Comparison of driving performance on-road and in a low-cost simulator using a concurrent telephone dialling task

Driving performance in an instrumented vehicle was compared with performance in a low-cost, fixed-based driving simulator. Six men and six women drove a freeway route while periodically dialling simulated phone calls. The same subjects drove a laboratory driving simulator using two visual fidelity levels: a colour scene with relatively high detail, and a monochrome (night) scene showing only road-edge markings. Lane position, speed, steering-wheel angle and throttle position were recorded in both contexts. Lane-keeping in the simulator was less precise than on the road, but speed control performance was comparable. The SD of lane position in normal driving was about twice as large, on average, in the simulator (0.360 versus 0.165 m). Lane keeping and speed control were less precise when dialling the phone than in normal driving, both in the simulator and on the road, but the performance decrement was greater in the simulator. The addition of the phone task increased the mean lateral speed in the car by about 43%, while in the simulator the mean lateral speed increased by 158% with the addition of the phone task. Subjects >60 years of age showed larger performance decrements during a concurrent phone dialling task than did subjects 20–30 years of age both in the simulator and on-road. No important differences in driving performance were found between the high and low simulator scene fidelity levels. The simulator demonstrated good absolute validity for measures of speed control and good relative validity for the effects of the phone task and age on driving precision.