Zone theories of color vision transform cone sensitivities to channel sensitivities before transmitting these signals to the brain. The concepts of and are fundamental to an understanding of this transformation. Saunders & van Brakel question the objectivity of these concepts. Statements in their target article indicate that the reason for this questioning stems from a failure to appreciate the constraints inherent in the definitions of these concepts.

This paper responds to Philipona & O’Regan (2006), which attempts to account for certain color phenomena by appeal to singularities in the space of “accessible information” in the light striking the retina. Three points are discussed. First, it is unclear what the empirical significance/import is of the mathematical analysis of the data regarding the accessible information in the light. Second, the singularity index employed in the study is both mathematically and empirically faulty. Third, the connection drawn between their findings and (...) some data from the World Color Survey is lacking in quantitative analysis in places where it is needed. The difficulties raised prevent Philipona & O’Regan’s conclusions from being accepted. (shrink)

Color-vision defects constitute a spectrum of disorders with varying degrees and types of departure from normal human color vision. One form of color-vision defect is dichromacy; by mixing together only two lights, the dichromat can match any light, unlike normal trichromatic humans, who need to mix three. In a philosophical context, our titular question may be taken in two ways. First, it can be taken at face value as a question about visible properties of external objects, and second, it may (...) be interpreted as the more intangible question of “what it’s like” to be color-blind. (shrink)

This chapter focuses on a factor widely considered by the standard view to be the basis for color-naming phenomena and explores some plausible, comparatively uninvestigated factors that might underlie color naming. These are illustrated, in part, through a reexamination of World Color Survey data as it has been presented by Kuehni. The aim of this chapter is to examine the appropriateness of the Hering opponent-color construct as a theoretical foundation for explaining patterns of color naming in datasets like the WCS, (...) which include many languages that do not use Hering color terms. The main conclusion reached is that a proper explanation for cross-cultural color naming and categorization should not depend on the Hering opponent-color construct. (shrink)

Contrary to argument that unique hues are undemonstrated, the World Color Survey shows that speakers of more than 100 minor and tribal languages focus color categories predominantly on 4 of the 40 hue columns of the ethnographic Munsell array. The pattern is not conditioned by saturation levels or other arbitrary structures among the color chips, nor is Western influence likely to be the cause. Moreover, all evidence suggests that color cognition is autonomous despite the connotations and polysemies of color terms.

Saunders & van Brakel set out to review color science research and to topple the belief that color-vision neurophysiology sets strong deterministic constraints on the cognitive processing of color. Although their skeptism and mission are worthwhile, they fail to give proper treatment to (1) findings that dramatically support some positions they aim to tear down, (2) existing research that anticipates criticisms presented in their target article, and (3) the progress made in the area toward understanding the phenomenon. At the very (...) minimum these oversights weaken the credibility of their arguments and leave the reader to wonder why their discussion ignores what is clearly omitted. (shrink)

Saunders and van Brakel question whether the special status of red, green, yellow, and blue in our perceptual organization is anything more than a shadow cast by the English language. I suggest that it is more than this. We can hardly imagine treating lime, purple, orange, and teal as unique hues, and the reason does not lie in special training. To settle the issue, I suggest some lines for psychological experiment and anthropological investigation.

Saunders & van Brakel's analysis of the phenomenal categorization and subsequent experimental research in unique hues fails to include contemporary methodological improvements. Alternative strategies are offered from the author's research that rely less on language and world knowledge and provide strong evidence for the general theoretical constructs of elemental hue, nonbasic, and basic color terms.

Saunders & van Brakel argue, inter alia, that there is for the claim that there are four unique hues (red, green, blue, and yellow), and that there are two corresponding opponent processes. We argue that this is quite mistaken.

Probably colour is the best worked-out example of allegedly neurophysiologically innate response categories determining percepts and percepts determining concepts, and hence biology fixing the basic categories implicit in the use of language. In this paper I argue against this view and I take C. L. Hardin's Color for Philosophers [1988] as my main target. I start by undermining the view that four unique hues stand apart from all other colour shades (Section 2) and the confidence that the solar spectrum is (...) naturally divided into four categories (Section 3). For such categories to be truly universal, they have to be true for all peoples and in Section 4 I show that Berlin and Kay's [1969] widely quoted theory of basic colour categories is not sufficiently supported to lend it any credibility.Having disposed of the view that inspection of language or ‘pure’ perception unveils the universal colour categories. I turn to neurophysiological and psychophysical theories of colour vision to see whether they provide a more solid basis for deciding what the innate response categories are. In Section 5 I show that Hardin's account of the opponent-process theory neither supports his view that ‘colour-coding’takes place early in the visual neural pathway, nor his view that knowledge of colour vision science will help us solve many philosophical mysteries about colour.In Section 6 I give a more detailed review of what is known today about the neurophysiology of colour vision and I show that there's nothing in the brain which could be called a colour module, let alone a module with homunculi for particular basic colour categories. In Section 7 I show that psychophysical models do not support such rigid constraints on category formation either. Hence (Section 8), at least in the case of colour, current science supports a plasticity in the formation of categories that goes far beyond the requirements of those naturalistic philosophers who would like to ground primitive concepts in biology. (shrink)

This expanded edition of C L Hardin's ground-breaking work on colour features a new chapter, 'Further Thoughts: 1993', in which the author revisits the dispute ...

Where are we to look for the unique hues? Out in the world? In the eye? In more central processing? 1. There are difficulties looking for the structure of the unique hues in simple combinations of cone-response functions like ( L − M ) and ( S − ( L + M )): such functions may fit pretty well the early physiological processing, but they don’t correspond to the structure of unique hues. It may seem more promising to look to, (...) e.g., Hurvich & Jameson’s ‘chromatic response functions’; but these report on psychophysical behaviour, not on underlying physiology. So ‘opponent processing’ isn’t any particular help on the unique hues—and even physiology in general seems not to have come up with any good correlate or explanation. 2. Wright ( Review of Philosophy and Psychology 2: 1–17, 2011 ) looks in a different place: to (a) magnitude of total visual response that a stimulus light provokes, the maxima and minima of which, he thinks, give us the boundaries of the main hue categories (Wright connects these with Thornton’s ‘prime’ and ‘antiprime’ colours in an illuminant: Journal of the Optical Society of America 61 ( 1971 ): 1155–1163); and (b) the ratio of chromatic to achromatic response, the maxima and minima of which, he suggests, give us the focal points of the unique hues. The suggestions are extremely interesting; but the desired correspondences have some counterexamples; and where they hold, one could wonder how much they depend upon the particular choice of functions to measure (a) and (b); and one could hope for more of an explanatory linkage between the sets of items in question. 3. Could the unique hues come from, so to speak, the external world? White and black can easily be defined as particular kinds of reflectance. What of the standard four unique hues? Variation in kinds of sunlight and skylight coincides well with variation along a line from unique yellow to unique blue (cf. Shepard 1992 , Mollon 2006 ). If we wanted something to calibrate our standards for unique yellow and blue as the lens of the eye changes with age, and despite interpersonal cone differences, this would be a good basis—and there are several ways this can be extended to surface colours. But is there any essential connection between these things: is there any rationale why the light of the sun and the sky should be counted as unique hued ? An answer may be: because in our environment, these illuminants are as close to white (or the natural illuminant colour) as you can get—to see things tinged with sunlight or skylight should be to see them minimally tinged with any alien colour. Whereas other hues in an illuminant would be treated as tinging with a more alien colour the thing seen. (shrink)

The terms red, green, yellow, and blue are both necessary and sufficient to describe our chromatic experience. Their uniqueness and opponent nature is supported by evidence obtained under supra-threshold conditions, especially hue cancellation. These constraints are nontrivial. How some electrophysiologically identified mechanisms contribute to colour appearance is not known, but their complexities do not refute our experience of elemental hues.

forthcoming in Color Ontology and Color Science, ed. J. Cohen and M. Matthen (MIT).

Saunders and van Brakel propose that we rethink or reject much of current colour theory. Many of the problems they cite appear to call for further research rather than a radical rethinking of colour theory. The controversy described in this target article appears to be itself a case of or something that does not exist.

In this target article the following hypotheses are discussed: (1) Colour is autonomous: a perceptuolinguistic and behavioural universal. (2) It is completely described by three independent attributes: hue, brightness, and saturation: (3) Phenomenologically and psychophysically there are four unique hues: red, green, blue, and yellow; (4) The unique hues are underpinned by two opponent psychophysical and/or neuronal channels: red/green, blue/yellow. The relevant literature is reviewed. We conclude: (i) Psychophysics and neurophysiology fail to set nontrivial constraints on colour categorization. (ii) Linguistic (...) evidence provides no grounds for the universality of basic colour categories. (iii) Neither the opponent hues red/green, blue/yellow nor hue, brightness, and saturation are intrinsic to a universal concept of colour. (iv) Colour is not autonomous. (shrink)

Sections R1 to R3 attempt to take the sting out of hostile commentaries. Sections R4 to R5 engage Berlin and Kay and the World Color Survey to correct the record. Section R6 begins the formulation of a new theory of colour as an engineering project with a technological developmental trajectory. It is recommended that the colour space be abandoned.