Basim Fatemeh, Goddard Erin, Yang Yueran, Webster Michael A
Graduate Program in Integrative Neuroscience, University of Nevada Reno, Reno, NV, USA.
School of Psychology, University of New South Wales, Sydney, Australia.
J Vis. 2025 Aug 1;25(10):17. doi: 10.1167/jov.25.10.17.
Anomalous trichromacy (AT) results from a reduced spectral separation between the L and M cone photopigments. This leads to smaller differential responses in the L and M cones and thus lower sensitivity to the colors signaled by the LvsM difference. Despite this, for stimuli above threshold, many color-anomalous observers report color experiences that resemble those of color-normal individuals, suggesting some form of perceptual compensation for their sensitivity losses. The nature and sites of this compensation remain uncertain, and may reflect many levels, from early sensory mechanisms to later post-perceptual processes. To assess potential sensory-level compensation, we compared the aftereffects of adaptation to chromatic contrast in 15 color-normal and 15 color-anomalous observers (10 deutan, 5 protan). Without compensation, the same adapting contrast should produce weaker adaptation effects in anomalous observers, because the same physical adaptor is a lower multiple of their threshold sensitivity. We quantified this prediction in color-normals by rescaling the LvsM contrasts to simulate the sensitivity losses. Although protan observers showed mixed results, the deutan observers exhibited adaptation effects that exceeded the predictions based on their threshold sensitivities, indicating partial compensation for the reduced LvsM signals. These findings are consistent with a post-receptoral sensory gain in contrast processing that compensates for the weaker LvsM cone signals available to anomalous observers, and could reflect a general normalization of contrast coding to match the color gamut of the observer's environment.
异常三色视觉（AT）是由L和M视锥色素之间光谱分离减少所致。这导致L和M视锥细胞的差异反应变小，从而降低了对L与M差异所表征颜色的敏感度。尽管如此，对于高于阈值的刺激，许多色觉异常的观察者报告的颜色体验与色觉正常个体相似，这表明他们对敏感度损失存在某种形式的感知补偿。这种补偿的性质和部位仍不确定，可能反映了从早期感觉机制到后期知觉后过程的多个层面。为了评估潜在的感觉水平补偿，我们比较了15名色觉正常和15名色觉异常观察者（10名绿色盲、5名红色盲）对颜色对比度适应后的后效应。若无补偿，相同的适应对比度在色觉异常观察者中应产生较弱的适应效应，因为相同的物理适应刺激是其阈值敏感度的较低倍数。我们通过重新调整L与M对比度来模拟敏感度损失，从而在色觉正常者中量化了这一预测。虽然红色盲观察者的结果不一，但绿色盲观察者表现出的适应效应超过了基于其阈值敏感度的预测，表明对L与M信号减弱有部分补偿。这些发现与对比度处理中感受器后感觉增益一致，该增益补偿了色觉异常观察者可用的较弱L与M视锥信号，并且可能反映了对比度编码的一般归一化，以匹配观察者环境的色域。
