Expectancy relates to a driver's readiness to respond to situations, events, and information in predictable and successful ways. It influences the speed and accuracy of information handling, and affects all aspects of highway design and operations, and information presentation. Aspects of the highway situation that are in accordance with prevalent expectancies aid the driving task, while expectancies that are violated lead to longer reaction time, confusion and driver error. Two classes of driver expectancy are operative throughout the driving task. The first are a priori expectancies that most drivers form through habit and experience, and that are brought into the task. The second are ad hoc ones that drivers form in transit based on the road and its environment. Each class of expectancy must be considered in the design and operation of the road and its information system. This report describes the concept of driver expectancy in the context of the driving task, and provides examples of expectancy and expectancy violations. It includes a procedure for identifying general and specific expectancy violations to enable engineers to develop remedial treatments to deal with expectancy problems. (Author/publisher)
Samenvatting