SEMANTIC & REPETITION PRIMING IN NORMAL & ABNORMAL AGING

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The broad objective of the research program is to understand the role of non-memory processes in the mild episodic and semantic memory impairments associated with normal aging and in the more severe memory impairments (especially in episodic memory) associated with Alzheimer's disease (AD; the most common type of abnormal neurological and cognitive aging). The first half of the proposed experiments utilize semantic priming para- digms, in which the effect on word processing time of a preceding related versus unrelated item is measured. These studies are designed to provide data on the effects of aging and AD on (1) the use of controlled, attentional semantic priming processes, (2) the extent to which semantic priming can reduce word-finding problems, and (3) susceptibility to intra-category inhibition effects (i.e., interference between concepts such as "horse" and "dog" which share many semantic features). The second half of the proposed experiments utilize an episodic memory paradigm, known as repetition priming, in which the effect on stimulus processing time of a previous occurrence of the same stimulus is measured. Repetition priming can be used to demonstrate storage of a previously experienced stimulus without the subject's memory being directly tested. Variables such as lag (between repetitions), mode of stimulus processing (active vs. passive), and compatibility of stimulus processing (between repetitions) will be manipulated. The proposed studies will yield important information about memory storage in "indirect" or "implicit" memory-testing situations which involve minimal effort, directed search and retrieval, and working memory capacity; this information will be obtained for AD compared to healthy elderly individuals and for healthy elderly compared to young individuals. The general hypothesis is that when measures of memory are used which minimize the use of resource-demanding, attentional processes, the AD patients' performance will be closer to, and in some cases indistinguishable from, that of controls. The outcomes of these experiments will have relevance for cognitive models of normal memory as well as for models of abnormal memory functioning in AD, and thus will speak to a wide audience. The proposed experiments also have practical relevance:. to the extent that memory storage capabilities are preserved in aging, despite the impairments in attention and working memory, memory training and compensation programs need to focus on the non-memory functions, which in turn, play a critical role in getting information into and out of memory storage. Further, to the extent that memory storage is less affected by AD pathophysiology than has been previously assumed, methods of assessing memory in AD (for diagnostic or drug treatment purposes) may need to be revamped.