23,037 research outputs found

    Neural Models of Seeing and Thinking

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    Air Force Office of Scientific Research (F49620-01-1-0397); Office of Naval Research (N00014-01-1-0624

    Perceiving environmental structure from optical motion

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    Generally speaking, one of the most important sources of optical information about environmental structure is known to be the deforming optical patterns produced by the movements of the observer (pilot) or environmental objects. As an observer moves through a rigid environment, the projected optical patterns of environmental objects are systematically transformed according to their orientations and positions in 3D space relative to those of the observer. The detailed characteristics of these deforming optical patterns carry information about the 3D structure of the objects and about their locations and orientations relative to those of the observer. The specific geometrical properties of moving images that may constitute visually detected information about the shapes and locations of environmental objects is examined

    Seeing Double: Assessing Kendall Walton’s Views on Painting and Photography

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    In this paper I consider Kendall Walton’s provocative views on the visual arts, including his approaches to understanding both figurative and nonfigurative painting. I introduce his central notion of fictionality, illustrating its advantages in explaining the phenomenon of ‘perceptual twofoldness’. I argue that Walton’s position treats abstract artwork reductively, and I outline two essential components of our aesthetic encounters with the nonfigurative that Walton excludes. I then offer some criticisms of his commitment to photographic realism, emphasising its theoretical inconsistencies with his account of representation. My own proposal is that in our apprehension of non-figurative artworks, our attention is drawn to the underlying structures of both emotive and perceptual experience. In this way, paintings, particularly abstract ones, disclose human cognition in a manner that makes fictionality an inappropriate tool for their analysis

    Concepts, Introspection, and Phenomenal Consciousness: An Information-Theoretical Approach

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    This essay is a sustained information-theoretic attempt to bring new light on some of the perennial problems in the philosophy of mind surrounding phenomenal consciousness and introspection. Following Dretske (1981), we present and develop an informational psychosemantics as it applies to what we call <em>sensory concepts</em>, concepts that apply, roughly, to so-called secondary qualities of objects. We show that these concepts have a special informational character and semantic structure that closely tie them to the brain states realizing conscious qualitative experiences. We then develop an account of introspection which exploits this special nature of sensory concepts. The result is a new class of concepts, which, following recent terminology, we call <em>phenomenal concepts</em>: these concepts refer to phenomenal experience itself and are the vehicles used in introspection. On our account, the connection between sensory and phenomenal concepts is very tight: it consists in different semantic uses of the same cognitive structures underlying the sensory concepts, like RED. Contrary to widespread opinion, we show that information theory contains all the resources to satisfy internalist intuitions about phenomenal consciousness, while not offending externalist ones. A consequence of this account is that it explains and predicts the so-called conceivability arguments against physicalism on the basis of the special nature of sensory and phenomenal concepts. Thus we not only show why physicalism is not threatened by such arguments, but also demonstrate its strength in virtue of its ability to predict and explain away such arguments in a principled way. However, we take the main contribution of this work to be what it provides in addition to a response to those conceivability arguments, namely, a substantive account of the interface between sensory and conceptual systems and the mechanisms of introspection as based on the special nature of the information flow between them

    Perspective. Theories and experiments on the “veduta vincolata” (restricted sight)

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    The modern perspective admits the free rotation of the eye situated in the projection centre (restricted sight) and with this, and with the motion of the eye, it is capable of simulating even the impression of curvature of the visual field that Panofsky erroneously ascribes to the curvature of the retina. The restricted sight admits an ample displacement of the observation point along the direction of the normal to the picture plane, whereas it is much less tolerant for a displacement parallel to the picture plane that emphasizes the ‘marginal aberrations’ and not only. This limit has been passed, during the 17th century, by artists like Agostino Tassi through the repetition of the primary point (which is also the vanishing point of the normals to the picture plane). Thus, there are two possible interpretive keys of an architectural perspective: on the one hand the geometrical key, which reveals itself by means of an inverse procedure, capable of describing the shapes that are represented in space; on the other the architectural key, which obtains the same result simply observing the typical characteristics of an architecture, like the symmetry, the horizontality of the architraves, the verticality of the pillars, the proportions of the Order

    Form Perception

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    National Science Foundation (SBE-0354378); Office of Naval Research (N00014-01-1-0624

    Neural Dynamics of 3-D Surface Perception: Figure-Ground Separation and Lightness Perception

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    This article develops the FACADE theory of three-dimensional (3-D) vision to simulate data concerning how two-dimensional (2-D) pictures give rise to 3-D percepts of occluded and occluding surfaces. The theory suggests how geometrical and contrastive properties of an image can either cooperate or compete when forming the boundary and surface representations that subserve conscious visual percepts. Spatially long-range cooperation and short-range competition work together to separate boundaries of occluding ligures from their occluded neighbors, thereby providing sensitivity to T-junctions without the need to assume that T-junction "detectors" exist. Both boundary and surface representations of occluded objects may be amodaly completed, while the surface representations of unoccluded objects become visible through modal processes. Computer simulations include Bregman-Kanizsa figure-ground separation, Kanizsa stratification, and various lightness percepts, including the Munker-White, Benary cross, and checkerboard percepts.Defense Advanced Research Projects Agency and Office of Naval Research (N00014-95-1-0409); National Science Foundation (IRI 94-01659, IRI 97-20333); Office of Naval Research (N00014-92-J-1309, N00014-95-1-0657

    Figure-Ground Separation by Visual Cortex

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    Office of Naval Research (N00014-95-1-0109, N00014-95-1-0657
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