Visuo-vestibular interaction in the perception of curvilinear trajectories for passive and active drivers

Abstract

Self-motion perception, which partly determines the realism of dynamic driving simulators, is based on multisensory integration. For curved trajectories, adding linear translations to visual stimulation seems to improve the perception of motion (Bertin et al., 2004). However, cornering means not only translational motion but also rotational motion in yaw. Wikie and Wand (2005) found no effect of yaw motion on steering performance, but it seems that higher rates of physical stimulation could have a more visible effect. However, the influence of yaw acceleration on cornering perception is still a matter of debate, especially when associated to optic flow. Therefore, the present study aims to analyze the respective role of vestibular (yaw acceleration) and visual stimulations for the perception of curvilinear trajectories. We designed two experiments in which the subjects had 1/to orally estimate their angular displacements as passive drivers, 2/to generate angular displacements by controlling the steering wheel as active drivers. In both experiments, subjects were submitted to three different conditions: (1) visual motion, (2) physical yaw acceleration, (3) combined visual and physical motions. Preliminary results of the first experiment show that visual stimulation produces greater overestimations of angular displacements than physical yaw motion, this overestimation being in between in the visuo-vestibular condition. They also suggest that the weights of visual and vestibular cues in cornering perception depend on the amplitude of the angular displacements. The second experiment should allow us to observe the evolution of visuo-vestibular interaction when subjects are active rather than passive drivers.