Color Patches Research Articles

High contrast yellow mosaic patterns are prey attractants for orb‐weaving spiders

Abstract Many animals improve their foraging success by producing signals that exploit the sensory biases of potential prey, but the specific properties that make these sensory traps effective remain unclear. We combine field experiments with phylogenetic comparative analyses to investigate the visual luring properties of different signal designs in web‐building spiders. Our field experiments used cardboard spider models to examine the effects of area of colour patches, colour and pattern on the foraging success of the colourful giant wood spider, Nephila pilipes. These experiments revealed that both the colour (yellow) and pattern (yellow and black mosaic) are essential for luring prey in a high ambient light environment. We subsequently used phylogenetic comparative analyses to demonstrate an evolutionary association between prey viewing environment and spider ventral signal among 63 species of orb‐weavers from 53 genera. Combined, our data show that (a) the colour of the bright body parts of orb‐weavers is essential for both diurnal and nocturnal prey attraction, whereas the pattern and area of colour patches are important for diurnal foraging and (b) the evolution of these visual lures is associated with the viewing environment, specifically ambient light intensity. We conclude that the effectiveness of colour luring might be a major driver of the convergent evolution of yellow mosaic patterns in phylogenetically divergent orb‐weavers. Our discoveries indicate that prey colour preferences and signal efficacy play a significant role in the evolution of visually mediated prey‐luring systems. A free Plain Language Summary can be found within the Supporting Information of this article.

Estimation of the Oxidative Deterioration of Turbine Oil Using Membrane Patch Color

Lubricating oils degrade into two main products: oxidation products and solid particles. Oxidation products, called varnish, of turbine oils for power generation have become a particularly serious problem in recent years. The first step in determining the potential to produce varnish is to determine the remaining life of the antioxidant in the oil, but even though turbine oil may have antioxidants of sufficient longevity, varnish problems still occur frequently. Accordingly, to prevent varnish, it is necessary to diagnose oil oxidation products. Thus, the authors have developed a diagnostic method using membrane patch color, but the relationship between membrane patch color and the remaining life of turbine oils has yet to be clarified. This paper investigates a new method for estimating the oxidative degradation of turbine oils that uses membrane patch color and the dry turbine oxidation stability test (dry TOST) based on oxidation products and the remaining life of the turbine oils. Sample oils were prepared and degraded by oxidation in the laboratory using a dry TOST apparatus, and the membrane patch color was measured using a colorimetric patch analyzer (CPA). The relationship between membrane patch color and the rotating pressure vessel oxidation test (RPVOT) residual rate was then investigated. The results show that the new estimation method using the CPA and dry TOST is able to monitor the decrease of the RPVOT residual rate from the early stages of oxidative deterioration.

Late disruption of central visual field disrupts peripheral perception of form and color.

Evidence from neuroimaging and brain stimulation studies suggest that visual information about objects in the periphery is fed back to foveal retinotopic cortex in a separate representation that is essential for peripheral perception. The characteristics of this phenomenon have important theoretical implications for the role fovea-specific feedback might play in perception. In this work, we employed a recently developed behavioral paradigm to explore whether late disruption to central visual space impaired perception of color. In the first experiment, participants performed a shape discrimination task on colored novel objects in the periphery while fixating centrally. Consistent with the results from previous work, a visual distractor presented at fixation ~100ms after presentation of the peripheral stimuli impaired sensitivity to differences in peripheral shapes more than a visual distractor presented at other stimulus onset asynchronies. In a second experiment, participants performed a color discrimination task on the same colored objects. In a third experiment, we further tested for this foveal distractor effect with stimuli restricted to a low-level feature by using homogenous color patches. These two latter experiments resulted in a similar pattern of behavior: a central distractor presented at the critical stimulus onset asynchrony impaired sensitivity to peripheral color differences, but, importantly, the magnitude of the effect was stronger when peripheral objects contained complex shape information. These results show a behavioral effect consistent with disrupting feedback to the fovea, in line with the foveal feedback suggested by previous neuroimaging studies.

Bioinspired structural color patch with anisotropic surface adhesion.

Patch plays an important role in clinical medicine for its broad applications in tissue repair and regeneration. Here, inspired by the diverse adhesion, anti-adhesion, and responsive structural color phenomena in biological interfaces, we present a hybrid hydrogel film with an adhesive polydopamine (PDA) layer and an anti-adhesive poly(ethylene glycol) diacrylate (PEGDA) layer in an inverse opal scaffold. It was demonstrated that the resultant hydrogel film could serve as a functional tissue patch with an excellent adhesion property on one surface for repairing injured tissues and an anti-adhesion property on the other surface for preventing adverse adhesion. Besides, because of the responsive structural color, the patch was imparted with self-reporting mechanical capability, which could provide a real-time color-sensing feedback to monitor the heartbeat activity. Moreover, the catechol groups on PDA imparted the patch with high tissue adhesiveness and self-healing capability in vivo. These features give the bioinspired patch high potential in biomedical applications.

Color lures in orb-weaving spiders: a meta-analysis

AbstractLures are deceptive strategies that exploit sensory biases in prey, usually mimicking a prey’s mate or food item. Several predators exploit plant–pollinator systems, where visual signals are an essential part of interspecific interactions. Many diurnal, and even nocturnal, orb-web spiders present conspicuous body coloration or bright color patches. These bright colors are regarded as color-based lures that exploit biases present in insect visual systems, possibly mimicking flower colors. The prey attraction hypothesis was proposed more than 20 years ago to explain orb-web spider coloration. Although most data gathered so far has corroborated the predictions of the prey attraction hypothesis, there are several studies that refute these predictions. We conducted a multilevel phylogenetic meta-analysis to assess the magnitude of the effect of conspicuous orb-web spider body coloration on prey attraction. We found a positive effect in favor of the prey attraction hypothesis; however, there was substantial heterogeneity between studies. Experimental designs comparing conspicuous spiders to painted spiders or empty webs did not explain between-studies heterogeneity. The lack of theoretical explanation behind the prey attraction hypothesis makes it challenging to address which components influence prey attraction. Future studies could evaluate whether color is part of a multicomponent signal and test alternative hypotheses for the evolution of spider colors, such as predator avoidance and thermoregulation.

Tone Mapping High Dynamic Range Images by Hessian Multiset Canonical Correlations

Tone mapping algorithms reproduce high dynamic range (HDR) images on low dynamic range images in the standard display devices such as LCD, CRT, projectors, and printers. In this paper, we propose a statistical clustering-based tone mapping technique that would be able to adapt the local content of an image as well as its color. At first, the HDR image is partitioned into many overlapped color patches and we disintegrate each color patch into three segments: patch mean, color variation and color structure. Then based on the color structure component, the extracted color patches are clustered into a number of clusters by k-means clustering technique. For each cluster, the statistical signal processing technique namely Hessian multi set canonical correlations (HesMCC) has been produced to ascertain the transform matrix. Moreover, the HesMCC are fundamentally utilized for performing the dimensionality reduction of patches and to form effective tone mapped images. Contrasting with the current strategies, the procedures in the proposed clustering-based strategy can better adapt image color and its local structures by exploiting the image in the worldwide repetition. Experimental results show that the running time of the proposed method is less about 88.32%, 92%, 68.9%, and 29.4%, while comparing with other existing tone mapping methods.

Feeling Blue or Seeing Red? Similar Patterns of Emotion Associations With Colour Patches and Colour Terms.

For many, colours convey affective meaning. Popular opinion assumes that perception of colour is crucial to influence emotions. However, scientific studies test colour–emotion relationships by presenting colours as patches or terms. When using patches, researchers put great effort into colour presentation. When using terms, researchers have much less control over the colour participants think of. In this between-subjects study, we tested whether emotion associations with colour differ between terms and patches. Participants associated 20 emotion concepts, loading on valence, arousal, and power dimensions, with 12 colours presented as patches (n = 54) or terms (n = 78). We report high similarity in the pattern of associations of specific emotion concepts with terms and patches (r = .82), for all colours except purple (r = .−23). We also observed differences for black, which is associated with more negative emotions and of higher intensity when presented as a term than a patch. Terms and patches differed little in terms of valence, arousal, and power dimensions. Thus, results from studies on colour–emotion relationships using colour terms or patches should be largely comparable. It is possible that emotions are associated with colour concepts rather than particular perceptions or words of colour.

Differential effects of early growth conditions on colour-producing nanostructures revealed through small angle X-ray scattering and electron microscopy.

The costs associated with the production and maintenance of colour patches is thought to maintain their honesty. Although considerable research on sexual selection has focused on structurally coloured plumage ornaments, the proximate mechanisms of their potential condition dependence, and thus their honesty, is rarely addressed, particularly in an experimental context. Blue tit (Cyanistes caeruleus) nestlings have ultraviolet (UV)-blue structurally coloured tail feathers, providing a unique opportunity for investigation of the causes of variation in their colour. Here, we examined the influence of early growing conditions on the reflectance and structural properties of UV-blue-coloured tail feathers of blue tit nestlings. We applied a two-stage brood size manipulation to determine which stage of development more strongly impacts the quality of tail feather colouration and microstructure. We used small-angle X-ray scattering (SAXS) and electron microscopy to characterise the nanoscale and microscale structure of tail feather barbs. Nestlings from the broods enlarged at a later stage of growth showed a sex-specific rectrix development delay, with males being more sensitive to this manipulation. Contrary to predictions, treatment affected neither the quality of the barbs' nanostructures nor the brightness and UV chroma of feathers. However, at the microscale, barbs' keratin characteristics were impaired in late-enlarged broods. Our results suggest that nanostructure quality, which determines the UV-blue colour in tail feathers, is not sensitive to early rearing conditions. Furthermore, availability of resources during feather growth seems to impact the quality of feather microstructure more than body condition, which is likely to be determined at an earlier stage of nestling growth.

Evaluation of expanded gamut software solutions for spot color reproduction

AbstractExpanded gamut printing is an approach in color reproduction that expands the color gamut of conventional CMYK printing processes via the use of additional colorants, such as Orange, Green, and Violet inks. This study evaluates the ability of commercial color management software to create an accurate solution for an expanded gamut printing system. In this study, two printing processes were used, an Epson SureColor P9000 inkjet printer/proofer and an HP Indigo 7900 digital production press, both with 7‐color expanded gamut ink sets. Software solutions from Alwan, CGS ORIS, ColorLogic, GMG Color, Heidelberg, and Kodak were evaluated. The systems were tested to see how well they could reproduce the colors in the entire PANTONE+ Solid Coated spot color library. It is shown that the solutions are able to reproduce 89% to 94% of the spot colors on the Epson P9000 inkjet printer and 77% to 87% of the library on the Indigo 7900, both to less than two CIEDE2000 (a typical tolerance in label and packaging work). The number of color patches in expanded gamut characterization test charts was noted, as this is still an area of proprietary, nonstandardized working practice. There are many different colorant combinations that can make the same color in expanded gamut printing. The ink build created by the different software solutions was studied, as it relates to press stability through appropriate choice of colorants. Pantone and Adobe provide everyday commercial tools for expanded color workflows. The study identified some issues with products from these companies that could confuse a less‐skilled user in a busy production environment. The conclusion of the study is that expanded gamut solutions for spot color printing produce totally acceptable results for digital printing processes; expanded gamut printing is ready, here and now. The findings show that expanded gamut printing can replace cumbersome conventional spot color workflows creating considerable savings and advantages, especially for label and packaging printers.

Uncovering the function of an enigmatic display: antipredator behaviour in the iconic Australian frillneck lizard

Abstract When faced with a predator, some animals engage in a deimatic display to startle the predator momentarily, resulting in a pause or retreat, thereby increasing their chance of escape. Frillneck lizards (Chlamydosaurus kingii) are characterised by a large, pronounced frill that extends from the base of the head to beyond the neck and, when displayed, can be up to six times the width of the head. We used behavioural assays with a model avian predator to demonstrate that their display conforms to deimatic display theory. First, juveniles and adults deployed the frill in encounters with a model predator. Second, the display revealed three colour patches (white and red–orange patches on the frill; yellow mouth palate) that facilitate a transition from a cryptic to a conspicuous state as perceived by a raptor visual system. Third, the display was performed with movements that amplified its effect. The frill area was larger in males than in females, which suggests that the frill might also be co-opted for male–male contests. If future research confirms a role of the frill in male agonistic interactions, frillneck lizards will be a rare case in which a structure has a dual function in a deimatic display and a sexually selected signal.

A comparison of colour appearance for surface colours between outdoor and indoor environments

AbstractPsychophysical experiments of colour appearance, in terms of lightness, colourfulness, and hue, were conducted outdoors and indoors to investigate whether there was any difference in colour appearance between outdoor and indoor environments. A panel of 10 observers participated in the outdoor experiment, while 13 observers took part in the indoor experiment. The reference white had an average luminance of 12784 cd/m2 in the outdoor experiment and 129 cd/m2 in the indoor experiment. Test colours included 42 colour patches selected from the Practical Coordinate Color System to achieve a reasonable uniform distribution of samples in CIECAM02. Experimental results show that for both outdoor and indoor environments, there was good agreement between visual data and predicted values by CIECAM02 for the three colour appearance scales, with the coefficient of variation values all lower than 25 and the R2 values all higher than 0.73, indicating little difference in the three dimensions of colour appearance between indoor and outdoor viewing conditions. Experimental data also suggest that the observers were more sensitive to variation in lightness for grayish colours than for highly saturated colours, a phenomenon that seems to relate with the Helmholtz‐Kohlrausch effect. This phenomenon was modeled for predicting perceived lightness (J′) using the present experimental data. The new J′ model was tested using three extra sets of visual data obtained both outdoors and indoors, showing good predictive performance of the new model, with an average coefficient of variation of 14, an average R2 of 0.88, and an average STRESS index of 14.18.

Novel procedure for generating continuous flash suppression: Seurat meets Mondrian.

Continuous flash suppression (CFS) entails presentation of a stationary target to one eye and an animated sequence of arrays of geometric figures, the mask, to the other eye. The prototypical CFS sequence comprises different sized rectangles of various colors, dubbed Mondrians. Presented as a rapid, changing sequence to one eye, Mondrians or other similarly constructed textured arrays can abolish awareness of the target viewed by the other eye for many seconds at a time, producing target suppression durations much longer than those associated with conventional binocular rivalry. We have devised an animation technique that replaces meaningless Mondrian figures with recognizable visual objects and scenes as inducers of CFS, allowing explicit manipulation of the visual semantic content of those masks. By converting each image of these CFS sequences into successively presented objects or scenes each comprised of many small, circular patches of color, we create pointillist CFS sequences closely matched in terms of their spatio-temporal power spectra. Randomly rearranging the positions of the pointillist patches scrambles the images so they are no longer recognizable. CFS sequences comprising a stream of different objects produces more robust interocular suppression than do sequences comprising a stream of different scenes, even when the two categories of CFS are matched in root mean square contrast and spatial frequency content. Factors promoting these differences in CFS potency could range from low-level, image-based features to high-level factors including attention and recognizability. At the same time, object- and scene-based CFS sequences, when themselves suppressed from awareness, do not differ in their durations of suppression, implying that semantic content of those images comprising CFS sequences are not registered during suppression. The pointillist technique itself offers a potentially useful means for examining the impact of high-level image meaning on aspects of visual perception other than interocular suppression.

The development of a 3D colour reproduction system of digital impressions with an intraoral scanner and a 3D printer: a preliminary study.

This study aimed to develop a three-dimensional (3D) colour reproduction system to improve the aesthetic effects of dental prostheses. The system’s colour accuracy was also evaluated. Based on the concept of colour management, 96 colour patches were selected to develop colour profiles for an intraoral scanner and a 3D printer using polynomial regression. The colour differences Δ{E}_{ab}^{ast } between colour patches reproduced using different colour profiles and the original colour patches were analysed to select the best combinations of colour profiles. The 3D colour reproduction system with the best-performing (i.e. third-order polynomial regression) colour profiles was finally evaluated using tooth and gum shades. The median Δ{E}_{ab}^{ast } was 6.940 ranging from 1.504 to 32.660. In terms of tooth and gum shade, the median Δ{E}_{ab}^{ast } was 6.313, and half of the shade blocks were above the mismatch threshold (Δ{E}_{ab}^{ast } > 6.80). In conclusion, the colour management based on polynomial regression can decrease the colour difference of the 3D colour reproduction system, but not to clinically acceptable levels. Further advances are needed to improve the methods and hardware.

Variation in Head Shape and Color at the Range Boundary of Gulf Coastal Slimy Salamanders (Plethodon glutinosus Complex), USA

Taxonomists currently recognize 16 cryptic species within the Plethodon glutinosus complex revealed by allozyme analysis but that typically do not differ in morphology or color pattern. Two putative species, P. grobmani and P. mississippi, are distributed across the Gulf Coastal Plain, with geographic ranges that are separated by Mobile Bay and the Alabama River. Character divergence is thought to distinguish the two species, with P. grobmani (east of Mobile Bay) having a short snout and extensive patches of white coloration, and P. mississippi (west of Mobile Bay) having an elongate snout and lacking extensive patches of white coloration. However, specimens used to characterize these two species were examined in life, were collected mainly from areas adjacent to Mobile Bay, and were evaluated by a single investigator. Additionally, the two traits (snout shape and color) were combined into a single variable, masking the contribution of each trait to individuating the two species. To test the utility of these characters, we applied identical measurements of the two traits to preserved specimens representing an east–west transect across the geographic ranges of the two putative species. Data were generated by three investigators who measured each specimen twice, a design that allowed examination of reproducibility within and among investigators. Traits were evaluated separately and as a combined score. Both snout shape and color were found to be traits that are reproducible for measurements within individual investigators and the measurement of these traits did not differ among investigators. Specimens from east of Mobile Bay had more extensive white coloration and higher total scores than those west of Mobile Bay; snout shape did not differ across Mobile Bay. Longitude was a significant correlate of color and total score, with the slope of the relationship differing on each side of Mobile Bay. Color and total score of specimens west of Mobile Bay had a positive association with longitude, while scores of specimens east of Mobile Bay had a negative association. Thus, rather than exhibiting character divergence across Mobile Bay, slimy salamanders converge on a phenotype with extensive white coloration at Mobile Bay. We find no color or morphological feature that distinguishes putative P. grobmani from putative P. mississippi, a line of evidence suggesting that those populations are a single species with regional change in color.

Crossmodal Correspondences in the Sounds of Chinese Instruments.

People tend to associate stimuli from different sensory modalities, a phenomenon known as crossmodal correspondences. We conducted two experiments to investigate how Chinese participants associated musical notes produced by four types of Chinese instruments (bowed strings, plucked strings, winds, and percussion instruments) with different colors, taste terms, and fabric textures. Specifically, the participants were asked to select a sound to match each color patch or taste term in Experiment 1 and to match the experience of touching each fabric in Experiment 2. The results demonstrated some associations between pitch and color, taste term, or the smoothness of fabrics. Moreover, certain types of Chinese instruments were preferentially chosen to match some of the colors, taste terms, and the texture of certain fabrics. These findings therefore provided insights about the perception of Chinese music and shed light on how to apply the multisensory features of sounds to enhance the composition, performance, and appreciation of music.

Development of cyclosporine-loaded nanoemulsion for topical treatment of psoriasis

Psoriasis is an autoimmune disease in which the symptoms are obviously appeared on the patient's body with thick, red/ salmon colour and dry patches. Clinically, topical treatment has been the first-line treatment for psoriasis, whether or not the systemic and phototherapy is required. Currently, cyclosporine is one of the standard oral medications used for moderate to a severe case of psoriasis. However, through oral delivery, it cannot be used for a long period and causes bad effects. Thus, a new delivery system of cyclosporine is in need to be developed to overcome its toxic effects by skipping the first pass body metabolism. A nanoemulsion colloidal system, as the main carrier for big, non-water-soluble cyclosporine, is believed could help in the delivery of activities through the stratum corneum of the skin layer. Nanoemulsion system, which mainly consists of oil phase (a mixture of virgin coconut oil, nutmeg oil, and cyclosporine), aqueous phase, and surfactant, was successfully being developed by using Mixture Experimental Design optimization tool with droplet size range between 110-160 nm. Stability studies were carried out with respect to; pH, storage at different temperatures, coalescence and Ostwald ripening mechanism, free-thaw cycle, and FTIR analysis. From the obtained results, this newly-developed nanoemulsion containing cyclosporine was proven to be stable and successfully maintained its physicochemical characteristics even after 3 months of storage at 4°C and 25°C temperature. Ostwald ripening mechanism contributed to the instability of the system at 45°C of storage. Introduction of standard cyclosporine, blank nanoemulsion, and nanoemulsion containing cyclosporine to the HaCaT cells in the treatment of MTT assay study has confirmed the safety of the nanoemulsion. Permeation study of the newly-developed nanoemulsion containing cyclosporine showed it was best fitted the Korsmeyer-Peppas kinetic model. In addition, the transepidermal water loss and hydration studies proved the efficacy of cyclosporine-loaded nanoemulsion in increasing the water storage of the volunteers’ normal skin after 3h of application.

Relation Between Working Memory Capacity of Biological Movements and Fluid Intelligence.

Studies have revealed that there is an independent buffer for holding biological movements (BM) in working memory (WM), and this BM-WM has a unique link to our social ability. However, it remains unknown as to whether the BM-WM also correlates to our cognitive abilities, such as fluid intelligence (Gf). Since BM processing has been considered as a hallmark of social cognition, which distinguishes from canonical cognitive abilities in many ways, it has been hypothesized that only canonical object-WM (e.g., memorizing color patches), but not BM-WM, emerges to have an intimate relation with Gf. We tested this prediction by measuring the relationship between WM capacity of BM and Gf. With two Gf measurements, we consistently found moderate correlations between BM-WM capacity, the score of both Raven’s advanced progressive matrix (RAPM), and the Cattell culture fair intelligence test (CCFIT). This result revealed, for the first time, a close relation between WM and Gf with a social stimulus, and challenged the double-dissociation hypothesis for distinct functions of different WM buffers.

High-throughput sequencing is revealing genetic associations with avian plumage color

Abstract Avian evolution has generated an impressive array of patterns and colors in the ~10,000 bird species that exist on Earth. Recently, a number of exciting studies have utilized whole-genome sequencing to reveal new details on the genetics of avian plumage color. These findings provide compelling evidence for genes that underlie plumage variation across a wide variety of bird species (e.g., juncos, warblers, seedeaters, and estrildid finches). While much is known about large, body-wide color changes, these species exhibit discrete color differences across small plumage patches. Many genetic differences appear to be located in regulatory regions of genes rather than in protein-coding regions, suggesting gene expression is playing a large role in the control of these color patches. Taken together, these studies have the potential to broadly facilitate further research of sexual selection and evolution in these charismatic taxa.

Divergent color signals from homologous unfeathered ornaments in two congeneric grouse.

Color‐based visual signals are important aspects of communication throughout the animal kingdom. Individuals evaluate color to obtain information about age and condition and to behave accordingly. Birds display a variety of striking, conspicuous colors and make ideal subjects for the study of color signaling. While most studies of avian color focus on plumage, bare unfeathered body parts also display a wide range of color signals. Mate choice and intrasexual competitive interactions are easily observed in lekking grouse, which also signal with prominent unfeathered color patches. Most male grouse have one pair of colorful bare part ornaments (combs), and males of several species also have inflatable air sacs in their throat. Previous studies have mostly focused on comb color and size, but little is known about the signaling role of air sac color. We measured comb size and the color properties of combs and air sacs in the Lesser and Greater Prairie‐Chickens (Tympanuchus pallidicinctus and T. cupido, respectively), and investigated whether these properties varied with age and mass. We found that mass predicted color properties of air sacs and that age predicted comb size in the Greater Prairie‐Chicken, suggesting that these ornaments indicate condition dependence. No conclusive relationships between color and age or size were detected in the Lesser Prairie‐Chicken. Color properties of both ornaments differed between the two species. Further research is needed to determine mechanisms that link condition to color and whether the information advertised by color signals from these ornaments is intended for males, females, or both.

The biological basis of the experience and categorization of colour.

We used the Land Colour Mondrian experiments in a Bayesian context to test the degree to which subjects vary in categorizing the colour of different patches, when each patch is made to reflect light of the identical wavelength-energy composition. The brain uses a ratio-taking mechanism to determine the ratio of light of every waveband reflected from a surface and from its surrounds. Our (Bayesian) hypothesis was that this ratio-taking mechanism is similar in all humans and therefore leads to a constant categorization of colours that differs little between them. The similarly categorized colours are the initial priors, with initial hues attached to them. Twenty subjects of different ethnic and cultural backgrounds, for all but one of whom English was not the primary language, viewed eight patches of different colour in two Mondrian displays; each patch, when viewed, was made to reflect identical ratios of long-, middle- and short-wave light. Subjects were asked to match the colour of the viewed patch with that of the Munsell chip coming closest in colour to that of the viewed patch, without using language. In terms of hue, there was less variability in matching warm hues than cool ones. In terms of colour categorization, there was little variability overall. We take the lack of significant variability between subjects in the matches made as a pointer to similar computational mechanisms being employed in different subjects to perceive colours, thus permitting them to assume that their categorization of colours has universal agreement and assent.