Brouwer and Withaar (1997; also see Withaar, Brouwer, and van Zomeren, 2000) introduced a distinction among three aspects of driving that may help explain the absence of expected age-related increases in crashes (when crash rates are not adjusted for distance driven). In their classification scheme, operational aspects refer to control of the car in reaction to continuously changing traffic conditions; tactical aspects refer to voluntary choice of cruising speed, following distance, and maneuvers; and strategic aspects refer to choice of travel mode, route, and time of traveling. It is possible that older drivers rely on their stable or increasing strategic and tactical knowledge acquired through experience to minimize dependence on operational abilities that may be declining.

In fact, when crash rates are adjusted for distance driven they do start to increase with age after age 65, and it is reasonable to expect that they would increase to an even greater extent if it were also possible to take into consideration when the individual is driving and under what conditions (e.g., during the day or at night, in the middle of the day or during rush hour, etc.). The applicability of the strategic-tactical-operational distinction to occupational contexts is not yet known. However, it is certainly possible that increased age is associated with declines in operational abilities in many work situations, but that the consequences of these declines are offset by age-related increases in strategic and tactical knowledge. Furthermore, to the extent that safety is positively associated with quality or quantity of tactical and strategic knowledge, the safety of older workers may be at least as great as that of young workers because an age-related increase in job-relevant knowledge (Warr, 1994).

Certain adaptations may be required on the part of the older worker, and possibly some accommodations on the part of the employer in order to maximize the capabilities of older workers. However, there appears to be little reason to expect age-related changes in cognitive functioning to adversely affect the health, safety, or productivity of workers who are continuing in the same job and are performing familiar activities.

Experience and Expertise

Examination of the physical, psychological, and social differences between older and younger workers indicates that aging processes tend to lower some functional capacity. Increased age, however, is also associated with increased experience that tends to raise experience-related functional capacities. These two aspects of age may trade off, particularly when experience leads to skill and expertise, a point stressed in some of the earliest literature in this field (e.g., Welford, 1958).

Is there evidence that experience or expertise can mitigate general age-related declines in basic mental abilities? The reason for being concerned by



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