Psychophysics of Reading - Normal and Low Vision

描述（由申请人提供）：美国有超过330万的低视力人群，其中大多数人有阅读困难。许多人患有黄斑变性和相关的中央视力丧失。本研究的主要目的是开发原则性训练方法，以提高低视力，特别是黄斑变性患者的阅读能力。我们的研究表明，视距大小的减小是低视力患者阅读速度下降的一个关键因素。阅读的视觉跨度是指文字中并排排列的字母的数量，不需要移动眼睛就能准确识别。视网膜的结构和中央视野的皮质放大产生一个小的视距，即使是正常的视力。由于眼病，这种小的视觉范围会进一步缩小。在一系列的心理物理研究中，我们将在先前的视觉广度研究的基础上，开发原则性的训练方法来提高低视力阅读。要评估的三种训练形式包括：1)垂直视距超过水平视距时的垂直阅读；2)动眼训练眼球注视，最大限度地提高信息在视广度上的传递速率；3)以扩大视觉广度为重点的感知学习。探索决定视觉广度大小的感官因素及其在阅读中的作用，将有利于阅读康复的应用。我们将研究空间因素（拥挤，位置不确定性）和时间因素决定视觉跨度的大小在中央和周边视觉。我们将使用功能磁共振成像来定位视觉范围内单词和字母识别的神经位点以及感知学习对其大小的影响。这些研究将为我们对视网膜首选位点（PRL）的视觉处理能力的心理物理探索提供信息，PRL是许多黄斑变性患者用于阅读的周围视网膜区域。美国有超过330万人患有低视力，其中大多数人有阅读困难。我们的大目标是利用视觉科学的发现来了解低视力人群的阅读困难。当前提案的一个主要目标是制定原则性训练方法，以提高低视力阅读，特别是对黄斑变性患者。

Description (provided by applicant): There are more than 3.3 million Americans with low vision, most of whom have reading difficulties. Many suffer from macular degeneration and associated loss of central vision. The primary purpose of this proposal is to develop principled training methods to enhance low-vision reading, particularly for those 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 for reading refers to the number of letters, arranged side-by-side as in text that can be recognized accurately without moving the eyes. Structure of the retina and cortical magnification of the central visual field produce a small visual span, even for normal vision. This small visual span is further diminished as a consequence of eye disease. In a series of psychophysical studies, we will build on our prior research on the visual span to develop principled training methods to enhance low-vision reading. The three forms of training to be evaluated include: 1) Vertical reading in cases where the vertical visual span exceeds the horizontal visual span; 2) Oculomotor training of eye fixations to maximize the information transfer rate through the visual span; and 3) Perceptual Learning which is focused on enlarging the size of the visual span. The applications to reading rehabilitation will benefit from our exploration of the sensory factors determining the size of the visual span and its role in reading. We will examine spatial factors (crowding, positional uncertainty) and temporal factors determining the size of the visual span in central and peripheral vision. We will use fMRI to localize the neural site of word and letter recognition within the visual span and the influence of perceptual learning on its size. These studies will inform our psychophysical exploration of the visual- processing capacity of the preferred retinal locus (PRL), the region of peripheral retina used for reading by many people with macular degeneration. PUBLIC HEALTH RELEVANCE There are more than 3.3 million Americans with low vision, most of whom have reading difficulties. Our broad goal is to use findings from vision science to understand the reading difficulties of people with low vision. A major goal of the current proposal is to develop principled training methods to enhance low-vision reading, particularly for people with macular degeneration.