The effects of visual field color and spatial complexity on self-motion perception were investigated by placing observers inside a large rotating cylinder (optokinetic drum). Under optokinetic-drum conditions visually induced self-motion (vection) is typically perceived within 30 s, even though all forms of sensory input (eg vestibular, proprioceptive, auditory), except vision, ...

Perceived color at a point in space is not determined simply by the color directly stimulating the corresponding retinal position. Surface color is informed by flanking edge signals, which also serve to inhibit the intrusion of signals from neighboring surfaces. Spatially continuous local interactions among color and luminance signals have ...

The perception of blur in images can be strongly affected by prior adaptation to blurry images or by spatial induction from blurred surrounds. These contextual effects may play a role in calibrating visual responses for the spatial structure of luminance variations in images. We asked whether similar adjustments might also ...

Surgeons using a fresh tissue dissection laboratory need specimens with tissue color and texture as close as possible to those of a living body. Completely unembalmed specimens kept in a cooler remain in good condition only for a few days, and then decay rapidly. Unembalmed specimens can be frozen for ...

We investigated how achromatic and chromatic cues interact to produce transparency. Observers were shown six-region stimulus displays similar to those used by R. Kasrai and F. A. A. Kingdom (2001) and made adjustments of the color and luminance attributes of one of the filter regions to achieve the best percept ...

When a stimulus repeatedly and rapidly changes color (e.g., between red and green) and motion direction (e.g., upwards and downwards) with the same frequency, it was found that observers were most likely to pair colors and motion directions when the direction changes lead the color changes by approximately 80 ms. ...

Most wavelengths change hue when mixed with white light. These changes, known as the Abney effect, have been extensively studied to characterize nonlinearities in the neural coding of color, but their potential function remains obscure. We measured the Abney effect in a new way--by varying the bandwidth of the spectrum ...

A gray region can be made to look colored by a colored surround. This phenomenon, chromatic induction, depends on color differences around the boundary of the region. We performed experiments on chromatic induction with small, initially achromatic, targets on nine different colored surrounds ranging in color from blue to red. ...

In asymmetric lightness matching tasks, observers sometimes report that they cannot achieve satisfactory matches between achromatic surfaces under different neutral illuminants. The surfaces appear different, yet no further adjustment of either surface improves the match. There are evident difficulties in interpreting data from a task that the observer cannot always ...

The acclimation of photosynthetic organisms to changes in light color is ubiquitous and may be best illustrated by the colorful process of complementary chromatic adaptation (CCA). During CCA, cyanobacterial cells change from brick red to bright blue green, depending on their light color environment. The apparent simplicity of this spectacular, ...

The use of spectrophotometry for the analysis of the cerebrospinal fluid (CSF) is reviewed. The clinically relevant CSF pigments--oxyhemoglobin and bilirubin--are introduced and discussed with regard to clinical differential diagnosis and potentially confounding variables (the four T's: traumatic tap, timing, total protein, and total bilirubin). The practical laboratory aspects of ...

We measured responses to red-green color variation in parvocellular (PC) neurons in the lateral geniculate nucleus of dichromatic ("red-green color blind") marmoset monkeys. Although these animals lack distinct visual pigments to distinguish between wavelengths in this range, many of the colored stimuli nevertheless produced robust responses in PC cells. We ...

How do induced brightness and darkness signals from local and remote surfaces interact to determine the final achromatic color percept of a target surface? An emerging theory of achromatic color perception posits that brightness and darkness percepts are computed by weighting and summing the induction signals generated at edges in ...

Color assimilation with bichromatic contours was quantified for spatial extents ranging from von Bezold-type color assimilation to the watercolor effect. The magnitude and direction of assimilative hue change was measured as a function of the width of a rectangular stimulus. Assimilation was quantified by hue cancellation. Large hue shifts were ...

The fractal dimensions of color-specific paint patterns in various Jackson Pollock paintings are calculated using a filtering process that models perceptual response to color differences (L*a*b* color space). The advantage of the L*a*b* space filtering method over traditional red-green-blue (RGB) spaces is that the former is a perceptually uniform (metric) ...

Large-field trichromacy is a general feature of protanope and deuteranope humans, provided that the stimuli size extends to an 8 degrees visual angle. In this study we compared the performance of five male and three female tufted capuchin monkeys (Cebus apella) in discriminating pairs of Munsell color papers. Human subjects ...

Bees, like humans, can continue to see a surface from its color even when the scene's global illuminant changes (which is a phenomenon called color constancy). It is not known, however, whether they can also generate color-constant behavior in more natural complex scenes that are lit by multiple lights simultaneously, ...

PURPOSE: Red signals are typically used to signify danger. This study was conducted to investigate a situation identified by train drivers in which red signals appear yellow when viewed at long distances (approximately 900 m) through progressive-addition lenses. METHODS: A laboratory study was conducted to investigate the effects of defocus, ...

Fading of artificial hair color has been investigated by simulating actual usage conditions through exposure to artificial radiation in a weatherometer, with 0.35 mW/(m(2) nm) at 340 nm, for 16 to 48 hours, and by periodical washing. Hair color was produced by using commercial two-part, permanent hair dyes with light ...

Color vision is useful for detecting surface boundaries and identifying objects. Are the signals used to perform these two functions processed by common mechanisms, or has the visual system optimized its processing separately for each task? We measured the effect of mean chromaticity and luminance on color discriminability and on ...

We present evidence that steady achromatic adapting fields can produce response saturation in color-opponent pathways. We measured tvi (log increment threshold illuminance versus log background illuminance) functions at four test wavelengths (430, 490, 575, and 660 nm) and nine background illuminances from 4.0 to 5.6 log Td. Foveal, 2 degrees ...

PURPOSE: To determine the difference in lightness, chroma, hue angle and color of four kinds of esthetic restorative materials of the same shade designation by the change of standard illuminants of D65 (daylight), A (incandescent lamp) and F2 (fluorescent lamp). METHODS: Spectral reflectance and color of four resin composites, a ...

Luminance-dependent change in color appearance--the Bezold-Brücke effect--was investigated in protanopes and related to that in normal trichromats. Spectral lights were presented at six luminance levels covering mesopic, low, and high photopic vision-across three log steps from 0.76 to 760 Td. To judge color appearance, a variant of the color-naming method ...

Coloration and figural properties of neon color spreading and the watercolor illusion are studied using phenomenal and psychophysical observations. Coloration properties of both effects can be reduced to a common limiting condition, a nearby color transition called the two-dot limiting case, which clarifies their perceptual similarities and dissimilarities. The results ...

No soft tissue shade guide is available for matching the color of denture resins to human intraoral soft tissues. To determine the color of both the gingiva and the alveolar mucosa, intraoral soft tissue colors of 150 men and women were assessed under standardized lighting conditions. Colors of the papilla, ...

Distant objects like clouds, mountains, and the Sun can appear to have colors that are significantly different from their intrinsic colors: the low Sun is often red, white clouds and snow-capped peaks appear yellow or pink, and dark green or gray mountains can appear blue or purple. The color alteration ...

The appearance of a patch of color or its contrast depends not only on the stimulus itself but also on the surrounding stimuli (induction effects-simultaneous contrast). A comprehensive computational physiological model is presented to describe chromatic adaptation of the first (retinal) and second (cortical) orders, and to predict the different ...

Studies were carried out on the growth of Chromatium sp. on seafood wastewater (SFWW), which under facultative conditions and light exposure produced red pigment. The strain grew and utilized organic matter in both dark and light exposure conditions, but it produced red pigment when exposed to light. The growth was ...

The aim of this study was to evaluate polymerization-dependent changes in the color and translucency parameter (TP) of resin composites and to compare results obtained using two color-difference metric formulae, CIELAB and CIEDE 2000. Twenty-eight shades of commercial resin composites were analyzed. Specimens (n = 5) were made as discs, ...

Nigella degenii ssp. barbro and ssp. jenny differ from related taxa in being dimorphic for pollen color, with some plants having dark pollen and others light pollen. In this study we performed experimental crosses to determine whether the difference in pollen color is governed by few or many loci and ...

Coloring in nature mostly comes from the inherent colors of materials, but it sometimes has a purely physical origin, such as diffraction or interference of light. The latter, called structural color or iridescence, has long been a problem of scientific interest. Recently, structural colors have attracted great interest because their ...

Chromatic assimilation is the shift in color appearance toward nearby light. Assimilation was measured using nearby light with time-varying chromaticity. This light induced time-varying assimilation within the test area. Assimilation was quantified by the amplitude of temporally varying test-area light--in counter-phase to the induced assimilation--required to null the assimilation. Unlike ...

The butterflies Graphium sarpedon nipponum Fruhstorfer and Papilio xuthus Linné show pupal protective color polymorphism, but the two species appear to have different sensory mechanisms for determining pupal coloration. When light was of sufficient illumination, the larvae of Graphium sarpedon became bright yellowish green pupae on white pupation boards and ...

An experimental approach was taken to evaluate the role of phenotypic plasticity in reptile coloration for three lizard species which exhibit dramatic variation in dorsal body darkness associated with different substrate environments. In southern New Mexico, blanched color morphs of Aspidoscelis inornata, Holbrookia maculata, and Sceloporus undulatus inhabit the gypsum ...

Animal color pattern phenotypes evolve rapidly. What influences their evolution? Because color patterns are used in communication, selection for signal efficacy, relative to the intended receiver's visual system, may explain and predict the direction of evolution. We investigated this in bowerbirds, whose color patterns consist of plumage, bower structure, and ...

In van Tuijl's neon configurations, an achromatic line segment on a blue inducer produces yellowish illusory color in the illusory area. This illusion has been explained based on the idea of the complementary color induced by the blue inducer. However, it is proposed here that this illusion can be also ...

We consider the reproduction of color subject to material and neighborhood constraints. By "material constraints," we mean any constraints that are applied to the amount of ink, lights, voltages, and currents that are used in the generation of color. In the first instance we consider the problem of reproducing a ...

We describe a device that can display very high intensity (up to 400,000 cd/m2), high-resolution visual stimuli. The device is inexpensive, is easily controlled by a conventional computer and video card, and can be calibrated for use in vision research or clinical applications. The display is capable of presenting highly ...

Our understanding of human visual perception generally rests on the assumption that conscious visual states represent the interaction of spatial structures in the environment and our nervous system. This assumption is questioned by circumstances where conscious visual states can be triggered by external stimulation which is not primarily spatially defined. ...

This article presents our recent studies on the effects of color temperature on the taste sense and the influence of color temperature on bright light exposure during night rest period. Ten male Japanese and ten male Chinese were exposed to four illumination conditions (200, 1500 lx x 3000, 7500 K). ...

Stimuli designed to selectively elicit motion or color processing were used in a developmental event-related potential study with adults and children aged 6, 7 and 8. A positivity at posterior site INZ (P-INZ) was greater to motion stimuli only in adults. The P1 and N1 were larger to color stimuli ...

In this work, sediment samples collected from several Spanish harbours were tested with two toxicity procedures, designed for solid samples: the Microtox Basic Solid-Phase Test (BSPT) and a modified procedure of the previous test protocol (mBSPT). According to the BSPT procedure, after initial light readings, pure bacteria were exposed to ...

We used the psychological refractory period paradigm, in which participants respond to two successive tasks (T1 and T2). We created in T2 spatial and color Simon effects, known to be caused by response selection processes. Previous studies in which the spatial Simon effect was manipulated in T2 showed that this ...

When a dark chromatic contour delineating a figure is flanked on the inside by a brighter chromatic contour, the brighter color will spread into the entire enclosed area. This is known as the watercolor effect (WCE). Here we quantified the effect of color spreading using both color-matching and hue-cancellation tasks. ...

Neurological case studies and qualitative measurements suggest that regions within human extrastriate cortex are specialized for different perceptual functions, including color. However, there are few quantitative measurements of human extrastriate color specializations. We studied the chromatic and temporal responses in several different clusters of human visual field maps using functional ...

Being the largest land mammals, elephants have very few natural enemies and are active during both day and night. Compared with those of diurnal and nocturnal animals, the eyes of elephants and other arrhythmic species, such as many ungulates and large carnivores, must function in both the bright light of ...

Switchable windows are being installed into modern buildings. We report on how the variable transmittance of gasochromic and electrochromic switchable windows changes the color rendering properties of the daylight passing through these windows. We present a series of color rendering examples. Correlated color temperature and color rendering indices are insufficient ...

PURPOSE: The use of incubator covers to enhance preterm infants' rest and recovery is common in the NICU. However, the kinds of covers used vary extensively among and within nurseries. Few data exist on the effectiveness of different types of covers in reducing light levels to the infant. This study ...

Distributed feedback microstructures play a fundamental role in confining and manipulating light to obtain lasing in media with gain. Here, we present an innovative array of organic, color-tunable microlasers which are intrinsically phase locked. Dye-doped helixed liquid crystals were embedded within periodic, polymeric microchannels sculptured by light through a single-step ...

Avian cone photoreceptors have an oil droplet in the outer portion of their inner segment that acts as a long-pass cut-off filter between incident light and visual pigment. Chick cone droplets are mainly red, orange, yellow, green, and colorless, and the colors are due to three carotenoid pigments with characteristic ...