The concept of articulation was first introduced by Katz [1935 The World of Colour (London: Kegan Paul, Trench, Trubner & Co)] to refer to the degree of complexity within a field. Katz, who created the basic research methods for studying lightness constancy, found that the greater the degree of articulation within a field of illumination, the greater the degree of constancy. Even though this co...

Human visual perception is a fundamentally relational process: Lightness perception depends on luminance ratios, and depth perception depends on occlusion (difference of depth) cues. Neurons in low-level visual cortex are sensitive to the difference (but not the value itself) of signals, and these differences have to be used to reconstruct the input. This process can be regarded as a 2-dimensio...

Shifts in the appearance of color under different illuminant chromaticity are known to be incomplete, and fit nicely with a simple linear transformation of cone responses that aligns the achromatic points under two illuminants. Most chromaticity-transfer functions with von-Kries-like transformations use only one set of values to fit the color shifts from one illuminant to another. However, an a...

The articulation effect refers to a change in lightness contrast induced by adding small patches of different luminances to a uniform background surrounding a target in a lightness contrast display. This study investigated how local luminance signals are integrated to generate the articulation effect. We asked whether spatial organization due to perceptual grouping can influence the articulatio...

This study investigated the individual differences of lightness filling-in on illusory contour figures with regard to the attention to figures; namely, to which information of hierarchical figures, the global information or the local information, subjects tended to allocate their attention. Subjects participated in a preliminary experiment to divide into a global group and a local group. The gl...

Two experiments were performed to relate the Bezold-Brücke (B-B) and lightness compression effects. The first used a calibrated screen to present an achromatic luminance staircase. In addition, it reproduced, the methodology and the essential aspects the lightness compression effect discovered by Cataliotti and Gilchrist (1995). That is, observers perceived a truncated grey scale (from white to...

A key challenge for the visual system is to extract constant object properties from incoming sensory information. This information is ambiguous because the same sensory signal can arise from many combinations of object properties and viewing conditions and noisy because of the variability in sensory encoding. The competing accounts for perceptual constancy of surface lightness fall into two cla...

The visual system's computation of lightness (perceived reflectance) leads to contrast effects in which a gray target region appears lighter on a black background than on a white one. Here we show a paradoxical contrast effect in which targets look lighter after adding regions that increase the scene's average luminance, and darker after adding regions that decrease this luminance. The paradoxi...

Most vision scientists are comfortable with the idea that perception is a multi-level process. For example we take it for granted that the two best understood properties of human colour vision, trichromacy and colour-opponency, are underpinned by physiological mechanisms operating at different stages in the visual pathway. The observation that any colour can be matched by a suitable mixture of ...

The anchoring theory of lightness perception (Gilchrist et al., Psychological Review 106 (1999) 795-834) has been described as one of the most successful approaches to lightness perception. Yet, not only does the original proposal contain serious gaps and inconsistencies, later expressions of the theory, which was never formally revised, seem to contradict the original claims while leaving the ...