COLLABORATIVE RESEARCH: RUI: Perceptual Grouping Effects on Perceived Lightness

BCS-0002050 PI：Cataliotti人类视觉系统感知灰色阴影具有显着的准确性，尽管在照明强度和周围表面的亮度变化很大。例如，一张中灰色的纸通常会显示为中灰色，无论它是被明亮的灯光还是昏暗的灯光照亮。照明的变化导致视网膜图像也非常不同，但在大多数情况下，纸张被感知为中间灰色。亮度、对比度和其他误差已经被研究，试图更全面地理解视觉系统的设计和确定灰色阴影的逻辑。同时亮度对比度（SLC）是这些误差中研究最广泛的误差之一。SLC通过将灰色目标放置在白色背景上并且将物理上相同的灰色目标放置在黑色背景上来说明。白色上的目标将比黑色上的目标更暗。试图解释SLC的模型可以分为两个主要类别：1）将SLC视为低水平视网膜过程（即侧抑制）的残留副产品的模型，以及2）基于视觉通路中必须发生在视网膜水平以上的感知分组过程的模型。感知分组模型没有很好地定义在生理结构和功能方面。该项目的主要目标是更充分地探讨知觉分组过程在确定知觉表面颜色中的作用。这项研究将集中在PI实验室最近发现的三种新范式上。一组实验将涉及SLC的变化，其中两个灰色目标似乎在各自的背景上移动。另一组实验将要求观察者将呈现给一只眼睛的灰色目标与呈现给另一只眼睛的背景融合。在第三组中，观察者将判断顺序呈现的目标的亮度，以努力理解一个表面的感知灰色阴影对随后观察的表面的感知灰色的影响。实验将测试这些最近发现的现象是否主要是视网膜过程或视觉系统中发生在更高层次的感知过程的结果。 这些实验的结果将有助于更好地理解这些影响的机制，它们的位置，以及参与确定感知表面颜色的子系统之间的相互作用。简而言之，对感知表面颜色重要的神经机制的搜索领域将缩小。基于感知分组的模型可能在神经生物学方面更好地操作定义。本研究将对知觉心理学、神经心理学和人工智能领域做出贡献。

BCS-0002050PI: Cataliotti The human visual system perceives shades of gray with remarkable accuracy despite large changes in the intensity of the illumination and the brightness of surrounding surfaces. For example, a middle gray piece of paper will generally appear middle gray regardless if it illuminated by a bright light or a dim light. The change in illumination results in retinal images that are also very different, yet in most cases the paper is perceived as middle gray. Lightness contrast and other errors have been studied in an attempt to understand more fully the visual system's design and logic in determining shades of gray. Simultaneous lightness contrast (SLC) has been one of the most widely studied of these errors. SLC is illustrated by placing a gray target on a white background and a physically identical gray target on a black background. The target on the white will appear darker than the target on black. Models attempting to explain SLC can be grouped into two main categories: 1) models that treat SLC as a residual byproduct of low-level retinal processes, namely, lateral inhibition, and 2) models based on perceptual grouping processes that must take place above the retinal level in the visual pathway. Perceptual grouping models are not well defined in terms of physiological structuresand functions. The main goal of the proposed project is to more fully explore the roles perceptual grouping processes play in determining perceived surface color. The research will focus on three novel paradigms recently discovered in the PIs' lab. One set of experiments will involve a variation of SLC in which two gray targets appear to move across their respective backgrounds. Another set of experiments will require the observer to fuse gray targets presented to one eye with backgrounds presented to the other eye. In a third set, the observer will judge the lightness of sequentially presented targets in an effort to understand the effect of the perceived gray shade of one surface on the perceived gray of a subsequently viewed surface. Experiments will test whether these recently discovered phenomena are primarily the results of retinal processes or perceptual processes that occur at a higher level in the visual system. The results of these experiments will contribute to a better understanding of the mechanisms underlying these effects, their location, and the interaction between subsystems involved in determining perceived surface color. In short, the search field for neurological mechanisms important for perceived surface color will be narrowed. Models based on perceptual grouping may be better operationally defined in terms of neurobiology. This research will contribute to the fields of perceptual psychology, neuropsychology and artificial intelligence.