International Conference Road Safety and Simulation RSS 2007 7,8,9 th November 2007 Rome, Italy Abstract— Drivers fix their gaze where they are planning to go. It is considered that steering is based on optic flow, the formation of visual motion at the moving eye. Different studies have analyzed the impact of visuomotor strategies on steering but, to our knowledge, few studies have compared visual strategies using similar urban video- projected environments. The aim of this study is to compare subjects’ visuomotor strategies on similar video- projected environments in a fixed-base driving simulator. Experienced car drivers are exposed to two visual environments: a real traffic urban scenario pre-recorded on video; and the 3D simulation of the same scene. The visual environment represents a district of the center of Paris, between the Louvre and the Opera. Subjects’ visual strategies are recorded using a binocular eye tracking system (Eyelink II). It is supposed that visuomotor strategies depend on the degree of similarity between both environments. The results indicate that eye movements differ between pre-recorded and virtual environment. Integration of information in the saccade buffer and visual attention control may explain these results. Index Terms - Binocular eye movement recording, driving simulator, visual environment, visuomotor strategy. I. INTRODUCTION Steering a car is a complex cognitive task, which necessitates the integration of various information such as visual, auditory, proprioceptive, motor, and spatial essentially. The aim of the present study is to examine visuomotor strategies when people are exposed to two similar visual environments. The effect of visual strategies on driving has been studied from various viewpoints [1]-[5]. However, their role in car driving tasks is still poorly understood [5]. In road driving, driver directs his/her gaze where s/he intends to go [6]. Studies show that with changes in driving parameters i.e., an increase in speed, gaze links more tightly to the driver’s intended goal [7], [2], [5], [3]. Visuomotor strategy is thought, therefore to, depend on optic flow properties [8]-[10]. Using two contrasted visual environments, e.g., traffic of the same road presented in real situation or in pictures, authors show [11] that eye-movements were significantly different. But when experimental conditions are similar this result is inverted. Drivers’ visual strategies have been investigated in real and virtual intersections using an HMD in a driving simulator [12]. It has been found that drivers tended to make longer left-right glances in virtual reality that they did in reality but there was no difference in the number of glances between both experimental situations. Using a monocular tracking system, researchers [13] have recently revealed that eye fixation time for traffic signs, e.g., information signs or road markings, was quite comparable between watching a video and actual driving. However, to our knowledge, the binocular recording of eye movement have never been investigated in pre-recorded and virtual environments. The above data suggest that the similarity of visuomotor strategies could depend on the similarity between visual environments. In order to examine this hypothesis, drivers aged 25 to 35 years were exposed to two visual environments in a fixed – base simulator: the first one was a pre-recorded scene of real urban traffic scenario; the second was the 3D simulation of same scene. Their visuomotor strategies were recorded using a binocular eye tracking system (eyelink II). II. METHOD A. Subjects Twenty-six experienced car drivers (13 men and 13 women) were examined. Their average age was 30 years (SD 3 years). All were licensed to drive in France for 5 years or more and have driven at least five times a week. None of the subjects had more than 10 hours of driving experience on a simulator. All had normal or corrected-to-normal vision and no history of neurological disease. An additional number of four subjects participated but excluded owing to technical problems (one subject) or of simulator sickness (three subjects). Before the experiment all subjects signed an informed consent form. Study approved by local ethic committee and conform Helsinki convention. B. Simulator The INRETS’ (MSIS-SIM 2 ) driving simulator, which is a fixed-based simulator, was used for this experiment. This simulator was composed of a vehicle (Xantia), fully functional pedals, speedometer, manual gearshift and three large flat screens. The screens stimulated 150 deg of subject visual field (120 deg horizontally and 37.5 deg vertically around). Three, IRIS BarcoGraphics 808s projectors, one for each screen, were used. Each projector runs 900 x 1600 pixels at 90 Hz refresh. Two visual environments, which correspond to two visual conditions, were used. A computer (AMD I. Giannopulu 1 , RJV. Bertin 1 1 Laboratoire Central des Ponts et Chaussés, 58, bd Lefèvre 75015 Paris, France irini.giannopulu@inrets.fr, rene.bertin@inrets.fr Z. Kapoula 2 2 IRIS-CNRS Hôpital G. Pompidou 20 Rue Leblanc 75015 Paris zoi.kapoula@egp.aphp.fr R. Brémond 1 , roland.bremond@lcpc.fr S. Espié 1 stephane.espie@inrets.fr Visuomotor strategies using driving simulators in virtual and pre-recorded environment