Psychophysics of Reading--Normal and Low Vision

描述（由申请人提供）：美国有超过350万人患有低视力，其中大多数人有阅读困难。本提案的主要目的是评估感知训练和视觉系统的可塑性对阅读康复的重要性，特别是对黄斑变性患者。我们的研究表明，视距大小的减小是解释低视力人群阅读速度下降的一个关键因素。视觉广度是在阅读过程中一眼就能识别出的字母的数量。我们发现，正常周边视觉的知觉训练可以扩大视觉广度，并相应提高阅读速度。在一系列的心理物理研究中，我们将评估这一发现对年轻和老年正常视力和低视力受试者康复的相关性。我们还将探讨空间注意力和位置信号如何影响视觉广度的大小。视力康复的潜力取决于眼病后视觉脑的可塑性。在一系列的fMRI实验中，我们将对低视力受试者进行研究，1)评估视觉皮层视网膜定位的变化，2)了解视觉皮层是否参与触觉感知。在第三个系列中，我们将对来自白内障和黄斑变性患者的两大组特征良好的低视力阅读数据（MNREAD）进行二次分析。我们将利用这些数据：1)分析阅读视力特征与视力障碍临床指标之间的关系；2)编制新的阅读能力量表，量化整体阅读能力；3)分析阅读能力与认知状况、心理健康状况等重要非视觉因素的关系。

DESCRIPTION (provided by applicant): There are more than 3.5 million Americans with low vision, most of whom have reading difficulties. The primary purpose of this proposal is to evaluate the importance of perceptual training and plasticity of the visual system to reading rehabilitation, particularly for people with macular degeneration.Our research indicates that decrease in the size of the visual span is a key factor explaining reduced reading speed in low vision. The visual span is the number of letters that are identified in a single glance during reading. We have found that perceptual training in normal peripheral vision can enlarge the visual span with a corresponding increase in reading speed. In a series of psychophysical studies, we will assess the relevance of this finding for rehabilitation in young and old subjects with normal and low vision. We will also ask how spatial attention and positional signals influence the size of the visual span.The potential for vision rehabilitation depends on the plasticity of the visual brain following eye disease. In a series of fMRI experiments, we will study low-vision subjects to 1) evaluate changes in retinotopic mapping in the visual cortex, and 2) ask whether visual cortex participates in tactile perception.In a third series, we will conduct secondary analyses on two large sets of well-characterized low-vision reading data (MNREAD) test), from cataract and macular-degeneration patients. We will use these data to 1) analyze the relationships between properties of reading vision and clinical measures of visual impairment; 2) develop a new reading ability scale for quantifying overall reading capacity, and 3) analyze the relationship between reading ability and important non-visual factors including cognitive status and mental-health status.