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Salthouse, T. A. (1990). Working memory as a processing resource in cognitive aging. Developmental Review, 10, 101-124.

Author of the summary: David Zach Hambrick, 1998, gt8781a@prism.gatech.edu

Salthouse (1990)


Salthouse reviews research relevant to question of whether experience moderates age-related changes in cognitive functioning. This question is important because basic aspects of cognitive functioning may be relevant for the performance of complex tasks outside of the laboratory. It is well established that the relations of age to cognitive functioning differ depending on the nature of the measure. Measure of fluid cognition decline with age, whereas measures of crystallized cognition remain stable or even increase slightly.


The question of whether experience reduces age-related declines is important because such age-differences "may be detrimental to older adultsí effectiveness in many occupational situations" (p. 552). Although age-related cognitive declines have real consequences for work performance is debatable, the question is also important from a theoretical perspective. The question of whether experience might attenuate decline is also extremely important, and is relevant to the use or lose it notion of cognitive aging. Salthouse reviews three classes of studies relevant to this issue.


Familiar Activities


The first class of studies involves comparisons of younger and older adults on familiar, or so-called ecologically-valid tasks (e.g., remembering phone numbers). If age-related declines in standard measures of cognitive functioning are attributable to the older adultsí lack of familiarity with the testing materials, then reduced age-related declines might be expected for more familiar tasks. Salthouse points out several problems with this notion. First, how can familiarity be operationalized, and do ratings of familiarity reflect processes involved in task performance or superficial features? Second, younger adults tend to outperform older adults even on tasks presumably familiar to both young and old adults. Thus, there is "little support for the proposal that age differences are restricted to novel and unfamiliar activities" (p. 556).


Practice and Training


Does training reduce age-related decline? Salthouse first points out that "it is simply impossible to draw conclusions about possible age-related differences in the benefits or experience without comparisons of two or more age groups" (p. 556). A number of other weaknesses of studies within this class are noted. For example, few studies document the representativeness of participants who are willing to participate in long-term studies. Conclusions are therefore qualified by the possibility of ability interactions. Furthermore, most studies within this class have included only one dependent variable. Therefore, it is possible that training reflects development of task-specific strategies rather than modification of underlying processes. These problems notwithstanding, the available evidence suggests that training effects are most often equivalent in young and old adults. However, absolute levels of performance are higher for younger adults then for older adults.


Select Populations


The final approach for investigating the relations among age, experience, and performance involves seeing whether age effects are reduced for highly learned, overpracticed activities. That is, "extensively performed activities might be maintained at high levels of proficiency even if there are age-related differences in the efficiency of performing the activities when first encountered or in the ease of acquiring high levels of proficiency" (p. 561). A straightforward approach is to simply examine the relations between age and work performance. However, Salthouse points out a number of problems. The first concerns the representativeness of older workers compared with younger workers. Competent workers are likely to be promoted, and incompetent workers are likely to drop out of the workforce before old age. The second problem is that job requirements for older workers and younger workers may be different. Second, measures of job performance are coarse. Salthouse explains that "It would be much more informative for the purpose of examining interrelations of age and experience on cognitive functioning if the age comparisons were reported on specific dimensions of job performance with known involvements of different types of cognitive abilities" (p. 561).


Several studies have compared the performance of younger and older adults on specially designed criterion tasks. A critical issue in these studies is whether the task is in fact relevant to occupational activities because "one cannot hope to reach meaningful conclusions about the contributions of experience when there is so little agreement about the frequency of the target activity in different occupations" (p. 562). Murrell reported that there were age differences among novices, but not experts, on a task related to using a drill-press. However, it is unclear whether the older sample was representative (selection attrition?). Studies of air-traffic controllers have found expected age-related declines on perceptual-motor tasks. Finally, Salthouse and colleagues found similar rates of age-related decline for architects, graduates of Tech, and unselected adults.


Comments and Questions


Salthouse points out that knowledge may be more important than fluid abilities, and stresses that future research should focus on the nature of this knowledge and how it contributes to performance. In addition, "It is possible . . . that the most pronounced effects of experience are not evident at the level of basic abilities but instead are operative at more global or molar levels" (p. 566). There are several ways that experience might preserve molar-level performance, including compensation, accommodation, elimination, and compilation.


editor's note: I don't think this is the right paper for this summary.
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