Precision of sustained fixation in trained and untrained observers
Precision of sustained fixation in trained and untrained observers
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DOI：
10.1167/12.6.31
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发表时间：
2012-01-01
影响因子：
1.8
通讯作者：
Rucci, Michele
中科院分区：
文献类型：
--
作者：
Cherici, Claudia;Kuang, Xutao;Rucci, Michele
在视觉固定期间，眼睛的微观运动将视网膜上的图像移动到大量的光感受器上。虽然这些运动已经被研究了将近世纪，但它们所产生的视网膜图像运动的量仍然不清楚。目前可用的估计依赖于从未被测试过的关于眼球运动的概率分布的假设。此外，这些估计是基于收集的数据，只有少数，经验丰富和积极的观察者，并可能不代表幼稚和缺乏经验的受试者在实验中需要稳定的固定不稳定。在这项研究中，我们使用了高分辨率的眼动仪估计的概率分布的凝视位置在一个相对较大的一组人类观察者，其中大多数是未经训练的，而他们被要求保持固定在一个统一的领域的中心，在存在/不存在的固定标记。在所有受试者中，凝视位置的概率分布偏离了正态性，这是大多数先前研究的基本假设。由此产生的凝视的固定分散比以前报道的要大得多，并且在个体之间差异很大。出乎意料的是，不同的观察者保持固定在标记上的精度是最好的预测眼漂移的属性，而不是那些微扫视。我们的结果表明，在注视期间，眼睛的移动量和速度比通常假设的要大，并强调了眼漂移在保持准确注视方面的重要性。
During visual fixation, microscopic eye movements shift the image on the retina over a large number of photoreceptors. Although these movements have been investigated for almost a century, the amount of retinal image motion they create remains unclear. Currently available estimates rely on assumptions about the probability distributions of eye movements that have never been tested. Furthermore, these estimates were based on data collected with only a few, highly experienced and motivated observers and may not be representative of the instability of naive and inexperienced subjects in experiments that require steady fixation. In this study, we used a high-resolution eye-tracker to estimate the probability distributions of gaze position in a relatively large group of human observers, most of whom were untrained, while they were asked to maintain fixation at the center of a uniform field in the presence/absence of a fixation marker. In all subjects, the probability distribution of gaze position deviated from normality, the underlying assumption of most previous studies. The resulting fixational dispersion of gaze was much larger than previously reported and varied greatly across individuals. Unexpectedly, the precision by which different observers maintained fixation on the marker was best predicted by the properties of ocular drift rather than those of microsaccades. Our results show that, during fixation, the eyes move by larger amounts and at higher speeds than commonly assumed and highlight the importance of ocular drift in maintaining accurate fixation.