Ergonomics and Aging - Fundamentals and Assessment Tools for Occupational Ergonomics - page 413

include altering the speed of the mouse clicks or making use of the keyboard to compensate for slow
clicking. Should these accommodations with computer mice fail, older adults might also benefit from
the use of other input devices such as touchscreens that allow direct input or a rotary encoder that
allows precise control (Rogers et al., 2005).
Cognitive changes that influence computer usage include declines in working memory as well as
retention of semantic memory. Working memory declines appear to explain why older adults have
difficulty performing complex computerized tasks such as Internet searches. While searching for
information within a website, older adults must remember what information they are searching
for, where they have looked for it, and where they are currently located within the site (Stronge
et al., 2002). As a result of declining working memory capacity, older adults have been observed to
revisit pages within a website that they have already browsed and have trouble keeping track of the
current page that they are visiting (Mead et al., 1997). Thus, poor working memory might result in
an inaccurate mental representation of the hierarchical structure of a website or more generally, a computer
system.
As semantic memory is preserved in older adults, well-learned tasks that require the use of familiar
computer systems should be minimally impacted by the aging process. Problems arise when technology
and systems are upgraded, thereby forcing older workers to acquire new skills through training. When
new information is encountered during training, it is often interpreted in the context of the pre-existing
knowledge base. For this reason, instructional materials should be presented using familiar terminol-
ogy that makes reference to earlier technology. Because metaphors tap well-developed crystallized
knowledge, they may be an effective means of simulating experience when teaching older adults
(Bowles et al., 2002).

17.8.8 Environmental Factors for Improving Worker Task Match

In addition to equipment design changes, environmental design changes that take into consideration
age-related changes can also improve productivity and safety for older adult workers. In light of
vision and hearing declines that often occur with aging, lighting optimization and noise reduction
may greatly improve the working environment for older adults. Older adults require higher levels of illu-
mination to see well compared to younger adults, although the optimal amount is a debated issue (e.g.,
Jaschinski, 1982). On a series of legibility tasks, Charness and Dijkstra (1999) found that the performance
of older office workers improved to a greater extent than younger adults when luminance increased.
Specifically, performance improved when luminance was in the 450 to 600 cd

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m 2 range. In general,
higher levels of illumination are needed as the size of the relevant visual details decrease and as the
demand for speed and accuracy increase (Charness and Bosman, 1992). Charness and Dijkstra (1999)
recommended that adults over the age of 40 should increase lighting when performing clerical tasks
such as finding information in a phonebook. Furthermore, the authors suggested that both younger
and older adults should increase lighting for clerical tasks such as proofreading. Given that the
optimal level of illumination may vary from person to person, Fozard and Popkin (1978) recommended
using individual preference to determine the level selected. While some findings suggested that individual
preference for illumination can predict optimal performance (e.g., Hughes and McNelis, 1978), other
results suggested that they do not (Boyce, 1981). Thus optimal lighting conditions are best determined
through performance comparisons under different lighting conditions.
Reducing background noise would also aid in optimizing environmental conditions for older workers.
This can be achieved by incorporating sound absorbing materials in offices and factories. One recent
invention called “quiet curtains,” were designed in an effort to reduce nocturnal noise in nursing
homes (Ahuja, 1999). The curtains are made by placing noise reducing materials between two pieces
of fabric. Ahuja's prototype reduced noise by approximately 7 (dB), and by adding a similarly made
floor extension and valance, noise was reduced by 12 (dB), which indicates a reduction of sound intensity
by a factor of 16. Given age-associated sensitivities to background noise, environments that make use of
sound reducing materials would be particularly beneficial for older adult workers.

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