Pursuit Eye-Movements in Curve Driving Differentiate between Future Path and Tangent Point Models

For nearly 20 years, looking at the tangent point on the road edge has been prominent in models of visual orientation in curve driving. It is the most common interpretation of the commonly observed pattern of car drivers looking through a bend, or at the apex of the curve. Indeed, in the visual science literature, visual orientation towards the inside of a bend has become known as “tangent point orientation”. Yet, it remains to be empirically established whether it is the tangent point the drivers are looking at, or whether some other reference point on the road surface, or several reference points, are being targeted in addition to, or instead of, the tangent point. Recently discovered optokinetic pursuit eye-movements during curve driving can provide complementary evidence over and above traditional gaze-position measures. This paper presents the first detailed quantitative analysis of pursuit eye movements elicited by curvilinear optic flow in real driving. The data implicates the far zone beyond the tangent point as an important gaze target area during steady-state cornering. This is in line with the future path steering models, but difficult to reconcile with any pure tangent point steering model. We conclude that the tangent point steering models do not provide a general explanation of eye movement and steering during a curve driving sequence and cannot be considered uncritically as the default interpretation when the gaze position distribution is observed to be situated in the region of the curve apex.近二十年来，在弯道驾驶的视觉定向模型框架内，注视道路边缘切线点（tangent point）的相关研究始终占据重要地位。这也是对驾驶员在弯道中视线穿透弯道、或注视曲线顶点这一常见行为模式的最主流解释。事实上，在视觉科学的相关文献中，朝向弯道内侧的视觉定向已被定义为“切线点定向（tangent point orientation）”。然而，驾驶员实际注视的是否确为切线点，或是同时、转而注视路面上的其他参照点乃至多个参照点，这一问题仍有待实证验证。近期在弯道驾驶中发现的视动追随眼动（optokinetic pursuit eye-movements），可作为传统注视位置测量手段之外的补充证据。本研究首次对真实驾驶场景中由曲线视觉运动流诱发的追随眼动展开了细致的定量分析。实验数据表明，在稳态转弯过程中，切线点以外的远距区域是重要的注视目标区域。这一发现与未来路径转向模型相符，但难以与纯粹的切线点转向模型兼容。本研究得出结论：切线点转向模型无法全面解释弯道驾驶序列中的眼动与转向行为；当观测到注视位置分布位于弯道顶点区域时，也不能不加批判地将其视为默认解释。