I argue that perception is necessarily situation-dependent. The way an object is must not just be distinguished from the way it appears and the way it is represented, but also from the way it is presented given the situational features. First, I argue that the way an object is presented is best understood in terms of external, mind-independent, but situation-dependent properties of objects. Situation-dependent properties are exclusively sensitive to and ontologically dependent on the intrinsic properties of objects, such as their (...) shape, size, and color, and the situational features, such as the lighting conditions and the perceiver’s location in relation to the perceived object. Second, I argue that perceiving intrinsic properties is epistemically dependent on representing situation-dependent properties. Recognizing situation-dependent properties yields four advantages. It makes it possible to embrace the motivations that lead to phenomenalism and indirect realism by recognizing that objects are presented a certain way, while holding on to the intuition that subjects directly perceive objects. Second, it acknowledges that perceptions are not just individuated by the objects they are of, but by the ways those objects are presented given the situational features. Third, it allows for a way to accommodate the fact that there is a wide range of viewing conditions or situational features that can count as normal. Finally, it makes it possible to distinguish perception and thought about the same object with regard to what is represented. (shrink)

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)

Tyler Burge presents an original study of the most primitive ways in which individuals represent the physical world. By reflecting on the science of perception and related psychological and biological sciences, he gives an account of constitutive conditions for perceiving the physical world, and thus aims to locate origins of representational mind.

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)

Neuropsychological findings used to motivate the "two visual systems" hypothesis have been taken to endanger a pair of widely accepted claims about spatial representation in conscious visual experience. The first is the claim that visual experience represents 3-D space around the perceiver using an egocentric frame of reference. The second is the claim that there is a constitutive link between the spatial contents of visual experience and the perceiver's bodily actions. In this paper, I review and assess three main sources (...) of evidence for the two visual systems hypothesis. I argue that the best interpretation of the evidence is in fact consistent with both claims. I conclude with some brief remarks on the relation between visual consciousness and rational agency. (shrink)

A coin rotating back in depth in some sense presents a changing, elliptical shape. How are we to understand such (in this case) ‘appearances of ellipticality’? How is the experiential sense of such shifting shape appearances related to the experiential sense of enduring shape definitive of perceived shape constancy? Is the experiential recovery of surface shape based on the prior (perhaps more fundamental) recovery of point or element 3D spatial locations?—or is the perception of shape a largely independent perceptual achievement? (...) Do we gain access to enduring shape properties by first detecting and working from ‘shape appearances’? These are some of the topics taken up in this paper. (shrink)

In the 1980s, a number of philosophers argued that perception is analog. In the ensuing years, these arguments were forcefully criticized, leaving the thesis in doubt. This paper draws on Weber’s Law, a well-entrenched finding from psychophysics, to advance a new argument that perception is analog. This new argument is an adaptation of an argument that cognitive scientists have leveraged in support of the contention that primitive numerical representations are analog. But the argument here is extended to the representation of (...) non-numerical magnitudes, such as luminance and distance, and shown to apply to perception and not just cognition. The relevant sense of ‘analog’ is also clarified, and two powerful objections are addressed. Finally, the question whether perception’s analog vehicles are located in conscious experience is explored and related to a well-known controversy within psychophysics. (shrink)

Quilty-Dunn et al.'s wide-ranging defense of the Language of Thought Hypothesis (LoTH) argues that vision traffics in abstract, structured representational formats. We agree: Vision, like language, is compositional – just as words compose into phrases, many visual representations contain discrete constituents that combine in systematic ways. Here, we amass evidence extending this proposal, and explore its implications for how vision interfaces with the rest of the mind.

You can perceive things, in many respects, as they really are. For example, you can correctly see a coin as circular from most angles. Nonetheless, your perception of the world is perspectival. The coin looks different when slanted than when head-on, and there is some respect in which the slanted coin looks similar to a head-on ellipse. Many hold that perception is perspectival because you perceive certain properties that correspond to the “looks” of things. I argue that this view is (...) misguided. I consider the two standard versions of this view. What I call the PLURALIST APPROACH fails to give a unified account of the perspectival character of perception, while what I call the PERSPECTIVAL PROPERTIES APPROACH violates central commitments of contemporary psychology. I propose instead that perception is perspectival because of the way perceptual states are structured from their parts. (shrink)

Analog representation is often cast in terms of an engineering distinction between smooth and discrete systems. The engineering notion cuts across interesting representational categories, however, so it is poorly suited to thinking about kinds of representation. This paper suggests that analog representations support a pattern of interaction, specifically open-ended searches for content across levels of abstraction. They support the pattern by sharing a structure with what they represent. Continuous systems that satisfy the engineering notion are exemplars of this kind because (...) they are uninterpretable unless they are structure-preserving. Analog representations, so understood, include pictures, images, diagrams, and most graphs. This conception of analogicity also fits well with a line of thought about what makes perceptual states distinctive: they satisfy a “parts principle”. (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)

A meta-analysis and an experiment show that the degree of compression of the in-depth dimension of visual space relative to the frontal dimension increases quickly as a function of the distance between the stimulus and the observer at first, but the rate of change slows beyond 7 m from the observer, reaching an apparent asymptote of about 50 %. In addition, the compression of visual space is greater for monocular and reduced cue conditions. The pattern of compression of the in-depth (...) dimension as a function of distance is similar to the ratio of in-depth to frontal visual angles of stimuli, but is not as extreme as this ratio would suggest, implying that observers are incapable of fully ignoring size information provided by cues to depth. Size and distance judgments may be described by an Affine transformation of physical space; however, the compression parameter in this model changes as a function of distance from the observer and other experimental conditions. (shrink)

To what extent is the external world the way that it appears to us in perceptual experience? This perennial question in philosophy is no doubt ambiguous in many ways. For example, it might be taken as equivalent to the question of whether or not the external world is the way that it appears to be? This is a question about the epistemology of perception: Are our perceptual experiences by and large veridical representations of the external world? Alternatively, the question might (...) be taken as asking whether or not the external world is like its ways of appearing to us, where the expression “ways of appearing” is intended to pick out aspects of our perceptual experiences themselves. This is a metaphysical version of the question of the relationship between appearance and reality: What is the relationship between the phenomenal features that characterize perceptual experience, on the one hand, and the mind-independent features of the external objects of perception, on the other? There are some philosophers who might resist distinguishing between these two questions. For them, “ways of appearing” in the phenomenal sense just are the ways that things appear to be (let’s call the latter the “intentional sense” of “ways of appearing”).1 That is, the phenomenal character of an experience is nothing over and above its representational content. Phenomenal properties are represented properties—the properties that an experience attributes to the external objects of perception. The question of whether or not phenomenal properties can be identified with the represented properties of an experience mirrors traditional questions in the philosophy of perception. If they can be identified with each other, then in veridical perception we might be said to “directly grasp” features of the external world through perception. The properties that are present to the mind are the very same properties that belong to the external objects of perception. Such a view affords.... (shrink)

Perceptual systems respond to proximal stimuli by forming mental representations of distal stimuli. A central goal for the philosophy of perception is to characterize the representations delivered by perceptual systems. It may be that all perceptual representations are in some way proprietarily perceptual and differ from the representational format of thought (Dretske 1981; Carey 2009; Burge 2010; Block ms.). Or it may instead be that perception and cognition always trade in the same code (Prinz 2002; Pylyshyn 2003). This paper rejects (...) both approaches in favor of perceptual pluralism, the thesis that perception delivers a multiplicity of representational formats, some proprietary and some shared with cognition. The argument for perceptual pluralism marshals a wide array of empirical evidence in favor of iconic (i.e., image-like, analog) representations in perception as well as discursive (i.e., language-like, digital) perceptual object representations. (shrink)

In Origins of Objectivity Burge advances a theory of perception according to which perceptions are, themselves, objective representations. The possession of veridicality conditions by perceptual states—roughly, non-propositional analogues of truth-conditions—is central to Burge’s account of how perceptual states differ, empirically and metaphysically, from sensory states. Despite an impressive examination of the relevant empirical literatures, I argue here that Burge has not succeeded in securing a distinction between perception and “mere” sensation.

Perceptual constancy, often defined as the perception of stable features under changing conditions, goes hand in hand with variation in how things look. A white wall in the orange afternoon sun still looks white, though its whiteness looks different compared with the same wall in the noon sun. Historically, this variation has often been explained in terms of our experience of “merely sensory” or subjective properties – an approach at odds with the fact that the variation does track objective features (...) of the perceptual situation, such as illumination. One approach, becoming more common, is to account for the variation in terms of further “dimensions” to perceptual experience. Especially in colour perception, this is a natural thought to have but the idea is often left vague. In this paper I argue that the “dimensional” strategy has problems of its own, but is useful in drawing out some interesting complications in the way perceptual experience is structured. Specifically, the structure of “constancy spaces” brings out the different ways in which there is stability and instability in the experience of constancy, without the need for novel or merely subjective features. Instability arises in a contingent structural feature of perceptual experience. (shrink)

An outline of Seeing, Doing, and Knowing (Oxford, 2005).

Representationalism is the position that the phenomenal character of an experience is either identical with, or supervenes on, the content of that experience. Many representationalists hold that the relevant content of experience is nonconceptual. I propose a counterexample to this form of representationalism that arises from the phenomenon of Gestalt switching, which occurs when viewing ambiguous figures. First, I argue that one does not need to appeal to the conceptual content of experience or to judgements to account for Gestalt switching. (...) I then argue that experiences of certain ambiguous figures are problematic because they have different phenomenal characters but that no difference in the nonconceptual content of these experiences can be identified. I consider three solutions to this problem that have been proposed by both philosophers and psychologists and conclude that none can account for all the ambiguous figures that pose the problem. I conclude that the onus is on representationalists to specify the relevant difference in content or to abandon their position. (shrink)

Mental capacities for perceiving, remembering, thinking, and planning involve the processing of structured mental representations. A compositional semantics of such representations would explain how the content of any given representation is determined by the contents of its constituents and their mode of combination. While many have argued that semantic theories of mental representations would have broad value for understanding the mind, there have been few attempts to develop such theories in a systematic and empirically constrained way. This paper contributes to (...) that end by developing a semantics for a ‘fragment’ of our mental representational system: the visual system’s representations of the bounding contours of objects. At least three distinct kinds of composition are involved in such representations: ‘concatenation’, ‘feature composition’, and ‘contour composition’. I sketch the constraints on and semantics of each of these. This account has three principal payoffs. First, it models a working framework for compositionally ascribing structure and content to perceptual representations, while highlighting core kinds of evidence that bear on such ascriptions. Second, it shows how a compositional semantics of perception can be compatible with holistic, or Gestalt, phenomena, which are often taken to show that the whole percept is ‘other than the sum of its parts’. Finally, the account illuminates the format of a key type of perceptual representation, bringing out the ways in which contour representations exhibit domain-specific form of the sort that is typical of structured icons such as diagrams and maps, in contrast to typical discursive representations of logic and language. (shrink)

We can start with a definition. “[C]olour constancy is the constancy of the perceived colours of surfaces under changes in the intensity and spectral composition of the illumination.” (Foster et al. 1997) Given the definition we can now ask a question: Does human color vision exhibit color constancy?1 The answer to the question depends in part on how we interpret it. If the question is understood as asking whether human color vision displays constancy for every possible scene across every possible (...) illumination then the answer is no.2 If the question is understood as asking whether human color vision displays some degree of constancy for some scenes across some range of illuminants then the answer is yes. The more interesting questions involve characterizing the degree of constancy human vision displays, the types of scenes and ranges of illuminants for which approximate constancy can be achieved and the.. (shrink)

Philosophical Issues, Volume 30, Issue 1, Page 175-191, October 2020.

This paper develops an appearance view of perception (focusing on vision). When we see an object, we see it by having it appear some way to us. We see the object, not the appearance; but we see the object via the appearance. The appearance is subjectively conditioned: aspects of it depend on attributes of the subject. We mentally have the appearance and can reflect on it as an appearance. But in the primary instance, of veridical perception, it is the object (...) that we focus on and experience. I contrast this view with naive realism (sometimes called disjunctivism) (Brewer, Campbell, Noe) and with intentionalist or representationalist views, which I call the physical content view (Dretske, Tye, Crane, Hill, Burge). I agree with these views in rejecting sense-data intermediaries and in affirming direct perception, but I argue that direct perception occurs via appearances, making mine a critical direct realism. The other views attempt to explain the spatial content of perception (shape, size, distance) entirely through the physical properties of objects and their physical relation to the perceiver (viewing position). I argue instead that there are ineliminably subjective aspects of normal spatial perception, which are systematically manifested as a lack of full phenomenal constancy. This systematic underconstancy can’t be accounted for at all by a consistent naive realism; for the physical content view, it requires that most of our ordinary perception is classified as illusory, violating the spirit of that view. Accepting phenomenal underconstancy as pervasive, I suggest that our ability to perceive the mind-independent properties of objects depends on developed conceptual abilities. In the final section, I compare my appearance view with the adverbialism of Chisholm and the critical direct realism of Roy Wood Sellars. (shrink)

The puzzle of cross-modal shape experience is the puzzle of reconciling the apparent differences between our visual and haptic experiences of shape with their apparent similarities. This paper proposes that we can resolve the cross-modal puzzle by reflecting on another puzzle. The puzzle of perspectival character challenges us to reconcile the variability of shape experience through shifts in perspective with its constancy. An attractive approach to the latter puzzle holds that shape experience is complex, involving both perspectival aspects and constant (...) aspects. I argue here that parallel distinctions between perspectival and constant aspects of shape experience arise in sight and touch, and that perspectival aspects are modality-specific while at least some constant aspects are constitutively multisensory. I then address a powerful challenge to the idea that aspects of spatial phenomenology are shared cross-modally. (shrink)

Perceptual constancy has played a significant role in philosophy of perception. It figures in debates about direct realism, color ontology, and the minimal conditions for perceptual representation. Despite this, there is no general consensus about what constancyis. I argue that an adequate account of constancy must distinguish it from three distinct phenomena:meresensory stability through proximal change, perceptualcategorizationof a distal dimension, and stability throughirrelevantproximal change. Standard characterizations of constancy fall short in one or more of these respects. I develop an account (...) of constancy that overcomes these problems. The account has two parts: an analysis of constancy mechanisms, and an analysis of the conditions under which a constancy capacity is exercised. I then employ this account to evaluate whether constancy is a necessary condition for perceptual representation, as some have conjectured. I argue that explanatory practice in perceptual psychology fails to support this view. Rather, it fits better with the weaker principle that representation requires specific tracking of a distal dimension. (shrink)

Many of the objects that we perceive have an important characteristic: When they move, they change shape. For instance, when you watch a person walk across a room, her body constantly deforms. I suggest that we exercise a type of perceptual constancy in response to changes of this sort, which I call structure constancy. In this paper I offer an account of structure constancy. I introduce the notion of compositional structure, and propose that structure constancy involves perceptually representing an object (...) as retaining its compositional structure over time. I argue that compositional structure is represented in visual phenomenology, and I also assemble empirical evidence in support of the claim that compositional structure is recovered by the visual system. Finally, I draw out consequences of this account. I argue that structure constancy has implications for the predictive capacities of perception, and that the phenomenon places important constraints on viable accounts of both the format and reference frame of visual experience. (shrink)

This article develops a view of shape representation both in visual experience and in subpersonal visual processing. The view is that, in both cases, shape is represented in a ‘layered’ manner: an object is represented as having multiple shape properties, and these properties have varying degrees of abstraction. I argue that this view is supported both by the facts about visual phenomenology and by a large collection of evidence in perceptual psychology. Such evidence is provided by studies of shape discriminability, (...) apparent motion, multiple-object tracking, and structure-from-motion. Recent neuroscientific work has also corroborated this psychophysical evidence. Finally, I draw out implications of the layered view for processes of concept acquisition. 1 Introduction2 Metric Properties andShape Properties3 Metric Views4 Against Metric Views of Visual Shape Experience5 The Visual System Uses Abstract Shape Properties6 Against Metric Views of Visual Shape Representation7 Neural Underpinnings of Abstract Shape Perception8 Implications. (shrink)

This is a book about how we see: the environment around us (its surfaces, their layout, and their colors and textures); where we are in the environment; whether or not we are moving and, if we are, where we are going; what things are good for; how to do things (to thread a needle or drive an automobile); or why things look as they do.The basic assumption is that vision depends on the eye which is connected to the brain. The (...) author suggests that natural vision depends on the eyes in the head on a body supported by the ground, the brain being only the central organ of a complete visual system. When no constraints are put on the visual system, people look around, walk up to something interesting and move around it so as to see it from all sides, and go from one vista to another. That is natural vision—and what this book is about. (shrink)

The theory of visual perception that Irvin Rock develops and supports in this book with numerous original experiments, views perception as the outcome of a process of unconscious inference, problem solving, and the building of structural descriptions of the external world.

Seeing, Doing, and Knowing is an original and comprehensive philosophical treatment of sense perception as it is currently investigated by cognitive neuroscientists. Its central theme is the task-oriented specialization of sensory systems across the biological domain. Sensory systems are automatic sorting machines; they engage in a process of classification. Human vision sorts and orders external objects in terms of a specialized, proprietary scheme of categories - colours, shapes, speeds and directions of movement, etc. This 'Sensory Classification Thesis' implies that sensation (...) is not a naturally caused image from which an organism must infer the state of the world beyond; it is more like an internal communication, a signal concerning the state of the world issued by a sensory system, in accordance with internal conventions, for the use of an organism's other systems. This is why sensory states are both easily understood and persuasive.Sensory classification schemes are purpose-built to serve the knowledge-gathering and pragmatic needs of particular types of organisms. They are specialized: a bee or a bird does not see exactly what a human does. The Sensory Classification Thesis helps clarify this specialization in perceptual content and supports a new form of realism about the deliverances of sensation: 'Pluralistic Realism' is based on the idea that sensory systems coevolve with an organism's other systems; they are not simply moulded to the external world. The last part of the book deals with reference in vision. Cognitive scientists now believe that vision guides the limbs by means of a subsystem that links up with the objects of physical manipulation in ways that bypass sensory categories. In a novel extension of this theory, Matthen argues that 'motion-guiding vision' is integrated with sensory classification in conscious vision. This accounts for the quasi-demonstrative form of visual states: 'This particular object is red', and so on. He uses this idea to cast new light on the nature of perceptual objects, pictorial representation, and the visual representation of space. (shrink)

A quarter of a century ago, the first systematic behavioral experiments were performed to clarify the nature of color constancy—the effect whereby the perceived color of a surface remains constant despite changes in the spectrum of the illumination. At about the same time, new models of color constancy appeared, along with physiological data on cortical mechanisms and photographic colorimetric measurements of natural scenes. Since then, as this review shows, there have been many advances. The theoretical requirements for constancy have been (...) better delineated and the range of experimental techniques has been greatly expanded; novel invariant properties of images and a variety of neural mechanisms have been identified; and increasing recognition has been given to the relevance of natural surfaces and scenes as laboratory stimuli. Even so, there remain many theoretical and experimental challenges, not least to develop an account of color constancy that goes beyond deterministic and relatively simple laboratory stimuli and instead deals with the intrinsically variable nature of surfaces and illuminations present in the natural world. (shrink)

What colour does a white wall look in the pinkish light of the late afternoon? Philosophers disagree: they hold variously that it looks pink, white, both, and no colour at all. A new approach is offered. After reviewing the dispute, a reinterpretation of perceptual constancy is offered. In accordance with this reinterpretation, it is argued that perceptual features such as color must always be predicated of perceptual objects. Thus, it might be that in pinkish light, the wall looks white and (...) the light looks pink. The paper concludes by discussing some criteria for object identification in perceptual states. (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)

Shape and slant judgments of rotated or frontoparallel ellipses were elicited from three groups of 10 subjects. A masking stimulus was introduced to control processing time. Backward masking trials were presented with interstimulus intervals of 0, 25, and 50 msec, Reduction of processing time altered shape judgments in the direction of projective shape and slant judgments in the direction of frontoparallelness. This finding is consistent with the shape-slant invariance hypothesis. In order to study the effects of processing load, one group (...) of subjects was given prior knowledge of the kind of judgment to be made on each trial, one group had no prior knowledge, and a third group made both judgments on each trial. The effects of the processing load manipulation were interpreted in terms of the role of attention in perceptual encoding. Consistent with previous findings, allocation of attention did not affect perceptual encoding. (shrink)

Loosely put, colour constancy for example occurs when you experience a partly shadowed wall to be uniformly coloured, or experience your favourite shirt to be the same colour both with and without sunglasses on. Controversy ensues when one seeks to interpret ‘experience’ in these contexts, for evidence of a constant colour may be indicative a constant colour in the objective world, a judgement that a constant colour would be present were things thus and so, et cetera. My primary aim is (...) to articulate a viable conception of Present Constancy, of what occurs when a constant colour is present in experience, despite the additional presence of some experienced colour variation (e.g., correlating to a change in illumination). My proposed conception involves experienced colour layering – experiencing one opaque colour through another transparent one – and in particular requires one of those experienced layers to remain constant while the other changes. The aim is not to propose this layering conception of colour constancy as the correct interpretation of all constancy cases, but rather to develop the conception enough to demonstrate how it could and plausibly should be applied to various cases, and the virtues it has over rivals. Its virtues include a seamless application to constancy cases involving variations in filters (e.g., sunglasses) and illuminants; its ability to accommodate experiences of partial colours and error-free interpretations of difficult cases; and its broad theoretical-neutrality, allowing it to be incorporated into numerous perceptual epistemologies and ontologies. If layered constancy is prevalent, as I suspect it is, then our experiential access to colours is critically nuanced: we have been plunged into a world of colour without being told that we will rarely, if ever, look to a location and experience just one of them. (shrink)