Assessing Road Sign Perception: A Methodological Review

Abstract

Mounting a legible and understandable road sign along the side of the road does not necessarily mean that drivers will perceive the message on that sign. Quite some research has tried to understand this principle, and by using different research methods, some insight into the process of perceiving signs has been provided. In this article I describe and discuss different research methods for studying road sign perception, all with their specific advantages and limitations. The methods described are eye movement studies, studies using verbal reports while driving, studies recording driving behavior, and studies asking drivers to recall or recognize a sign after having passed it. Although I do not claim to provide a complete overview of all available literature on road sign perception, the idea of this article is to stimulate the reader to think about drawbacks of some methodological issues when choosing methods or experimental setups dealing with investigating road sign perception. There seems to be quite a large difference between the perception of those drivers who are actively searching for some information and those drivers who are not actively searching for information. When drivers are actively searching for information, a strong contrast of the sign against the environment and the size of the sign are important factors. In the case of drivers who are not actively searching for information, the sign content in terms of the significance that the message has to the driver seems to play a crucial role. With all methods having their specific limitations, a combination of several research methods when experimentally investigating road sign perception is to be recommended. In the future, more research should be directed toward establishing the interfering effect of one method on the other, toward investigating the effects of signs on action preparedness of drivers, and toward the effect of drivers' expectations in the perception of road signs.