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Biomedical subjects

D M Baxter

Publications and source records attributed to D M Baxter.

6 recordsLinked to original sources
PubMed1989

The origins of utilization behaviour.

Utilization behaviour has previously been described clinically by Lhermitte (1983). An experimental investigation is reported of utilization behaviour in a patient with a localized inferior medial bifrontal lesion. The patient picked up and used irrelevant objects not only when place directly in front of him--the procedure developed by Lhermitte--but also when he had been instructed to carry out other tasks and his attention had not been directed to the objects. The behaviour occurred most frequently in the brief intervals between tasks, and more often when auditory-verbal rather than visuomotor tasks were being performed. The results are interpreted within an information-processing model of frontal lobe function. A differentiation is made between two forms of utilization behaviour--an 'incidental' form, as exhibited by the patient, and an 'induced' form where it occurs only when Lhermitte's procedure is adopted.

Behavior↗
PubMed1987

Transcoding sound to spelling: single or multiple sound unit correspondence?

We report a detailed analysis of the written spelling of an aphasic patient, KT, in whom no viable comprehension could be demonstrated despite accurate repetition and fluent speech (transcortical sensory aphasia). His spelling conformed in all respects with the definition of an orthographic/lexical dysgraphic such that his writing of regular, orthographically unambiguous words and nonsense syllables was entirely satisfactory. Lexical variables such as word class or word frequency had no effect on his performance. Irregular or ambiguously spelled words were selectively impaired. An independent measure of orthographical ambiguity was defined in relation to the frequency with which a phoneme was represented by a particular grapheme and the number of alternative graphemes for the same sound. For the majority of sounds studied, KT was able to demonstrate the use of all the most frequent alternative transcoding units for each sound but he did not use them in the same frequency with which they occurred in written English. Thus his performance bore little or no relationship to predictions based on single phoneme/grapheme counts and there was unequivocal evidence for his ability to use multiple sound-unit correspondences.

Aphasia, Wernicke↗
PubMed1986

Ideational agraphia: a single case study.

A case study investigates the writing, spelling and praxic skills of one patient who was found to have a selective impairment in his ability to write letters and words in the absence of difficulty in copying these same letters and words. He appeared to have difficulty accessing the correct motor programmes or sequences for writing which we term "ideational agraphia" analagous to the syndrome of ideational apraxia. These findings are related to Margolin's information-processing model of writing.

Aged↗
PubMed1985

Category specific phonological dysgraphia.

The present case study describes a phonological dysgraphic with intact comprehension who had difficulties spelling certain classes of words. Nouns were easier than adjectives which in turn were easier than verbs and function words. A difference between verbs and nouns remained even when level of concreteness was controlled. The findings are discussed in relation to current models of the organization of spelling in relation to other cognitive skills.

Aged↗