ABSTRACT
During curve driving, drivers often tilt their head laterally towards the interior of the curve. Such head behavior may be elicited in response to centripetal forces, with drivers aligning their head axis to the resulting gravito-inertial force. However, previous work has suggested that this behavior might depend less on vestibular than on visual input. In the present study, we tested this hypothesis, using a fixed-base simulator in which, by definition, no centripetal forces are generated during driving. The experimental task consisted in driving along a winding road, constituted of a randomly ordered succession of curves of various radii separated by portions of straight lines. Head orientation was recorded, using an electromagnetic sensor, in synchrony with driving behavior. Results indicated that subjects exhibited systematic head roll tilts toward the interior of curves and that the amount of tilt angle increased with road curvature. However, head roll amplitude was inferior to that observed in real driving conditions. Head yaw orientation was clearly correlated with the tangent point location and represented about 56% of the tangent point eccentricity. Finally, the magnitude of roll and yaw movements of the head were significantly correlated. These results argue in favor of the hypothesis that visual determinants trigger head movements during curve driving, and suggest that head orientation may be part of a global gaze-head visual anticipatory strategy during curve driving.
