Levi D M, Klein S A
Nature. 1986;320(6060):360-2. doi: 10.1038/320360a0.
The human visual system is capable of making spatial discriminations with extraordinary accuracy. In normal foveal vision, relative position, width or size can be judged with an accuracy much finer than the size or spacing of even the smallest foveal cones. This remarkable accuracy of spatial vision has been termed 'hyperacuity'. Almost a century ago Ewald Hering proposed that the accuracy of Vernier acuity could be accounted for by averaging of discrete samples along the length of the lines comprising the targets; however, the discovery that Vernier acuity of a few arc seconds could be achieved with dots has rendered the nature and role of sampling in spatial discrimination unclear. We have been investigating the sampling of spatial information in central and peripheral vision (the perifovea) of normal human observers and in observers with strabismic amblyopia. Our results, presented here, show that peripheral vision and central vision of strabismic amblyopes differ qualitatively in their sampling characteristics from those of the normal fovea. Both the periphery and the central visual field of strabismic amblyopes demonstrate marked positional uncertainty which can be reduced by averaging of spatial information from discrete samples.
人类视觉系统能够以极高的精度进行空间辨别。在正常的中央凹视觉中，相对位置、宽度或大小的判断精度甚至比最小的中央凹视锥细胞的大小或间距还要精细得多。这种非凡的空间视觉精度被称为“超敏锐度”。大约一个世纪前，埃瓦尔德·赫林提出，游标视力的精度可以通过对构成目标的线条长度上的离散样本进行平均来解释；然而，用点可以实现几角秒的游标视力这一发现，使得采样在空间辨别中的性质和作用变得不明确。我们一直在研究正常人类观察者以及患有斜视性弱视的观察者在中央视觉和周边视觉（中央凹周围区域）中的空间信息采样情况。我们在此展示的结果表明，斜视性弱视患者的周边视觉和中央视觉在采样特征上与正常中央凹的采样特征存在质的差异。斜视性弱视患者的周边视野和中央视野都表现出明显的位置不确定性，这种不确定性可以通过对离散样本的空间信息进行平均来降低。
