Use of Fixation Heat Maps to Evaluate Visual Behavior of Unfamiliar Drivers on Horizontal Curves

Abstract

This paper presents an innovative method of visualizing eye-tracking data by using heat maps (color-coded contour maps showing distributed data). Heat maps of eye fixation points were created from data collected while drivers navigated a rural road. Comparable road segments were used to identify how a driver's visual attention changed while the driver approached and navigated a curve and to address how chevrons and time of day affected fixation patterns. Measures of the centroid and dispersion of each heat map were used to quantify the changes in visual behavior. The results suggest that as drivers approach curves, their fixation patterns become more focused, particularly during the daytime, when their gazes are more prone to shift away from the road scene on long tangents. Chevrons are most useful at night and guide drivers to select a narrower field of view on curve approaches. There were no consistent differences in fixation points within curves that had chevrons as compared with curves that did not, for either daytime or nighttime conditions. This finding suggests that drivers derive little benefit from chevrons within the curve as compared with on the approach. This research is particularly valuable because it investigates a new method for evaluating the effectiveness of traffic control devices and characterizing the driving experience.