Department of Psychology, Northeastern University, Boston, MA, USA.
J Vis. 2022 Sep 2;22(10):4. doi: 10.1167/jov.22.10.4.
Degraded viewing conditions caused by either natural environments or visual disorders lead to slow reading. Here, we systematically investigated how eye movement patterns during reading are affected by degraded viewing conditions in terms of spatial resolution, contrast, and background luminance. Using a high-speed eye tracker, binocular eye movements were obtained from 14 young normally sighted adults. Images of text passages were manipulated with varying degrees of background luminance (1.3-265 cd/m2), text blur (severe blur to no blur), or text contrast (2.6%-100%). We analyzed changes in key eye movement features, such as saccades, microsaccades, regressive saccades, fixations, and return-sweeps across different viewing conditions. No significant changes were observed for the range of tested background luminance values. However, with increasing text blur and decreasing text contrast, we observed a significant decrease in saccade amplitude and velocity, as well as a significant increase in fixation duration, number of fixations, proportion of regressive saccades, microsaccade rate, and duration of return-sweeps. Among all, saccade amplitude, fixation duration, and proportion of regressive saccades turned out to be the most significant contributors to reading speed, together accounting for 90% of variance in reading speed. Our results together showed that, when presented with degraded viewing conditions, the patterns of eye movements during reading were altered accordingly. These findings may suggest that the seemingly deviated eye movements observed in individuals with visual impairments may be in part resulting from active and optimal information acquisition strategies operated when visual sensory input becomes substantially deprived.
阅读条件退化，无论是自然环境还是视觉障碍导致的，都会导致阅读速度变慢。在这里，我们系统地研究了阅读过程中的眼动模式如何受到空间分辨率、对比度和背景亮度等退化观看条件的影响。使用高速眼动追踪器，从 14 名视力正常的年轻成年人中获得了双眼眼动数据。通过改变背景亮度（1.3-265 cd/m2）、文本模糊（严重模糊到无模糊）或文本对比度（2.6%-100%）来操纵文本片段的图像。我们分析了在不同观看条件下，关键眼动特征（如扫视、微扫视、回扫、注视和回扫）的变化。在测试的背景亮度值范围内，没有观察到明显的变化。然而，随着文本模糊度的增加和对比度的降低，我们观察到扫视幅度和速度显著降低，注视持续时间、注视次数、回扫比例、微扫视率和回扫持续时间显著增加。所有这些变化中，扫视幅度、注视持续时间和回扫比例对阅读速度的影响最大，共同解释了阅读速度变化的 90%。我们的研究结果表明，在呈现退化的观看条件时，阅读过程中的眼动模式会相应地发生改变。这些发现可能表明，在视觉感知输入明显剥夺的情况下，个体的视觉障碍患者表现出的看似异常的眼动可能部分是由于积极和最佳的信息获取策略。
