Luo Gang, Woods Russell L, Peli Eli
Department of Ophthalmology, Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts 02114, USA.
Invest Ophthalmol Vis Sci. 2009 Sep;50(9):4509-15. doi: 10.1167/iovs.08-2916. Epub 2009 May 20.
A device was developed to provide an expanded visual field to patients with tunnel vision by superimposing minified edge images of the wide scene, in which objects appear closer to the heading direction than they really are. Experiments were conducted in a virtual environment to determine whether users would overestimate collision risks.
Given simulated scenes of walking or standing with intention to walk toward a given direction (intended walking) in a shopping mall corridor, participants (12 normally sighted and 7 with tunnel vision) reported whether they would collide with obstacles appearing at different offsets from variable walking paths (or intended directions), with and without the device. The collision envelope (CE), a personal space based on perceived collision judgments, and judgment uncertainty (variability of response) were measured. When the device was used, combinations of two image scales (5x minified and 1:1) and two image types (grayscale or edge images) were tested.
Image type did not significantly alter collision judgment (P > 0.7). Compared to the without-device baseline, minification did not significantly change the CE of normally sighted subjects for simulated walking (P = 0.12), but increased CE by 30% for intended walking (P < 0.001). Their uncertainty was not affected by minification (P > 0.25). For the patients, neither CE nor uncertainty was affected by minification (P > 0.13) in both walking conditions. Baseline CE and uncertainty were greater for patients than normally sighted subjects in simulated walking (P = 0.03), but the two groups were not significantly different in all other conditions.
Users did not substantially overestimate collision risk, as the x5 minified images had only limited impact on collision judgments either during walking or before starting to walk.
开发了一种装置，通过叠加宽场景的缩小边缘图像，为管状视野患者提供扩大的视野，在该场景中物体看起来比实际更靠近前进方向。在虚拟环境中进行了实验，以确定用户是否会高估碰撞风险。
在商场走廊中给定模拟的行走或站立场景，参与者（12名视力正常者和7名管状视野患者）报告在有无该装置的情况下，他们是否会与出现在不同偏离可变行走路径（或预期方向）的障碍物发生碰撞。测量了碰撞包络（CE），即基于感知碰撞判断的个人空间，以及判断不确定性（反应的变异性）。使用该装置时，测试了两种图像比例（5倍缩小和1:1）和两种图像类型（灰度或边缘图像）的组合。
图像类型对碰撞判断没有显著影响（P>0.7）。与无装置基线相比，缩小比例对视力正常的受试者在模拟行走时的CE没有显著改变（P = 0.12），但在预期行走时CE增加了30%（P<0.001）。他们的不确定性不受缩小比例的影响（P>0.25）。对于患者，在两种行走条件下，CE和不确定性均不受缩小比例的影响（P>0.13）。在模拟行走中，患者的基线CE和不确定性高于视力正常的受试者（P = 0.03），但在所有其他条件下，两组没有显著差异。
用户没有大幅高估碰撞风险，因为5倍缩小的图像在行走过程中或开始行走前对碰撞判断的影响有限。
