Banks M S, Ehrlich S M, Backus B T, Crowell J A
Department of Psychology, University of California, Berkeley 94720, USA.
Vision Res. 1996 Feb;36(3):431-43. doi: 10.1016/0042-6989(95)00122-0.
The ability to judge heading during tracking eye movements has recently been examined by several investigators. To assess the use of retinal-image and extra-retinal information in this task, the previous work has compared heading judgments with executed as opposed to simulated eye movements. For eye movement velocities greater than 1 deg/sec, observers seem to require the eye-velocity information provided by extra-retinal signals that accompany tracking eye movements. When those signals are not provided, such as with simulated eye movements, observers perceive their self-motion as curvilinear translation rather than the linear translation plus eye rotation being presented. The interpretation of the previous results is complicated, however, by the fact that the simulated eye movement condition may have created a conflict between two possible estimates of the heading: one based on extra-retinal solutions and the other based on retina-image solutions. In four experiments, we minimized this potential conflict by having observers judge heading in the presence of rotations consisting of mixtures of executed and simulated eye movements. The results showed that the heading is estimated more accurately when rotational flow is created by executed eye movements alone. In addition, the magnitude of errors in heading estimates is essentially proportional to the amount of rotational flow created by a simulated eye rotation (independent of the total magnitude of the rotational flow). The fact that error magnitude is proportional to the amount of simulated rotation suggests that the visual system attributes rotational flow unaccompanied by an eye movement to a displacement of the direction of translation in the direction of the simulated eye rotation.
最近，几位研究人员对追踪眼球运动过程中判断方向的能力进行了研究。为了评估在这项任务中视网膜图像信息和视网膜外信息的使用情况，之前的研究将方向判断与实际执行的眼球运动进行了比较，而非模拟眼球运动。对于大于1度/秒的眼球运动速度，观察者似乎需要视网膜外信号提供的眼球速度信息，这些信号伴随着追踪眼球运动。当不提供这些信号时，比如模拟眼球运动时，观察者会将自身运动感知为曲线平移，而不是呈现出的线性平移加眼球旋转。然而，之前结果的解释较为复杂，因为模拟眼球运动条件可能在两个可能的方向估计之间产生了冲突：一个基于视网膜外解决方案，另一个基于视网膜图像解决方案。在四项实验中，我们通过让观察者在由实际执行和模拟眼球运动混合组成的旋转情况下判断方向，将这种潜在冲突降至最低。结果表明，当仅由实际执行的眼球运动产生旋转流时，方向估计更为准确。此外，方向估计误差的大小基本上与模拟眼球旋转产生的旋转流大小成正比（与旋转流的总大小无关）。误差大小与模拟旋转量成正比这一事实表明，视觉系统将没有眼球运动伴随的旋转流归因于平移方向在模拟眼球旋转方向上的位移。
