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McKeefry D J - - 2004
We have studied the influence of chromatic adaptation upon the perceived visual position of a test stimulus using a Vernier alignment task. Maximum and minimum offsets in spatial position are generated when the adapting and test stimuli lie on the same and orthogonal axes in MBDKL color space, respectively. When ...
Nascimento Sérgio M C - - 2004
Relational color constancy refers to the constancy of the perceived relations between the colors of surfaces of a scene under changes in the spectral composition of the illuminant. Spatial ratios of cone excitations provide a natural physical basis for this constancy, as, on average, they are almost invariant under illuminant ...
Tran Ngoc H - - 2004
STATEMENT OF PROBLEM: External prostheses composed of silicone elastomers exhibit an unwanted color change over time. PURPOSE: This study evaluated color stability when an ultraviolet light absorber and hindered amine light stabilizer were mixed in the maxillofacial elastomer containing either organic or inorganic pigments. MATERIAL AND METHODS: The materials used ...
Monaci Gianluca - - 2004
The spectral properties of chromatic-detection mechanisms were investigated using a noise-masking paradigm. Contrast-detection thresholds were measured for a signal with a Gaussian spatial profile, modulated in the equiluminant plane in the presence of spatial chromatic noise. The noise was distributed within a sector in the equiluminant plane, centered on the ...
Pinna Baingio B Universität Freiburg, AG Hirnforschung, Freiburg, - - 2004
A new visual phenomenon that we call flashing anomalous color contrast is described. This phenomenon arises from the interaction between a gray central disk and a chromatic annulus surrounded by black radial lines. In an array of such figures, the central gray disk no longer appears gray, but assumes a ...
Foster David H - - 2004
If surfaces in a scene are to be distinguished by their color, their neural representation at some level should ideally vary little with the color of the illumination. Four possible neural codes were considered: von-Kries-scaled cone responses from single points in a scene, spatial ratios of cone responses produced by ...
Monnier Patrick - - 2004
Chromatic induction from patterned backgrounds depends on the spatial as well as the chromatic aspects of the background light. Color appearance with patterned and uniform backgrounds was compared using chromaticities distinguished by only the S cones; all backgrounds were equivalent to equal-energy white in terms of L-cone and M-cone stimulation. ...
Rosenholtz Ruth - - 2004
Many previous studies have shown that background color affects the discriminability and appearance of color stimuli. However, research on visual search has not typically considered the role that the background may play. Rosenholtz (2001a) has suggested that color search asymmetries result from the relationship between the stimuli and the background. ...
Pearson Joel - - 2004
The inability of the human visual system to fuse dissimilar patterns in corresponding regions of the two eyes results in stochastic alternation of perceptual dominance between the two patterns: rivalry. When rivalrous stimuli are presented intermittently their perception is stabilized (Leopold, Wilke, Maier, & Logothetis, 2002). This stability indicates the ...
Breitmeyer Bruno G - - 2004
Using a metacontrast masking paradigm, prior studies have shown (a) that a target's color information and form information, can be processed without awareness and (b) that unconscious color processing occurs at early, wavelength-dependent levels in the cortical information processing hierarchy. Here we used a combination of paracontrast and metacontrast masking ...
Dominy Nathaniel J - - 2004
Here we describe correlations among visual ecology and the physiochemical properties of fruits and leaves consumed by four species of catarrhine primate: Cercopithecus ascanius, Colobus guereza, Pan troglodytes, and Piliocolobus badius. Collectively, their diet was diverse, with each species relying on fruits and leaves to different extents. The mean chromaticity ...
Guibal Christophe R C - - 2004
Luminance and color are strong and self-sufficient cues to pictorial depth in visual scenes and images. The present study investigates the conditions under which luminance or color either strengthens or overrides geometric depth cues. We investigated how luminance contrast associated with the color red and color contrast interact with relative ...
Bimler David - - 2004
The structure of color perception can be examined by collecting judgments about color dissimilarities. In the procedure used here, stimuli are presented three at a time on a computer monitor and the spontaneous grouping of most-similar stimuli into gestalts provides the dissimilarity comparisons. Analysis with multidimensional scaling allows such judgments ...
Scuello Michael - - 2004
We had shown earlier that viewers prefer to look at artworks under illuminants of approximately 3600 K. In the latest paper we tested the hypothesis that the preferred illuminant is one that appears neither warm nor cool and repeated the settings at each of four illuminances to test the stability ...
Navon David - - 2004
It has been repeatedly found (e.g., Beck, 1982; Beck & Ambler, 1973) that a tilted T is detected better than an L when presented on the background of a number of upright Ts, although in isolation both are discriminated from an upright T about equally well. We demonstrate that an ...
Bonato Frederick - - 2004
Lightness, the perceived gray shade of a surface, and the perception of self-luminous surfaces--that is, surfaces that appear to glow--have most often been studied with paper displays and computer-generated stimuli presented on CRT monitors. Although both methods are often effective, experiments that require a wide range of luminance values in ...
Rowe M P - - 2004
Male threespine stickleback ( Gasterosteus aculeatus) use nuptial colors to attract mates and intimidate rivals. We quantified stickleback color and environmental lighting using methods independent of human perception to evaluate the information transmitted by male signals in a habitat where these signals are displayed. We also developed models of chromatic ...
Hurlbert Anya - - 2004
Color constancy--by which objects tend to appear the same color under changes in illumination--is most likely achieved by several mechanisms, operating at different levels in the visual system. One powerful contributory mechanism is simultaneous spatial color contrast. Under changes in natural illumination the spatial ratios of within-type cone excitations between ...
Amano K - - 2004
When both color and motion direction of visual stimuli are alternated in physical synchrony at a relatively higher frequency (approximately 2 Hz), the changes in motion direction are perceived to be delayed. On the other hand, color and motion direction changes are perceived to be in phase when the motion ...
Barbur John L - - 2004
Background perturbation techniques using both static and dynamic luminance contrast and chromatic contrast noise have been employed to investigate the interaction between luminance and chromatic contrast signals. A number of experiments involving contrast detection thresholds for static stimuli, simple reaction times, and pupil color responses yield evidence for independent processing ...
Shinozaki T - - 2004
Previous psychophysical studies have reported a few hundred millisecond difference in the reaction time (RT) to luminance versus color motion in low speed condition. Electroencephalogram (EEG) studies have reported a small difference between initial responses to luminance and color motion, but a big difference comparable to that reported in psychophysical ...
Bacci Mauro - - 2003
Photoinduced alterations of light-sensitive artifacts represent one of the main problems that conservators and curators have to face for environmental control in museums and galleries. Therefore, increasing attention has been recently devoted to developing strategies of indoor light monitoring, especially aimed at minimizing the cumulated light exposure for the objects ...
Liu Taosheng - - 2003
A network of fronto-parietal cortical areas is known to be involved in the control of visual attention, but the representational scope and specific function of these areas remains unclear. Recent neuroimaging evidence has revealed the existence of both transient (attention-shift) and sustained (attention-maintenance) mechanisms of space-based and object-based attentional control. ...
Hagman Mattias - - 2003
Conspicuous coloration is often used in combination with chemical defenses to deter predators from attacking. Experimental studies have shown that the avoidance inducing effect of conspicuous prey coloration increases with increasing size of pattern elements and with increasing body size. Here we use a comparative approach to test the prediction ...
Barkat S - - 2003
The color and odor of cosmetics have been shown to be crucial for affective states and able to influence autonomic responses. We report an original procedure to measure the effect on subjects of the color and odor of cosmetic products, and to quantify the correlation between objective (psychophysiological recording) and ...
Long Fuhui - - 2003
The color context effects referred to as color contrast, constancy, and assimilation underscore the fact that color percepts do not correspond to the spectral characteristics of the generative stimuli. Despite a variety of proposed theories, these phenomena have resisted explanation in a single principled framework. Using a hyperspectral image database ...
Stolz Uwe - - 2003
The Jamaican click beetle Pyrophorus plagiophthalamus (Coleoptera: Elateridae) is unique among all bioluminescent organisms in displaying a striking light color polymorphism [Biggley, W. H., Lloyd, J. E. & Seliger, H. H. (1967) J. Gen. Physiol. 50, 1681-1692]. Beetles on the island vary in the color of their ventral light organs ...
Sakurai Masato - - 2003
To provide the fundamental data for a color zone map, the color appearances of nearly unique hue stimuli presented over the entire visual field were qualitatively and quantitatively evaluated by hue and saturation judgments, blackness evaluation, and categorical color naming. The hue of red and green stimuli shifts toward a ...
Wente Wendy H - - 2003
Pacific tree frogs Hyla regilla are typically either green or brown in dorsal coloration. The frequency of green and brown individuals is known to fluctuate seasonally. Previous investigators have generally assumed that the green and brown body colors represent a "fixed" polymorphism and that seasonal changes in the proportion of ...
Bedell Harold E - - 2003
Recent psychophysical studies have been interpreted to indicate that the perception of motion temporally either lags or is synchronous with the perception of color. These results appear to be at odds with neurophysiological data, which show that the average response-onset latency is shorter in the cortical areas responsible for motion ...
Swift Paul D - - 2003
We present modeled results of the luminous and color outputs of a three-layer stack of fluorescent planar concentrators (FPCs). FPCs have the potential to provide sufficient luminous output to illuminate moderate-sized rooms for reasonably-sized collecting areas. It is of course necessary not only that the lumens be sufficient, but also ...
Monnier Patrick - - 2003
The perceived color of a light varies with the background on which it is seen. In the present study, patterned backgrounds composed of two different chromaticities caused larger shifts in perceived color than did a uniform background at either chromaticity within the pattern. Cortical receptive-field organization, but not optical factors ...
Gong Yingyan - - 2003
The aim of this study was to investigate the relationship between the workers occupationally exposed to a mixture of organic solvents and their visual functions. Here the visual functions included color vision (CV), visual contrast sensitivity (CS) and visual evoked potentials (VEP). Test subjects were 182 workers at 53 furniture ...
Tsujimoto Satoshi - - 2004
The present study investigated the division of attention between different visual attributes, which is a cognitive function implicated in the selection of information in a given condition. To examine the underlying mechanisms, we focused on motion and color as visual attributes. In Experiment 1, performance on single- and dual-judgment for ...
Garcia Tiffany Sacra - - 2003
Although many organisms show multiple types of trait responses to predation risk (e.g., shifts in behavior, morphology, color, chemistry or life history), relatively few studies have examined how prey integrate these multiple responses. We studied the joint expression of color and behavioral responses to predation risk in two sister species ...
Kingdom Frederick A A - - 2003
In natural scenes, chromatic variations, and the luminance variations that are aligned with them, mainly arise from surfaces such as flowers or painted objects. Pure or near-pure luminance variations, on the other hand, mainly arise from inhomogeneous illumination such as shadows or shading. Here, I provide evidence that knowledge of ...
Lin Chin-Chiuan - - 2003
A laboratory study was carried out to investigate the effects of illumination, viewing distance, and lighting color on perception time with center high-mounted stop lamps comprised of light-emitting diodes. Analysis indicated that illumination, viewing distance, and lighting color are significant factors in perception time. Low illumination resulted in shorter perception ...
Merilaita Sami - - 2003
Cryptic animal coloration or camouflage is an adaptation that decreases the risk of detection. The study of the evolution of camouflage has strongly emphasized the minimization of visual information that predators receive from prey, by means of background matching. However, the evolutionary effects of information processing after its reception have ...
Nagy Allen L - - 2003
Experiments were designed to investigate the effects of set size and variation in the chromaticity of distractor stimuli on thresholds for detecting a target stimulus that differed from distractors only in chromaticity. Distractor chromaticities were selected from a line in the isoluminant color plane and targets were selected from lines ...
Mitchell Jude F - - 2003
When two differently colored, superimposed patterns of dots rotate in opposite directions, this yields the percept of two superimposed transparent surfaces. If observers are cued to attend to one set of dots, they are impaired in making judgments about the other set. Since the two sets of dots are overlapping, ...
Santos Laurie R - - 2003
Few studies have examined whether non-human tool-users understand the properties that are relevant for a tool's function. We tested cotton-top tamarins (Saguinus oedipus) and rhesus macaques (Macaca mulatta) on an expectancy violation procedure designed to assess whether these species make distinctions between the functionally relevant and irrelevant features of a ...
Heywood Charles A - - 2003
Brain damage can entirely abolish color vision in cases of complete achromatopsia. Other processes that depend on wavelength differences, however, can be retained. Form and motion defined by pure color differences can be perceived readily even when the colors themselves cannot be told apart. The loss of color vision in ...
Takeuchi Tatsuto - - 2003
We examined the role of color in the processing of motion of a luminance-varying pattern by alternating the color of a moving pattern and measuring the luminance contrast required for accurate discrimination of the motion direction. We report that the contrast threshold for perceiving the direction of motion of luminance-varying ...
Vollmer S H - - 2003
Science is concerned not just with objects but also with their various aspects, such as their colors, temperatures, sizes, and shapes. These aspects, or properties, are generally thought to be of at least two kinds: primary properties, such as shape, size, and motion and secondary ones, such as temperature and ...
Earley Joseph E JE - - 2003
The traditional distinction between primary (observation independent) and secondary (observation dependent) qualities is not based on a difference that can be sustained in the full light of contemporary scientific understanding. An alternative division of physical and chemical properties is proposed. Like the traditional division of qualities, the alternative system has ...
Chase Christopher - - 2003
A review of the neurophysiological literature suggests that the magnocellular pathway has adequate spatial-frequency and contrast sensitivity to perceive text under normal contrast conditions (>10%) and also is suppressed by red light. Results from three experiments involving color and reading show that red light impairs reading performance under normal luminance ...
Nachman Michael W - - 2003
Identifying the genes underlying adaptation is a major challenge in evolutionary biology. Here, we describe the molecular changes underlying adaptive coat color variation in a natural population of rock pocket mice, Chaetodipus intermedius. Rock pocket mice are generally light-colored and live on light-colored rocks. However, populations of dark (melanic) mice ...
Sjöstrand F S - - 2003
The discovery that color vision extends to low illumination reported in this communication eliminates the duplicity theory as an explanation of vision differing at high and low illumination. Instead, an explanation of the difference was found when analyzing synaptic interaction between retinal neurons, made possible by revealing the synaptic connections ...
d'Avossa Giovanni - - 2003
Changes in regional blood oxygen level dependent (BOLD) signals in response to brief visual stimuli can exhibit a variety of time-courses. To demonstrate the anatomical distribution of BOLD response shapes during a match to sample task, a formal analysis of their time-courses is presented. An event-related design was used to ...
MacLeod Donald I.A. - - 2003
Colors are generally ordered in three dimensions, with hue and saturation as polar coordinates of a color circle, and brightness as the third dimension. Intuitively, lines of constant hue (but variable saturation) in such a color space should converge on an achromatic point devoid of hue. However, in new experiments ...
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