Just Noticeable Differences in some Vehicle Handling Variables

Abstract

Experiments were carried out to determine the ability of drivers to detect changes in several vehicle characteristics which affect the “handling” of the vehicle. The experiments determined these just noticeable differences for vehicle response time, stability factor and steering ratio. They show a very high differential sensitivity to changes of response time and reasonably good ability to detect changes of steering ratio and stability factor. There are great differences between the discriminatory ability of different subjects and also within the same subject on different occasions. The “constant stimuli” and “up-and-down” methods were used in establishing the JND's. The magnitude of the time interval between presentation of the standard and comparison vehicles and the speed at which the test was made also affected the magnitude of the just noticeable difference.