Long-term memory in adulthood: An examination of the development of storage and retrieval processes at acquisition and retention

Although it is generally acknowledged that decrements in long-term memory play an important role in the decline of everyday cognitive functioning in adulthood, problems have arisen in localizing the source of these memory deficits. In this article we address three of the methodological and measurement issues that have led to difficulties in interpreting research on adulthood developmental differences in acquisition and long-term retention. Specifically, these issues are stages-of-learning confounds, failures to separate storage and retrieval processes, and failures to separate forgetting from other factors that influence long-term retention tests. A general framework is presented in which each of these problems is dealt with. This model is subsequently applied to an experiment that examined the acquisition and long-term retention of pictures and words in associative memory in both young and old adults. The major findings were that (a) the picture-word manipulation had asymmetrical effects on acquisition and retention, (b) these asymmetries were different for the young and old adults, and (c) the locus (storage/retrieval) of age differences was different at acquisition than at retention. These results strongly suggest that the rules governing acquisition and forgetting are different, not only within age groups, but also across developmental levels in adulthood. More importantly, because the locus of developmental differences was different for acquisition and forgetting, it may be that different mechanisms underly the processing deficits experienced by the elderly when acquiring information than when trying to retain that information over extended periods of time.