Effects of Conformal and Nonconformal Vision Enhancement Systems on Older-Driver Performance

The effects of two types of vision enhancement system (VES) displays on younger- and older-driver performance were systematically examined in various contexts. Younger and older drivers used either a conformal or a nonconformal VES display while driving in a fixed-base driving simulator. Within each block of trials, traffic scenarios were used to test driver performance: everyday driving, intersection approaches, emergency events, and VES failure. Conformal imagery directly highlighted aspects of the traffic environment, whereas nonconformal displays were coupled to environmental events but not superimposed on them. In all driving scenarios, conformal displays had a performance advantage over nonconformal displays. These advantages, however, depended on what was highlighted and whether a highlight covered or obscured important information about the environment. The perceived benefits of VESs are in situations where visibility is limited by weather (e.g., fog, snow, or rain), time of day (e.g., night or dusk), or roadway geometry (e.g., curves or railway crossings). Implications of the results for the design of conformal and nonconformal VESs and for future research are discussed.