Abstract
A measurement-instrumented car was used to test the hypothesis that older drivers organise their car-controlling movements in a more serial way in order to reduce the momentary mental workload produced by complex traffic situations. Forty-two older drivers (65+, mean age 67.5) and 36 young middle-aged drivers (26-49, mean age 36.8) drove a measurementinstrumented car around a 7.4 km route in normal traffic. The use of car controls (e.g. clutch, brake) was registered by sensors connected to a computer. In the most complex parts of the test route (e.g. during which three or more controls were in use simultaneously), the older drivers tended to use three controls rather than four or more, whereas the younger group had a greater percentage of four or more controls. This percentage was positively related to speed. However, although older drivers drove more slowly in general, in pairs matched for speed, they still drove in a less parallel manner. Irrespective of age, parallel use of controls was positively related to the level of skill as indicated by the amount of cumulated driving experience. The shift towards more serial operation of controls possibly represents an empirical demonstration of a compensatory mechanism allowing older drivers to maintain their level of performance.
