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)

The chapter argues from an ethology-inspired internalist perspective that ‘colour’ is not a homogeneous and autonomous attribute, but rather plays different roles in different conceptual forms underlying perception. It discusses empirical and theoretical evidence that indicates that core assumptions underlying orthodox conceptions are grossly inadequate. The assumptions pertain to the idea that colour is a kind of autonomous and unitary attribute. It is regarded as unitary or homogeneous by assuming that its core properties do not depend on the type of (...) ‘perceptual object’ to which it pertains and that‘colour per se’ constitutes a natural attribute in the functional architecture of the perceptual system. It is regarded as autonomous by assuming that it can be studied in isolation of other perceptual attributes. More generally, the chapter argues on the bases of corresponding empirical and theoretical evidence that perception cannot be understood as the ‘recovery’ of physical world structure from sensory structure by input-based computational processes. Rather, the sensory input serves as a kind of sign for biologically relevant aspects of the external world that activates biologically given conceptual forms with their internal parameters. Although the sensory input is a causally necessary requirement for the activation of conceptual forms, the perceptual computations triggered are under the control of an internal programme based on a set of conceptual forms. (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)

Visual space can be distinguished from physical space. The first is found in visual experience, while the second is defined independently of perception. Theorists have wondered about the relation between the two. Some investigators have concluded that visual space is non-Euclidean, and that it does not have a single metric structure. Here it is argued that visual space exhibits contraction in all three dimensions with increasing distance from the observer, that experienced features of this contraction are not the same as (...) would be the experience of a perspective projection onto a fronto-parallel plane, and that such contraction is consistent with size constancy. These properties of visual space are different from those that would be predicted if spatial perception resulted from the successful solution of the inverse problem. They are consistent with the notion that optical constraints have been internalized. More generally, they are also consistent with the notion that visual spatial structures bear a resemblance relation to physical spatial structures. This notion supports a type of representational relation that is distinct from mere causal correspondence. The reticence of some philosophers and psychologists to discuss the structure of phenomenal space is diagnosed in terms of the simple materialism and the functionalism of the 1970s and 1980s. (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)

Dynamic surface completion is a phenomenon of visual filling-in where a colored pattern perceptually spreads onto an area confined by virtual contours in a multi-aperture motion display. The spreading effect is qualitatively similar to static texture spreading but widely surpasses it in strength, making it particularly suited for quantitative studies of visual interpolation processes. I carried out six experiments to establish with objective tasks that homogeneous color, as well as non-uniform texture spreading is a genuine representation of surface qualities and (...) thus goes beyond mere contour interpolation. The experiments also serve to relate the phenomena to ongoing discussions about potentially responsible mechanisms for spatiotemporal integration: With a phenomenological method, I examined to what extent simple sensory persistence might be causally involved in the effect under consideration. The findings are partially consistent with the idea of sensory persistence, and indicate that information fragments are integrated over a time window of about 100 to 150 ms to form a complete surface representation. (shrink)

Physicalism claims that colors are physical properties of physical objects. For more than three centuries this philosophical stand has been denied because it was considered not to be “scientifically serious”. In this article we offer a critical review of the history of this accusation to conclude that the apparent incompatibility between the best science and physicalism must be, at least, re-examined.