A series of experiments is proposed to investigate normal age- related differences in three different types of memory: procedural, episodic, and semantic. Most extant aging research has concentrated on episodic memory, i.e., memory requiring conscious recollection of an experienced event. Some recent research has investigated age differences in semantic memory -- knowledge of facts and vocabulary -- but very few aging investigations have delved into procedural memory. This type of memory is driven by previously experienced stimuli and requires no conscious recollection. Age-related investigations of different types of memory are crucial to our understanding of brain- behavior relationships, since it appears that aging might affect these different memory systems selectively. It is hypothesized that while episodic memory declines with normal aging, both semantic and procedural memory remain intact. Normative age differences will be investigated cross-sectionally by comparing young (ages 18-35) to healthy older adults (65-80) and young-old (65-80) to the oldest old (85+) within the elderly. Procedural memory will be measured via repetition priming in picture naming and category decision latencies, perceptual identification of words, picture fragment identification, and homophone spelling. These tasks provide memory measures sensitive to prior experience without requiring conscious recollection. Experimental manipulations of these tasks are hypothesized to produce dissociations from more standard episodic memory tasks such as recall and recognition. Specifically, typical age-related declines are expected for episodic measures, whereas age differences should be nonexistent for measures that tap semantic and procedural memory. Additionally, a factor-analytic approach will make it possible to examine the implicit memorial structure of these various memory systems. The findings should 1) further our understanding of age-related changes in memory functioning, and 2) provide additional evidence bearing on the important question of how many memory systems there are. Evidence for the intact funtioning of selective memory systems may prove beneficial to future applications for the general cognitive functioning of both healthy elderly and demented patients.
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