Chen S C, Hallum L E, Suaning G J, Lovell N H
Graduate School of Biomedical Engineering, University of New South Wales, Sydney, 2052, Australia.
J Neural Eng. 2007 Mar;4(1):S108-23. doi: 10.1088/1741-2560/4/1/S13. Epub 2007 Feb 26.
In most current vision prosthesis designs, head movement is the sole director of visual gaze and scanning due to the head-mounted nature of the camera. Study of this unnatural behaviour may provide insight into improved prosthesis designs and rehabilitation procedures. In this paper, we conducted a psychophysical study to investigate the characteristics of head movements of normally sighted subjects undergoing a visual acuity task in simulated prosthetic vision (SPV). In 12 naïve, untrained subjects, we recorded spontaneous changes in the amount of head movements during SPV sessions compared to control (normal vision) sessions. The observed behaviour continued to be refined until five or six sessions of practice. Increased head movement velocity was shown to be correlated to improved visual acuity performance, up to 0.3 logMAR, an equivalent of detecting details at half the physical size compared to complete deprivation of head movements. We postulate that visual scanning can as much as double the spatial frequency information in prosthetic vision. Increased head movement velocity observed when subjects were attempting smaller test items and for low-pass filtering schemes with higher cut-off frequencies may be further evidence that higher frequency content may be available through visual scanning, unconsciously driving subjects to increase head movement velocity.
在当前大多数视觉假体设计中，由于摄像头安装在头部，头部运动是视觉注视和扫描的唯一导向。对这种不自然行为的研究可能有助于改进假体设计和康复程序。在本文中，我们进行了一项心理物理学研究，以调查在模拟假体视觉（SPV）中执行视力任务的正常视力受试者的头部运动特征。在12名未接触过且未受过训练的受试者中，我们记录了与对照（正常视力）会话相比，SPV会话期间头部运动量的自发变化。观察到的行为在经过五到六次练习后持续得到改善。结果显示，头部运动速度的增加与视力表现的改善相关，最高可达0.3 logMAR，这相当于与完全禁止头部运动相比，能够检测到物理尺寸一半大小的细节。我们推测，视觉扫描在假体视觉中可以使空间频率信息增加一倍。当受试者尝试较小的测试项目以及采用更高截止频率的低通滤波方案时，观察到的头部运动速度增加可能进一步证明，通过视觉扫描可能可以获得更高频率的内容，从而无意识地促使受试者提高头部运动速度。
