This paper resolves a paradox concerning colour constancy. On the one hand, our intuitive, pre-theoretical concept holds that colour constancy involves invariance in the perceived colours of surfaces under changes in illumination. On the other, there is a robust scientific consensus that colour constancy can persist in cerebral achromatopsia, a profound impairment in the ability to perceive colours. The first stage of the solution advocates pluralism about our colour constancy capacities. The second details the close relationship between colour constancy and (...) contrast. The third argues that achromatopsics retain a basic type of colour constancy associated with invariants in contrast processing. The fourth suggests that one person-level, conscious upshot of such processing is the visual awareness of chromatic contrasts ‘at’ the edges of surfaces, implicating the ‘colour for form’ perceptual function. This primitive type of constancy sheds new light on our most basic perceptual capacities, which mark the lower borders of representational mind. (shrink)

Naive observers viewed a sequence of colored Mondrian patterns, simulated on a color monitor. Each pattern was presented twice in succession, first under one daylight illuminant with a correlated color temperature of either 16,000 or 4,000 K and then under the other, to test for color constancy. The observers compared the central square of the pattern across illuminants, either rating it for sameness of material appearance or sameness of hue and saturation or judging an objective property—that is, whether its change (...) of color originated from a change in material or only from a change in illumination. Average color constancy indices were high for material appearance ratings and binary judgments of origin and low for hue–saturation ratings. Individuals’ performance varied, but judgments of material and of hue and saturation remained demarcated. Observers seem able to separate phenomenal percepts from their ontological projections of mental appearance onto physical phenomena; thus, even when a chromatic change alters perceived hue and saturation, observers can reliably infer the cause, the constancy of the underlying surface spectral reflectance. (shrink)

I defend a solution to a long-standing problem with perceptual appearances, brought about by the phenomenon of perceptual constancy. The problem is that in conditions which are non-ideal, yet within the range that perceptual constancy works, we see things veridically despite an “appearance” which is traditionally taken to be non-veridical. For example, a tilted coin is often taken to have an “elliptical appearance”, shadowed surfaces a “darker appearance”. These appearances are puzzling for a number of reasons. I defend and elaborate (...) on an approach taken by Sean Kelly, and earlier by the art historian E.H. Gombrich, according to which we can be tricked by our ability to bring about a kind of Gesltalt shift between different possible perceptual interpretations of a scene. (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)

There is nothing in this World constant but Inconstancy. [Swift 1711: 258] In this paper I argue that two standard characterizations of colour constancy are inadequate to the phenomenon. This inadequacy matters, since, I contend, philosophical appeals to colour constancy as a way of motivating illumination-independent conceptions of colour turn crucially on the shortcomings of these characterizations. After critically reviewing the standard characterizations, I provide a novel counterfactualist understanding of colour constancy, argue that it avoids difficulties of its traditional rivals, (...) and defend it from objections. Finally, I show why, on this improved understanding, colour constancy does not have the philosophical consequences that have been claimed for it in the literature. (shrink)

For a stable visual world, the colours of objects should appear the same under different lights. This property of colour constancy has been assumed to be fundamental to vision, and many experimental attempts have been made to quantify it. I contend here, however, that the usual methods of measurement are either too coarse or concentrate not on colour constancy itself, but on other, complementary aspects of scene perception. Whether colour constancy exists other than in nominal terms remains unclear.

The target article is an attempt to make some progress on the problem of color realism. Are objects colored? And what is the nature of the color properties? We defend the view that physical objects (for instance, tomatoes, radishes, and rubies) are colored, and that colors are physical properties, specifically types of reflectance. This is probably a minority opinion, at least among color scientists. Textbooks frequently claim that physical objects are not colored, and that the colors are "subjective" or "in (...) the mind." The article has two other purposes: first, to introduce an interdisciplinary audience to some distinctively philosophical tools that are useful in tackling the problem of color realism and, second, to clarify the various positions and central arguments in the debate. (shrink)

This article proposes an account of color constancy based on an examination of the relevant scientific literature. Differences in experimental settings and task instructions that lead to variation in subject performance are given particular attention. Based on the evidence discussed, the core of the proposal made is that there are two different forms of color constancy, one phenomenal and the other projective. This follows the hypothesis of Reeves et al. (Perception & Psychophysics 70:219–228, 2008). Unlike Reeves et al. (Perception & (...) Psychophysics 70:219–228, 2008), it is argued that projective color constancy is crucially dependent upon phenomenal color constancy and certain aspects of scene perception. Additionally, it is hypothesized that capacities that support projective color constancy have an important role to play in facilitating our ability to quickly recognize scenes with diagnostic chromatic properties independently of assignments of colors to object surfaces. (shrink)

Are colors relational or non-relational properties of their bearers? Is red a property that is instantiated by all and only the objects with a certain intrinsic (/non-relational) nature? Or does an object with a particular intrinsic (/non-relational) nature count as red only in virtue of standing in certain relations - for example, only when it looks a certain way to a certain perceiver, or only in certain circumstances of observation? In this paper I shall argue for the view that color (...) properties are relational (henceforth, relationalism), and against the view that colors are not relational (henceforth, anti- or non-relationalism). (shrink)

Whether or not one endorses realism about colour, it is very tempting to regard realism about determinable colours such as green and yellow as standing or falling together with realism about determinate colours such as unique green or green31. Indeed some of the most prominent representatives of both sides of the colour realism debate explicitly endorse the idea that these two kinds of realism are so linked. Against such theorists, the present paper argues that one can be a realist about (...) the determinable colours of objects, and thus hold that most of the colour ascriptions made by competent speakers are literally true, while denying that there are any positive facts of the matter as to the determinate colours of objects. The result is a realistic colour realism that can certify most of our everyday colour ascriptions as literally correct, while acknowledging the data regarding individual variation. (shrink)

b>. Computational models of colour vision assume that the biological function of colour vision is to detect surface reflectance. Some philosophers invoke these models as a basis for 'externalism' about perceptual content (content is distal) and 'objectivism' about colour (colour is surface reflectance). In an earlier article (Thompson et al. 1992), I criticized the 'computational objectivist' position on the basis of comparative colour vision: There are fundmental differences among the colour vision of animals and these differences do not converge on (...) the detection of any single type of environmental property. David R. Hilbert (1992) has recently defended computational objectivism against my 'comparative argument;' his arguments are based on the externalist approach to perceptual content originally developed by Mohan Matthen (1988) and on the computationally inspired theory of the evolutionary basis for trichromacy developed by Roger N. Shepard (1990). The present article provides a reply to Hilbert with extensive criticism of both Matthen's and Shepard's theories. I argue that the biological function of colour vision is not to detect surface reflectance, but to provide a set of perceptual categories that can apply to objects in a stable way in a variety of conditions. Comparative research indicates that both the perceptual categories and the distal stimuli will differ according to the animal and its visual ecology; therefore externalism and objectivism must be rejected. (shrink)

Representationalism, the view that phenomenal character supervenes on intentional content, has attracted a wide following in recent years. Most representationalists have also endorsed what I call 'standard Russellianism'. According to standard Russellianism, phenomenal content is Russellian in nature, and the properties represented by perceptual experiences are mind-independent physical properties. I argue that standard Russellianism conflicts with the everyday experience of colour constancy. Due to colour constancy, standard Russellianism is unable to simultaneously give a proper account of the phenomenal content of (...) colour experience and do justice to its phenomenology. (shrink)

This article attempts to do two things. The first is to make it plausible that any adequate dispositional view of color will have to associate colors with complex functions from a wide range of normal circumstances to a wide range of (simultaneously) incompatible color appearances, so that there will be no uniquely veridical appearance of any given color. The second is to show that once this move is made, dispositionalism is in a position to provide interesting answers to some of (...) the most challenging objections that have been pressed against it. It explains why colors do not seem to come on when the lights come on, and why the right thing to say seems to be that the light causes the objects to reveal their colors. It explains why the content of visual experience need not be problematically circular. It eliminates the problem of intrapersonal variation in color appearance. And it even provides resources for dealing with the problem of interpersonal variation. It is true that in moving to the more complex view, the dispositionalist becomes subject to a new objection, which has been called the problem of unity. The paper offers a solution to this problem as well. (shrink)

In this paper, I defend a representationalist account of the phenomenal character of color experiences. Representationalism, the thesis that phenomenal character supervenes on a certain kind of representational content, so-called phenomenal content, has been developed primarily in two different ways, as Russellian and Fregean representationalism. While the proponents of Russellian and Fregean representationalism differ with respect to what they take the contents of color experiences to be, they typically agree that colors are exhaustively characterized by the three dimensions of the (...) color solid: hue, saturation, and lightness. I argue that a viable version of representationalism needs to renounce this restriction to three dimensions and consider illumination to be a genuine phenomenal dimension of color. My argument for this thesis falls into two parts. I first consider the phenomenon of color constancy in order to show that neither Russellian nor Fregean representationalism can do justice to the phenomenal significance of local illumination. I subsequently formulate a version of representationalism that accounts for illumination by taking it as a phenomenal dimension of color. (shrink)

What is the function of color vision? In this paper, I focus on perceptual phenomena studied in psychophysics and argue that the best explanation for these phenomena is that the color visual system is a perceptual enhancement system. I first introduce two rival conceptions of the function of color vision: that color vision aims to detect or track the fine-grained colors of distal objects and scenes (Seeing Color) and that it aims to help organisms discriminate, detect, track and/or recognize ecologically (...) important objects, properties, and relations more directly (Seeing with Color). I then discuss two kinds of systematic perceptual phenomena investigated by psychophysicists: approximate color constancy and color induction. I argue from the premise that Seeing with Color better accommodates and explains these phenomena to the conclusion that it is the conception that an empirically-guided philosopher of color ought to adopt. (shrink)

The 18th-century Scottish ‘common sense’ philosopher Thomas Reid argued that perception can be distinguished on several dimensions from other categories of experience, such as sensation, illusion, hallucination, mental images, and what he called ‘fancy.’ We extend his approach to eleven mental categories, and discuss how these distinctions, often ignored in the empirical literature, bear on current research. We also score each category on five properties (ones abstracted from Reid) to form a 5 × 11 matrix, and thus can generate statistical (...) measures of their mutual dependencies, a procedure that may have general interest as illustrating what we can call ‘computational philosophy.’. (shrink)

In this article, I argue that popular explanatory frameworks in perceptual psychology suggest the truth of color realism. I focus on perceptual judgments and their evidential basis: namely perceptual representation. I first draw a distinction between two sorts of normativities with respect to which we can evaluate representational capacities and systems: biological and psychological normativities. The former is defined in terms of evolutionary fitness, and the latter in terms of representational accuracy. Generally, representational systems achieve psychological and biological success hand (...) in hand, but in special circumstances, a representational system can be such that it serves the organism best while not generally furnishing the organism with accurate representations. I argue in this essay that an explanation how and why our ancestors developed color vision that cleaves its biological success conditions from its psychological success conditions cannot be given unless we are prepared to say the same about the visual perception of distance and other geometrical features of the world. Moreover, it is difficult to see how the anti-realist could begin to specify psychological success conditions for color representations. Hence, we ought to accept the biological utility of color vision as evidence that it is typically representationally successful, and regard our perceptual judgments about color as generally true. (shrink)

Colour vision plays a foundational explanatory role in the philosophy of colour, and serves as perennial quarry in the wider philosophy of perception. I present two contributions to our understanding of this notion. The first is to develop a constitutive approach to characterizing colour vision. This approach seeks to comprehend the nature of colour vision qua psychological kind, as contrasted with traditional experiential approaches, which prioritize descriptions of our ordinary visual experience of colour. The second contribution is to argue that (...) colour vision does not constitutively involve the ability to see colours, in a natural and categorically committed sense. I argue that two subjects exactly alike in respect of their constitutive colour vision abilities could differ in respect of whether or not they have categorical perception of colour. The argument is supported by thought experiment and dissociations observed in cognitive neuropsychology. The argument also bears connections to recent neo-Whorfian accounts of colour categorization. _1._ Introduction _2._ Colour Vision, Experience, and Natures _3._ The Central Argument _3.1._ Colour constancy and discrimination _3.2._ Dissociating colour vision and categorical perception for colour _4._ Whorf and the View from Cognitive Neuropsychology _5._ Conclusion. (shrink)

Colour constancy is a foundational and yet puzzling phenomenon. Standard appearance invariantism is threatened by the psychophysical matching argument, which is taken to favour variantism. This argument, however, is inconclusive. The data at best support a pluralist view: colour constancy is sometimes variantist, sometimes invariantist. I add another potential explanation of these data, complex invariantism, which adopts an atypical six-dimensional model of colour appearance. Finally I prospect for a unifying conception of constancy among two neglected notions: discriminatory colour constancy and (...) relational colour constancy. The former arguably marks a common core capacity that is present across widely differing viewing contexts. (shrink)

In this paper, I consider a view that explains colour experience by the independent representation of surface and illumination. This view implies that surface colour is a phenomenal perceptual content. I argue from facts of colour phenomenology to the conclusion that surface colour is not a phenomenal perceptual content. I then argue from results of surface-matching experiments to the conclusion that surface colour is neither a perceptual content of any kind nor any sort of computational output of the perceptual system. (...) These conclusions contradict widely accepted views in both the philosophy of perception and colour science. I finish by considering and rejecting a competing account of the surface-matching results, according to which surface colour is represented indeterminately in perception. (shrink)

Students of perception have long puzzled over a range of cases in which perception seems to tell us distinct, and in some sense conflicting, things about the world. In the cases at issue, the perceptual system is capable of responding to a single stimulus — say, as manifested in the ways in which subjects sort that stimulus — in different ways. This paper is about these puzzling cases, and about how they should be characterized and accounted for within a general (...) theory of perception. After rehearsing the sort of case at issue (§1), I’ll examine critically some of the strategies by which philosophers and perceptual psychologists have attempted to account for them (§2). Finally, I’ll present an alternative computational account of the puzzle cases, argue that this view is superior to its competitors, and examine some of its implications (§3). (shrink)

It is a familiar experience to perceive a material object as maintaining a stable shape even though it projects differently shaped images on our retina as we move with respect to it, or as maintaining a stable color throughout changes in the way the object is illuminated. We also perceive sounds as maintaining constant timbre and loudness when the context and the spatial relations between us and the sound source change over time. But where does this perceptual invariance ‘come from’? (...) What is it about our perceptual systems that makes them able to ‘transform’ incoming unstable and fluctuating sensory inputs into generally stable and coherent conscious experiences? And what exactly do we experience as invariant in cases like those described above? There are two main approaches to the Problem of Perceptual Invariance: the Local-Inferential approach and the Global-Structural approach. Although both approaches include an account of the sub-personal perceptual mechanisms ‘stabilizing’ variant and invariant components in incoming sensory stimulation and a proposal regarding the phenomenology of perceptual invariance, in this paper I argue that the latter provides a better solution to the problem overall. (shrink)

Students of perception have long known that perceptual constancy is an important aspect of our perceptual interaction with the world. Here is a simple example of the phenomenon concerning color perception: there is some ordinary sense in which an unpainted ceramic coffee cup made from a uniform material looks a uniform color when it is viewed under uneven illumination, even though the light reflected by the shaded regions to our eyes is quite different from the light reflected by the unshaded (...) regions to our eyes (see figure 1). Or consider this example concerning size perception: there is some ordinary sense in which two telephone poles look the same size when the first is viewed from 100 meters and when the second is viewed from 1 meter, even though the visual angle subtended by the two poles on our retinae is very different (see figure 2). Or consider this example concerning shape perception: there is some ordinary sense in which a penny looks round both when viewed head on and when viewed from an acute angle, even though the area projected by the penny onto our retinae under these two conditions is very different (see figure 3). Or, finally, consider this example concerning auditory volume perception (which I cannot depict graphically): there is some ordinary sense in which a speaker’s voice sounds the same volume when heard from across the room and when heard from a distance of 1 meter, even though the energy striking our ears under these two conditions is very different. (shrink)

The subject of the present thesis is the phenomenon of simultaneous colour contrast: As is well known, the perceived colour of a given light stimulus depends almost as strongly on the stimulation of neighbouring regions of the visual field as on the local stimulus itself. Thus, the perceived colour of a target stimulus can be manipulated either by changing the colour co-ordinates of the target itself, or, alternatively, by changing the colour co-ordinates of the surround. Classical models of simultaneous contrast (...) are based on the implicit assumption that the changes in perceived colour brought about by these two kinds of manipulation are basically of the same kind, and thus may compensate each other. This ‘compensation assumption’ is equivalent to the widespread assumption that the space of perceived colours is three-dimensional. In principle, though, the well-established facts of trichromatic theory are compatible with a dimensionality of the space of perceived colours higher than three (namely three times the number of differently coloured regions in the visual field). One of the central results of the present investigations is that the compensation assumption seems to be unwarranted in the case of simple centre-surround stimuli. This instilled the expectation that classical methods for measuring simultaneous contrast effects, such as grey settings and asymmetric colour matching, may sometimes be inappropriate, and thus yield misleading results. In further experiments it is shown that this is indeed the case when uniformly coloured surrounds are used. In the case of variegated surrounds, however, matters appear to be much less complicated. This difference seems to be due to impressions of perceptual transparency being evoked by uniform surrounds, but not by variegated ones. (shrink)