New Measure of Inattentiveness to Forward Roadway

Long glances inside a vehicle when driving are predictive of crashes on the road. Laboratory studies have shown that novice drivers are more likely to make such long in-vehicle glances than are more experienced drivers. Moreover, a training program for novice drivers, FOCAL, has been shown to reduce the number of long glances. However, it is not clear what the best measure is for assessing how risky the pattern of glances is. This paper proposes a new measure, summed excess glance durations, to assess the glance behavior in an interval of time in which the participant is attempting to do a task within the vehicle while driving. This measure gives a plausible estimate of the likelihood of a crash and is not subject to the same problems as are extant measures. Moreover, the measure can be used to estimate the threshold above which glance durations become unsafe, confirming previous, complementary, work on a driving simulator. Although the analyses suggest that approximately a 1.5-s threshold for evaluating excess glances appears to be best, any excess glance threshold between 1.0 and 2.5 s is a good discriminator between novice and experienced drivers. The authors also discuss how one can bridge the gap between laboratory observations and crash rates and argue that the threshold value for predicting crash rates is likely to depend on driving situations. The authors argue that the measure proposed, when suitably adjusted for driving conditions, is likely to be an excellent predictor of crash rates.