What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception.
What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception.
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DOI：
10.3389/fnhum.2015.00205
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发表时间：
2015
影响因子：
2.9
通讯作者：
McCourt ME
中科院分区：
文献类型：
--
作者：
Blakeslee B;McCourt ME
亮度感知的研究集中在理解视觉系统用于将视网膜强度分布（近端刺激）解析为场景的表面反射和照明分量（远端刺激-地面真实）的先验假设和处理策略。人们一致认为，视觉系统必须比较视觉图像的不同区域来解决这个逆问题;然而，比较的性质及其背后的机制是激烈辩论的主题。知觉错觉是有价值的，因为它们揭示了关于这些视觉处理机制的重要信息。我们提出了一个框架的亮度研究，解决了文献中的困惑和悖论，并提供了深入的视觉系统采用的机制来解决逆问题。主要的想法是，在文献中的大部分争论和混乱源于这样一个事实，即亮度，定义为表观反射率，是不够的，是指三种不同类型的判断是不可比的。在包含可见光照明成分（如阴影边界）的刺激条件下，观察者可以区分和匹配无色体验的三个独立维度：表观强度（亮度），表观局部强度比（亮度-对比度）和表观反射率（亮度）。然而，在没有可见照明边界的情况下，非彩色视觉减少到两个维度，并且根据刺激条件和观察者的指示，对亮度的判断与对亮度或亮度对比度的判断相同。此外，由于亮度判断是基于不同条件下的不同信息，因此它们在难度和准确性方面可能有很大差异。这可能部分解释了研究中亮度恒定性的巨大变化。
Research in lightness perception centers on understanding the prior assumptions and processing strategies the visual system uses to parse the retinal intensity distribution (the proximal stimulus) into the surface reflectance and illumination components of the scene (the distal stimulus—ground truth). It is agreed that the visual system must compare different regions of the visual image to solve this inverse problem; however, the nature of the comparisons and the mechanisms underlying them are topics of intense debate. Perceptual illusions are of value because they reveal important information about these visual processing mechanisms. We propose a framework for lightness research that resolves confusions and paradoxes in the literature, and provides insight into the mechanisms the visual system employs to tackle the inverse problem. The main idea is that much of the debate and confusion in the literature stems from the fact that lightness, defined as apparent reflectance, is underspecified and refers to three different types of judgments that are not comparable. Under stimulus conditions containing a visible illumination component, such as a shadow boundary, observers can distinguish and match three independent dimensions of achromatic experience: apparent intensity (brightness), apparent local intensity ratio (brightness-contrast), and apparent reflectance (lightness). In the absence of a visible illumination boundary, however, achromatic vision reduces to two dimensions and, depending on stimulus conditions and observer instructions, judgments of lightness are identical to judgments of brightness or brightness-contrast. Furthermore, because lightness judgments are based on different information under different conditions, they can differ greatly in their degree of difficulty and in their accuracy. This may, in part, explain the large variability in lightness constancy across studies.