The universality, invariance, and elegance of principles governing the universe may be reflected in principles of the minds that have evolved in that universe – provided that the mental principles are formulated with respect to the abstract spaces appropriate for the representation of biologically significant objects and their properties. (1) Positions and motions of objects conserve their shapes in the geometrically fullest and simplest way when represented as points and connecting geodesic paths in the six-dimensional manifold jointly determined by the (...) Euclidean group of three-dimensional space and the symmetry group of each object. (2) Colors of objects attain constancy when represented as points in a three-dimensional vector space in which each variation in natural illumination is canceled by application of its inverse from the three-dimensional linear group of terrestrial transformations of the invariant solar source. (3) Kinds of objects support optimal generalization and categorization when represented, in an evolutionarily-shaped space of possible objects, as connected regions with associated weights determined by Bayesian revision of maximum-entropy priors. Key Words: apparent motion; Bayesian inference; cognition; color constancy; generalization; mental rotation; perception; psychological laws; psychological space; universal laws. (shrink)

: According to a consensus of psycho-physiological and philosophical theories, color sensations (or qualia) are generated in a cerebral "space" fed from photon-photoreceptor interaction (producing "metamers") in the retina of the eye. The resulting "space" has three dimensions: hue (or chroma), saturation (or "purity"), and brightness (lightness, value or intensity) and (in some versions) is further structured by primitive or landmark "colors"—usually four, or six (when white and black are added to red, yellow, green and blue). It has also been (...) proposed that there are eleven semantic universals—labeling the previous six plus the "intermediaries" of orange, pink, brown, purple, and gray. There are many versions of this consensus, but they all aim to provide ontological, epistemological and semantic blueprints for the brute fact of the reality of color ordained by Nature (evolution). In contrast to this consensus, we have argued that "seeing color" is not a matter of light waves impacting on our eyes, producing sensations to be categorized and labeled in the "color space" in the brain. While electrochemical events may unproblematically be regarded as the causal precondition for seeing color, the reception of sensations in "the color space" as semantically labeled natural categories, kinds, or information, is a "just so" story: it is Wittgenstein's beetle in a box. In contrast we consider that the authority of this consensus might better be regarded not as the result of the truth-tracking of nature, but as the sociohistorical outcome of philosophical presuppositions, scientific theories, experimental practices, technological apparatus, and their feed forward into the lifeworld. The question we shall therefore explore is whether, or to what extent, we ourselves are changed, as the conditions of production of color science change. Thus we are doing a kind of anthropology at two levels: of color science itself (and its effect on our own lifeworld), and of those studied by the "anthropology of color". As befits this stance we are agnostic about the theoretical entities of color science (cf. van Fraassen 2001), and within this new context, we propose to cross-cut object-and-subject, organism-and-environment (the bedrock of color science) in socio-historical ways. Our approach is in part inspired by, but not the same as, that of Gibson, in that we wish to pursue the notion of "social affordances" (Burmudez 1995). We suggest that color has become a naturalization through science-based technologies, which, through praxes and materializations, have become the perceptual and cultural entities that structure experience and understanding in the lifeworld. It is this naturalization that we shall refer to and characterize as "the historically inflected exosomatic organ". Consequently we shall explore the historical ontology of "color" without assuming an underlying biological constant (Dupré 2001). In part 1 we show the flimsiness of the evidence for the three dimensions of color, borrowed from physics, and fine-tuned to a "standard observer" (a "spectral creature" with a phenomenal "color space"). In part 2 we address the structuring of hue through the development of color circles and color spaces. This is followed by a review of the evidence for unique hues. Again the evidence is shown to be flimsy. We then show that an isolated domain of color is a particular kind of model, not a "natural given". In part 3, after reviewing what is referred to as "the isomorphy thesis," we discuss the exemplary case study of Berlin and Kay (1969). This illustrates the pull of stadial models presupposed by their evolutionary theory of color language. The Berlin and Kay paradigm proposes that American English color terms are incorrigible and can provide the universal metalanguage. We conclude by presenting an alternative account, namely that we ourselves are changed as the conditions of production of color science change. We argue that it is better to regard "seeing-color" as a historically inflected exosomatic organ that provides social affordances for those trained to grasp them. (shrink)

In this commentary I argue that Byrne & Hilbert commit a number of philosophical solecisms: They beg the question of “realism,” they take the phenomenon and the theoretical model to be the same thing, and they surreptitiously substitute data sets for the life-world.

In visual science, color is usually regarded as a subjective phenomenon. The relationship between the specific color experiences that are evoked by a visual scene and the physical properties of the surfaces viewed in that scene are complex and highly dependent on spatial context. There is no simple correspondence between experienced color and a stable class of physical reflectances.

Color vision provides accurate measures of the phase and intensity of daylight, and also a means of discriminating between objects. Neither property implies that objects are colored.

I argue that Byrne & Hilbert (B&H) have not answered Hardin's objection to physicalism about color concerning the unitary-binary structure of the colors for two reasons. First, their account of unitary-binary structure seems unsatisfactory. Second, pace B&H, there are no physicalistically acceptable candidates to be the hue-magnitudes. I conclude with a question about the justification of physicalism about color.

The paper examines the notion, widespread in the contemporary color science, that there are certain hues, specifically focal red, yellow, green and blue, that are unique or privileged in human prelinguistic color perception, all other chromatic hues being perceptually composed of these. I successively consider and reject all motivations that have been provided for this opinion; namely the linguistic, “phenomenological”, and some minor or historical motivations. I conclude that, contrary to the standard opinion, there is no solid reason to claim (...) that the RYGB hues are unique among colors in a sense that would allow for direct neurophysiological explanation. The notion also has no relevance for the construction of perceptual color spaces and is not defensible as an explanatory principle with respect to the existing crosslinguistic patterns of color categorization. (shrink)

Visual percepts are called veridical when a “real” object can be identified as their cause, and illusions otherwise. The perceived position and color of a flashed object may be called veridical or illusory depending on which viewpoint one adopts. Since “reality” is assumed to be fixed (independent of viewpoint) in the definition of veridicality (or illusion), this suggests that “perceived” position and color are not properties of “real” objects.

While color realism is endorsed, Byrne & Hilbert's (B&H's) case for it stretches the notion of “physical property” beyond acceptable bounds. It is argued that a satisfactory account of color should do much more to respond to antirealist intuitions that flow from the specificity of color experience, and a pointer to an approach that does so is provided.

Two experiments compared “Red-Green” dichromats’ empirical and metacognized capacities to discriminate basic color categories and to use the corresponding basic color terms. A first experiment used a 102-related-colors set for a pointing task to identify all the stimuli that could be named with each BCT by each R-G dichromat type. In a second experiment, a group of R-G dichromats estimated their difficulty discriminating BCCs-BCTs in a verbal task. The strong coincidences between the results derived from the pointing and the verbal (...) tasks indicated that R-G dichromats have very accurate metacognition about their capacities and limitations in the use of BCTs. Multidimensional scaling solutions derived from both tasks were very similar: BCTs in R-G dichromats were properly represented in 2D MDS solutions that clearly show one chromatic dimension and one achromatic dimension. Important concordances were found between protanopes and deuteranopes. None of these dichromats showed substantial difficulty discriminating the Red-Green pair. So, to name them “R-G” dichromats is misleading considering their empirical capacities and their metacognition. Further reasons to propose the use of the alternative denomination “Brown-Green” dichromats are also discussed. We found some relevant differences between the “Brown-Green” dichromats’ empirical and self-reported difficulties using BCTs. Their metacognition can be considered a “caricature” of their practical difficulties. This caricature omits some difficulties including their problems differentiating “white” and “black” from other BCTs, while they overestimate their limitations in differentiating the most difficult pairs. Individual differences scaling analyses indicated that the metacognition regarding the use of BCTs in “Brown-Green” dichromats, especially deuteranopes, is driven slightly more by the chromatic dimension and driven slightly less by the achromatic dimension, than their practical use of BCTs. We discuss the relevance of our results in the framework of the debate between the linguistic relativity hypothesis and the universal evolution theories. (shrink)

“The problem of color realism” as defined in the first section of the target article, is crucial to the argument laid out by Byrne & Hilbert. They claim that the problem of color realism “does not concern, at least in the first instance, color language or color concepts” (sect. 1.1). I argue that this claim is misconceived and that a different characterisation of the problem, and some of their preliminary assumptions makes their positive proposal less appealing.

Byrne & Hilbert conceive of color perception as the representation of a physical property “out there.” In our view, their approach does not only have various internal problems, but is also apt to becloud both the intricate and still poorly understood role that “ color ” plays within perceptual architecture, and the complex coupling to the “external world” of the perceptual system as an entirety. We propose an alternative perspective, which avoids B&H's misleading dichotomy between a purely subjective and a (...) realist conception of “ color.”. (shrink)

Byrne & Hilbert are right that it might be an objective fact that a particular tomato is unique red, but wrong that it cannot simultaneously be yellowish-red (not only objectively, but from somebody else's point of view). Sensory categorization varies among organisms, slightly among conspecifics, and sharply across taxa. There is no question of truth or falsity concerning choice of categories, only of utility and disutility. The appropriate framework for color categories is Nominalism and Pluralistic Realism.

Can we maintain that purple seems composed of red and blue without giving up the impenetrability of the red and blue parts that compose it? Brentano thinks we can. Purple, according to him, is a chessboard of red and blue tiles which, although individually too small to be perceived, are together indistinctly perceived within the purple. After a presentation of Brentano’s solution, we raise two objections to it. First, Brentano’s solution commits him to unperceivable intentional objects (the chessboard’s tiles). Second, (...) his chessboard account fails in the end to explain the phenomenal spatial continuity of compound colours. We then sketch an alternative account, which, while holding fast to the phenomenal compoundedness of the purple and to the impenetrability of component colours, avoids introducing inaccessible intentional objects and compromising on the continuity of the purple. According to our proposal, instead of being indistinctly perceived spatial parts of the purple, red and blue are distinctly perceived non- spatial parts of it. (shrink)

Byrne & Hilbert propose that color can be identified with explicit properties of physical surfaces. I argue that this claim must be qualified to take into account constraints needed to make recovery of surface color information possible. When these constraints are satisfied, then a biological visual system can establish a correspondence between perceived surface color and specific surface properties.

For all animals, color is an indicator of the substance and state of objects, for which purpose reflectance is just one among many relevant optical properties. This broader meaning of color is confirmed by linguistic evidence. Rather than reducing color to a simple physical property, it is more realistic to embrace its full phenomenology.

This study examines the cross‐cultural generality of Hering's (1878/1964) color‐opponent theory of color appearance. English‐speaking and Somali‐speaking observers performed variants of two paradigms classically used to study color‐opponency. First, both groups identified similar red, green, blue, and yellow unique hues. Second, 25 English‐speaking and 34 Somali‐speaking observers decomposed the colors present in 135 Munsell color samples into their component Hering elemental sensations—red,green,blue, yellow, white, and black—or else responded “no term.” Both groups responded no term for many samples, notably purples. Somali (...) terms for yellow were often used to name colors all around the color circle, including colors that are bluish according to Hering's theory. Four Somali Grue speakers named both green and blue elicitation samples by their term for green. However, that term did not name the union of all samples called blue or green by English speakers. A similar pattern was found among three Somali Achromatic speakers, who called the blue elicitation sample black or white. Thus, color decomposition by these Somali‐speaking observers suggests a lexically influenced re‐dimensionalization of color appearance space, rather than a simple reduction of the one proposed by Hering. Even some Somali Green‐Blue speakers, whose data were otherwise similar to English, showed similar trends in yellow and blue usage. World Color Survey data mirror these results. These within‐ and cross‐cultural violations of Hering's theory do not challenge the long‐standing view that universal sensory processes mediate color appearance. However, they do demonstrate an important contribution of language in the human understanding of color. (shrink)

The Gestalt principle of isomorphism reveals the primacy of subjective experience as a valid source of evidence for the information encoded neurophysiologically. This theory invalidates the abstractionist view that the neurophysiological representation can be of lower dimensionality than the percept to which it gives rise.

Revelation, the thesis that the full intrinsic nature of colors is revealed to us by color experiences, is false in Byrne & Hilbert's (B&H's) view, but in an interesting and nonobvious way. I show what would make Revelation true, given B&H's account of colors, and then show why that situation fails to obtain, and why that is interesting.

Reflectance and spectral power functions are poor predictors of color experiences. Only in completely relativized conditions (single observer, non-metameric set of stimuli, and single set of viewing conditions) is the relationship close. Variation in reflectance of Munsell chips experienced by color-normal observers as having a unique green hue encompasses approximately sixty percent of the complete range of hues falling under the category “green”; and in recent determinations of unique hues, ranges of yellow and green as well as green and blue (...) unique hues overlap. (shrink)

What makes it the case that we draw the boundary between “blue” and “green” where we draw it? Do we draw this boundary where we draw it because our perceptual system is biologically determined in this way? Or is it culture and language that guide the way we categorize colors? These two possible answers have shaped the historical discussion opposing so-called universalists to relativists. Yet, the most recent theoretical developments on color categorization reveal the limits of such a polarization.

For over a century, the question of the relation of language to thought has been extensively discussed in the case of color categorization, where two main views prevail. The relativist view claims that color categories are relative while the universalistic view argues that color categories are universal. Relativists also argue that color categories are linguistically determined, and universalists that they are perceptually determined. Recently, the argument for the perceptual determination of color categorization has been undermined, and the relativist view has (...) regained some ground. This paper argues that although the universalistic account of color categorization has been called into question, this is not enough to establish relativism. Color categories can still be said to be universal or particular, independent of the accounts of their universality or relativity. Because of its polarization, the debate has disregarded some issues that are key in our understanding of color categorization: the question of what a color category is and how to identify it. (shrink)

For over a century, the question of the relation of language to thought has been extensively discussed in the case of color categorization, where two main views prevail. The relativist view claims that color categories are relative while the universalistic view argues that color categories are universal. Relativists also argue that color categories are linguistically determined, and universalists that they are perceptually determined. Recently, the argument for the perceptual determination of color categorization has been undermined, and the relativist view has (...) regained some ground. This paper argues that although the universalistic account of color categorization has been called into question, this is not enough to establish relativism. Color categories can still be said to be universal or particular, independent of the accounts of their universality or relativity. Because of its polarization, the debate has disregarded some issues that are key in our understanding of color categorization: the question of what a color category is and how to identify it. (shrink)

We make three points. First, the concept of productance value that the authors propose in their defense of color physicalism fails to do the work for which it is intended. Second, the authors fail to offer an adequate physicalist account of what they call the hue-magnitudes. Third, their answer to the problem of individual differences faces serious difficulties.

Those who identify colours with physical properties need to say how the content of colour experiences relate to their favoured identifications. This is because it is not plausible to hold that colour experiences represent things as having the physical properties in question. I sketch how physical realists about colour might tackle this item of unfinished business.

B&H understate the difficulties facing their version of color realism. We doubt that they can fix reflectance types and magnitudes in a way that does not invoke relations to perceivers. B&HÂ’s account therefore resembles the dispositional or ecological accounts that they dismiss. This is a good thing, for a dispositional account is promising if understood in an ecological framework.

Because our only access to color qualities is through their appearance, Byrne & Hilbert's insistence on a strict distinction between apparent colors and real colors leaves them without a principled way of determining when, if ever, we see colors as they really are.