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Performance on Perceptual-structural Priming Tasks in Patients with Probable Alzheimer's Disease (AD)

出版	University of California, San Diego, 1998
URL	http://books.google.com.hk/books?id=sw7IDdChi88C&hl=&source=gbs_api

註釋While AD patients typically demonstrate impairment on "conceptually-driven" priming tasks, discrepant findings have emerged with regard to their performance on "data-driven," or perceptual, priming tasks. In an attempt to explain this variable priming performance, Gabrieli et al. (1994) proposed that implicit memory tasks may be driven by two separate systems: one mediating memory for "lexical-semantic" information and the other mediating memory for "perceptual-structural" material. The performance of AD patients on a series of perceptual priming tasks was examined. First, the possibility was addressed that findings of intact perceptual priming in AD may be partially explained by inadequate task sensitivity. Thus, within all experiments, (1) a finer measure of priming performance was used (e.g., reaction times) and (2) the test materials covered a range of difficulty. Further, experiments 2 and 3 addressed the need to evaluate perceptual priming using test materials that require little to no lexical or semantic processing. Participants were 15 AD patients and 15 age-matched normal control subjects (NCs). In experiment 1, a picture fragment identification task was administered. Findings revealed that the AD patients showed impaired priming relative to the NCs. Within experiment 2, two separate priming tasks were administered, one requiring the speeded copying of words and the other requiring the copying of patterns. Findings revealed no group difference in priming within either task, even when baseline differences in copying speed were statistically accounted for. Experiment 3 compared performance on two repetition priming tasks requiring that participants make speeded decisions about whether two stimuli were the same or different. One of the tasks used words as test stimuli while the other used meaningless objects. Findings revealed that the AD patients were significantly impaired relative to the NCs on the object, but not the word, priming task. Follow-up analyses within all three experiments revealed differential effects of item difficulty on priming performance. The current findings of impaired perceptual priming in AD in two out of five tasks do not support Gabrieli's multiple memory systems view. Degree of task sensitivity appears to influence the appearance of impaired priming performance in AD.