The present study investigates drivers' visual search for a traffic sign when approaching intersections. More specifically, it examines the balance between top-down search induced by the expectations of the road user and data-driven search induced by the properties of the objects present in the visual field. In the present experiment, the subjects viewed video recordings of intersection approaches. During this approach, the subjects had to search for a blue traffic sign. Given the layout of the particular scene, the target sign could be located at an expected (right side of the road) or an unexpected (left side of the road) location within this scene. Dependent on the distractor condition, another traffic sign or a traffic sign and crossing pedestrian were present in the scene. In order to influence expectations regarding the location of the target sign before the search for the target sign started, the subjects first saw the intersection from a distance. During search for the target sign eye movement patterns were recorded. The results reveal the importance of top-down induced search in natural traffic scenes: eye movements were first directed to those locations where target objects were likely to be found. The importance of the role of expectations inducing strategic search was strengthened by the finding that the presence of a distracting sign and a pedestrian hardly altered this search pattern. Specific aspects of the eye movement scan paths within the scene are discussed.
Abstract