Sensitivity to grammatical structure in so-called agrammatic aphasics

Comprehension failures in agrammatic aphasics, as well as their difficulties in sentence construction, have been attributed to an underlying deficit involving the retrieval of syntactic structure. In this study we show that four agrammatic patients display a remarkable sensitivity to structural information, as indicated by their performance on a grammaticality judgment task. These results indicate significant sparing of syntactic knowledge in agrammatism, and suggest that the sentence comprehension disturbances in these patients do not reflect loss of the capacity to recover syntactic structure. In particular, accounts of the comprehension deficit in agrammatism that implicate a failure to exploit information carried by the closed class (function word) vocabulary are called seriously into question. Alternative explanations of the comprehension problem in agrammatism are explored.     

Syntactic comprehension deficits in agrammatism

Eleven agrammatic and 16 fluent aphasic patients were given a comprehension task consisting of simple, active and passive reversible sentences. The purpose of the study is to reconsider the comprehension disorders in agrammatism, and particularly of passive reversible sentences, to test to what extent Grodzinsky's trace deletion hypothesis (TDH) is generalizable to other types of NP-movement, and finally to ascertain whether the pattern of impairment observed in agrammatism differs from that of fluent aphasic patients. The study confirms that trace analysis may be selectively impaired in agrammatism. However, this deficit is not the only mechanism underlying comprehension disorders and cannot be said to occur in all agrammatic patients. Comprehension disorders also involve the processing of clitic object pronouns which also underly NP-movement. Finally, the impairment found in fluent aphasic patients differs, both in type and severity, from that of agrammatic patients, thus confirming the peculiar aspects of the agrammatic comprehension deficit suggested by Grodzinsky's TDH.     

Grammatism

Findings from the literature on language development, dyslexia, and adult sentence processing provide a vehicle for comparing two models of the symptom complex associated with agrammatism. One model contends that agrammatism represents a deficit in linguistic structures. The other model maintains that the linguistic behavior associated with agrammatism is the result of a limitation in language processing. To adjudicate between the models, the present paper examines one linguistic construction, the restrictive relative clause. The results of experimental investigations across several subject populations reveal parallel patterns of linguistic behavior on this construction. The findings favor the processing limitation account of the linguistic difficulties experienced by agrammatic aphasics in comprehending sentences with a restrictive relative clause.     

Comprehension of nonlexical categories in agrammatism

The focus of the paper is a proposal advanced by Grodzinsky (1984, 1986, 1990) concerning a possible syntactic deficit in agrammatism with respect to nonlexical categories. Eight native speakers of Serbo-Croatian, who presented a clinical picture of Broca's aphasia with agrammatism, were tested. Subject's sensitivity to traces and their knowledge of the inflectional and determiner system was investigated using a grammaticality judgment paradigm. The processing load was further minimized by use of short sentences that unequivocally exemplified different syntactic violations. These steps led to significant improvement in the performance of agrammatic aphasics, a result that is incompatible with the claim that the content of nonlexical elements is lost in agrammatism.A partial account of the findings was presented at the 31 st Meeting of the Academy of Aphasia, October 24–26, 1993. Tucson, Arizona. The authors gratefully acknowledge help in data collection from Mile Vukovi, Faculty of Defectology, University of Belgrade, and from Jovanka Jezdimirovi and Veronika Ispanovi-Radojkovi, the Institute for Mental Health in Belgrade. This research was supported in part by a grant (HD-01994) to Haskins Laboratories from the National Institute of Child Health and Human Development.     

Dissociations among functional categories in Korean agrammatism

This study investigated the hypothesis that the syntactic trees formed by individuals with agrammatic aphasia cannot be constructed any higher than an impaired node as suggested by the tree-pruning hypothesis (Friedman, 1994; Friedmann & Grodzinsky, 1997) and hypothesis. It also examined their following implication that the members of a certain functional category are subject to the same degree of impairment. Two experiments were conducted to investigate a Korean agrammatic patient's use and understanding of three functional categories--Mood, Tense, and Complementizer. The results showed a dissociation among functional categories that preserves the higher node while leaving the lower node impaired both in production and comprehension. Another dissociation was found among members of the same category depending on their linear position in the clause. These results contrast with the predictions of the tree-pruning hypothesis, suggesting that the nearer to the end of the clause a functional element is located, the better it is preserved in Korean agrammatism.     

A psychometric analysis of functional category production in English agrammatic narratives

Hierarchical models of agrammatism propose that sentence production deficits can be accounted for in terms of clausal syntactic structure [Friedmann, N., & Grodzinsky, Y. (1997). Tense and agreement in agrammatic production: Pruning the syntactic tree. Brain and Language, 56, 397-425; Hagiwara, H. (1995). The breakdown of functional categories and the economy of derivation. Brain and Language, 50, 92-116]. Such theories predict that morpho-syntactic elements associated with higher nodes in the syntactic tree (complementizers and verb inflections) will be more impaired than elements associated with lower structural positions (negation markers and aspectual verb forms). While this hypothesis has been supported by the results of several studies [Benedet, M. J., Christiansen, J. A., & Goodglass, H. (1998). A cross-linguistic study of grammatical morphology in Spanish- and English-speaking agrammatic patients. Cortex, 34, 309-336; Friedmann, N. (2001). Agrammatism and the psychological reality of the syntactic tree. Journal of Psycholinguistic Research, 30, 71-88; Friedmann, N. (2002). Question production in agrammatism: The tree pruning hypothesis. Brain and Language, 80, 160-187], it has also been challenged on several grounds [Burchert, F., Swoboda-Moll, M., & De Bleser, R. (2005a). Tense and agreement dissociations in German agrammatic speakers: Underspecification vs. hierarchy. Brain and Language, 94, 188-199; Lee, M. (2003). Dissociations among functional categories in Korean agrammatism. Brain and Language, 84, 170-188; Lee, J., Milman, L. H., & Thompson, C. K. (2005). Functional category production in agrammatic speech. Brain and Language, 95, 123-124]. In this paper the question of hierarchical structure was re-examined within the framework of Item Response Theory [IRT, Rasch, G. (1980). Probabilistic models for some intelligence and attainment tests (Expanded ed.). Chicago: University of Chicago Press]. IRT is a probabilistic model widely used in the field of psychometrics to model behavioral constructs as numeric variables. In this study we examined production of functional categories (complementizers, verb inflections, negation markers, and aspectual verb forms) in narrative samples elicited from 18 individuals diagnosed with nonfluent aphasia and 18 matched controls. Data from the aphasic participants were entered into an IRT analysis to test (1) whether production of clausal functional categories can be represented as a variable on a numeric scale; and (2) whether production patterns were consistent with hierarchical syntactic structure. Pearson r correlation coefficients were also computed to determine whether there was a relation between functional category production and other indices of language performance. Results indicate that functional category production can be modeled as a numeric variable using IRT. Furthermore, although variability was observed across individuals, consistent patterns were evident when the data were interpreted within a probabilistic framework. Although functional category production was moderately correlated with a second measure of clausal structure (clause length), it was not correlated with more distant language constructs (noun/verb ratio and WAB A.Q.). These results suggest that functional category production is related to some, but not all, measures of agrammatic language performance.     

Language deficits and the theory of syntax

A new structural account of agrammatism is proposed, which analyzes the deficit in terms of one current theory of syntax. First, the motivation for accounts of this kind is given. Then, a variety of experimental findings from sentence comprehension in agrammatism are examined and accounted for in a unified way. It is shown that a minimal change in the syntactic model (achieved by imposing a special condition on a construct called trace), results in a model which accounts for all the data at hand. A number of possible objections to this proposal is then examined, and reasons are given to dismiss these objections. Also, it is shown that this proposal is preferable to other structural accounts which have been recently proposed. Finally, the empirical consequences of this account are discussed, with a special emphasis on the implications for models of language processing.     

Variation in the pattern of omissions and substitutions of grammatical morphemes in the spontaneous speech of so-called agrammatic patients

We describe the patterns of omissions (and substitutions) of freestanding grammatical morphemes and the patterns of substitutions of bound grammatical morphemes in 20 so-called agrammatic patients. Extreme variation was observed in the patterns of omissions and substitutions of grammatical morphemes, both in terms of the distribution of errors for different grammatical morphemes as well as in terms of the distribution of omissions versus substitutions. Results are discussed in the context of current debates concerning the possibility of a theoretically motivated distinction between the clinical categories of agrammatism and paragrammatism and, more generally, concerning the theoretical usefulness of any clinical category. The conclusion is reached that the observed heterogeneity in the production of grammatical morphemes among putatively agrammatic patients renders the clinical category of agrammatism, and by extension all other clinical categories from the classical classification scheme (e.g., Broca's aphasia, Wernicke's aphasia, and so forth) to more recent classificatory attempts (e.g., surface dyslexia, deep dysgraphia, and so forth), theoretically useless.     

The word order problem in agrammatism : II. Production

This study demonstrates that agrammatic aphasics have difficulty describing relations that are signified by the order of noun phrases around verbs or prepositions. The word order deficit is found in a Sentence Order Task, in which written words must be arranged linearly to form a sentence, as well as in oral production. Ordering tendencies reflect factors like animacy or potency, rather than the systematic use of syntactic rules. These results point to a fundamental syntactic disorder in agrammatism.     

Training agrammatic subjects on passive sentences: implications for syntactic deficit theories

We trained two subjects with chronic agrammatic aphasia on production of passive sentences using a computerized, iconic-based communication system. After training, one of the subjects demonstrated significant improvements in his abilities to comprehend and verbally produce English passive voiced sentences, including sentences with conjoined subjects and objects. These results suggest that agrammatism does not represent a fixed syntactic deficit.     

When "macrocefalo (macrocephalous)" is read "minicervello (minibrain)": evidence from a single case study

We report the case of a patient who showed a marked deficit in compound reading after almost complete recovery from his aphasic disturbances. Omission of one of the two compound components was his most frequent type of error. The patient also produced many paraphasias, which always respected the compound structure of the target. Similar errors were found on tasks of naming and writing to dictation. A deficit in retrieving the verb component of verb-noun compounds was also observed, consistent with the patient's residual agrammatism, and with decomposition at some point in processing. We suggest that this pattern of performance is compatible with a dual route model that hypothesises two stages of compound retrieval, a whole word stage followed by a decomposition into two constituent morphemes.     

The linguistic interpretation of aphasic syndromes: Agrammatism in Broca's aphasia,an example

One of the most striking characteristics typical of the speech of Broca's aphasics is its agrammatism — the omission of ‘function’ words and inflectional morphemes. Agrammatism is generally viewed as being symptomatic of a syntactic deficit. We argue here that such an account lacks grammatical systematicity, and that the only uniform and systematic interpretation of this deficit is in terms of phonological structure. A natural class consisting of ‘function’ words and some bound morphemes can be defined with reference to the junctural properties of sentences which characterize phonological words. It is this class of elements which tend to be omitted in agrammatic speech. The goal of this paper is not only to provide an hypothesis for the interpretation of one aphasic syndrome, but also to test and illustrate the efficacy of paying close attention to substantive universals of grammatical structure in proposing accounts of linguistic deficits.     

Text-level representations as one determinant for lexical retrieval and sentence production deficits in aphasia: comments on L. B. Zingeser and R. Sloan Berndt "Retrieval of nouns and verbs in agrammatism and anomia".

This note discusses the explanation put forward by Zingeser and Berndt (1990) in their attempt to account for agrammatism by reference to word-level representations. These authors have suggested that agrammatism could be the expression of some particular difficulties with the lexical retrieval of verbs. The present discussion suggests an alternative explanation making reference to text-level representations, and particularly to the lexicalization of predicates.     

Syntactic loss versus processing deficit: an assessment of two theories of agrammatism and syntactic comprehension deficits

This research evaluated Grodzinsky's (1984, 1986a) syntactic loss and Kolk and van Grunsven's (1985) working memory impairment explanations of syntactic comprehension deficits in agrammatic aphasics. Four aphasic patients were evaluated who showed different patterns of impairment on morphological and structural aspects of production. The comprehension tasks compared performance on full and truncated passive sentences. The syntactic loss hypothesis predicted worse performance on truncated than full passives, while the working memory deficit hypothesis predicted the reverse. Neither hypothesis was supported, as the patients performed at a similar level on both types of passives. In addition, there was little relation between the patients' production indices and their comprehension level. The results argue against any global theory of agrammatism that attempts to attribute all agrammatic speech and co-occurring syntactic comprehension deficits to the same source.     

There is an entity called agrammatic aphasia.

Agrammatism as a phenomenon of neuropsychological relevance has been recently attacked--from conceptual and empirical angles. This article examines the facts, as they emerge from three recent experimental studies that have concluded that agrammatism does not exist (Miceli et al., 1989; Martin et al., 1989, Badecker et al., in press), and draws the opposite conclusion: that agrammatism is of interest to students of language and that patients belonging in this clinical category also reveal uniform patterns of aberrant behavior that are of great linguistic and psycholinguistic relevance.     

Question production in agrammatism: the tree pruning hypothesis

This study investigated question production in agrammatic aphasia, focusing on the comparison between Wh questions and yes/no questions and on the interaction between the question production deficit and language-specific properties. A total of 16 agrammatic aphasics (13 Hebrew speakers, 2 Palestinian Arabic speakers, and 1 English speaker) participated in the study, which included sentence elicitation and repetition tasks. In addition, the patients' spontaneous speech, containing 2272 utterances, was analyzed. The main findings were that Hebrew- and Arabic-speaking agrammatics encounter severe difficulties in Wh question production but retain the ability to produce yes/no questions. English-speaking agrammatics do not show this dissociation and can form neither Wh nor yes/no questions. These dissociations as well as the error pattern, are explained by reference to the Tree Pruning Hypothesis, according to which the highest nodes of the syntactic tree, which are required for Wh questions in Hebrew, Arabic, and English and for yes/no questions in English, are impaired or inaccessible in agrammatism.     

Squaring the round: An unusual progressive graphomotor impairment with post‐mortem findings

Investigations of neurodegenerative disorders may reveal functional relationships in the cognitive system. C.S. was a 63‐year‐old right‐handed man with post‐mortem confirmed Pick's disease with a range of progressive impairments including non‐fluent aphasia, speech, limb, oculomotor, and buccofacial apraxia, but mostly intact intelligence, perception, orientation, memory, semantics, and phonology. During progression, agrammatism in writing with impairments in syntactic comprehension emerged in parallel with an unusual graphomotor deficit in drawing and writing, with an increasing deterioration of graphic short‐term memory. We investigated C.S.'s graphomotor deficit longitudinally using tests of writing and drawing on letters, words, and sentences and drawing to command and copying. We also tested C.S.'s short‐term graphemic buffer experimentally. Analysis showed deficits on selective aspects of graphomotor implementation of writing and drawing, mainly affecting the production of circles and curves, but not short straight lines in drawing and writing, and graphomotor short‐term memory, which paralleled impairments of written syntax and syntactic comprehension. We believe this to be the first detailed analysis of such an unusual progressive impairment in graphomotor production, which may be related to problems with agrammatic agraphia and impairments affecting shared components of cognition reflecting damage to shared neural networks. Alternatively, they may simply reflect the effects of coincidental damage to separate mechanisms responsible for aspects of writing, drawing, and syntactic processing. Longitudinal investigations of emerging deficits in progressive conditions like C.S.'s provides an opportunity to examine the progressive emergence of symptoms in an individual with multiple progressive impairments as they appear and examine putative relationships between them.     

A review of theories of human amnesia

Six theories of human amnesia are examined. Each is categorized according to the processing ability that is conceived to underlie the amnesic deficit. The theories fall into one of four categories: consolidation, retrieval, semantic encoding, and context encoding deficit theories. The recently proposed context encoding deficit theories are found to offer the most satisfactory account of the human amnesic syndrome. It is suggested that the other theoretical approaches are best viewed as special cases of these context encoding deficit theories.     

Agrammatic comprehension of relative clauses

Four hypotheses that attempt to account for the comprehension deficit in agrammatism are put to an empirical test. The interest in them is in that they all view the deficit as highly selective. The first, proposed by D. Caplan and C. Futter (1986, Brain and Language, 27, 117-134), argues that agrammatic patients cannot carry out normal syntactic analysis beyond the category label of each incoming lexical item and are reduced to the use of a cognitive strategy that commends assignment of thematic roles to noun phrases merely by their linear position in the string. A second, less radical hypothesis (Y. Grodzinsky, 1986a, Brain and Language, 27, 135-159), accounts for the deficit differently, by deleting a particular kind of syntactic object (trace) from the otherwise normal representation, and augmenting the resulting, underspecified representation by a strategy, whose use is quite restricted. A third account that is tested contends that agrammatic aphasics fail to comprehend perceptually complex constructions, where the metric for complexity is determined by results obtained from comprehension tests of normal listeners. The fourth account (M. F. Schwartz, M. C. Linebarger, E. M. Saffran, and D. S. Pate, 1987, Language and Cognitive Processes, 2, 85-113) argues that the thematic transparency of a construction (whether or not thematic roles are assigned directly to positions) is the best predictor of the manner by which agrammatics can handle it. An empirical test is thus constructed, both to extend the evidential basis concerning the comprehension skills of these patients and to distinguish between the accounts. Four types of relative clauses are presented to the patients, where embedding type (center vs. right) is one variable, and location of gap (subject vs. object position) is the other. The patients are tested in a sentence-picture matching paradigm. The finding, that is rather robust, is that gap location is the best predictor of agrammatic performance: the patients perform well above chance on both types of subject gap relatives, and at chance levels on object gaps. It is then shown that the Trace-Deletion Hypothesis (Grodzinsky, 1986a) is the only one among the accounts considered that is compatible with these data.