The noun-verb problem in Chinese aphasia.

Previous studies have shown that Broca's aphasics experience a selective difficulty with action naming inside or outside of a sentence context. Conversely, it has been suggested that Wernicke's aphasics are particularly impaired in object naming. A number of explanations have been offered to account for this double dissociation, including grammatical accounts according to which the main verb problem in agrammatic Broca's aphasics is viewed as a by-product of their syntactic and/or morphological impairment, due perhaps to the greater morphological load carried by verbs (compared with nouns). In the Chinese language, there are no verb conjugations and no declensions. Hence there is no reason to expect a relationship between morphological impairment and deficits in action naming. We examined comprehension and production of object and action names, outside of a sentence context, in a sample of Chinese-speaking Broca's and Wernicke's aphasics. There was an interaction between patient group and object/action naming, but no corresponding interaction on the comprehension task. We conclude that action-naming deficits in Broca's aphasia (and/or the corresponding sparing of action names in Wernicke's aphasia) cannot be attributed to morphological differences between nouns and verbs. We also found a sublexical variant of the noun/verb dissociation applied to the internal structure of compound words made up of a verbal and a nominal element: Broca's aphasics tended to lexicalize the verbal portion of these words more often than the nominal compound, while Wernicke's showed the opposite pattern. These sublexical effects are difficult to explain in syntactic terms nor do they fit the standard lexical view. A modified lexical account is proposed, emphasizing semantic/conceptual effects in a distributed lexicon.     

Aphasic adults' understanding of complex adverbial sentences

Twelve aphasics with relatively preserved auditory comprehension were tested for their understanding of four adverbial sentence types expressing the temporal order of events. The relative effects of order of mention, adverbial choice, and adverbial clause placement on subjects' comprehension were investigated. Only adverbial choice was significant with aphasics producing more errors of temporal order on after than before sentences. Subjects' error patterns were not similar to those of children acquiring language. The results are discussed with respect to the theory of lexical marking and the regression hypothesis.     

Agrammatic production of subject-verb agreement: the effect of conceptual number.

Three experiments tested the hypothesis that the deficit underlying agrammatic sentence production difficulties can be characterized as a limitation of computational resources and that these resources are not restricted to syntactic processing. This hypothesis was tested by eliciting subject-verb agreement errors in a sentence fragment completion paradigm. Sentence fragments were complex noun phrases, containing a subject (head) noun and a modifying prepositional phrase, containing a "local" noun. We varied the number of "tokens" a singular head noun referred to. Therefore, in one condition, grammatical and conceptual number of the head noun mismatched, whereas these numbers were the same in another condition. In Experiments 1 and 2, we observed an effect of this variable (i.e., more agreement errors when conceptual number was plural and grammatical number singular) in normal controls. Broca's aphasics, on the other hand, showed no effect. Experiment 3 consisted of a sentence/picture matching test. This test showed that the lack of effect with Broca's aphasics cannot be attributed to a comprehension deficit. We argue that these results are incompatible with the notion of a limitation in resources specific for syntactic processing. Instead, we interpret this as the result of a trade-off: Broca's aphasics lack computational resources to take into account both grammatical and conceptual information in morphosyntactic processing and rely on grammatical information only.     

Syntactic frame and verb bias in aphasia: plausibility judgments of undergoer-subject sentences

This study investigates three factors that have been argued to define "canonical form" in sentence comprehension: Syntactic structure, semantic role, and frequency of usage. We first examine the claim that sentences containing unaccusative verbs present difficulties analogous to those of passive sentences. Using a plausibility judgment task, we show that a mixed group of aphasics performed significantly better on unaccusatives than on passives. We then turn to the observation that passives are generally harder than actives for aphasics. We show that this effect is modulated by lexical bias, i.e., the likelihood that a verb appears in a given syntactic structure: Passives of passive-bias verbs were significantly easier than passives of active-bias verbs. More generally, sentences whose structure matches the lexical bias of the main verb are significantly easier than sentences in which structure and lexical bias do not match. These findings suggest that "canonical form" reflects frequency and lexical biases.     

Reconstructing from a degraded trace: A study of sentence repetition in agrammatism

Six agrammatic aphasics repeated simple active and passive voice sentences, varying in degree of semantic constraint: plausible, reversible, and implausible. Frequency of correct response was not sensitive to this semantic manipulation, but error pattern was. In general, errors to plausible targets consisted of relatively inconsequential transformation of the open or closed class vocabulary, while errors to implausible targets implicated a change of syntactic voice. In making these errors, the patients displayed evidence of productive control of the passive morphology and a degree of sensitivity to the syntactic and thematic consequences consequences of passive voice. The repetition errors did not transform the surface order of the major lexical items. The results are interpreted as evidence for a sentence memory trace that preserves, minimally, the major grammatical roles of the target sentence and that serves as input to a reconstructive process that is biased toward the production of semantically plausible sentences.     

Some aspects of language comprehension in anterior aphasia

The competency of language comprehension was evaluated in three groups: anterior aphasics, posterior aphasics, and normal control subjects. Test material was divided into two sentence groups (Fill in the Blank and True/False) emphasizing either (1) semantic, “real world,” identity words or (2) syntactic, relational words, and one paragraph interpretation task. Matching auditory and visual (written) presentations were given. The control subjects performed almost flawlessly but many errors were made by each aphasia group. Qualitative study revealed a marked difference in the comprehension problem of the two groups. The anterior aphasic group performed well on semantically weighted sentences but made errors on syntactically weighted material, regardless of mode of presentation. In contrast, the posterior aphasics made almost the same number of errors on both types of material, regardless of mode of presentation. These findings support the concept of defective language comprehension in anterior aphasia and further suggest that the defect centers on the syntactical structures which are also poorly handled in expressive output.     

Comprehension of sentences with stylistic inversion by French aphasic patients

Three French-speaking agrammatic aphasics and three French-speaking Conduction aphasics were tested for comprehension of Active, Passive, Cleft-Subject, Cleft-Object, and Cleft-Object sentences with Stylistic Inversion using an object manipulation test. The agrammatic patients consistently reversed thematic roles in the latter sentence type, and the Conduction aphasics performed at chance. The results are discussed in relationship to existing models of aphasic impairments in assigning syntactic structures and using them to determine thematic roles in sentences. We conclude that the results for the agrammatic patients demonstrate the importance of compensatory mechanisms underlying aphasic comprehension and the results in the Conduction aphasics indicate the importance of working memory deficits in determining such deficits. The results are also relevant to models of normal syntactic structure.     

Syntactic priming effects in aphasia: an investigation of local syntactic dependencies

This study explored on-line processing of local syntactic dependencies in normal subjects and in Broca's and Wernicke's aphasics using a lexical decision paradigm. In addition, subjects performed a grammatically judgement task on the real word pairs used in the lexical decision tasks. Results of two experiments for normal subjects indicated different syntactic priming effects as a function of the type of local syntactic dependency. Word pairs that formed a single constituent phrase, i.e., a verb phrase, showed both facilitory and inhibitory effects, whereas word pairs that reflected local syntactic dependencies across a phrase boundary, i.e., pronoun verb, showed only inhibitory effects. Broca's aphasics failed to show facilitory effects when presented with word pairs forming a single constituent phrase but, similar to normals, did show inhibition when presented with word pairs that reflected local syntactic dependencies across a phrase boundary. In contrast, Wernicke's aphasics failed to show inhibitory effects in both experiments. The implications of these results for theories of language processing deficits in aphasia are considered.     

Contrasting effects of phonological priming in aphasic word production

Two fluent aphasics, IG and GL, performed a phonological priming task in which they repeated an auditory prime then named a target picture. The two patients both had selective deficits in word production: they were at or near ceiling on lexical comprehension tasks, but were significantly impaired in picture naming. IG's naming errors included both semantic and phonemic paraphasias, as well as failures to respond, whereas GL's errors were mainly phonemic and formal paraphasias. The two patients responded very differently to phonological priming: IG's naming was facilitated (both accuracy and speed) only by begin-related primes (e.g. ferry-feather), whereas GL benefited significantly only from end-related primes (e.g. brother-feather), showing no more than a facilitatory trend with begin-related primes. We interpret these results within a two-stage model of word production, in which begin-related and end-related primes are said to operate at different stages. We then discuss implications for models of normal and aphasic word production in general and particularly with respect to sequential aspects of the phonological encoding process.     

Agrammatic Broca's aphasia is not associated with a single pattern of comprehension performance

One influential hypothesis posits that the brain regions implicated in Broca's aphasia are responsible for specific syntactic operations that are necessary for the comprehension and production of sentences (Grodzinsky, 1986, 1990, in press). The empirical basis of this hypothesis is the claim that Broca's aphasics have no difficulty understanding sentences in the active voice (and other "canonical" sentence types, such as subject relatives and clefts with negative predicates), but perform at chance level with passive voice constructions (and other "noncanonical" sentences such as object-gap relatives and object clefts). In the face of well-established results indicating that Broca's aphasics can exhibit several different performance patterns on these sentence types, Grodzinsky, Pi?ango, Zurif, and Drai (1999) argued that these conflicting results do not challenge the theory when the data are analyzed appropriately. They carried out a creative statistical analysis of the comprehension performance of published cases of Broca's aphasia and concluded that all of these cases are in agreement with the predicted pattern: chance on passives and 100% correct on actives. Here we show that the statistical reasoning adopted by Grodzinsky et al. (1999) is flawed. We also show that the comprehension performance of a substantial number of the Broca's aphasics in their own sample does not conform to the pattern required. Rather, contrary to these authors' claim, Broca's aphasia is not associated with a consistent pattern of sentence comprehension performance, but allows for a number of distinct patterns in different patients.     

Selective word-learning deficits in aphasia

The purpose of this study was to determine whether patients with focal brain damage can learn anything about a new word, and if so, whether selected aspects of the new word are acquired depending on the nature of the patient's language processing deficit. In the context of drawing pictures with a number of felt pens identical in all respects except color, agrammatic Broca's aphasics and fluent aphasics were exposed to the new word "bice," an adjective referring to the dark green portion of the color spectrum. Our findings revealed that brain-damaged patients can engage in lexical acquisition, but Broca's aphasics and fluent aphasics apparently learn about different aspects of the new word. Specifically, on successive exposures to "bice," both Broca's aphasics and fluent aphasics exhibit progressively more accurate hypotheses for identifying a bice-colored object. During subsequent assessments, agrammatic aphasics reveal on a metalinguistic judgment task their significant difficulty appreciating the grammatical form class of "bice"; on an object classification task, fluent aphasics are significantly impaired in their classification of bice-colored objects as "bice." Taken together, these unique word-learning profiles reinforce earlier observation on the selective nature of language processing deficits after focal left-hemisphere insult, and support the claim that separate language processing devices may be selectively compromised in different groups of aphasics. The relationship between syntactic and lexical semantic processing is discussed.     

Sentence comprehension and working memory limitation in aphasia: a dissociation between semantic-syntactic and phonological reactivation

The relation between working memory (WM) limitation and sentence comprehension was assessed in Hebrew-speaking aphasics, three conduction aphasics and three agrammatics. The study compared sentences that required different types of reactivation-syntactic-semantic reactivation, in relative clauses, and word form/phonological reactivation, in sentences with reanalysis of lexical ambiguity. The effect of phonological memory load, manipulated by number of words intervening between the activation and the reactivation, on comprehension of the two sentence types was examined. The findings were that agrammatic aphasics failed in the comprehension of object relatives but not on subject relatives irrespective of their antecedent-gap distance. Conduction aphasics, on the other hand, who showed severe WM limitation, comprehended well all types of relative clauses and were unaffected by antecedent-gap distance. The conduction aphasics failed to understand the sentences that required phonological reactivation when the phonological distance was long. These results suggest that the type of reactivation required by the sentence, as well as the type of memory overload are crucial in determining the effect of WM limitation on sentence comprehension.     

Recognition deficits resulting from focussed attention in aphasia

Summary Two nonverbal short-term memory tasks, a Picture Recognition and a Paired Association Task, were performed by matched groups of aphasics and brain-damaged controls (N=52 each). For both tasks the alternatives on the answer forms differed systematically on three dimensions, one of which had been highlighted experimentally for each item before the target picture was indicated. In both tasks aphasics made more errors than braindamaged controls only with respect to those features that had been stressed beforehand; they were less able than controls to take advantage of focussed attention. The number of these errors was correlated with performance in the Token Test, a picture naming and a word comprehension task.There were no differences between the groups in response to variations in the semantic saliency of the discriminating features or in the semantic and phonetic relationship between words denoting the reference stimuli. The lack of interactions might have been due to a strong ceiling effect in both tasks.     

Lexical knowledge in anterior and posterior aphasics

A semantic categorization task was used to assess the structure of lexical knowledge in anterior and posterior aphasics. In general responses were faster for typical category members than for atypical ones and slower for semantically related nonmembers than for unrelated ones. Both groups performed at a high level of accuracy when classifying typical category members and semantically unrelated nonmembers. Their performance diverged at the category boundary. Anterior aphasics maintained relatively high levels of accuracy when classifying atypical category members and semantically related nonmembers while posterior aphasics did not. These results point to differences in the status of lexical knowledge for anterior and posterior aphasics.     

Reading and listening comprehension in Broca's aphasia: Lexical versus syntactical errors

Ten agrammatic Broca's aphasics were presented with a series of four picture plates together with a spoken or written sentence stimulus. All sentence stimuli were of the structure, the + N + is/are + V + ing + the + N. The four pictures on each stimulus plate represented (a) the correct response, (b) a reversal of the stimulus sentence subject and object, (c) a change in the number of the subject of the stimulus sentence, and (d) a change in one of the major lexical items of the stimulus sentence. Subjects selected the correct picture most often. When they erred, they usually selected a subject-object reversal. Number errors were less frequent, and the patients seldom selected a change in major lexical item. This pattern occurred with both written and spoken sentences. These results were interpreted as reflecting the dependence of agrammatic Broca's aphasics on the semantic interpretation of the lexicon for decoding sentences in the face of deficits in syntactical-grammatical interpretation, irrespective of comprehension modality.     

Lexical, morphological, and syntactic aspects of verb production in agrammatic aphasics

Agrammatic aphasics do not exhibit a normal pattern of verb production; their spontaneous speech is said to lack verbs, and the verbs that are produced lack inflection. The current article focuses on the lexical, morphological, and syntactic aspects of verbs in spontaneous speech of a group of Dutch agrammatic speakers. Dutch is a so-called verb-second language in which the finite verb in the matrix clause is in the second position and nonfinite verbs are in the final position. The analysis shows that agrammatic speakers are sensitive to this relation; they virtually never produce finite verbs in the final clause position or nonfinite verbs in the second position. Nevertheless, they produce significantly fewer finite clauses than do non-brain-damaged speakers. The diversity of the lexical verbs in spontaneous speech is also lower than in non-brain-damaged speakers, but this is due to less variation in the finite lexical verbs. Hence, it is suggested that the problems with verbs in Dutch agrammatic spontaneous speech are restricted to finite lexical verbs. In an experiment, it was evaluated whether these problems with finite lexical verbs are caused by a morphological deficit or a syntactic deficit. The data show that a syntactic deficit is more likely; Dutch agrammatic speakers produce finite verbs in the base-generated position (i.e., in the embedded clause) significantly better than finite verbs that have been moved to the second position (i.e., in the matrix clause). From these data, the authors conclude that in Dutch, a verb-second language, agrammatic aphasics demonstrate specific problems with moved finite verbs, although they are perfectly aware of the relation between verb position and verb finiteness. This syntactic problem affects not only the proportion of finite verbs but also the diversity of the verbs and, hence, communicative contents.     

Accessibility of case and gender contrasts for agent--object assignment in Broca's aphasics and fluent anomics

Yugoslav agrammatic Broca's aphasics, fluent anomics, and control subjects were tested for comprehension of agent-object relations in a series of simple Serbo-Croatian sentences in the conversational past tense, consisting of two nouns and a transitive action verb. The availability of two closed class cues--case contrasts and gender contrasts--as well as the availability of an open class lexical cue--animacy contrasts--was varied across sentences. An analysis of subjects' agent-object assignments yielded the following results: Both Broca's aphasics and fluent anomics showed a selective impairment in sensitivity to closed class morphology, although anomics were considerably less impaired than Broca's aphasics. This finding was interpreted as evidence for a non-syndrome-dependent vulnerability of abilities to process closed class morphology for comprehension. In addition, the pattern of agent-object assignments for Broca's aphasics revealed that the degree to which they were able to access the two closed class cues depended on a convergence of the various cues to agent-object relations. In particular, a convergence of case and gender contrasts had an interactive effect on Broca's responses: Gender agreement cues were accessed only in the presence of convergent case contrasts. Conversely, sensitivity to case contrasts was dramatically heightened in the presence of convergent gender contrasts. These results were consistent with a view that the two cues function as intrasentential "primes" or "retrieval cues" for one another.     

A study of repetition in aphasic patients

The ability of the aphasic patient to repeat a message is a capacity of considerable diagnostic value. While it is well known that certain aphasic groups (e.g., transcortical aphasics) repeat better than other groups (e.g., conduction aphasics), possible qualitative differences among the groups have not been subjected to analysis. To secure information on repetition profiles in various aphasic subgroups, a test consisting of 11 types of items, presented under conditions of both immediate and delayed recall, was administered to eight groups of aphasic patients. The results documented a significant difference across aphasic groups, one related to site of lesion but not to severity of comprehension defect. Performance proved to be a joint product of the length and the meaningfulness of the stimulus items. The delayed condition aided Broca's aphasics and impeded anomic aphasics; in addition, nonsense syllables proved to be easier on immediate recall, while meaningful stimuli, particularly those which were number related, were relatively easier on delayed recall. Finally, sound errors were more likely to be made by Broca's and “mixed anterior” aphasics, while meaning errors were particularly prominent among conduction aphasics. These results are discussed in terms of the mechanisms which may mediate repetition in aphasic patients.     

Verb inflection and verb diversity in three populations: agrammatic speakers, normally developing children, and children with specific language impairment (SLI)

The present study focuses on the relation between a grammatical and a lexical-semantic aspect of verb production. The spontaneous speech of three different populations (normally developing children, agrammatic aphasics, and children with a specific language impairment) has been analyzed with respect to the proportion of finite clauses and the diversity of the produced lexical verbs. The group results show that in the three populations both the proportion of finite verbs and the variability of the lexical verbs is low. When the individual scores are considered, differences between the normally developing children and the language-impaired subjects show up. Whereas in normally developing children verb finiteness and verb variability go hand-in-hand, the reverse relationship between these variables is observed in the agrammatic aphasics and the children with a specific language impairment. Given this reverse relationship, it is probable to assume two separate disorders. We therefore suggest an impairment at the interface level where lexical information and syntactic structure are integrated during sentence production.     

Processing passive sentences in aphasia: deficits and strategies

Broca's and Wernicke's aphasics' ability to process passive sentences in the absence of semantic cues was investigated in an experiment which varies syntactic complexity and word order. The results indicate that Broca and Wernicke patients use different strategies for sentence comprehension. Wernicke patients use rather general strategies for interpretation, which assign syntactic function according to sequential arrangements of words. Broca's aphasics, by contrast, base their interpretation on specific structural elements of the sentence's surface form, without, however, being able to exploit the full syntactic information of these elements. The different strategies are interpreted to reflect differential underlying deficits.