Cognitive organization of roadway scenes

The present report describes a series of studies investigating the cognitive organization of road-way scenes. These scenes were represented by still photographs taken on a number of roads outside of built-up areas, which were used by Oei and Mulder (1993) in their study of driving speeds. Sites were stratified by two regions (the Western and the South-Eastern regions of the Netherlands), three road situations (curves, intersections, and straight-road sections), andthe seven road classes used by Oei and Mulder (op. cit.): Class 1:dual carriageway highways (100 km/h speed limit); Class 2:single carriageway highways (100 km/h); Class 3:dual carriageway roads closed to all `slow traffic' (80 km/h); Class 4:single carriageway two-lane roads closed to all `slow traffic' (80km/h); Class 5:single carriageway two-lane roads closed to bicycles and pedestrians (80 km/h); Class 6:single carriageway two-lane roads open to all traffic (80 km/h); Class 7:single carriageway one-lane roads open to all traffic (80 km/h). Seventy-eight drivers, stratified by age and sex to mimic the Dutch driving population, participated. Subjects were recruited from the population of readers of a local shopping newspaper, students, and administrative SWOV personnel. Six studies were conducted. In the first study, subjects were asked to sort the photographs presented to them into piles of similar photographs. These piles were intended to be `meaningful' and `useful' to the subjects (as determined by the subjects themselves) in their roles as automobile drivers. The sorting data was then collected into similarity matrices, and analyzed by means of Multi-Dimensional Scaling and Analysis of Variance. Theresults were quite clear. When drivers (in their role as drivers) view a road scene, three factors (on average) are of primary importance: -the presence of an intersection; -the number (and breadth) of carriageways; -the presence of a curve. In a second study, the same subjects were again asked to sort the same photographs into new piles on the basis of two new criteria: -the different types of problems that in-experienced drivers might have; -the other types of traffic that the subjects might have problems with. In other studies, other subjects: -sorted homogenous subsets (as determined in the first two studies) of the same photographs; -named differences in pairs of widely different photographs (as determined by the previous study); -estimated a safe driving speed and the chance of encountering `slow' traffic for each of the above mentioned photographs; -learned to classify each photograph in a pre-determined category. Some subjects learned the seven classes mentioned above; others learned seven categories derived in the first two studies. The results of these studies generally re-emphasized the three factors mentioned above, while adding additional nuances. In general, the distinctions mentioned above are very easy to learn and apply. The categories based on the seven road classes mentioned above, on the other hand, are much more difficult to identify, to learn, and to apply, atleast on the basis of local, road-side information. It is suggested that this problem could give rise to safety problems. Finally, a number of suggestions for future research are made, and it is proposed that psychological models of road user behaviour be explicitly studied