O'Shea R P, Williams D R
Department of Psychology, University of Otago, Dunedin, New Zealand. r
Vision Res. 1996 Jun;36(11):1561-71. doi: 10.1016/0042-6989(95)00227-8.
To test whether the binocular contour rivalry mechanism is tritanopic, we presented isoluminant, rival stimuli visible only via the short-wavelength-sensitive (S) cones. We stimulated only the S cones with violet gratings superimposed on a bright yellow field that adapted the responses of the middle- and long-wavelength-sensitive (M and L) cones. We found that an S-cone grating presented to one eye rivalled with an orthogonal grating presented to the other. Rivalry persisted over a range of luminances and contrasts of the S-cone stimuli, and was greater than could be accounted for by nonrival fading. The spatial spread of rivalry from S-cone stimuli is similar to that for the same stimuli when visible also to the M and L cones (luminance stimuli). We found that an S-cone stimulus would rival with a luminance stimulus, and exploited this to determine the equivalent luminance contrast of S-cone stimuli by putting them in a rivalry competition with luminance stimuli. For rivalry, the equivalent luminance contrast of isoluminant, S-cone stimuli is much less than their S-cone contrast. The existence of rivalry with isoluminant stimuli, along with earlier evidence that such stimuli can support stereopsis, challenges the view that an achromatic channel alone drives certain higher level functions such as depth perception.
为了测试双眼轮廓竞争机制是否是蓝黄色盲的，我们呈现了等亮度的、仅通过短波敏感（S）视锥细胞可见的竞争刺激。我们用叠加在亮黄色背景上的紫色光栅刺激仅S视锥细胞，亮黄色背景会使中波和长波敏感（M和L）视锥细胞的反应适应。我们发现呈现给一只眼睛的S视锥细胞光栅与呈现给另一只眼睛的正交光栅相互竞争。在一系列S视锥细胞刺激的亮度和对比度范围内，竞争持续存在，且大于非竞争消退所能解释的程度。S视锥细胞刺激产生的竞争的空间传播与M和L视锥细胞也可见时（亮度刺激）相同刺激的情况相似。我们发现S视锥细胞刺激会与亮度刺激相互竞争，并利用这一点通过将它们与亮度刺激进行竞争来确定S视锥细胞刺激的等效亮度对比度。对于竞争而言，等亮度的S视锥细胞刺激的等效亮度对比度远小于它们的S视锥细胞对比度。等亮度刺激存在竞争，以及早期证据表明此类刺激可以支持立体视觉，这对仅由一个非彩色通道驱动某些高级功能（如深度感知）的观点提出了挑战。
