Common sense takes the physical world to be populated by mind-independent particulars. Why and with what right do we hold this view? Early phenomenologists argue that the common sense view is our natural starting point because we experience objects as mind-independent. While it seems unsurprising that one can perceive an object being red or square, the claim that one can experience an object as mind-independent is controversial. In this paper I will articulate and defend the claim that we can experience (...) mind-independence by mainly drawing on the work of the Gestalt psychologist Karl Duncker who, in turn, built on Husserl’s work. In the development of this claim the notion of a limit – either a maximum or minimum – of perception will play an important role. (shrink)

The Mona Lisa is probably the most celebrated example of ambiguous expression in art. Soranzo and Newberry demonstrated that a similar ambiguity can be perceived also in La Bella Principessa, another portrait credited to Leonardo da Vinci by many. The paper aims to show that an ambiguous expression can be perceived in a further painting attributed to Leonardo: The Lady with Dishevelled Hair, or La Scapigliata. An experiment was conducted whereby participants rated on a 7-point Likert scale the perceived level (...) of contentment of La Scapigliata and that of a comparable painting created by Andrea di Cione, alias Il Verrocchio. The two artworks were presented in random order to two groups of participants. One group could see the artworks from Close whilst the other group from Far from a Close or Far condition. Results show that the change of distance affected the perceived level of contentment of Leonardo’s figure but not that of Verrocchio’s. Specifically, whilst both artworks received similar ratings of contentment from the close-up condition, La Scapigliata was perceived to be more content from afar. It is concluded that La Scapigliata exhibits an ambiguous expression, and that this ambiguity is similar to the one observed in the Mona Lisa and La Bella Principessa. This result can be only partially interpreted within the spatial frequency hypothesis advanced by Livingstone and shows that a phenomenological account of Leonardo’s work might be more suited to capture the full extent of the phenomenon. Specifically, it is suggested that the principles of perceptual belongingness may need to be considered to fully capture the extent of the ambiguity depicted by Leonardo. (shrink)

The empirical study of visual space has centered on determining its geometry, whether it is a perspective projection, flat or curved, Euclidean or non-Euclidean, whereas the topology of space consists of those properties that remain invariant under stretching but not tearing. For that reason distance is a property not preserved in topological space whereas the property of spatial order is preserved. Specifically the topological properties of dimensionality, orientability, continuity, and connectivity define “real” space as studied by physics and are the (...) spatial properties that characterize the physical universe as being an integral whole. By contrast the geometrical analysis of VS has taken little cognizance of its topology. Instead such properties have been presupposed a priori rather than being established a posteriori by empirical means, perhaps because these properties are self-evident. Applying the method of coordinative definition expounded by Hans Reichenbach for determining geometrical and topological properties of physical space, it can be shown that VS fulfills the topological criteria of being a “real” space sui generis. Though theorized to be produced by the brain, the topology of VS is not topologically equivalent with the structure and activity of the brain because, as will be shown, the topology of VS cannot be formed from the topology of the brain without tearing and/or cutting and pasting. (shrink)

How do we reconcile Husserl’s repeated criticism of Mach’s phenomenalism almost everywhere in his work with the leading role that Husserl seems to attribute to Mach in the genesis of his own phenomenology? To answer this question, we shall examine, first, the narrow relation that Husserl establishes between his phenomenological method and Mach’s descriptivism. Second, we shall examine two aspects of Husserl’s criticism of Mach: the first concerns phenomenalism and Mach’s doctrine of elements, while the second concerns the principle of (...) economy of thought, which Husserl closely associates with a form of psychologism in his Logical Investigations . Our working hypothesis is that the apparent contradictory comments of Husserl regarding Mach’s positivism can be partially explained by the double status he confers to his own phenomenology—as a philosophical program radically opposed to positivism, and as a method akin to Mach’s descriptivism. (shrink)

Como conciliar as repetidas críticas ao fenomenismo de Mach, um pouco por toda a obra de Husserl, com o papel proeminente que Husserl parece nele reconhecer em seus últimos trabalhos, quanto à gênese de sua própria fenomenologia? Para responder a essa questão, examinaremos, primeiramente, a relação estreita que Husserl estabelece entre o método fenomenológico e o descritivismo de Mach à luz do debate que opõe nativismo e empirismo sobre a origem da percepção do espaço. Em seguida, examinaremos dois aspectos da (...) crítica que Husserl faz ao positivismo de Mach: o primeiro se refere ao fenomenismo e sua doutrina dos elementos, enquanto o segundo, ao princípio de economia de pensamento, que Husserl associa a uma forma de psicologismo em Prolegômenos. A hipótese que nos guiará nesse estudo é que as opiniões aparentemente contraditórias de Husserl sobre o positivismo de Mach se explicam em parte pelo estatuto duplo que a fenomenologia recebe em seus últimos trabalhos: enquanto programa filosófico, ela se opõe explicitamente ao positivismo; enquanto método, ela se aparenta ao descritivismo de Mach. Concluiremos com a ideia de que esses dois filósofos de origem checa perseguiam o objetivo comum de apreender o sentido originário de positividade. (shrink)

Poorly saturated colors are closer to a pure grey than strongly saturated ones and, therefore, appear less “colorful”. Color saturation is effectively manipulated in the visual arts for balancing conflicting sensations and moods and for inducing the perception of relative distance in the pictorial plane. While perceptual science has proven quite clearly that the luminance contrast of any hue acts as a self-sufficient cue to relative depth in visual images, the role of color saturation in such figure-ground organization has remained (...) unclear. We presented configurations of colored inducers on grey ‘test’ backgrounds to human observers. Luminance and saturation of the inducers was uniform on each trial, but varied across trials. We ran two separate experimental tasks. In the relative background brightness task, perceptual judgments indicated whether the apparent brightness of the grey test background contrasted with, assimilated to, or appeared equal (no effect) to that of a comparison background with the same luminance contrast. Contrast polarity and its interaction with color saturation affected response proportions for contrast, assimilation and no effect. In the figure-ground task, perceptual judgments indicated whether the inducers appeared to lie in front of, behind, or in the same depth with the background. Strongly saturated inducers produced significantly larger proportions of foreground effects indicating that these inducers stand out as figure against the background. Weakly saturated inducers produced significantly larger proportions of background effects, indicating that these inducers are perceived as lying behind the backgrounds. We infer that color saturation modulates figure-ground organization, both directly by determining relative inducer depth, and indirectly, and in interaction with contrast polarity, by affecting apparent background brightness. The results point towards a hitherto undocumented functional role of color saturation in the genesis of form, and in particular figure-ground percepts in the absence of chromatostereopsis. (shrink)

Do the physical facts of the viewed environment account for the ordinary experiences we have of that environment? According to standard philosophical views, distal facts do account for our experiences, a phenomenon explained by appeal to perceptual constancy, the phenomenal stability of objects and environmental properties notwithstanding physical changes in proximal stimulation. This essay reviews a significant but neglected research tradition in experimental psychology according to which percepts systematically do not correspond to mind-independent distal facts. Instead, stability of percept values (...) comes in degrees, and physical facts about the viewed environment alone do not account for our ordinary experiences of the world. I conclude that more attention to descriptive research in psychophysics is warranted if what is sought is a philosophical theory of the nature of our perceptual relation with the world. (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)

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)

We show that true colors as defined by Chevreul (1839) produce unsuspected simultaneous brightness induction effects on their immediate grey backgrounds when these are placed on a darker (black) general background surrounding two spatially separated configurations. Assimilation and apparent contrast may occur in one and the same stimulus display. We examined the possible link between these effects and the perceived depth of the color patterns which induce them as a function of their luminance contrast. Patterns of square-shaped inducers of a (...) single color (red, green, blue, yellow, or grey) were placed on background fields of a lighter and a darker grey, presented on a darker screen. Inducers were always darker on one side of the display and brighter on the other in a given trial. The intensity of the grey backgrounds varied between trials only. This permitted generating four inducer luminance contrasts, presented in random order, for each color. Background fields were either spatially separated or consisted of a single grey field on the black screen. Experiments were run under three environmental conditions: dark-adaptation, daylight, and rod-saturation after exposure to bright light. In a first task, we measured probabilities of contrast, assimilation, and no effect in a three-alternative forced-choice procedure (background appears brighter on the ‘left’, on the ‘right’ or the ‘same’). Visual adaptation and inducer contrast had no significant influence on the induction effects produced by colored inducers. Achromatic inducers produced significantly stronger contrast effects after dark-adaptation, and significantly stronger assimilation in daylight conditions. Grouping two backgrounds into a single one was found to significantly decrease probabilities of apparent contrast. Under the same conditions, we measured probabilities of the inducers to be perceived as nearer to the observer inducers. These, as predicted by Chevreul’s law of contrast, were determined by the luminance contrast of the inducers only, with significantly higher probabilities of brighter inducers to be seen as nearer, and a marked asymmetry between effects produced by inducers of opposite sign. Implications of these findings for theories which attempt to link simultaneous induction effects to the relative depth of object surfaces in the visual field are discussed. (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)

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)