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Title: Acquired disorders of numerical processing
Author: Cipolotti, Lisa
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 1993
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This thesis aims, by three single case designs, to help identify the component processes involved in numerical skills. The first patient (C.G.), following a left hemisphere stroke, presented with a dense acalculia. C.G. showed a preserved ability to process numbers below 4 while she was totally unable to process numbers above 4. The consistency of responses and the ineffectiveness of cueing indicated that numbers above 4 were lost not difficult to access. Her deficit was not paired with a general semantic memory problem, a difficulty in understanding quantities or in the reasoning abilities thought to underlie number concepts. The second (S.F.) and third (S.A.M.) patients suffered from a progressive neurological degenerative condition of unknown origin. S.F. had difficulty in reading aloud multidigit arabic numerals whilst being able to read aloud written number names, letters and words. This observation realized a double dissociation with the "number sparing effect" observed in alexic patients (e.g., Dejerine, 1892) indicating that words and arabic numerals are read by two, at least in part, dissociable processes. S.F. could recognize and understand arabic numerals and produce verbal numerals as responses to number fact or "what comes next." questions. His performance was interpreted as a consequence of damage to a postulated asemantic route for arabic numeral reading. A follow up study of this patient 18 months later replicated the arabic numeral dyslexia finding. S.A.M. could recognize and understand arabic and verbal numerals but not read and write them. However, he had a well maintained ability to perform oral and written calculations. This finding realized a double dissociation with the "number transcoding sparing effect" observed in acalculic patients (e.g., Warrington, 1982). Asemantic transcoding mechanism additions to the McCloskey (1992) model were suggested.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Psychology