Working memory and the Self-Ordered Pointing Task: further evidence of early prefrontal decline in normal aging.

Two major lines of investigation are currently clarifying the nature of the impairment of working memory associated with normal aging. Cognitive psychology has formulated the problem in terms such as the balance of impairment of encoding, retrieval, storage and/or attention, whereas neuropsychology has formulated the problem in terms such as the balance of frontal (executive) versus temporal (mnemonic) degeneration. The findings of this study support the contention that the primary impairment of working memory in early normal aging is an active attentional executive processing deficit. Specifically, on the Self-Ordered Pointing Task, there is significantly ineffective exploitation of top-down clustering strategy as a function of aging. On this task, self-organization of encoding and retrieval must occur simultaneously with ongoing responding. The finding cannot be explained as an impairment of encoding, retrieval, storage, or build-up and/or release of proactive interference, since indexes of these did not discriminate young-adult from middle-aged samples.