Older drivers are at high risk for traffic accidents and their numbers are increasing rapidly. The cars they drive are changing as well. Human factors is not keeping up with these changes. Although there are some human factors guidelines for the dynamic display of information, the literature contains almost no studies on the usability of these new displays with regard to driving, and there has been little study of the impact of these displays on older drivers. This report examines four experiments of display monitorability. The studies employed a common dual task workload assessment technique to evaluate 12 simulated automobile displays, and compare the performance of younger and older drivers in monitoring these displays. Subjects were required to engage concurrently in a tracking task and a computer-generated display monitoring task. While subjects maintained tracking performance, one of four monitored displays began to display a "critical reading". Subjects' latencies to respond to this reading and their tracking proficiency were analyzed in an attempt to measure display monitorability in a variety of situations. An Apple Macintosh with a colour monitor was used to present all stimuli and collect subjects' responses. The focus of these studies was not to determine whether older drivers responded more slowly or made more tracking errors; any other finding would have been suspect given the large body of literature which demonstrates such age effects. These experiments were conducted in order to determine whether there are display characteristics which could decrease the attentional load on all drivers and reduce the magnitude of age-related performance decrements for older drivers. Of the 12 displays tested, the binary readout was clearly the most "monitorable" by all subjects. For all other displays the data were not so unequivocal. Older subjects were generally slower at responding, but performed about as fast as younger subjects when detecting critical readings on bar graphs or right oriented analog displays. But, all subjects made a substantial number of errors in direction and location when monitoring bar graphs, particularly horizontal bar graphs. Other findings are related to display configuration, display pairing, color facilitation, and gender differences. (A)
Abstract