Anticipatory coarticulation in aphasia: some methodological considerations.
Explore the source record for details and available documents.
SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Seven agrammatic Broca's aphasics and ten normal control subjects performed a word-monitoring task to determine the degree to which violations of syntax would affect word-monitoring performance. Both local and long-distance dependencies were explored, as well as the effects of additional interceding words. Results indicated that normal subjects' word-monitoring latencies were significantly slower to target words in ungrammatical contexts for both local and long-distance dependencies. Aphasic subjects showed a significant sensitivity to ungrammaticality in the local dependency condition; for the long-distance dependencies, however, no reaction time difference emerged between grammatical and ungrammatical stimuli. Results are discussed in relation to current theories of the nature of agrammatic deficits.
After surgical removal of a parasitic cyst in the right prerolandic area, an educated 25-year-old male exhibited obvious deficits in one of his three languages (Gujarati), with no measurable deficits in the other two (French and Malagasy). The patient spoke all three languages fluently before the operation. Gujarati and Malagasy had been acquired in infancy. Gujarati was the language of his parents and relatives. Malagasy the language of the local population. All the patient's schooling had been in French, the only language in which he was literate. He used French daily at work. Since the acquisition history for Gujarati and Malagasy was identical, while French had been acquired in a different context, one would have predicted, on the basis of W. Lambert and S. Fillenbaum's (1959, Canadian Journal of Psychology, 13, 28-34) hypothesis, that Gujarati and Malagasy should have been equally affected, with French possibly differently so. However, 8 months postoperatively, the patient had regained control of Gujarati, while Malagasy had deteriorated considerably, and his French remained unimpaired. Two years later, the patient had recovered full use of his three languages.
Seventeen spontaneous speech measures and scores on a naming test, employed to characterize the expressive performance of 121 aphasics, were subjected to a factor analysis. Five factors were obtained: (1) Syntactic ability, (2) Phonological paraphasia, (3) Neologistic paraphasia, (4) Articulatory impairment, and (5) Vocabulary. Relationships of the factors to naming error types were examined in order to elucidate the nature of some of the factors. Also, the relationships of the expressive factors to auditory comprehension tests were explored, such an exploration being relevant to the issue of the overlap between expressive and receptive functions.
Explore the source record for details and available documents.
The limitations inherent in group versus case studies appear to lie in a complementary distribution, underscoring the importance of combining both strategies within a single research program. However, this compromise approach requires analytic tools that permit us to combine and evaluate individual and group data in a common format. Maximum likelihood estimation (MLE) belongs to a family of procedures for determining goodness of fit. MLE can be used in conjunction with a linear or nonlinear model of the way that sources of information combine to determine a given behavioral outcome; such models can be used to estimate the distance between two groups, the degree to which an individual case deviates from a given empirically or theoretically defined group profile, and the degree to which one individual case resembles another. We offer a demonstration of how MLE can be used to evaluate group and individual profiles, in a cross-linguistic study of sentence comprehension in nonfluent aphasic speakers of English, Italian, and German. This includes a demonstration in which the MLE models for each language are "lesioned" to simulate several competing accounts of receptive agrammatism.
Explore the source record for details and available documents.
Turkish speech production was studied in 7 Broca's and 10 Wernicke's aphasics. Turkish is an agglutinative language, with few free-standing closed-class morphemes. The speech of Broca's patients was not telegraphic; although nonfluent, noun and verb suffixes were used appropriately. The speech of Wernicke's aphasics was fluent, using a wide range of often inappropriate forms. Both groups used appropriate nominal morphology. Broca's patients used a limited set of verb forms in contextually appropriate fashion. Wernicke's patients used a wide range of verb forms, all morphosyntactically correct, but often semantically anomalous. Both groups retained canonical subject-object-verb word order and controlled various types of pragmatically appropriate word order variation. It is proposed that aphasic speech patterns reflect retrieval problems rather than impairment of a portion of the language system.
The research reported here investigated the effect of phonological and syntactic factors on the processing of pronouns by aphasics. The comprehension of these "closed-class" elements was studied in three different languages: French, Dutch, and German. The cross-linguistic design made it possible to vary phonological status (clitic/nonclitic) and phrasal category (noun phrase/prepositional phrase) as well as grammatical relation (direct/indirect object) while keeping class membership (closed class) and meaning constant. A sentence-picture matching task was given to 20 German-speaking, 16 Dutch-speaking, and 14 French-speaking aphasics, half of each language group being classified as agrammatic Broca's and half as paragrammatic Wernicke's aphasics. The results suggest that Broca's aphasics' limitations in retrieving pronouns, and therefore other closed-class elements, are not a function of either phonological status, phrasal category, or grammatical relation. These subjects' observed high level of performance on pronouns in language comprehension appears due to the kind of semantic and syntactic information they encode. Our findings indicate that a more refined distinction than closed class vs. open class is necessary.
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.
Are the linguistic forms that are memorized in the mental lexicon and those that are specified by the rules of grammar subserved by distinct neurocognitive systems or by a single computational system with relatively broad anatomic distribution? On a dual-system view, the productive -ed-suffixation of English regular past tense forms (e.g., look-looked) depends upon the mental grammar, whereas irregular forms (e.g., dig-dug) are retrieved from lexical memory. On a single-mechanism view, the computation of both past tense types depends on associative memory. Neurological double dissociations between regulars and irregulars strengthen the dual-system view. The computation of real and novel, regular and irregular past tense forms was investigated in 20 aphasic subjects. Aphasics with non-fluent agrammatic speech and left frontal lesions were consistently more impaired at the production, reading, and judgment of regular than irregular past tenses. Aphasics with fluent speech and word-finding difficulties, and with left temporal/temporo-parietal lesions, showed the opposite pattern. These patterns held even when measures of frequency, phonological complexity, articulatory difficulty, and other factors were held constant. The data support the view that the memorized words of the mental lexicon are subserved by a brain system involving left temporal/temporo-parietal structures, whereas aspects of the mental grammar, in particular the computation of regular morphological forms, are subserved by a distinct system involving left frontal structures.
This study asked whether aphasic adults show different noun/verb retrieval patterns based upon their clinical categorization as fluent or nonfluent. Participants selected either the noun or the verb meaning of target words, as presented in three contexts. The framework was that nouns (associated with temporal lobe function) are processed, stored, and retrieved separately from verbs (associated with frontal lobe function), implying separate status in the mental lexicon. Stimuli were homophonic homographs, words that are spelled and pronounced the same but which have different meanings (in this case, noun and verb meanings). Another contrast was the putative difference between systematic pairs (e.g., "kiss" and "farm"), in which noun and verb meanings are transparently related, and may be stored as a unit, and unsystematic pairs (e.g., "squash" and "sink"), in which noun and verb meanings are apparently unrelated, implying discrete storage. Results demonstrated significant interactions between fluent and nonfluent participants, suggesting that, as expected, fluent aphasic adults have more difficulty with nouns, nonfluent aphasic adults have more difficulty with verbs. There was no effect of systematicity. Contrary to expectations, verbs proved less vulnerable, rather than more vulnerable, to aphasic impairment.
Research has shown that Broca's and Wernicke's aphasic patients show different impairments in auditory lexical processing. The results of an experiment with form-overlapping primes showed an inhibitory effect of form-overlap for control adults and a weak inhibition trend for Broca's aphasic patients, but a facilitatory effect of form-overlap was found for Wernicke's aphasic participants. This suggests that Wernicke's aphasic patients are mainly impaired in suppression of once-activated word candidates and selection of one winning candidate, which may be related to their problems in auditory language comprehension.
The processing of words and pictures representing actions and objects was tested in 21 aphasic patients and 20 healthy controls across three word production tasks: picture-naming (PN), single word reading (WR) and word repetition (WRP). Analysis 1 targeted task and lexical category (noun-verb), revealing worse performance on PN and verb items for both patients and control participants. For Analysis 2 we used data collected in a concurrent gesture norming study to re-categorize the noun-verb items along hand imagery parameters (i.e., objects that can/cannot be manipulated and actions which do/do not involve fine hand movements). Here, patients displayed relative difficulty with the 'manipulable' items, while controls displayed the opposite pattern. Therefore, whereas the noun-verb distinction resulted simply in lower verb accuracy across groups, the 'manipulability' distinction revealed a 'double-dissociation' between patients and control participants. These results carry implications for theories of embodiment, lexico-semantic dissociations, and the organization of meaning in the brain.
Explore the source record for details and available documents.
Phonological short-term memory was investigated in 24 aphasic left brain-damaged patients and in 12 matched controls. Aphasic patients have a reduced auditory and visual immediate memory span and show the standard detrimental effect of phonological similarity on immediate retention only when the stimuli are auditorily presented, while in the control group the effect is present with both auditory and visual input. Most patients have phonological processing deficits, but two patients have an impaired immediate verbal memory in the absence of analysis disorders. These results, in line with most individual case studies of patients with selective deficits of verbal short-term memory, are interpreted with reference to a model distinguishing a phonological short-term store component of memory, to which auditory input has direct and automatic access, and a rehearsal component, that, after phonological recoding, conveys visually presented stimuli to the phonological store. This latter system, that appears to become fully operational later in development, is less resistive to brain damage.
Explore the source record for details and available documents.
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.