Null subject pronouns in Broca's speech production

Background: Pronouns are known to be often missing from the spontaneous speech production of Broca's aphasic patients. Null subject pronouns are found in nonfinite utterances. These structures may result from the underspecification of the Tense head and the unavailability of Nominative case for a subject. It is not clear, though, whether null subject pronouns are restricted only to nonfinite structures. Aims: The paper investigates the occurrence of null subject pronouns in finite sentences of Broca's patients. A detailed study into the syntactic and distributional properties of finite null subjects will reveal their nature and origin in aphasic speech production. Methods & Procedures: The spontaneous speech of 13 Dutch patients was investigated. The following variables were included: finiteness (finite versus nonfinite utterances), sentence position (initial versus non‐initial position), and type of pronoun (personal versus demonstrative pronoun). The speech production of the patients was contrasted to normal spoken Dutch. Outcomes & Results: The results demonstrate that finite null subject pronouns in Broca's speech production can be interpreted as instances of normal omission phenomena found in Germanic languages (Topic Drop and I‐Drop). Conclusion: A unified account is proposed for nonfiniteness and finite null subjects in terms of underspecification of functional heads in the syntactic structure. Underspecification is not due to a linguistic impairment, but rather a means to reduce the processing load of the utterance. It is concluded that nonfiniteness is a core phenomenon in Broca's speech production, while finite null subjects reflect an additional omission phenomenon.     

The role of morphology in the comprehension of wh-dependencies in Croatian aphasic speakers

Background: Recent research on the comprehension of subject and object wh-questions in English Broca's aphasic speakers has shown the existence of a specific pattern: subject and object who questions, as well as subject which NP questions, are comprehended above chance, while object which NP questions are comprehended at chance. Since English is a strict word-order language, the subject–object asymmetry is identified as an asymmetry both in word order and in thematic role assignment. The present study investigated the comprehension of wh-dependencies in Croatian, which is a language with relatively free word order that does not necessarily associate thematic roles with specific syntactic positions.

Aims: The goal of the study was to determine whether the pattern of comprehension of wh-dependencies that has been reported for English Broca's aphasic speakers is also exhibited by Croatian aphasic speakers. We hypothesised that due to the role of morphological features such as case in sentence comprehension in a free word-order language like Croatian, aphasic speakers of that language would exhibit a different pattern.

Methods & Procedures: We tested the comprehension of six types of wh-dependencies formed with tko “who” and koji “which” (direct, embedded, long-distance with za, long-distance without za, and passivised questions, and relative clauses with koji) in six Croatian aphasic speakers. All participants had had a lesion to the left hemisphere: three of them were Broca's aphasic speakers and three were mixed cases of non-fluent aphasia.

Outcomes & Results: The main finding of the study is that Croatian Broca's aphasic speakers do not exhibit the same subject–object asymmetry that has been reported for English Broca's aphasic speakers. Some asymmetry was found in the three patients with mixed aphasia, whose comprehension was better on object- than subject-extracted structures.

Conclusions: The asymmetric pattern found in the cases of mixed aphasia runs in the opposite direction to the asymmetry typically reported in the literature. Relying on cross-linguistic findings from the processing-based research on subject–object comprehension asymmetries in neurologically intact populations we assume that, in Croatian, thematic roles are assigned directly to case-marked arguments without the mediation of syntactic information, and propose a morphological account of the Croatian data based on the validity of case cues in MacWhinney and Bates' competition model.     

Verbal communication abilities of aphasic patients: The everyday language test

Abstract

The focus of research on aphasia has been directed toward the assessment of the aphasic person's linguistic impairments. In contrast, there has been little attention given to the question of how aphasic speakers get intended messages across in verbal interactions. This issue is of both theoretical and pragmatic importance. In this paper we report results of a study designed to determine the verbal communicative competence of aphasic persons in ordinary daily life situations. The test involves role-playing in 15 everday life situations such as going to the bank. Each scenario elicits highly consistent responses from non-neurologically impaired adults. These responses have two components: (a) necessary elements, e.g. asking a bank teller for change and noting when the incorrect change is given; and (b) socially conventional elements which are elaborative but non-essential. The consistency of normal subjects' verbal responses in these scenarios allows for the establishment of an objective scoring procedure and to make meaningful comparisons among aphasic and normal subjects' responses. In this study Broca's and Wernicke's aphasic subjects were found to be successful in verbally communicating necessary information, even in the face of severe linguistic (notably, syntactic) limitations. Conversely, both aphasic populations showed a significant reduction in their use of informationally inessential but socially conventional elements.     

Binding in agrammatic aphasia: Processing to comprehension

Background: Theories of comprehension deficits in Broca's aphasia have largely been based on the pattern of deficit found with movement constructions. However, some studies have found comprehension deficits with binding constructions, which do not involve movement.

Aims: This study investigates online processing and offline comprehension of binding constructions, such as reflexive (e.g., himself) and pronoun (e.g., him) constructions in unimpaired and aphasic individuals in an attempt to evaluate theories of agrammatic comprehension.

Methods & Procedures: Participants were eight individuals with agrammatic Broca's aphasia and eight age-matched unimpaired individuals. We used eyetracking to examine online processing of binding constructions while participants listened to stories. Offline comprehension was also tested.

Outcomes & Results: The eye movement data showed that individuals with Broca's aphasia were able to automatically process the correct antecedent of reflexives and pronouns. In addition, their syntactic processing of binding was not delayed compared to normal controls. Nevertheless, offline comprehension of both pronouns and reflexives was significantly impaired compared to the control participants. This comprehension failure was reflected in the aphasic participants' eye movements at sentence end, where fixations to the competitor increased.

Conclusions: These data suggest that comprehension difficulties with binding constructions seen in agrammatic aphasic patients are not due to a deficit in automatic syntactic processing or delayed processing. Rather, they point to a possible deficit in lexical integration.     

Lexical biases in aphasic sentence comprehension: An experimental and corpus linguistic study

Background: This study investigates the role of lexical information in normal and aphasic sentence comprehension. Effects of verb biases in normal comprehension have been well documented in previous studies (e.g., Spivey-Knowlton & Sedivy, 1995; Trueswell, Tanenhaus, & Kello, 1993), but their role in aphasic language processing has largely been ignored (with the exceptions of Menn et al., 1998, and Russo, Peach, & Shapiro, 1998). Aims: The aim of the study is to test the lexical bias hypothesis, i.e., the hypothesis that sentence comprehension is influenced by lexical biases in aphasic listeners, as well as in normals. Method & Procedures: Using a sentence plausibility judgement task, we probe for sensitivity to verb transitivity bias, i.e., the likelihood, as estimated from corpus counts, that a verb will be transitive, rather than intransitive. Five normal controls and eighteen participants with aphasia (six with Broca's aphasia, four with Wernicke's aphasia, two with conduction aphasia, and six with anomic aphasia) are included in the study. Based on the lexical bias hypothesis, we predicted that participants would make more errors in sentences with a mismatch of verb bias and syntactic structure, such as a transitive sentence containing a verb with intransitive bias. Outcomes & Results: Both the group of normal controls and the mixed group of aphasic patients make significantly more errors on sentences in which there is a mismatch between verb bias and syntactic structure, as predicted by the lexical bias hypothesis. Specifically, patients with fluent aphasia types, particularly anomic aphasia, show a sensitivity to verb bias, contrary to earlier findings. Conclusions: These results are consistent with the view that lexical factors, not purely syntactic ones, are to blame for many previously observed patterns in aphasic comprehension. The results are further consistent with the view that many aphasic errors differ not qualitatively but quantitatively from normal comprehension errors.     

Comprehension of reversible active and passive sentences in agrammatism

Agrammatism is a language disorder characterised by a morphological and/or syntactic deficit in spontaneous speech. Such deficits are usually associated with comprehension disorders - though it is said that this is not always the case - which result in a certain degree of variability in syntactic, lexical, and morpholexical performance. The purpose of this study is to reconsider the nature of comprehension disorders in agrammatism, to test whether Grodzinsky's Trace Deletion Hypothesis (TDH) can be generalised to all agrammatic patients, and to ascertain whether the pattern of impairment observed in agrammatism differs from that present in fluent aphasic patients. Eleven agrammatic patients were tested by means of a sentence comprehension task comprising simple active and passive reversible sentences. The performance of the agrammatic patients was compared to that of 16 fluent aphasic (10 Wernicke's and 6 conduction) and 10 control subjects. The deficits observed in the agrammatic subjects were compatible with the TDH, but there was also impaired processing of pronouns (elements that are also subject to movement) and a mild deficit on the processing of simple active sentences. The fluent aphasic patients showed a similar pattern of impairment. A logistic regression analysis was then applied to each single case separately, in order to study the homogeneity of the patients' performance within each aphasic subgroup. Of the 11 agrammatic patients, 3 did not show comprehension disorders, 5 had a specific deficit for passive movement, 1 a lexical deficit for pronouns only, and 1 a pattern of impairment compatible with Linebarger et al.'s trade-off theory. The last patient showed a deficit for simple active reversible sentences compatible with damage to the mapping of grammatical functions to thematic roles. Similar patterns of impairment were also found in the fluent aphasic sample. Overall, the results lead to the conclusion that the TDH cannot be generalised to all agrammatic patients, that the mechanism it invokes is not the only source responsible for agrammatic comprehension disorders and also contributes to comprehension disorders in fluent aphasic patients.     

Neural substrates of word category information as the basis of syntactic processing

The ability to use word category information (WCI) for syntactic structure building has been hypothesized to be the essence of human language faculty. The neural substrate of the ability of using the WCI for the complex syntactic hierarchical structure processing, however, is yet unknown. Therefore, we directly conducted an fMRI experiment by using a pseudo‐Chinese artificial language with syntactic structures containing a center‐embedded relative clause. Thirty non‐Chinese native (Korean) speakers were randomly divided into two groups: one acquired WCI and WCI‐based syntactic rules (the WCI group) before the scanning session, and the other did not (the non‐WCI group). Both groups were required to judge the grammaticality of the testing sentences, with critical long‐distance dependencies between two elements (the main verb and the relativizer). Behaviorally, the WCI group's accuracy was significantly higher and its reaction time was shorter. The scanning results showed that the left superior temporal gyrus (STG) and Broca's area were more strongly activated for the WCI group, and the dynamic causal modeling analyses revealed a distinct effective connectivity pattern for this group. Therefore, the present research, for the first time, reveals that the activation of and the functional connectivity between Broca's area and the left STG play a critical role in the ability of the rule‐based use of the WCI which is crucial for complex hierarchical structure building, and might be substantially corresponding to the “labeling competence” within the linguistic framework.     

Syntactic processing in agrammatism: Evidence from lexical decision and grammaticality judgement tasks

Abstract

This study explored the ability of aphasic patients to process the same sentences varying in syntactic structure in an on-line task (lexical decision) and an off-line task (grammaticality judgement). Eight agrammatic and six age-matched normal subjects were tested on a lexical decision task which probed ten types of ungrammaticalty (five syntactic and five morphological). Normal subjects showed a sensitivity to ungrammaticalty as demonstrated by a significant increase in reaction time to target words in ungrammatical as compared to grammatical contexts. On a grammaticality judgement task using these same stimuli, normal subjects' performance was near ceiling level. The aphasic subjects failed to show a comparable increase in RT on the lexical decision task. In addition, while the agrammatic aphasics performed above chance, they did not perform as well as expected on the grammaticality judgement task. Results are discussed in terms of the nature of the routines involved in the processing of sentences, particularly with respect of agrammatism.     

Treating agrammatic aphasia within a linguistic framework: Treatment of Underlying Forms

Background : Formal linguistic properties of sentences—both lexical, i.e., argument structure, and syntactic, i.e., movement —as well as what is known about normal and disordered sentence processing and production, were considered in the development of Treatment of Underlying Forms (TUF), a linguistic approach to treatment of sentence deficits in patients with agrammatic aphasia. TUF is focused on complex, non-canonical sentence structures and operates on the premise that training underlying, abstract, properties of language will allow for effective generalisation to untrained structures that share similar linguistic properties, particularly those of lesser complexity. Aims : In this paper we summarise a series of studies focused on examining the effects of TUF. Methods & Procedures : In each study, sentences selected for treatment and for generalisation analysis were controlled for their lexical and syntactic properties, with some structures related and others unrelated along theoretical lines. We use single-subject experimental designs—i.e., multiple baseline designs across participants and behaviours—to chart improvement in comprehension and production of both trained and untrained structures. One structure was trained at a time, while untrained sentences were tested for generalisation. Participants included individuals with mild to moderately severe agrammatic, Broca's aphasia with characteristic deficits patterns. Outcomes & Results : Results of this work have shown that treatment improves the sentence types entered into treatment, that generalisation occurs to sentences which are linguistically related to those trained, and that treatment results in changes in spontaneous discourse in most patients. Further, we have found that generalisation is enhanced when the direction of treatment is from more to less complex structures, a finding that led to the Complexity Account of Treatment Efficacy (CATE, Thompson, Shapiro, Kiran, & Sobecks, 2003). Finally, results of recent work showing that treatment appears to affect processing of trained sentences in real time and that treatment gains can be mapped onto the brain using functional magnetic resonance imaging (fMRI) are discussed. Conclusions : These findings indicate that TUF is effective for treating sentence comprehension and production in patients who present with language deficit patterns like those seen in our patients. Patients receiving this treatment show strong generalisation effects to untrained language material. Given the current healthcare climate, which limits the amount of treatment that aphasic patients receive following stroke, it is important that clinicians deliver treatment that results in optimal generalisation in the least amount of time possible.     

Neighbourhood density effects in auditory non‐word processing in aphasic listeners

This study investigates neighbourhood density effects on lexical decision performance (both accuracy and response times) of aphasic patients. Given earlier results on lexical activation and deactivation in Broca's and Wernicke's aphasia, the prediction was that smaller neighbourhood density effects would be found for Broca's aphasic patients, compared to age‐matched non‐brain‐damaged control participants, whereas enlarged density effects were expected for Wernicke's aphasic patients. The results showed density effects for all three groups of listeners, and overall differences in performance between groups, but no significant interaction between neighbourhood density and listener group. Several factors are discussed to account for the present results.     

The use of spontaneous gesture by aphasic patients

Abstract

In order to determine the extent to which aphasic patients are able to use hand gestures in their spontaneous communication, informally structured 20-minute interviews were conducted with three Wernicke's aphasics, four Broca's aphasics and five non-neurologically impaired control subjects. The study has been designed to overcome some of the methodological problems inherent in existing research, notably; (1) the classification of subjects according to the type of aphasia present, (2) the analysis of representative samples of naturally occurring conversation, (3) the use of a well-defined and reliable system of gesture classification, and (4) the interpretation of results based on formal statistical analyses. Overall, it was found that there were significant differences between the three groups in their use of hand gestures. The results of the study indicate that hand gestures are used most by Broca's aphasics and least by non-aphasic controls. Batons, ideographs and deictic movements were associated predominantly with Broca's aphasics, while both Wernicke's and Broca's aphasics used kinetographs significantly more than the non-neurologically impaired comparison group. The results are discussed in terms of the model of communication favoured by Cicone et al. (1979) which considers that expressive communication is governed by a ‘central organizer’ which initiates and controls the clarity and complexity of both speech and gesture. Based on the differential usage of gestures by the Wernicke's and Broca's aphasics, different approaches to the problem of remediation in aphasia are considered.     

Recursion in aphasia

This study investigates how aphasic impairment impinges on syntactic and/or semantic recursivity of human language. A series of tests has been conducted with the participation of five Hungarian speaking aphasic subjects and 10 control subjects. Photographs representing simple situations were presented to subjects and questions were asked about them. The responses are supposed to involve formal structural recursion, but they contain semantic-pragmatic operations instead, with ‘theory of mind’ type embeddings. Aphasic individuals tend to exploit the parallel between ‘theory of mind’ embeddings and syntactic-structural embeddings in order to avoid formal structural recursion. Formal structural recursion may be more impaired in Broca's aphasia and semantic recursivity may remain selectively unimpaired in this type of aphasia.     

Response strategies in aphasic sentence comprehension: An analysis of two cases

Background: A consistent pattern of responding in a test of sentence comprehension has been interpreted both as a direct reflection of the aphasic patient's ability to understand specific sentence types, and as an indirect indication of the operation of systematic response strategies. Less attention has been directed at the questions of how residual comprehension abilities and response strategies might jointly influence response patterns, and of the potential modifiability of such strategies through intervention. Aims: This study illustrates how patients' response patterns reflect a complex interaction between residual syntactic knowledge and different response strategies. These strategies may change in response to simple task manipulations and in response to therapeutic feedback. Methods & Procedures: We report sentence comprehension data from two aphasic patients who produced dissimilar comprehension patterns for semantically reversible sentences tested in three experiments: sentence–picture verification (yes/no), sentence–picture matching (forced choice), and in response to systematic feedback (intervention). Outcomes & Results: Both patients' performance was shown to reflect response strategies with distinct potential for modification by changes in task demands and by therapeutic intervention. The strategies adopted appeared to reflect differences in retained knowledge about structural cues to sentence meaning; paradoxically, the more superficial strategy—reflecting no initial appreciation of sentence structure—was the more amenable to modification. Conclusions: Results highlight the importance of assessing comprehension with a number of different tasks, and of recognising patients' tendencies to rely on response strategies, when interpreting aphasic sentence comprehension. The clinical utility of identifying such response biases and comprehension strategies as a basis for intervention is discussed.     

A comparison of the BAT and BDAE-SF batteries in determining the linguistic ability in Greek-speaking patients with Broca's aphasia

The aim of this study is to test the validity and reliability of the Bilingual Aphasia Test as a measure of language impairment in a Greek-speaking Broca's aphasic population and to investigate relationships with the same aphasic group's performance on the Greek version of the short form of the Boston Diagnostic Aphasia Examination battery, mainly focusing on a series of subtests which are shared by the two batteries, yet occasionally differ in content. Correlation analyses showed that the two instruments yielded highly comparable results with respect to the measurement of reading and listening comprehension, as well as in the performance-based measurement of the automated sequence capacity of the patients. Nevertheless, the Bilingual Aphasia Test, as a more extensive battery, proved to be more sensitive and objective in characterizing the patients' language abilities in a number of individual language functions, including commands, sentence repetition, naming, verbal fluency and syntactic comprehension.     

The interpretation of stressed and non-stressed pronouns in Spanish language breakdown

Background: Earlier research has indicated that patients with agrammatic Broca's aphasia have problems with constraints on the intra-sentential interpretation of object pronouns, incorrectly allowing them to refer to the subject of the same sentence. However, these studies do not show how agrammatic patients deal with constraints on the extra-sentential interpretation of pronouns. Also, studies that did investigate patients' extra-sentential interpretation of pronouns were on English and Dutch, languages with a pronominal system that differs substantially from the pronominal system of Romance languages, such as Spanish.

Aims: To test Spanish agrammatic patients on the interpretation of stressed and non-stressed subject and object pronouns in coordinated structures (the Spanish counterparts of sentences such as “First the girl pushed the mother, and than she / SHE pushed the boy”), in order to investigate whether they exhibit the same referential preferences as non-brain-damaged individuals and English- and Dutch-speaking patients.

Methods & Procedures: In the present study seven Spanish patients with agrammatic Broca's aphasia and six non-brain-damaged adults were tested with a picture selection task on their interpretation of non-stressed and stressed pronouns in coordinated sentences. Patients were presented coordinated sentences and were shown four pictures, one on the left page, three on the right page. The left page picture represents the first conjunct of the test sentence, the right page represent the two theoretically possible referents of the pronoun (subject of the first conjunct, or object of the first conjunct) and a non-related picture. The patient's task was to indicate out of the three pictures the one that correctly represented the meaning of the second conjunct of the test sentence.

Outcomes & Results: Agrammatic individuals exhibit difficulties with the interpretation of non-stressed object pronouns, and even more difficulties with the interpretation of contrastively stressed pronouns. An additional finding is that they tend to prefer subjects as the antecedents of pronouns.

Conclusions: We claim that patients' problems with the interpretation of pronouns are not the result of missing syntactic knowledge, but are due to patients' limited ability to keep syntactic configurations in their syntactic working memory. We argue that their preference for subjects as antecedents for pronouns reflects a fall-back strategy in agrammatic patients when, as a result of limited processing resources, syntax-based interpretative operations fail.     

Cognitive sequence processing and syntactic comprehension in schizophrenia

It has been repeatedly demonstrated that schizophrenic patients are impaired in the comprehension of sentences with complex syntax. We investigated the hypothesis that this syntactic comprehension impairment in schizophrenia is not a purely linguistic dysfunction, but rather the reflection of a cognitive sequence processing impairment that is revealed as task complexity increases. We tested 10 schizophrenic patients using a standard measure of syntactic comprehension, and a non-linguistic sequence processing task, both of which required simple and complex transformation processing. Patients' performance impairment on the two tasks was highly correlated (r2 = 0.84), and there was a significant effect for complexity, independent of the task. These results are quite similar to those of aphasic patients with left hemisphere lesions. This suggests that syntactic comprehension deficits in schizophrenia reveal the dysfunction of cognitive sequence processing mechanisms that can be expressed both in linguistic and non-linguistic sequence tasks.     

Syntactic Processing Deficits in Aphasia

Four aphasic patients were tested in several tasks to determine their ability to use syntactic information. Two patients classified as Broca's aphasics and presenting markedly different levels of severity of aphasia were deficient in their ability to use syntactic information in sentence comprehension and construction. It is argued that the syndrome of Broca's aphasia undermines patients' ability to perform the syntactic analyses that are necessary to understand and to produce sentences in both language modalities. a third patient tested was a conduction aphasic who presented a pattern of sentence comprehension similar to the Broca patient, but produced no other evidence of syntactic impairment. The argument is advanced that the conduction patient's apparently selective impairment of syntactic .processing in comprehension is actually a reflection of a severe auditory-verbal short-term memory deficit. The fourth patient was classified as a mildly-impaired Wernicke's aphasic, who presented no evidence of a selective disturbance of syntactic processing abilities. These results are interpreted as support for the hypothesis that the syndrome of Broca's aphasia results from an impairment to the syntactic component of the language processing system.     

Beta EEG band: A measure of functional brain damage and language reorganization in aphasic patients after recovery

Functional reorganization of language was investigated in a group of eleven non-fluent aphasic patients after linguistic recovery and in a group of matched healthy adults. The ElectroEncephaloGram (EEG) was recorded from 38 scalp electrodes and high-beta band (21–28 Hz), an index of cognitive cortical arousal, was computed as normalized percentage across 0–100 Hz spectral range in six electrode clusters during three linguistic tasks: Phonological, Semantic and Orthographic/visuo-perceptual. During the Phonological task, controls showed greater beta activation on left versus right central cluster, whereas aphasic patients exhibited an inverted pattern of lateralization. In addition, patients' left central cluster, located over the core lesion, showed reduced beta activity with respect to controls. A similar inhibited activation was found in aphasics' left posterior cluster located over undamaged areas. At left anterior locations, aphasics, unlike controls, exhibited larger left versus right beta activity during both Phonological and Orthographic/visuo-perceptual tasks. Results point to substantial reorganization of language in recovered non-fluent aphasics at left prefrontal sites located anterior to the damaged Broca's area and inhibited language-related activation in left posterior undamaged, but disconnected, regions.     

The utility of computerized visual communication for improving natural language in chronic global aphasia: Implications for approaches to treatment in global aphasia

A computerized communication system (C-VIC) was employed as a diagnostic and therapeutic tool to identify propositional language abilities in a chronic, globally aphasic patient. The patient demonstrated the ability to construct sentences during training according to abstract syntax-like rules by manipulating iconic symbols representing nouns and verbs. Further, he produced correct symbolic order to express the thematic relationships in sentences. The effect of C-VIC as a therapeutic intervention to improve the patient's natural language abilities was examined using pre- and post-training assessments. Improvements specific to training were observed but neither improvements in natural language nor generalization to production of multiple sentences using C-VIC was found. The results are discussed with regard to current debates concerning treatment approaches and the use of augmentative communication devices for globally aphasic patients.