Experienced drivers obtain visual information from two sections of their view of the road ahead, in order to maintain a correct position in lane whilst steering their vehicle around a curve. The further of these two sections is used to predict the road's future curvature. This section is optimally 0.75 to 1.00 seconds ahead of the driver and contains the tangent point (that point where the inside edge of a curve reverses its apparent direction and the driver's line of sight forms a tangent to the road edge). This section of road is used by a feedback mechanism to `fine tune' the driver's position in lane. As either lane edge approaches the vehicle, the driver steers away from it, correcting his/her road position. This combination of two mechanisms enables the trained driver to steer an accurate course on roads of varying curvature. Experiments using video based eye-head tracking equipment have shown that the feedback mechanism is present in most people regardless of their experience of driving (although its accuracy is higher in those with experience), but that the feedforward mechanism is learned through experience of steering tasks (that can include riding a bicycle, computer driving games, etc). Eye-head tracking experiments on learner drivers during their tuition have indicated that use of the section of the road containing the tangent point increases with experience, then decreases as drivers learn to optimise their visual search patterns, allowing them to spend more of their visual resources on other visual tasks both related and unrelated to driving. (A)
Abstract