Abstract
In Japan, the ratio of the middle-aged population is rapidly increasing, and the number of middle-aged drivers is expected to increase in the future, and urgent safety measures are desired. There are no studies that examine the visibility and responsiveness of the information inside and outside the car during actual driving and age factors. In this study, we focused on the speedometer as the in-car information in order to contribute to the design guideline of the in-car information display for middle-aged and elderly people. The purpose of this study is to clarify the relationship between visibility and responsiveness of middle-aged and elderly people when driving a car by comparing the results of the simulation experiment and the actual driving experiment. Simulator experiments were conducted with 20 young, middle-aged and elderly people under three conditions and four conditions, respectively, which correspond to the brightness in the evening, the brightness on a cloudy day and the brightness on a clear day without direct sunlight. The experiment was conducted under four conditions with 12 young and middle-aged people in total under clear skies. In both experiments, the reaction time with respect to the magnitude of the number displayed on the velocimeter in each condition was measured. The results showed that the reaction time of the speed display when driving a car was significantly longer in middle-aged people than in younger people, and that the age factor greatly affected the visibility and responsiveness of the information in the car during driving. The reaction time of the speed display should be shortened by the size of the speed display 25×50 mm （3°34’ viewing angle） for both young and middle-aged people. From the results of the simulator experiments, it was found that under the present experimental conditions, the influence of the illuminance factor on the visibility and responsiveness of the speed display was significantly smaller than that of the age factor or the size factor of the speed display.
