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E Bates

Publications and source records attributed to E Bates.

10 recordsLinked to original sources
PubMed1992

Language development.

Recent research suggests that our ability to learn language is innate, but not necessarily domain-specific. That is, language development appears to be based on a relatively plastic mix of neural systems that also serve other cognitive and perceptual functions. Evidence in support of this conclusion includes neural network simulations of language learning, event-related brain potential studies of normal language development, and studies of language development in several clinical populations of subjects suffering focal brain injury, specific language impairment, and contrasting forms of mental retardation.

Humans↗
PubMed1991

A maximum likelihood procedure for the analysis of group and individual data in aphasia research.

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.

Aphasia↗
PubMed1991

Statistical constraints on the use of single cases in neuropsychological research.

In a recent study by Miceli, Silveri, Romani, and Caramazza (Brain and Language, 1989, 36, 447-492), free speech records for 20 unselected Italian-speaking agrammatic patients were analyzed along a variety of linguistic parameters, with particular emphasis on substitution and omission errors within traditional "part of speech" categories. The authors draw two strong conclusions: (1) the variability observed in this sample is too great to justify grouping these patients (or any coherent subset of the patients) into the "same" clinical category; (2) the extensive variability displayed by these patients reflects meaningful and very specific patterns of dissociation that would be lost if patients were grouped together in a common category called "aggrammatism." In a reanalysis of the Miceli et al. data, we conclude that the evidence does not justify either of these conclusions. First, we provide a set of mathematical simulations demonstrating that the dissociations claimed by Miceli et al. could have occurred entirely by chance, if samples of speech were drawn randomly from a "universe of discourse" characterized by error rates similar to those displayed by patients in this study. This randomization method has considerable generality, and could prove useful to other investigators interested in determining the number and type of dissociations that are likely to occur by chance in individual and/or group studies. Second, we demonstrate that there are many confounding factors that could account for the variability observed by Miceli et al., including differences in neurological status, education, and the strategies that patients elect to deal with their limitations.

Aphasia, Broca↗
PubMed1991

Early lexical development in children with focal brain injury.

Early lexical development in 27 children with focal brain injury was studied cross-sectionally and longitudinally. Data were obtained from children between 12 and 35 months of age who acquired their lesion prenatally or within the first 6 months of life. Results for the group as a whole provide clear evidence for delays in lexical comprehension and production, and for a larger number of comprehension/production dissociations than would be expected by chance. In addition, a significant number of children were observed having unusual difficulty mastering predication and/or using an atypically high proportion of closed class words (suggesting reliance on holistic/formulaic speech). Analyses by lesion type revealed no effect of lesion size. Analyses according to side of lesion revealed that children with right-hemisphere damage produced a higher proportion of closed class words, suggesting heavy reliance on well-practiced but under-analyzed speech formulae. Children with left-hemisphere damage were slightly better in comprehension than children with right-hemisphere damage. In addition, left posterior lesions were associated with greater delays in expressive language, and delays were more protracted in children with left posterior damage. No differential effects of left posterior damage were found for lexical comprehension.

Brain Injuries↗
PubMed1991

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.

Adult↗
PubMed1991

A crosslinguistic study of grammaticality judgments in Broca's aphasia.

Crosslinguistic studies of sentence comprehension and production in Broca's aphasia have yielded two complementary findings: (1) grammatical morphology appears to be more impaired than word order principles in every language studied, but (2) the degree to which grammatical morphology is retained by aphasic patients depends upon the "strength" or importance of those morphemes in the patient's premorbid language. In an earlier study comparing violations of word order and agreement, we found that English-speaking Broca's aphasics showed greater sensitivity to errors of ordering than to errors of agreement, providing further evidence for the selective vulnerability of morphology. However, because English is a rigid word order language with a relatively weak inflectional system, it could be argued that word order is resilient to brain damage because it is the strongest source of information in this language. The present study compared the performance of English-speaking Broca's aphasics and normal controls with their Italian counterparts in the same grammaticality judgment experiment. Four predictions relating to our previous work were confirmed. (1) Italian aphasics, like their English-speaking counterparts, showed general preservation of grammatical knowledge and (2) they were able to use this knowledge in an "on-line" fashion. (3) Within each language, Broca's aphasics showed greater impairment in their ability to recognize errors of morphological selection (i.e., agreement) compared with errors made by moving the same words to an incorrect position downstream. Nevertheless (4), crosslinguistic differences observed in previous studies of comprehension and production were also observed in this grammaticality judgment task: a processing advantage for agreement errors in Italian normals and aphasics, and a processing advantage for ordering errors in English normals and aphasics.

Adult↗
PubMedDate not supplied

Philosophy of care.

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Aged↗