Yan Jing-Jiang, Lorv Bailey, Li Hong, Sun Hong-Jin
Key Laboratory of Cognition and Personality, Ministry of Education, Southwest University, Chongqing, China.
J Vis. 2011 Oct 14;11(12):7. doi: 10.1167/11.12.7.
As an object approaches an observer's eye, the optical variable tau, defined as the inverse relative expansion rate of the object's image on the retina (D. N. Lee, 1976), approximates the time to collision (TTC). Many studies have provided support that human observers use TTC, but evidence for the exclusive use of TTC generated by tau remains inconclusive. In the present study, observers were presented with a visual display of two sequentially approaching objects and asked to compare their TTCs at the moment these objects vanished. Upon dissociating several variables that may have potentially contributed to TTC perception, we found that observers were most sensitive to TTC information when completing the task and less sensitive to non-time variables, such as those that specified distance to collision, speed, and object size. Moreover, when we manipulated presented variables to provide conflicting TTC information, TTC specified by tau was weighted much more than TTC derived from distance and speed. In conclusion, our results suggested that even in the presence of other monocular sources of information, observers still had a greater tendency to specifically use optical tau when making relative TTC judgments.
当一个物体靠近观察者的眼睛时，光学变量τ（定义为物体在视网膜上的图像的相对膨胀率的倒数，D. N. 李，1976）近似于碰撞时间（TTC）。许多研究支持人类观察者使用TTC，但关于仅使用由τ产生的TTC的证据仍然没有定论。在本研究中，向观察者呈现两个依次靠近的物体的视觉显示，并要求他们在这些物体消失的瞬间比较它们的TTC。在分离了几个可能对TTC感知有潜在贡献的变量后，我们发现观察者在完成任务时对TTC信息最敏感，而对非时间变量（如指定碰撞距离、速度和物体大小的变量）不太敏感。此外，当我们操纵呈现的变量以提供相互冲突的TTC信息时，由τ指定的TTC比从距离和速度得出的TTC权重更大。总之，我们的结果表明，即使存在其他单眼信息源，观察者在进行相对TTC判断时仍然更倾向于专门使用光学τ。
