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Biomedical subjects

A Caramazza

Publications and source records attributed to A Caramazza.

At least 91 records · Page 5Linked to original sources
PubMed1984

On the basis for the agrammatic's difficulty in producing main verbs.

Current theories of agrammatism do not provide a clear explanation for the co-occurrence of omission of grammatical markers and main verbs in this disorder. This study tested the hypothesis that the two symptom features have distinct underlying causes. Specifically, that the omission of main verbs in agrammatic speech is caused, at least in part, by a lexical (as opposed to a syntactic) deficit. Agrammatic and anomic aphasics and normal controls were given an object and action naming test. Agrammatic patients showed a marked impairment in naming actions in contrast to anomic aphasics and normal controls who named actions better than objects. The action naming impairment in agrammatic patients was interpreted as evidence for the lexical deficit hypothesis of verb omission in the speech of these patients and as a demonstration that agrammatism is a heterogeneous disorder that implicates damage to both lexical and syntactic mechanisms.

Adult↗
PubMed1983

The selective impairment of phonological processing: a case study.

A case study is reported of an aphasic patient with fluent speech and markedly superior comprehension of written vs. spoken words. Results of extensive testing supported the hypothesis that the patient suffers from a phonological processing deficit that affects performance in all tasks that require the generation of a phonological code. This selective deficit is interpreted as the underlying cause of diverse symptoms such as asyntactic comprehension of written sentences, the commission of spelling errors in writing, and the production of literal paraphasias and neologisms in spontaneous speech. Alternative possibilities for the classification of this patient are discussed.

Adult↗
PubMed1983

An analysis of writing in a case of deep dyslexia.

In tests of her ability to produce written and spoken language, this deep dyslexic patient produced semantic, visual, and derivational errors, including functor substitutions, and exhibited part-of-speech and abstractness effects in oral reading, oral and written naming, and writing to dictation, but not in repetition of single words and copying from memory. This patient therefore provides confirmation of the hypothesis presented in Nolan and Caramazza (1982) that the defining symptoms of deep dyslexia will be observed in responses to any task which requires lexical mediation. The patient's written responses in all tasks but direct copying were characterized by spelling errors which included transpositions, omissions, substitutions, and additions of letters. A model of writing is proposed which explains these errors in terms of a disruption of a phoneme-grapheme conversion process which normally functions to prevent decay of information from a Graphemic Buffer.

Agraphia↗
PubMed1983

Closed- and open-class lexical access in agrammatic and fluent aphasics.

Bradley, Garrett, and Zurif (Bradley, Computational distinctions of vocabulary type. Unpublished doctoral dissertation, MIT Press; Cambridge, MA, 1978; Biological studies of mental processes, MIT Press, Cambridge, MA, 1980) have suggested that closed-class word access is normally mediated by a different route than the open-class one, and that the loss of this closed-class route might account for agrammatism. However, in an earlier study (Gordon & Caramazza, Brain and Language, 15, 143-160, 1982) we were not able to confirm a meaningful difference between closed- and open-class word frequency responsiveness of the type Bradley (unpublished dissertation, 1978) had seemed to find in normal subjects. We have now done a direct comparison of closed-class frequency sensitivity in agrammatic and nonagrammatic aphasics, to directly test Bradley and colleagues' hypotheses and to avoid some of the experimental problems with between-class frequency comparisons. We find that closed-class words behave similarly whether or not the subject is agrammatic. Therefore, the differences between agrammatic and nonagrammatic aphasics must arise at a deeper level (or levels) of lexical processing than the one probed by the frequency sensitivity effect.

Aphasia↗
PubMed1982

Short-term memory performance in the absence of phonological coding.

These experiments examined the short-term memory performance of an aphasic patient with posterior damage who shows a selective deficit in phonological coding. In recognition memory tests, the patient relied on both visual and semantic coding, and often showed an essentially normal level of accuracy. However, for memory sets consisting of four function words, his performance was quite impaired. Also, his retention of order information was far below that of normal controls. The implications of these deficits in short-term memory for language comprehension and production are discussed.

Aphasia↗
PubMed1981

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 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.

Aphasia↗
PubMed1980

Classification in well-defined and ill-defined categories: evidence for common processing strategies.

Early work in perceptual and conceptual categorization assumed that categories had criterial features and that category membership could be determined by logical rules for the combination of features. More recent theories have assumed that categories have an ill-defined structure and have prosposed probabilistic or global similarity models for the verification of category membership. In the experiments reported here, several models of categorization were compared, using one set of categories having criterial features and another set having an ill-defined structure. Schematic faces were used as exemplars in both cases. Because many models depend on distance in a multidimensional space for their predictions, in Experiment 1 a multidimensional scaling study was performed using the faces of both sets as stimuli, In Experiment 2, subjects learned the category membership of faces for the categories having criterial features. After learning, reaction times for category verification and typicality judgments were obtained. Subjects also judged the similarity of pairs of faces. Since these categories had characteristic as well as defining features, it was possible to test the predictions of the feature comparison model (Smith et al.), which asserts that reaction times and typicalities are affected by characteristic features. Only weak support for this model was obtained. Instead, it appeared that subjects developed logical rules for the classification of faces. A characteristic feature affected reaction times only when it was part of the rule system devised by the subject. The procedure for Experiment 3 was like that for Experiment 2, but with ill-defined rather than well-defined categories. The obtained reaction times had high correlations with some of the models for ill-defined categories. However, subjects' performance could best be described as one of feature testing based on a logical rule system for classification. These experiments indicate that whether or not categories have criterial features, subjects attempt to develop a set of feature tests that allow for exemplar classification. Previous evidence supporting probabilistic or similarity models may be interpreted as resulting from subjects' use of the most efficient rules for classification and the averaging of responses for subjects using different sets of rules.

Concept Formation↗
PubMed1979

Lexical semantics and memory for words in aphasia.

Aphasic and non-neurological patients were assessed on a word recognition memory task. On any one trial, some words were instances of the same superordinate category, thus presupposing a common abstract conceptual feature, and some words could be linked thematically in the sense of forming context-dependent relations. Observing the temporal order in which patients pointed to the words they recognized permitted an assessment of the extent to which they clustered their responses either in terms of superordinate categories or along thematic lines. The conceptual structures indicated by these clusters were compared with those observed in a previous task requiring judgments of word relatedness. The data suggest that verbal memory limitations in aphasia are only in part linked to constraints on the conceptual features structuring lexical knowledge; and relatedly they raise the possibility that aphasics may have a disturbance of mnemonic processing quite apart from any disruption to language.

Adult↗