Grace Roessling¹, Brett Fajen¹; ¹Rensselaer Polytechnic Institute

It is well established that online visual information plays a critical role in the guidance of high-speed steering during automobile driving. Visual information can inform the driver of their current speed, heading direction, and lane position, as well as the upcoming road curvature. However, relatively little is known about the role of spatial knowledge of road geometry in the control of high-speed steering. The present study was designed to investigate if spatial knowledge contributes to the control of steering along a winding road by examining how steering behavior differs when drivers follow familiar versus unfamiliar roads. Two groups of subjects (N = 20) used a steering wheel and foot pedal system to guide a car along a set of ten winding roads (~3 km long) in a simulated environment. Each road comprised eight distinct curved segments (90° turns, U-turns, S-turns) interleaved with straight segments. The geometry of the road was identical across trials in the Constant Track condition. In the Variable Track condition, road geometry varied across trials but was the same as that in the Constant Track condition on Trial 10, allowing us to compare behavior across groups on the same road. Patches of fog were also added to some segments to determine whether the role of spatial knowledge depends on visibility. Results showed an effect of visibility on speed, speed variance, and steering variance but no significant effects or interactions involving track constancy. These findings suggest that either the experimental conditions (e.g. the number of trials) were not sufficient for the Constant Track group to learn the road geometry or that spatial knowledge plays a negligible role in the control of steering during everyday driving. Discussion focuses on the implications of these findings for models of control strategies used by drivers when following a winding road.