Metamerism is a rather common feature of objects. The authors see it as problematic because they are concerned with a special case: metamerism in standard conditions. Such metamerism does not, however, pose a problem for color realists. There is an apparent problem in cases of metameric light sources, but to see such metamers as problematic is to fail to answer Berkeley's challenge.

Summary Since at least the time of Helmholtz, the process of visual perception has been regarded as a two-stage affair consisting of an initial sensory stage corresponding to the proximal stimulus and a subsequent cognitive stage corresponding to the distal object. This construction amounts to an awkward mind body dualism wherein part of perception is done by the body and the other part is done by the mind. Gestalt theory rejected both raw sensations and their cognitive interpretation, offering a single (...) unified perceptual process that responds to an extended pattern of stimulation. They proposed organizational rules that describe how objects arise from the indifferent retinal mosaic. The same grouping principles by which objects are segmented also function to segregate regions of uniform illumination. Lightness values can then be computed by comparing luminance values within each such framework of illumination, with no need for the mystical concept of taking the illumination into account. (shrink)

In two experiments, we examined the impact of color on cognitive performance by asking participants to categorize stimuli presented in three different colors: red, green, and gray (baseline). Participants were either asked to categorize the meaning of words as related to the concepts of “go” or “stop” (Experiment 1) or to indicate if a neutral verbal stimulus was a word or not (lexical decision task, Experiment 2). Overall, we observed performance facilitation in response to go stimuli presented in green (vs. (...) red or gray) and performance inhibition in response to go stimuli presented in red. The opposite pattern was observed for stop‐related stimuli. Importantly, results also indicated that color might also be used to categorize neutral stimuli. Overall, these findings provide support to the green‐go and red‐stop color associations and test the potential functional autonomy acquired by these colors and the boundary conditions to their effects on stimuli categorization. (shrink)

Byrne & Hilbert's thesis, that color be associated with reflectance-type, is questioned on the grounds that it is far from clear that the human visual system is able to determine a surface's reflectance-type with sufficient accuracy. In addition, a (friendly) suggestion is made as to how to amend the definition of reflectance-type in terms of CIE (Commission Internationale de l'Eclairage) coordinates under a canonical illuminant.

Byrne & Hilbert defend color realism, which assumes that: (a) colors are properties of objects; (b) these objects are physical; hence, (c) colors are physical properties. I accept (a), agree that in a certain sense (b) can be defended, but reject (c). Colors are properties of perceptual objects – which also have underlying physical properties – but they are not physical properties.

A general definition of consciousness is: ‘consciousness is a mental aspect of a system or a process, which is a conscious experience, a conscious function, or both depending on the context’, where the term context refers to metaphysical views, constraints, specific aims, and so on. One of the aspects of visual consciousness is the visual subjective experience (SE) or the first person experience that occurs/emerges in the visual neural-network of thalamocortical system (which includes dorsal and ventral visual pathways and frontal (...) cortex) during dynamic interactions among widely distributed neuronal groups. In this article, however, consciousness and SE are interchangeably used unless noted. Consciousness can be either access (reportable) or phenomenal consciousness. For access consciousness, the interactions are between feed forward stimulus dependent signals and fronto-parietal feedback attentional signals. The necessary ingredients for access (reportable) consciousness are (i) wakefulness, (ii) reentrant interactions among neural populations, (iii) fronto-parietal and thalamic-reticular-nucleus attentional signals that modulate consciousness, (iv) working memory that retains information for consciousness, (v) stimulus at or above threshold level, and (vi) neural-network proto-experiences (PEs) that are superposed SEs embedded in a neural-network. Attention and the ability to report are not necessary for phenomenal consciousness. The neural source for the arousal system is the ascending reticular activating system in the brain stem, which brings the thalamocortical neural networks to wakeful state as a baseline for consciousness to occur. Reentrant interactions among neural populations bind stimulus attributes (such as location and features) and entail consciousness. Attention could be the results of reentry and competitive interactions, and modulates the stimulus related feed forward signal and consciousness. The ‘sources’ of attention may be thalamic reticular nucleus for bottom-up or frontal cortex for top-down direction. The ‘target’ of visual attention is ‘V4/V8/VO’ for Red-Green (R-G) channel. The neural correlates of the psychophysical entity R-G channel appear to be ‘V4/V8/VO’-neural-network (retina → LGN ↔ V1 ↔ V2 ↔ ‘V4/V8/VO’, and areas for attention, memory, and wakefulness). The psychophysical Red-Green Channel, its neurophysiological correlates V4/V8/VO-neural-network, and related experience (such as redness) are integrated. The dual-aspect-dual-mode PE-SE framework (Vimal, J Integr Neurosci 7:49–73, 2008) was used to address the explanatory gap problem of materialism. Neural-network and related SEs are the results of the co-evolution and co-development of the material aspect (mass, charge, spin, force, quanta, and space-time) and the mental aspect of fundamental particles (strings or elementary particles (fermions and bosons)). Their mental aspects are considered as the carriers of superposed multiple possible experiences (SEs/PEs) in unexpressed form. These possibilities are actualized when neural-networks are formed via neural Darwinism, and a specific SE is selected by a matching process when the necessary ingredients of consciousness/SE are satisfied. A simple experimental design is suggested to address the necessary and sufficient attributes of consciousness. (shrink)

In this paper I first discuss the colour-octahedron and the position of this model as an idealized system with respect to the remarks on colour-concepts in Remarks on Colour (RC). The next part examines the notion of aspect seeing in the light of the colour-octahedron and RC. From there a connection is made with On Certainty (OC). By linking the remarks on colour, seeing aspects and certainty, it may become clear that the investigations of Wittgenstein concerning colour and certainty direct (...) us towards a reflective dynamics and an anthropological interpretation of his ideas. (shrink)

Quality-space theory (QST) explains the nature of the mental qualities distinctive of perceptual states by appeal to their role in perceiving. QST is typically described in terms of the mental qualities that pertain to color. Here we apply QST to the olfactory modalities. Olfaction is in various respects more complex than vision, and so provides a useful test case for QST. To determine whether QST can deal with the challenges olfaction presents, we show how a quality space (QS) could be (...) constructed relying on olfactory perceptible properties and the olfactory mental qualities then defined by appeal to that QS of olfactory perceptible properties. We also consider how to delimit the olfactory QS from other modalities. We further apply QST to the role that experience plays in refining our olfactory discriminative abilities and the occurrence of olfactory mental qualities in non-conscious olfactory states. QST is shown to be fully applicable to and useful for understanding the complex domain of olfaction. (shrink)

If all the participants in the color ontology debate are naturalists with good sciences on their side, how could color subjectivism win? The apparent reason is that subjectivism is supported by the opponent process theory that is a successful neurophysiological reduction of colors. We will argue that the real reason is the unique reductive methodology of the opponent paradigm. We will undermine subjectivism by arguing against the methodology.

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)

Colour information not only helps sustain the survival of animal species by guiding sexual selection and foraging behaviour but also is an important factor in the cultural and technological development of our own species. This is illustrated by examples from the visual arts and from state-of-the-art imaging technology, where the strategic use of colour has become a powerful tool for guiding the planning and execution of interventional procedures. The functional role of colour information in terms of its potential benefits to (...) behavioural success across the species is addressed in the introduction here to clarify why colour perception may have evolved to generate behavioural success. It is argued that evolutionary and environmental pressures influence not only colour trait production in the different species but also their ability to process and exploit colour information for goal-specific purposes. We then leap straight to the human primate with insight from current research on the facilitating role of colour cues on performance training with precision technology for image-guided surgical planning and intervention. It is shown that local colour cues in two-dimensional images generated by a surgical fisheye camera help individuals become more precise rapidly across a limited number of trial sets in simulator training for specific manual gestures with a tool. This facilitating effect of a local colour cue on performance evolution in a video-controlled simulator (pick-and-place) task can be explained in terms of colour-based figure-ground segregation facilitating attention to local image parts when more than two layers of subjective surface depth are present, as in all natural and surgical images. (shrink)