Peripheral detection as a measure of driver distraction. A study of memory-based versus system-based navigation in a built-up area

Abstract

The effect of in-vehicle information systems (IVIS) on traffic safety is currently under debate and suitable methods for measuring and comparing the impact of such devices on driver behaviour are urgently required. The secondary-task technique may be a good tool for objective measurement of driver distraction caused by IVIS.The present study summarises previous results of secondary-task studies in traffic contexts and investigates the suitability of one secondary-task method, the peripheral detection task (PDT)-method, as a standard procedure for safety testing and evaluation of IVIS. The study was concerned with the effect of navigation messages on PDT-performance (reaction time and hit rate) taking into account also behavioural variables. Professional drivers served as subjects. They had extensive prior local-knowledge and experience of driving in the built-up area in which the experiment took place. They were required to drive two different routes, one after memory and the other in accordance with navigation messages a standard navigation system installed in the car. In the navigation system condition subjects were subdivided into three groups, receiving either verbal, visual or both visual and verbal (full) navigation messages.Driving behaviour was virtually uninfluenced by navigation condition (memory versus navigation system) and message modality (full, visual or verbal) whereas PDT-performance, showed some effects of navigation condition on subjects' reaction times and hit rates. Pairwise comparison of message modality within each three groups showed a prolongation in reaction time and a marginally significant decrease in hit rate with full navigation messages (combined visual and verbal ones). Visual navigation messages affected only hit rate and no significant differences between navigation conditions were observed for the group presented with verbal messages. The pattern of results suggests that the PDT-method is biased toward visual sources of information from IVIS. As visual information processing is an important component in safe driving, the PDT-method is suitable as a predominant method in a test battery, but for unbiased measurement of distraction, methods less dependent on mode of presentation would be more appropriate. © 2002 Elsevier Science Ltd. All rights reserved.