Mechanisms of Color Detection, Induction and Adaptation

颜色视觉最重要的功能可能是识别光源中的物体和材质，以及识别物体集合中的光源。在颜色恒定的文献中，几乎所有的实验工作和大多数计算模型都表明，神经系统应该忽略光源，这样物体的颜色才会看起来恒定。然而，这个项目是建立在对比观察的基础上的，在许多情况下，物体在不同的光源下确实看起来有系统地不同的颜色。当 光源光谱的变化，反射光光谱的变化导致所有自然物体的锥体吸收的类似乘性变化。使用真实和模拟的刺激，我们将询问观察者是否可以使用这些变化来识别物体和光源，使用外观的相似性或外观变化的比较。在光源之间的识别依赖于将对象中的颜色变化与背景中的颜色变化进行比较，我们将推导出所使用的几何颜色关系。我们将使用定理作为一致性检验来研究感知颜色空间的内在几何，并测试其对光源变化的不变性。世界上大多数物体的颜色都不一致，所以我们将测试有图案的物体，看看识别局部对比度是否有助于识别材料。当只有一种光源时，外观的稳定性是识别材料的最佳线索。我们将进行测试，看看 恒定机制在空间上延伸，或者在空间上是局部的，但在时间上延伸，并测试结果是否需要适应模型或知觉参照系。我们将直接测量 光源的感知颜色，识别在该估计中使用的场景统计信息，并测试该估计是否用于颜色恒定。这个项目的结果将提供对日常颜色任务背后的神经计算和表征的见解。这里开发的方法将有助于识别色觉缺陷的功能后果。

Possibly the most important functions of color vision are the identification of objects and materials across illuminants, and of illuminants across sets of objects. In the color constancy literature, almost all experimental work, and most computational models, suggest that the nervous system should discount the illuminant so that colors of objects appear constant. This project, however, is based on the contrasting observation that, in many situations, objects do appear to be of systematically different colors under different illuminants. When the illuminant spectrum changes, changes in the spectra of reflected lights result in similar multiplicative changes in cone absorptions for all natural objects. Using real and simulated stimuli, we will ask whether observers can use these shifts to identify objects and illuminants, using similarity of appearance or comparisons of shifts in appearance. Where identification across illuminants depends on comparing color changes in objects to color changes in backgrounds, we will derive the geometric color relations that are used. We will study the intrinsic geometry of perceptual color space by using theorems as consistency checks, and test its invariance to illuminant changes. Most objects in the world are not uniform in color, so we will test patterned objects to see whether identification of local contrasts helps in identifying materials. When only a single illuminant is present, constancy of appearance is the best cue for material identification. We will perform tests of whether constancy mechanisms extend over space or are spatially local but extend across time, and also test whether the results require models of adaptation or perceptual frames of reference. We will directly measure the perceived color of the illuminant, identify the scene statistics that are used in this estimation, and test if thisestimate is used in color constancy. The results of this project will provide insights into neural computations and representations underlying everyday color tasks. The methods developed here will be useful in identifying functional consequences of color vision deficits.