The Effect of Cellular Phone Use on Driving Performance

Many experiments using driving simulators or real roads have shown that using a cellular phone while driving may cause an accident because it delays visual information processing by the driver. In this research, we examined the influence on driving performance of cellular phone use on a course that simulated streets. Driving conditions were driving only, listening to the car radio, hands-free cellular phone use and using a cellular phone with the left hand. Driving performance measurements included braking response time to the brake lights of a preceding car, eye movement, distance from the vehicle in front and lane observance. The subjects were 50 drivers, including ten driving instructors. The mean glance duration when manipulating a cellular phone was longer than when manipulating a hands-free set or car stereo. Braking reaction delay time increased in the following order: driving only, car radio, hands-free and, longest of all, cellular phone. When the cellular phone was used, car speed was slowest, and the distance from the vehicle in front became the longest. Glance duration other than to the front, indicating divided attention, was shortest during the cellular phone use and there were also fewer instances of eye movement. In the case of cellular phone use, stable driving appeared to be more difficult, as there was substantial steering wheel deflection. In this experiment, it was confirmed that use of a hands-free set is effective to some extent, but driving performance was poorer than with driving only. Even though different forms of in-vehicle information apparatus were used, a delay in information processing was consistently found.