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Title: A study of implicit memory and temporal gradients in retrograde amnesia and semantic dementia.
Author: Townshend, Julia Margaret.
Awarding Body: University of Sussex
Current Institution: University of Sussex
Date of Award: 2000
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This thesis sets out to test some of the predictions proposed by a recent connectionist model of memory and amnesia. The model proposes a time limited role for the hippocampus in memory consolidation in which memories once dependent on the hippocampus become independent of the hippocampus over time and fully supported by the neocortex. The predictions that are made by the model are that there will be memories in retrograde amnesia that are only available through implicit tests of memory; that implicit memory in retrograde amnesia will show a temporal gradient; that semantic dementia patients will show a 'reverse temporal gradient' in retrograde amnesia; and that implicit learning in semantic dementia will be impaired. Chapter 1 reviews some of the current literature relevant to these predictions. Chapter 2 contains the psychometric details of the patient groups taking part, relating these to the underlying neuropathology. Chapter 3 describes three studies which examine recognition and familiarity of famous faces and names from the retrograde period and temporal gradients in familiarity responses. The results are discussed in terms of face and name recognition models. Chapter 4 describes a study that provides evidence of implicit knowledge of famous faces using an indirect method of testing. Chapter 5 is a single-case study using a reaction time measure for new words introduced into the English language during the retrograde period. Chapter 6 is a single-case study of a patient with semantic dementia. The three experiments in this chapter investigate implicit learning in a repetition priming task and the relationship between forced choice recognition of famous faces and famous names. Finally, Chapter 7 discusses the findings in terms of the predictions of the connectionist model of memory and amnesia. The conclusion is that whilst there is evidence of implicit memory in retrograde amnesia, this is unlikely to show a temporal gradient. The prediction that there would be a 'reverse temporal gradient' and impaired implicit memory in semantic dementia was not upheld, and this is discussed in terms of the underlying neuropathology and how it relates to this and other models of memory.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Psychology Psychology