In Basic Color Terms, Berlin and Kay argued for a restricted number of "basic" color words—words they claimed to be culturally universal. This claim about language was buttressed by psychologist Eleanor Rosch's famous work on color prototypes. Together, the works of Berlin and Kay and Rosch are the foundation for a contemporary research tradition investigating the biological foundations of color naming. In this article, the author describes some common objections to the works of Berlin and Kay and Rosch and argues (...) that they are not significant. The claim that explanations of color naming ought to be strictly cultural also is discussed and rejected. (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)

This paper defends a non-reductive realist view of the sensible qualities—roughly, the view that the sensible qualities are really instantiated by the external objects of perception, and not reducible to response-independent physical properties or response-dependent relational properties. I begin by clarifying and motivating the non-reductive realist view. I then consider some familiar difficulties for the view. Addressing these difficulties leads to the development and defence of a general theory, inspired by Russellian Monist theories of consciousness, of how the sensible qualities (...) relate to physical reality. I conclude by showing how this theory, which I call ‘Secondary Quality Russellian Monism’, resolves the most significant difficulties for the non-reductive realist view of the sensible qualities. (shrink)

One of the most important objections to sense data theory comes from the phenomenon of indeterminate perception, as when an object in the periphery of one’s visual field looks red without looking to have any determinate shade of red. As sense data are supposed to have precisely the properties that sensibly appear to us, sense data theory evidently has the implausible consequence that a sense datum can have a determinable property without having any of its determinates. In this article, I (...) show that a parallel objection applies to standard forms of colour relationism. In light of the phenomenon of indeterminate perception, the colour relationist must either reject intuitively obvious claims about the determinate–determinable structure of colour space or reject the plausible and widely accepted principle that nothing can have a determinable without having one of its determinates. (shrink)

(Tye 2006) presents us with the following scenario: John and Jane are both stan- dard human visual perceivers (according to the Ishihara test or the Farnsworth test, for example) viewing the same surface of Munsell chip 527 in standard conditions of visual observation. The surface of the chip looks “true blue” to John (i.e., it looks blue not tinged with any other colour to John), and blue tinged with green to Jane.¹ Tye then in effect poses a multiple choice question.

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)

University of Connecticut Storrs, CT 06279-2054. Recent versions of objectivism can reply to the argument from metamers. The deeper rift between subjectivists and objectivists lies in the question of how to explain the structure of qualitative similarities among the colors. Subjectivism grounded in this fashion can answer the circularity objection raised by Dedrick. It endorses skepticism about the claim that there is some one property of objects that it is the function of color vision to detect. Color vision may enable (...) us to detect differences in spectral composition without granting us the capacity to detect identities. (shrink)

Truth conditional semantics is the project of ‘determining a way of assigning truth conditions to sentences based on A) the extension of their constituents and B) their syntactic mode of combination’. This research program has been subject to objections that take the form of underdetermination arguments, an influential instance of which is presented by Travis: … consider the words ‘The leaf is green,’ speaking of a given leaf, and its condition at a given time, used so as to mean what (...) they do mean in English. How many distinct things might be said in words with all that true of them? Many.… Suppose a Japanese maple leaf, turned brown, was painted green for a decoration. In sorting leaves by colour, one might truly call this one green. In describing leaves to help identify their species, it might, for all the paint, be false to call it that. (shrink)

Sensory classification is a central theme of Mohan Matthen's wonderful book, Seeing, Doing, and Knowing. ( All page references are to Matthen 2005 unless otherwise indicated.) My plan for this commentary is simple: I shall list a series of claims that Matthen makes about the classes involved in sensory classification. Each member of the series is admirable, and seems credible on its own. The question at the end is whether we can hold them all, together.

How, if at all, does the internal structure of human phenomenological color space map onto the internal structure of objective reflectance‐profile space, in such a fashion as to provide a useful and accurate representation of that objective feature space? A prominent argument (due to Hardin, among others) proposes to eliminate colors as real, objective properties of objects, on grounds that nothing in the external world (and especially not surface‐reflectance‐profiles) answers to the well‐known and quite determinate internal structure of human phenomenological (...) color space. The present paper proposes a novel way to construe the objective space of possible reflectance profiles so that (1) its internal structure becomes evident, and (2) that structure’s homomorphism with the internal structure of human phenomenological color space becomes obvious. The path is thus reopened to salvage the objective reality of colors, in the same way that we preserved the objective reality of such features as temperature, pitch, and sourness—by identifying them with some objective feature recognized in modern physical theory. (shrink)

The Hurvich-Jameson (H-J) opponent-process network offers a familiar account of the empirical structure of the phenomenological color space for humans, an account with a number of predictive and explanatory virtues. Its successes form the bulk of the existing reasons for suggesting a strict identity between our various color sensations on the one hand, and our various coding vectors across the color-opponent neurons in our primary visual pathways on the other. But anti-reductionists standardly complain that the systematic parallels discovered by the (...) H-J network are just empirical correspondences, constructed post facto, with no predictive or explanatory purchase on the intrinsic characters of qualia proper. The present paper disputes that complaint, by illustrating that the H-J model yields some novel and unappreciated predictions, and some novel and unappreciated explanations, concerning the qualitative characters of a considerable variety of color sensations possible for human experience, color sensations that normal people have almost certainly never had before, color sensations whose accurate descriptions in ordinary language appear semantically ill-formed or even self-contradictory. Specifically, these "impossible" color sensations are activation-vectors (across our opponent-process neurons) that lie inside the space of neuronally possible activation-vectors, but outside the central 'color spindle' that confines the familiar range of sensations for possible objective colors. These extra-spindle chimerical-color sensations correspond to no reflective color that you will ever see objectively displayed on a physical object. But the H-J model both predicts their existence and explains their highly anomalous qualitative characters in some detail. It also suggests how to produce these rogue sensations by a simple procedure made available in the latter half of this paper. The relevant color plates will allow you to savor these sensations for yourself. (shrink)

1. The “puzzle” Physical objects are coloured: roses are red, violets are blue, and so forth. In particular, physical objects have fine-grained shades of colour: a certain chip, we can suppose, is true blue (unique, or pure blue). The following sort of scenario is commonplace. The chip looks true blue to John; in the same (ordinary) viewing conditions it looks (slightly) greenish-blue to Jane. Both John and Jane are “normal” perceivers. Now, nothing can be both true blue and greenish-blue; since (...) the chip is true blue, it is not greenish-blue. Hence Jane, unlike John, is misperceiving the chip. Generalizing, the conclusion is that there is widespread misperception of fine-grained shades. According to Tye (2006), and Cohen, Hardin, and McLaughlin (2006), the previous paragraph amounts to a paradox: an apparently unacceptable conclusion has been drawn from apparently acceptable premises via apparently acceptable reasoning. (See also Hawthorne and Kovakovich 2006, 180-1.) Tye swallows the conclusion, aided by a dose of evolutionary speculation. Hardin (1988), on the other hand, rejects the first premise, and denies that physical objects are coloured. Cohen (2004) and McLaughlin (2003) claim that both Jane and John have the colour of the chip right. Our opening paragraph concealed a crucial parameter. In fact, the chip looks greenish-blue-relative-to- circumstances-C to Jane, and true-blue-relative-to-circumstances-C* to John, and the chip has both these relativized colours.1 All this ingenious philosophizing would be in vain, of course, if the conclusion of the opening paragraph were not puzzling or problematic. So, why is it supposed to be? According to Tye, the conclusion is puzzling because John and Jane are both “normal perceivers” (xx). He seems to think that it is (prima facie) plausible to assume.. (shrink)

Newell & Shanks (N&S) argue that an explanation for blindsight need not appeal to unconscious brain processes, citing research indicating that the condition merely reflects degraded visual experience. We reply that other evidence suggests blindsighters' predictive behavior under forced choice reflects cognitive access to low-level visual information that does not correlate with visual consciousness. Therefore, while we grant that visual consciousness may be required for full visual experience, we argue that it may not be needed for decision making and judgment.

Is color experience cognitively penetrable? Some philosophers have recently argued that it is. In this paper, we take issue with the claim that color experience is cognitively penetrable. We argue that the notion of cognitive penetration that has recently dominated the literature is flawed since it fails to distinguish between the modulation of perceptual content by non-perceptual principles and genuine cognitive penetration. We use this distinction to show that studies suggesting that color experience can be modulated by factors of the (...) cognitive system do not establish that color experience is cognitively penetrable. Additionally, we argue that even if color experience turns out to be modulated by color-related beliefs and knowledge beyond non-perceptual principles, it does not follow that color experience is cognitively penetrable since the experiences of determinate hues involve post-perceptual processes. We conclude with a brief discussion of the implications that these ideas may have on debates in philosophy. (shrink)

Back when researchers thought about the various forms that color vision could take, the focus was primarily on the retinal mechanisms. Since that time, research on human color vision has shifted from an interest in retinal mechanisms to cortical color processing. This has allowed color research to provide insight into questions that are not limited to early vision but extend to cognition. Direct cortical connections from higher-level areas to lower-level areas have been found throughout the brain. One of the classic (...) questions in cognitive science is whether perception is influenced, and if so to what extent, by cognition and whether a clear distinction can be drawn between perception and cognition. Since perception is seen as providing justification for our beliefs about properties in the external world, these questions also have metaphysical and epistemological significance. The aim of this paper is to highlight some of the areas where research on color perception can shed new light on questions in the cognitive sciences. A further aim of the paper is to raise some questions about color research that are in dire need of further reflection and investigation. (shrink)

Representationalism holds that a perceptual experience's qualitative character is identical with certain of its representational properties. To date, most representationalists endorse atomistic theories of perceptual content, according to which an experience's content, and thus character, does not depend on its relations to other experiences. David Rosenthal, by contrast, proposes a view that is naturally construed as a version of representationalism on which experiences’ relations to one another determine their contents and characters. I offer here a new defense of this holistic (...) representationalism, arguing that some objections to atomistic views are best interpreted as supporting it. (shrink)

In philosophical discussions of the secondary qualities, color has taken center stage. Smells, tastes, sounds, and feels have been treated, by and large, as mere accessories to colors. We are, as it is said, visual creatures. This, at least, has been the working assumption in the philosophy of perception and in those metaphysical discussions about the nature of the secondary qualities. The result has been a scarcity of work on the “other” secondary qualities. In this paper, I take smells and (...) place them front and center. I ask: What are smells? For many philosophers, the view that colors can be explained in purely physicalistic terms has seemed very appealing. In the case of smells, this kind of nonrelational view has seemed much less appealing. Philosophers have been drawn to versions of relationalism—the view that the nature of smells must be explained (at least in part) in terms of the effects they have on perceivers. In this paper, I consider a contemporary argument for this view. I argue that nonrelationalist views of smell have little to fear from this argument. (shrink)

The nature of the colors—what they are like, whether they are instantiated by objects or are projected by our minds, whether their nature is revealed to us in color perception, and whether there could be alien colors (e.g. reddish-green)—has been one of the central topics in philosophy for centuries. This entry focuses on the contemporary philosophical debate about the nature of the colors.

Michael Jacovides For Locke, the first step in inquiring into perception should be reflection: “What Perception is, every one will know better by reflecting on what he does himself, when he sees, hears, feels, etc. or thinks, than by any discourse of mine” (2.9.2). As a second step, I say, we may learn from reading him. Locke’s use of the term ‘perception’ is somewhat broad. At one point, he tells us that “having Ideas and Perception” are “the same thing” (2.1.9). (...) Elsewhere, he includes the perceiving the agreement of ideas and perceiving the meaning of signs among the varieties of perception (2.21.5). What I have to say will be about perception as psychologists classify it nowadays. I will first discuss sensation in general and then elucidate some of the subtleties of Locke’s account of the visual perception of shape. I’ll close with some remarks on Locke account of time perception. (shrink)

This dissertation defends the reliability of first-person methods for studying consciousness, and applies first-person experiments to two philosophical problems: the experience of size and of the self. In chapter 1, I discuss the motivations for taking a first-person approach to consciousness, the background assumptions of the dissertation and some methodological preliminaries. In chapter 2, I address the claim that phenomenal judgements are far less reliable than perceptual judgements (Schwitzgebel, 2011). I argue that the main errors and limitations in making phenomenal (...) judgements are due to domain-general factors, which are shared in the formation of perceptual judgements. Phenomenal judgements may still be statistically less reliable than perceptual judgements, though I provide reasons for thinking that Schwitzgebel (2011) overstates the case for statistical unreliability. I also provide criteria for distinguishing between reliable and unreliable phenomenal judgements, hence defending phenomenal judgements against general introspective scepticism. Having identified the main errors in making phenomenal judgements, in chapter 3, I discuss how first-person experiments can be used to control for these errors. I provide examples, and discuss how they overcome attentional and conceptual errors, minimise biases, and exhibit high intersubjective reliability. In chapter 4, I investigate size experience. I use first-person experiments and empirical findings to argue that distant things looking smaller cannot be explained as an awareness of instantiated objective properties (visual angle or retinal image size). I also discuss how an awareness of uninstantiated objective properties cannot adequately account for the phenomenal character of size experience. This provides support for a subjectivist account of variance in size experience. In chapter 5, I investigate the sense of self. I distinguish between a weak sense of self (for-me-ness) and a strong sense of self in which there is a polarity between subject and object. I use first-person experiments from Douglas Harding to demonstrate an explicit strong sense of self, specifically when I point at where others see my face. I also argue that this sense of self is not explained by inference, thoughts, feelings, imagination nor the viewpoint. Rather, it is part of the structure of experience that I seem to be looking from here. Even if there is a sense of self, there may be no self. The question of chapter 6 is whether there can be a direct experience of the self. I argue that to function as a bearer of experience the subject must be single and lack sensory qualities in itself. I use Harding’s first-person experiments to investigate the visual gap where I cannot see my head. I argue that it conforms to the above criteria, and hence is a candidate for being the subject. This finding, in conjunction with the fact that I seem to be looking from the same location, provides prima facie evidence for the reality of the subject. I hold then that contrary to Hume and most philosophers since, that there can be a direct self-experience, if one knows which direction to attend. (shrink)

It is often claimed, following Joseph Levine, that there is an ‘explanatory gap’ between ordinary physical facts and the way we perceive things, so that it is impossible to explain, among other things, why colours actually look the way they do. C.L. Hardin, by contrast, argues that there are sufficient asymmetries between colours to traverse this gap. This paper argues that the terms we use to characterize colours, such as ‘warm’ and ‘cool’, are not well understood, and that we need (...) to understand the neurological basis for such associations if we are even to understand what is fully meant by saying, for example, that red is a warm colour. This paper also speculates on how Hardin’s strategy can be generalized. A PowerPoint presentation that depicts inverted colour qualia is attached as an appendix. (shrink)

Some sounds have pitch, some do not. A tuba’s notes are lower pitched than a flute’s, but the fuzz from an untuned radio has no discernible pitch. Pitch is an attribute in virtue of which sounds that possess it can be ordered from “low” to “high”. Given how audition works, physics has taught us that frequency determines what pitch a sound auditorily appears to have.

This dissertation explores issues in the philosophy of psychology and metaphysics through the lens of the emotion of disgust, and its corresponding property, disgustingness. The first chapter organizes an extremely large body of data about disgust, imposes two constraints any theory must meet, and offers a cognitive model of the mechanisms underlying the emotion. The second chapter explores the evolution of disgust, and argues for the Entanglement thesis: this uniquely human emotion was formed when two formerly distinct mechanisms, one dedicated (...) to monitoring food intake and protecting against poisons, the other dedicated to protecting against parasitic infection, where driven together until they became functionally integrated. The third chapter explores the sorts of acquisition mechanisms that could give rise to the patterns of individual and cultural level variation we find with disgust elicitors. It argues for the Empathic Acquisition thesis, which holds that one important route for the social acquisition and transmission of disgust elicitors is linked to empathic recognition of facial expressions of the emotion. The fourth chapter builds on the Entanglement thesis, and embeds the emotion of disgust in gene-culture coevolutionary theory and the tribal instincts hypothesis. The Co-opt thesis is defended, which maintains that disgust was co-opted to play an important role in our moral psychology, particularly in our cognition of social norms and ethnic boundary markers. In doing so, however, it brings to bear many features initially linked to poisons and parasites. This explains the puzzling and troublesome character of moral judgments linked to disgust. After shifting gears from psychology to metaphysics, the fifth chapter recasts the Humean tradition of projectivism in the terminology of cognitive science. Using examples such as disgust, I argue that a psychologized projectivism is able to make sense of the idea that some properties are projected onto the world, rather than found there to begin with. The final chapter criticizes three other accounts of the property of disgustingness, two inspired by functionalism in the philosophy of color, one inspired by fittingness accounts in metaethics. I argue that none provide nearly as satisfactory account of the property as the psychologized projectivism articulated previously. (shrink)

The nature of color is an open philosophical and scientific question. In this work I develop a physicalist relationist theory of color. So far, attempts to identify color as a physical property of objects have not been convincing because no physical property used by scientists seems to be well correlated with color sensations. I define a new physical property which I call transformance and show that transformance is 100% correlated with color sensations. Intuitively, transformance is a very general abstract physical (...) property that describes how a system transforms or modifies light or information that characterizes light. It turns out that transformance is a relational property of objects like velocity and weight. Transformance is related to surface reflectance as weight is related to mass. Transformance is a much better candidate to be color than surface reflectance because it is 100% correlated with color sensations, precisely models surround effects and fully explains all issues that relate to perceptual variation or the lack thereof. Several concrete examples are provided that show how the transformance of different systems should be modeled. After defining transformance, I defend the theory that color is transformance against possible objections while contrasting my theory with the theory that color is surface reflectance. I then discuss the relations between color and color sensation and the more general objections to any physicalist theory of color. The final part of the thesis deals with epistemological issues related to my theory of color including two apparent paradoxes that I believe every theory of color must answer: 1) How is it that human beings get along so well with an erroneous theory of color? 2) How can science, which is based on the common sense theory of color, conclude that the common sense theory is wrong? I show that my theory provides answers to these questions. (shrink)

The thesis is intended to contribute to the growing understanding of the indispensable role played by phenomenal consciousness in human cognition, and specifically in making our concepts of the external world available. The focus falls on so called observational concepts, a type of rudimentary, perceptually-based objective concepts in our repertoire — picking out manifest properties such as colors and shapes. A theory of such concepts gets provided, and, consequently, the exact role that perceptual consciousness plays in making concepts of this (...) sort available gets settled. In the first half of the thesis, observational concepts get construed as a special type of recognitional concepts. On an analogy with perceptual demonstratives, having such concepts would involve having non-trivial knowledge of their reference. The experiential basis of such concepts would, among other things, provide for such constitutive knowledge. The theoretical background relevant to the hypothesis gets provided in the first chapter. A defence of the hypothesis follows in the second. In the second half of the thesis, care is taken to distinguish among two ways in which the constitutive knowledge of the reference of an observational concept could be fleshed out. In the third chapter, perceptual experience is shown to provide the basis both for knowledge of observational properties by acquaintance, and for knowledge of the essence of such properties — provided that knowledge of essence gets construed in the right, modest way. It might be natural to take knowledge by acquaintance to be the sort relevant to observational concept possession, especially given that in the case of perceptual demonstratives this is the role likely played by experience. However, this initial impression proves to be mistaken. The constitutive knowledge of the referent of an observational concept turns out to consist in the capacity to determine a priori the essence of the respective property. To show this, an argument gets provided in the penultimate fourth chapter, based on the key role played by experiences of instances of observational properties in optimal viewing conditions in enabling the possession of the respective observational concept. (shrink)

I offer a novel defence of radically externalist theories of perception, via a strikingly spare and broadly physicalist metaphysics. The core, motivating claim is what I call a natural view of perception, according to which perception involves direct awareness of our environment, such that the phenomenology of experience consists of the worldly things perceived, as they appear to the perspective of the subject. To underpin this natural view, I propose a simple metaphysical picture of perception, which identifies the perceptual experience (...) with the relation of awareness holding between subject and object, a relation that can be described in familiar physical terms as a causal process involving the thing perceived and the perceiver. Distinctively, the simple metaphysical picture has no place for the notion of ‘experiences’ understood as distinctively ‘mental’ states or events internal or otherwise belonging to the subject. Although there is some limited precedent for the simple metaphysical picture of perception, I offer the first detailed argument for its role in underpinning the natural view. The thesis offers new and detailed arguments to show that the simple metaphysical picture can not only account for normal perceptual experiences, but can also accommodate and explain other forms of sensory experience that have widely been considered to undermine the natural view of perception. These ‘problem’ cases include perceptual illusion, hallucination, and the role of memory and beliefs in influencing how things appear perceptually. In all of these cases, the simple metaphysical picture accounts for the phenomenology of the experience purely in terms of awareness of worldly objects, albeit in some cases objects that are not currently present in the subject’s environment. The simple metaphysical picture thus promises to explain not just perceptual experience but phenomenal consciousness more generally. The natural view is explicitly a commitment of some varieties of naïve realism, but I argue that the two theses come apart. For one thing, the simple metaphysical picture offers a solution to hallucination and other ‘problem’ cases quite different to the solutions offered by naïve realists. However, the most striking and novel claim advanced here is that the natural view can be defended without a commitment to realism. In this regard, I cite evidence for the subject-relativity or experience-dependence of certain perceived qualities, notably colour, and show the simple metaphysical picture allows us to square this with the natural view that colours are ‘out there’ in the environment. I discuss the metaphysical implications of rejecting realism while adhering to the simple metaphysical picture, and outline a radical – and radically simple – metaphysics of the world in general that might preserve the natural view and accommodate the simple metaphysical picture of phenomenal consciousness more generally. This metaphysics takes the form of a process monism in which the governing metaphysical structuring principle is one of top-down determination, such that whole processes determine the nature of their constituent parts. (shrink)

In this paper I shall defend a projectivist view of sensory experience. The case I shall focus on is that of color experience. Projectivism has recently been criticized by some authors who claim that it is unintelligible, or at least implausible, and that it makes a severe category mistake. I shall argue that despite some prima facie impressions of implausibility, projectivism can be made intelligible, and plausible, if its details are spelled out in a reasonable way. In addition, projectivism is (...) ubiquitous in human psychology, and certain cases of projection are reasonably viewed as making a category mistake. Viewed from this perspective, sensory projection is just one instance of projectivism, brought about by low-level perceptual processing. Whether sensory projection is one that makes a category mistake is not obvious. However, even if it does, this is perfectly compatible with the evolutionary advantage of sensation and perception. (shrink)

The primary issues concern whether objects have colours, and what sorts of properties the colours are. Some philosophers hold that nothing is coloured, others that colour are powers to affect perceivers, and others that colours are physical properties.

Some philosophers have regarded the connection between hues and certain arousal or affective qualities as so intimate as to make them inseparable, and this “necessary concomitance view” has been invoked to defend functionalism against arguments based on inverted spectra. Support for the necessary concomitance view has sometimes been thought to accrue from experiments in psychology. This paper examines three experiments, two of which apparently offer support for the view. It argues that careful consideration of these experiments undermines this appearance of (...) support. General lessons are drawn concerning the problem that individual differences present for functionalism, and the difficulty of supporting strong conclusions about concomitance by using the methods of experimental psychology. (shrink)

Our understanding of human visual perception generally rests on the assumption that conscious visual states represent the interaction of spatial structures in the environment and our nervous system. This assumption is questioned by circumstances where conscious visual states can be triggered by external stimulation which is not primarily spatially defined. This work discusses psychophysical experiments investigating flicker induced subjective experiences of colour and form. Using the presentation of spatially uniform flicker with a precise temporal resolution it is shown that subjective (...) experiences do not only depend on stimulation frequency, but also on stimulation phase. In addition, the occurrence of one subjective experience appears to be associated with the occurrence of others. The phenomenology of subjective colour and form is further explored and the physiological mechanisms underlying subjective colour are investigated using electroencephalography. While these data indicate that conscious visual experience may be evoked directly by particular variations in the flow of spatially unstructured light over time it may be assumed that the systems reponsible are essentially temporal in character and capable of representing a variety of visual forms and colours, coded in different frequencies or at different phases of the same processing rhythm. (shrink)