Department of Psychology, University of Washington Seattle, WA, USA.
Front Hum Neurosci. 2014 Dec 5;8:977. doi: 10.3389/fnhum.2014.00977. eCollection 2014.
Accurate perception of surface reflectance poses a significant computational problem for the visual system. The amount of light reflected by a surface is affected by a combination of factors including the surface's reflectance properties and illumination conditions. The latter are not limited by the strength of the illuminant but also include the relative placement of the light illuminating the surface, the orientation of the surface and its 3d shape, all of which result in a pattern of luminance gradients across the surface. In this study we explore how luminance gradients contribute to lightness perception. We introduce a novel, simple lightness illusion. It consists of six separate checks, organized in rows of two. Each check has a negative luminance gradient across it. The top and the bottom rows are the same: with the darker check on the left, and the lighter check on the right. Two checks in the middle row are identical; however, the check on the right appears darker than the check on the left. As there are no shared borders between the checks, simultaneous contrast cannot explain the effect. However, there are multiple possible explanations including spatial filtering (Blakeslee and McCourt, 2004) or some higher-order mechanism such as perceptual grouping or amodal completion. Here, we explore these possibilities by manipulating the luminance configurations and the gradient slopes of the checks.
准确感知表面反射率对视觉系统来说是一个重大的计算难题。表面反射的光量受到多种因素的影响，包括表面的反射特性和照明条件。后者不仅受光源强度的限制，还包括照亮表面的光的相对位置、表面的方向和其 3D 形状，所有这些都会导致表面亮度梯度的模式。在这项研究中，我们探讨了亮度梯度如何影响光感。我们引入了一种新颖、简单的光错觉。它由六个单独的方格组成，分为两行两列。每个方格都有负的亮度梯度。顶行和底行相同：左边是较暗的方格，右边是较亮的方格。中间两行的两个方格完全相同；然而，右边的方格看起来比左边的方格暗。由于方格之间没有共同的边界，因此同时对比无法解释这种效果。然而，有多种可能的解释，包括空间滤波（Blakeslee 和 McCourt，2004）或一些更高阶的机制，如知觉分组或同型完形。在这里，我们通过操纵方格的亮度配置和梯度斜率来探索这些可能性。
