TIME HEADWAY IN CAR FOLLOWING AND OPERATIONAL PERFORMANCE DURING UNEXPECTED BRAKING

The relation between car-following behaviour and braking performance w as studied in a driving simulator. The theoretical perspective was tha t individual differences in tactical car-driving behaviour may be rela ted to skills on the operational level of the driving task via a proce ss of adaptation. In a sample of 16 young and middle-aged experienced drivers independent assessments were made of preferred time headway du ring car following and of braking skill. Starting from modem theories of visual-motor learning, braking performance was analyzed in terms of a reaction time component, an open-loop visual-motor component, and a closed-loop visual-motor component involving the precise adjustment o f braking (timing and force) to the situation. The efficiency of the v isual-motor component of braking was a strong and significant predicto r of choice of time headway to the lead vehicle in such a way that les s efficient braking indicated a preference for a longer time headway. This result supports the theory of adaptation on the individual level.