Working Memory and Aging

Introduction

As people age, they go through physical, cognitive, and emotional changes. For some, the changes are gradual while others experience them more abruptly. In any case, these are realities that must be dealt with. Perhaps some of the most frustrating changes are those dealing with mental processes. Current research tells us that one of these changes is in working memory. It is now basically an accepted idea that working memory does decrease in old age. However, it is not known what exactly is responsible for this decline.

What We Know About Working Memory and What We Are Still Learning

Many types of research have shown that working memory does decline in old age. One example is a study done by Suzanne Norman, Susan Kemper, and Donna Kynette (1992). They hypothesized that there is a decline and that this affects elderly adults' reading comprehension and processing of complex syntax. Thirty young adults and 59 elderly adults, all with similar levels of education, participated. The elderly were divided into a young-old group of 32 adults between the ages of 60 and 74 and an old-old group of 27 adults between the ages of 75 and 92. Three tests, the forward and backward Digit Span subtest from the WAIS-R and the Daneman and Carpenter Sentence Span Test were used to test working memory. Results indicated that performance on all three working memory tests declined with age. A significant difference was found in the scores of the old-old group compared with the scores of the young adult group and the young-old group. There was no significant difference between the young adults and the young-old age group. This replicates results that have been found in other studies as well. It seems that, among fairly healthy individuals, the norm is for working memory to start showing obvious signs of decline when they reach the old-old category.

So now we have evidence that working memory does not function so well in old age. Many people may wonder if there is something that they can do to keep their memory functioning better as they get older. Various theories suggest different aspects of life that may correlate with high memory functioning until death. Yet, perhaps more important is figuring out which specific parts of the memory process are responsible for the decline. This is an area that is very complex and is not totally understood.

One theory by Gerard et al. (1991) focused on retrieval processes. Their idea is that interference in retrieval processes is the key to decline in older adults' working memory. They performed a study using the basic fan effect paradigm, which involves distinguishing between learned target facts and unstudied foil facts made from repairing parts of the target facts together. The more facts that are learned about a particular concept, the longer it takes to retrieve any of the facts and the more errors that are made. Interference occurs because facts sharing the same concepts compete with each other at retrieval. They theorize that inhibitory attentional mechanisms don't function as well in old age and more irrelevant information gains access to working memory, causing interference. Their study included 27 young adults and 27 elderly adults. The results to this study supported their hypothesis. The older adults did indeed have greater problems with retrieval interference. Consistent with this was the finding that the foil facts, which required a more extensive search of memory than did target facts, produced larger differences on a speeded recognition test than the studied target facts did.

One researcher who has dedicated a large portion of his work to studies about working memory is Timothy Salthouse. He has also attempted to find some evidence about how working memory functions. In one line of research (1991), he did three consecutive studies that focused on the role that working memory and speed of processing play in the differences in cognition of adults depending on their age. Cognitive performance was assessed by the number of items answered correctly and in terms of the accuracy of the items attempted. Working memory was also measured under the assumption that speed of processing might exert its effects on cognition by altering the functioning of working memory.

Two hundred and twenty adults between the ages of 20 and 84 participated. Each study used a different measure of assessing cognition. In all three studies, comparison speed was measured. Working memory was assessed with the Computation Span and Listening Span tests which required the subject to remember information while processing other information.

The results indicated age related effects of cognitive functioning were mainly mediated by age related reduction in working memory. The results also showed that a large proportion of the age related differences in working memory is mediated by processing speed. It seems, then, that with age people's cognitive functioning is reduced because working memory is reduced. Why is working memory reduced? Probably largely because processing speed is reduced, according to this study.

Another group of studies by Renee Babcock and Timothy Salthouse (1990) were designed to determine the relationship between capacity of storage and efficiency in processing. Are age related working memory differences a cause of age related decline in one or both of these? The first study, using only young adults, was to determine if greater processing requirements lead to more involvement of a central processor in memory. The results supported the notion that there is greater involvement of the central processor when both storage and processing are required than when just storage is required. The next two studies examined age differences. Thirty-eight young adults and seventeen older adults participated in the second study and 40 young adults and 41 elderly adults took part in the third. They hypothesized that if there is a decrease with age in the efficiency of central processing, greater performance impairments might be expected for older adults than for younger adults as the processing demands are increased. However, the results did not support their predictions when they compared little, modest, and substantial processing demands. The age differences in memory span seem to be independent of the amount of processing.

Conclusion

After reviewing the previous studies, we can see there is no easy answer about working memory. It is understandable why there are so many hypotheses surrounding this topic. One thing we are fairly sure of is that memory functioning is negatively correlated with age once you reach late adulthood. In the first study discussed (Norman, Kemper, & Kynette, 1992), they found that reading comprehension declines in the same way that working memory does with age and consequently, it's likely that the decrease in working memory is to blame. Studies like are important because we then see what aspects of daily life are affected by memory's reduced functioning. Researchers like Salthouse, Babcock, and Gerard et al. give us ideas about the complex system of working memory. Hopefully, continued research will lead to an eventual understanding.

References

Babcock, Renee L. & Salthouse, Timothy A. (1990). Effects of increased processing demands on age differences in working memory. Psychology and Aging, 5(3), 421-428. (Note: Renee is a 1986 Hope grad)

Gerard, Linda, Zacks, Rose T., Hasher, Lynn, & Ravansky, Gabriel A. (1991). Age deficits in retrieval: The fan effect. Journal of Gerontology, 46(4), 131-136.

Norman, Suzanne, Kemper, Susan, & Kynette, Donna (1992). Adults' reading comprehension: Effects of syntactic complexity and working memory. Journal of Gerontology, 47(4), 258-265.

Salthouse, Timothy A. (1991). Mediation of adult age differences in cognition by reductions in working memory and speed of processing. Psychological Science, 2(3), 179-183.

Contributed by Ellen Schultz, September 30, 1997.

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