properties of verbs are retrieved whenever the lexical form of the verb is retrieved (i.e., even in naming tasks). Deficits that involve those syntactic properties in some way could selectively undermine verb retrieval. Such an account requires that the better production of verbs than nouns by anemic aphasics reflects an enhancement of retrieval abilities for verbs relative to nouns as a result of intact syntactic processes (see Zingeser & Berndt, 1988, for speculation along these lines).

NOUN

AND VERB RETRIEVAL

27

It is also possible, however, that the dissociation found between noun and verb production does not reflect lexical or syntactic factors, but is the result of a semantic category-specific deficit. In single word tasks, verbs were elicited by presenting pictures or definitions of actions, while nouns were elicited by presenting pictures or definitions of objects. The deficits demonstrated, then, might reflect selective difficulty producing labels for the semantic categories of actions and objects. This is the view taken by McCarthy and JVarrington (1985) who argued that a categoryspecific degradation of the meaning of the class of action words was responsible for the difficulty experienced by the agrammatic patient they studied in the production of verbs in naming and in spontaneous speech. This view is given theoretical support by some traditional views of the grammar in which form class information is characterized chiefly in terms of semantic properties (Lyons, 1966). It is not possible to rule out an underlying semantic category-specific deficit without determining whether the impairments in verb or noun retrieval found in this study would extend to verbs that are not actions kg., “think”) and nouns that are not objects (e.g., “idea”). Further assessment of the general integrity of the semantic system of each aphasic patient would also help to decide this issue, since semantic category deficits are defined by patterns of impaired and preserved categories (see Berndt, 1988, for review). Another consideration relevant to determining whether noun/verb dissociations represent syntactic or semantic deficits is the relationship of verb retrieval to sentence production. The group effects that have been reported previously and replicated here suggest a possible causal relationship between verb retrieval and sentence production, which, if supported, would favor a form class basis for verb retrieval problems. Recent modifications to Garrett’s (1975) model of sentence production have provided some suggestions as to how such an influence might work (Bock, 1987; Dell, 1986). Following recent trends in linguistic theory that have tended to place more emphasis on the information carried by specific lexical items in the formulation of sentences, Bock (1987) has considered the retrieval of the verb to be one of the primary events that determines how other sentence structural elements will evolve during production. Unlike the earlier model (Garrett, 1975) in which a set of processes mediated between levels of representation expressing functional relationships among entities (who does what to whom) and grammatical relationships (subject, object), Bock assumes that information about how functional and grammatical relationships map onto one another is part of the information contained in the verb’s lexical representation. Once the verb and the sentence subject are retrieved, there are automatic consequences about the structure that the sentence will take. In addition, Bock has produced a series of experimental results demonstrating consistent effects of the accessibility of specific words on subjects’ produc-

28

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tion of different syntactic structures. Within this framework, there are a variety of ways that the relative inability to retrieve verbs could affect the production of sentence structures. Although these possibilities are of considerable interest for theoretical as well as clinical reasons, it is no easy matter to demonstrate unambiguously that such a causal relationship exists. Inspection of individual patient data from the present study, in fact, suggests that the nature of the relationship between verb retrieval and sentence production may be complicated indeed. For one agrammatic patient, TM, it appears that the ability to produce other aspects of sentences may be aiding verb retrieval, since noun/verb ratio was much closer to normal levels in connected speech than in tasks of single word production. In contrast, FM and LR seem if anything to be disadvantaged in verb retrieval by the necessity of producing the verb within a syntactic frame, since verb retrieval was much better in single word tasks than in connected speech. It is difficult to postulate a unitary explanation for the verb retrieval deficits of “agrammatic” patients that could accommodate both of these patterns. In fact, the development of a coherent explanation for associations of symptoms involving lexical retrieval and sentence production would seem to require detailed investigation of the structural abilities of individual patients with differing ability to retrieve nouns and verbs. Several studies along these lines are currently in progress. APPENDIX NOUN/VERB

Verb write follow sit carry add read buy teach hang listen eat sing shoot sell swim pour beg dig melt Pray

Frequency Cumulative/Base 561/106 540197 314166 304/88 291/88 274/89 162/68 153141 131126 123/50 122/58 120/27 117/26 108139 55110, 48/7 34/11 32/9 32/4 30112

NAMING

A

TASK ORGANIZED

BY VERB FREQUENCY

Noun (matched to cumulative) eye city door office book road club dog bed letter leg ball sun yard shoe milk belt leaf tail shirt

524 521 348 301 292 262 178 147 139 260 126 123 117 100 58 49 36 33 31 29

Noun (matched to base) mouth doctor desk bridge knife glass chair moon cow wagon tree fence bird bread fox sword bee mouse badge egg

103 87 65 79 72 96 64 46 28 52 56 30 25 40 9 6 10 9 5 12

29

NOUN AND VERB RETRIEVAL APPENDIX-Continued shave bleed sew bake rob rip drown lick bow decorate spill sharpen erase

bell rope pie vase ghost deer cane globe trunk violin crib oven robot

2316 1812 18/4 15/3 1512 14/5 1413 1413 1313 1212 9/t 7/l 5/l

ant broom thorn clown owl witch raft skull noose butterfly crutch carrot camel

23 19 19 15 16 13 13 14 13 13 8 8 4

6 2 3 3 2 5 3 3 3 2 1 1 I

APPENDIX B RAW SCORES, MEANS,

AND STANDARD

DEVIATIONS

FOR SINGLE WORD TASKS

Tasks Pictures Nouns 1

Nouns 2

30 27 19 27 26 25.8 4.09

30 26 19 27 25 25.4 4.04

19 15 14 18 20 17.2 2.59

17 22 25 26 30 24 4.85

17 22 25 26 30 24 4.85

30 30 30 29 30 29.8 0.45

30 29 30 30 30 29.8 0.45

Group Agrammatic FM TM LR JS AT Mean = SD

Anemic HY JSt GW RS KH Mean = SD

Control EF FL EH PK MD Mean = SD

Definitions Verbs Nouns I (N = 30 each)

Nouns 2

Verbs

21 20 13 18 21 18.6 3.36

27 20 11 20 19 19.4 5.68

14 12 9 13 14 12.4 2.07

21 16 26 28 29 24 5.43

16 14 21 22 28 20.2 5.50

15 11 22 23 18 19.8 6.76

21 20 28 28 30 25.4 4.56

29 28 30 30 30 29.4 0.89

29 30 29 30 30 29.6 0.55

30 29 30 29 30 29.6 0.55

30 29 30 30 30 29.4 0.55

30

ZINGESER AND BERNDT APPENDIX C INDIVIDUAL

SUBJECT DATA,

NOUN/VERB

Single word

Agrammatic FM TM LR JS AT Anemic HY JSt RS GW KH Control EC FL EH PK MD

RATIO FOR ALL

TASKS

Connected speech

Pictures”

Definitions

1.58 1.77 1.36 1.50 1.28

1.71 1.67 1.33 1.46 1.43

2.45 (.ll) .93 (.20) 4.29 (.47) 1.22 (.14) 1.52 (.14)

4.06 27 3.50 2.70 1.68

.81 1.38 .% .93 1.03

.74 .63 .77 .80 .77

.85 (.09) .71 (.07) .86 (. 15) .57 (do) .72 (07)

A4 1.03 .89 .97 .79

1.03 1.05 1.00 .98 1.00

.98 1.02 .98 .98 .77

.86 (.07) .95 (39) 90 (.06) 1.13 (13) .82 (46)

.86 1.18 .79 1.50 .82

Action Description Stories (Target verb/Total verbs)

a The mean number correct for two 30-item noun lists was used as the numerator of the ratio. APPENDIX D SAMPLE OF PATIENTS’

FM TM LR JS AT

HY

REWJNSES

IN ACTION

DESCRIPTION TASKS (CHRISTMAS)

Agrammatic patients Christmas . . . me and Priscilla and kids (2 set) outside is (4 set) lights outside and uh bulbs outside in the window (2 set) inside (2 set) Christmas tree (2 set) cards uh cards many people me and you everybody I went I went to to Christmas (5 set) I went to Christmas (2 set) party no I went to uh (5 set) tree . . . tree . . up the (3 set) I went to (13 set) I want to (6 set) the Christmas tree was up Early Christmas eve (6 set) package lots of package and uh for Christmas and toys and tree large tree (3 set) lots of food . . . buy the package but oh the store and uh pies or something Christmas pie but uh singing carols I’m cold and uh Christmas (3 set) uh I’m fix the Christmas and and I’m going to uh (3 set) (unintelligible) Christmas no I’m money the man uh (10 set) I’m uh the Christmas uh bell All the family and urn I decorate it balls and ornaments and balls and urn family help . . . decorate it I clean the whole house on it and upstairs I urn I fix the bed and urn all the things I do Anemic patients Well we usually go out and buy things that we’re gonna give away as gifts and we hide ‘em (3 set) and uh we make sure there’s plenty food in the house to eat ‘specially Christmas things we buy all kinds of food and uh candy (7 set) and things to give away

NOUN AND VERB RETRIEVAL

31

APPENDIX-Conrinued JSt

GW

RS

KH

Well my wife and I we are together and joining . . . the house . . . of beautifying it by starting to . . . cobweb and then we start to (2 set) wash down all the clothes and then then uh (3 set) she got the dust and vacuum and all the things are right Well the first thing we do is clean up real good and then we would oh (3 set) go out in the (2 set) and hunt around for a good Christmas tree . . a good well-shaped Christmas tree and uh (6 set) we would then bring it in if it’s time for it to set it up (3 set) and we would decorate it Well uh the Christian people around Christmas time they of course the house is usually pretty clean and then they bring bring a Christmas tree in the house and they decorate the Christmas tree with all types of uh ornaments and all lights and so forth We we start thinking about Christmas cards . . we may have been shopping before Thanksgiving I start thinking about cleaning what I’m gonna do what I have to do in the house getting my decorations up and urn at the shop and whether I’m going to be cooking at home

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