Chima Akash S, Formankiewicz Monika A, Waugh Sarah J
Anglia Vision Research, Anglia Ruskin University, Cambridge, UK.
J Vis. 2015 Mar 26;15(3):22. doi: 10.1167/15.3.22.
Presenting two sufficiently dissimilar images, one to each eye, may result in interocular suppression. The present study measured interocular suppression depth and extent in binocularly normal participants when blurring one eye only with varying dioptric lens powers (+0.5, +1, +2, and +4 D). Visual stimuli consisted of eight concentric rings of alternate polarity, divisible into eight sectors, within the central circular 24° visual field. Binocular "ring" stimuli therefore consisted of 64 individually testable dichoptic sectors. Using a two-alternative forced choice paradigm with a staircase procedure, signal strength of each dichoptic sector in the blurred eye was adjusted to perceptually match that of the surrounding ring from the nonblurred eye, determining the point of subjective equality. Rings were defined by differences in luminance (L), luminance-modulated noise (LM), or contrast-modulated noise (CM). Suppression depth was similar irrespective of sector location within the visual field and increased with increasing difference in interocular blur. Adding dynamic noise (LM vs. L stimuli) reduced the effect of blur on measured suppression depth. Significantly deeper suppression was measured for CM than for LM stimuli, both created using dynamic noise, the difference increasing at higher levels of interocular blur. As binocularity is disrupted with interocular blur, this result suggests that CM envelope combination may be processed by later mechanisms receiving binocular input than those required for the processing of LM stimuli. Differences in suppression depth between LM and CM stimuli could not be attributed to differences in spatial summation properties, stimulus visibility, noise modulation, or differential effects on blur discriminability.
向每只眼睛呈现两个足够不同的图像可能会导致双眼抑制。本研究测量了双眼正常参与者在仅用不同屈光度镜片（+0.5、+1、+2和+4 D）模糊一只眼睛时的双眼抑制深度和范围。视觉刺激由中央24°视野内交替极性的八个同心环组成，可分为八个扇区。因此，双眼“环”刺激由64个可单独测试的双眼视区组成。使用带有阶梯程序的二选一强制选择范式，将模糊眼内每个双眼视区的信号强度调整到在感知上与未模糊眼周围环的信号强度相匹配，从而确定主观相等点。环由亮度（L）、亮度调制噪声（LM）或对比度调制噪声（CM）的差异定义。无论视野内扇区位置如何，抑制深度相似，并且随着双眼模糊差异的增加而增加。添加动态噪声（LM与L刺激）会降低模糊对测量的抑制深度的影响。对于CM刺激测量到的抑制明显比LM刺激更深，两者均使用动态噪声创建，在更高水平的双眼模糊时差异增大。由于双眼性因双眼模糊而受到干扰，该结果表明CM包络组合可能由比处理LM刺激所需的机制接收双眼输入更晚的机制进行处理。LM和CM刺激之间抑制深度的差异不能归因于空间总和特性、刺激可见性、噪声调制或对模糊辨别力的差异影响。
