Studies have shown that wireless phone use while driving contributes to crashes [1]. To address this phenomenon the U.S. Department of Transportation’s National Highway Traffic Safety Administration (NHTSA) designed research to assess the impact of wireless phone use on driving behavior and performance. This research focused on the examination of the effects of interface type (i.e., hand-held versus hands-free) on driving performance. Unconstrained, on-road research examined drivers’ wireless phone use in a real-world setting. Research using the National Advanced Driving Simulator (NADS) examined the effects of wireless phone use on driving performance in a controlled environment.

Research findings highlighted the impact of wireless phones on driving performance and behavior. The results of the on-road study indicated that phone use alters drivers’ attention, as evidenced by changes in patterns of eye glance behavior. However, the variability of driving conditions observed in this study hindered the identification of specific patterns of degraded driving behavior. Although hands-free interfaces allow drivers to steer using both hands, in practice drivers were observed to steer using two hands quite infrequently during routine driving as well as during hands-free phone use. In the more controlled laboratory study, we found that phone use degraded driving performance, including measures of vehicle control and car following. There were also differences between interfaces. Specifically, handheld phone interfaces were shown to interfere with steering and lane position variability more than hands-free interfaces, however the hand-held interface was associated with faster dialing times and fewer dialing errors than the hands-free interfaces.