Eyeson-Annan M, Brown B
Department of Optometry, Queensland University of Technology, Brisbane, Australia.
Perception. 1992;21(6):813-23. doi: 10.1068/p210813.
The importance in mobility performance of the rate of presentation of visual information, binocular versus monocular vision, the use of multiple rather than single reference points, and local motion parallax was investigated in two experiments. In each experiment ten subjects walked a triangular mobility course in a totally darkened room; the only visible targets were light emitting diodes (LEDs), mounted on poles, at the apices of the triangle. The LEDs were mounted so that one or two could be used in a trial; if two were used the distance between them was varied horizontally (in experiment 1) and vertically (in experiment 2). The subjects walked around the course under a range of conditions, including two 'optimal trials' in full light. The LEDs were flashed for 1 ms at frequencies of 0.5, 1 and 5 Hz in experiment 1 and at 1 and 5 Hz in experiment 2. Mobility was measured with the use of an ultrasonic locator system which measured the subject's position on the course 10 times per second. The mean velocity of the subject in traversing the course was significantly reduced when the flash rate was slower, when the subject had one eye occluded, or when there was only one LED on the pole; when the spacing between the LEDs was varied, either vertically or horizontally performance was unaffected. These results imply that the frequency of updating of visual information is important in determining mobility performance, as are binocular cues, but that local motion parallax is not important. The number of LEDs on each pole had a significant effect on mobility performance an 'object' (two lights) gave more information than a point reference.
在两个实验中，研究了视觉信息呈现速率、双眼视觉与单眼视觉、使用多个而非单个参考点以及局部运动视差对移动性能的重要性。在每个实验中，十名受试者在完全黑暗的房间里沿着三角形移动路线行走；唯一可见的目标是安装在三角形顶点的杆子上的发光二极管（LED）。LED的安装方式使得在一次试验中可以使用一个或两个；如果使用两个，则它们之间的距离在水平方向（实验1）和垂直方向（实验2）上变化。受试者在一系列条件下绕着路线行走，包括在全光下的两次“最佳试验”。在实验1中，LED以0.5、1和5Hz的频率闪烁1毫秒，在实验2中以1和5Hz的频率闪烁。使用超声波定位系统测量移动性，该系统每秒测量受试者在路线上的位置10次。当闪光速率较慢、受试者一只眼睛被遮挡或杆子上只有一个LED时，受试者穿越路线的平均速度显著降低；当LED之间的间距在垂直或水平方向上变化时，性能不受影响。这些结果表明，视觉信息更新的频率在决定移动性能方面很重要，双眼线索也是如此，但局部运动视差并不重要。每根杆子上LED的数量对移动性能有显著影响，一个“物体”（两个灯）比一个点参考提供更多信息。
