There is a large literature characterizing human perception of the lightness and color of matte surfaces arranged in coplanar arrays. In the past ten years researchers have begun to examine perception of lightness and color using wider ranges of stimuli intended to better approximate the conditions of everyday viewing. One emerging line of research concerns perception of lightness and color in scenes that approximate the three-dimensional environment we live in, with objects that need not be matte or coplanar and with geometrically complex illumination. A second concerns the perception of material surface properties other than color and lightness, such as gloss or roughness. This special issue features papers that address the rich set of questions and approaches that have emerged from these new research directions. Here, we briefly describe the articles in the issue and their relation to previous work. Keywords: color perception, material perception Citation: Maloney, L. T., & Brainard, D. H. (2010). Color and material perception: Achievements and challenges. Journal of Vision, 10(9):19, 1-6, http://www.journalofvision.org/content/10/9/19, doi:10.1167/10.9.19. Introduction The classic perceptual correlates of object surface properties are lightness and color. Although there are notable exceptions (e.g., Over the past decade, research has increasingly begun to focus on two rich generalizations of the classic "flatmatte" paradigm (for reviews, see In 2004, we edited a special issue in the Journal of Vision entitled "Perception of color and material properties in complex scenes" Characterizing, estimating, and discriminating the light field One of the most important themes in color and material perception is the role of scene illumination. In flat-matte scenes, the placement and directionality of light sources was little emphasized Journal of Vision Complex light fields and surface color/lightness perception In parallel with direct assessment of the perception of the light field, the past decade has seen a slew of papers that study how the visual system achieves color and lightness constancy in the context of spatially complex light fields (e.g., Along these lines in the current issue, Radonjić, Todorović, and Gilchrist (2010) examine surface lightness perception in three-dimensional scenes with directional lighting and show how grouping principles such as adjacency and surroundedness can help organize the empirical phenomena. Olkkonen, Witzel, Hansen, and Gegenfurtner (2010) study color categorization for real surfaces and daylight illuminants. An entire room with controlled illumination served as the laboratory. They find that color categorization was little changed by marked changes in daylight illumination. Surface material perception: Gloss, roughness A very active area of research is the assessment of lighting and environmental conditions that affect the perception of material properties such as gloss and roughness, and how these properties interact with the perception of color and lightness. Important early work includes Surface material perception is represented by a number of papers in this issue; Kim and Anderson Interactions There are several studies that examined interactions among different material properties. In this issue, Giesel and Gegenfurtner (2010) systematically investigate color perception for real objects made of different materials varying in roughness and gloss from smooth and glossy to matte and corrugated. They show that hue is quite stable across their manipulations, but that other attributes interact. Olkkonen and Brainard (2010) study how changes in real-world illumination affect perceived glossiness and lightness with emphasis on testing independence principles. They show, for example, that the effect of geometric changes in the light field on perceived glossiness is independent of the diffuse reflectance component of the surfaces. Novel themes A number of papers in the current issue introduce novel themes. Wolfe and Myers (2010) examine visual search performance when targets and distractors are characterized by surface material. They find that, although it may be easy to discriminate "fur" or "stone," searching for a patch of fur among the stones is difficult and time-consuming. Visual search based on material differences is inefficient. Motoyoshi (2010) examines how the relationship between highlights and shading triggers perception of translucency and transparency. Goddard, Solomon, and Colin (2010) study the adaptable neural mechanisms responsible for surface color constancy. Boyaci, Fang, Murray, and Kersten (2010) also consider mechanism. They report behavioral results showing how lightness across occlusion depends on spatially distant image features and show (using brain imaging) that human early visual cortex responds strongly to occlusion-dependent lightness variations. They conclude that early cortical processing of lightness is affected by three-dimensional scene interpretation
