nities to use the physical environment to off load working-memory demands, resulting in dramatic effects in their abilities to solve problems and reduce errors. Similarly, Ballard, Hayhoe, and Pelz ( 1995) found that when participants were allowed to choose their own task parameters in an everyday hand-eye task, they used eye movements to defer gathering task relevant information until just before it was needed--in efforts to minimize their working-memory load.
Although it may not be possible to offset or eliminate all of the factors that place excessive demands on control processes and contribute to working-memory load, we believe it is possible and desirable to redesign many existing displays and task environments to support working memory. We also believe that as information and display designers learn more about how to distribute processing demands in the physical world, both younger and older adults will benefit. Although the importance of consistency has been stressed in discussions of age-related research (see Fisk & Rogers, 1991), much additional work is still needed to understand how to take advantage of various consistencies to support control processes, in addition to fostering the acquisition of automatic processes. The foregoing experiments show that changes in spatial layout can have significant consequences for how accurately and quickly changing values can be monitored and updated--for both older and younger adults. Moreover, we believe many other types of consistencies can be used to lessen the burden on limited control processes and working memory. Consistencies that could offset placekeeping demands, both at encoding and retrieval, seem particularly worth exploring. For example, presenting items in a consistent order would provide a predictable structure for the information to be remembered. And having all of changing information constantly available on the display would provide many more opportunities for performers to encode and rehearse the changing values.
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