Visual Control of Mobility in Low Vision

患有严重视力障碍的人发现在不熟悉的环境中行走非常困难，因此，他们经常限制自己的独立旅行。这反过来又增加了他们丧失独立性、抑郁和整体健康状况下降的风险即使是有中度视力障碍的人也比视力正常的人有更多的磕碰和绊倒，摔倒的风险也更高虽然视力障碍对运动能力的影响已经确定，但对视力障碍如何影响视觉控制运动的机制知之甚少。本研究的目的是了解视力障碍如何影响信息的探索方式以及用于指导移动的环境信息的来源。有了这些知识，就可以制定更有效的培训协议，设计出智能移动设备。该研究旨在通过分析视障受试者行走到指定目标时的行走时间、凝视模式和路径轨迹，来确定视力障碍如何影响视觉探索。此外，还将采用视觉搜索范式来确定低层次感觉因素对搜索时间的作用。拟议中的研究还旨在确定区分视力受损程度相似的熟练旅行者和不熟练旅行者的认知因素。两项实验将决定熟练的旅行者是否能迅速掌握上下文线索和/或将注意力更多地转移到任务相关信息上。最后，本研究旨在确定旅行者用于指导行动的视觉信息的来源，并确定听觉信息是否增强了视觉信息，以指导视障旅行者的行动。当受试者在环境信息被操纵的路线上行走时（例如，视觉运动提示距离），将测量凝视模式和路径轨迹。几个拟议的实验需要一个虚拟环境（VE）来系统地控制和/或操纵环境因素。初步数据表明，VE在研究探索行为方面可能是有效的。

People with advanced vision impairment find walking in unfamiliar environments extremely difficult and, for this reason, often limit their independent travel 1, 2. This in turn increases their risk for loss of independence, depression, and an overall decline in health.3 Even people with moderate vision impairment have more bumps and stumbles and have a higher risk of falling than do persons with normal vision.2 While the effects of vision impairment on mobility performance have been identified, little is known about how vision impairments affect the mechanisms for the visual control of mobility. The objective of this research is to understand how vision impairment affects the ways in which information is explored and the source(s) of environmental information that is used to guide mobility. With this knowledge, more effective training protocols can be developed and smart mobility devices designed. The proposed research aims to determine how vision impairment affects visual exploration by analyzing travel time, gaze patterns and path trajectories of vision-impaired subjects as they walk to specified targets. In addition, a visual search paradigm4 will be employed to determine the role of low-level sensory factors on search time. The proposed research also aims to identify the cognitive factors that differentiate skilled from unskilled travelers with similar degrees of vision impairment. Two experiments will determine whether skilled travelers quickly learn contextual cues and/or direct their attention more to task- relevant information. Finally, the proposed research aims to determine the sources of visual information that travelers use to guide mobility and to determine if auditory information augments visual information to guide mobility for visually impaired travelers. Gaze patterns and path trajectories will be measured as subjects walk through routes where environmental information is manipulated (e.g. visual motion cue to distance). Several of the proposed experiments require a virtual environment (VE) to systematically control and/or manipulate environmental factors. Preliminary data demonstrate that VE is likely to be valid in studying exploratory behavior.