Online research in philosophy

We can perceive shapes visually and tactilely, and the information we gain about shapes through both sensory modalities is integrated smoothly into and functions in the same way in our behavior independently of whether we gain it by sight or touch. There seems to be no reason in principle we couldn't perceive shapes through other sensory modalities as well, although as a matter of fact we do not. While we can identify shapes through other sensory modalities—e.g., I may know by smell (the scent of mango) that the object causing my sensory experience is round—this is not perceiving an object as shaped, but rather inferring from the character of one's sensory experience and collateral information that an object of a certain shape caused it. That it is possible to perceive shape by other modalities, however, is suggested by the case of bats and aquatic mammals like dolphins which navigate through their environment by a form of sonar. It is plausible that they have some form of auditory representation of space, and so of shape. These facts about shape perception raise important questions about the relation between those features of perceptual experience which are intrinsic to different sensory modalities and the nature of our perceptual representation of shapes, and, more generally, of the space within which we perceive shaped objects to be located. John Campbell's paper, "Molyneux's Problem" (see above), raises a number of interesting and important questions about the nature of our perception of shape properties, particularly the cross-modal nature of shape perception, and ties them to more general questions about the nature both of perceptual..

In this paper, I critically assess the enactive account of visual perception recently defended by Alva Noë (2004). I argue inter alia that the enactive account falsely identifies an object’s apparent shape with its 2D perspectival shape; that it mistakenly assimilates visual shape perception and volumetric object recognition; and that it seriously misrepresents the constitutive role of bodily action in visual awareness. I argue further that noticing an object’s perspectival shape involves a hybrid experience combining both perceptual and imaginative elements – an act of what I call ‘make-perceive.’.

The central text of this article is Thomas Reid’s response to Berkeley’s argument for distinguishing tangible from visual shape. Reid is right to hold that shape words do not have different visual and tangible meanings. We might also perceive shape, moreover, with senses other than touch and sight. As Reid also suggests, the visual perception of shape does not require perception of hue or brightness. Contrary to treatments of the Molyneux problem by H. P. Grice and Judith Jarvis Thomson, I argue that breakdowns of a certain kind between tangible and visible shape are conceivable.

A coin rotating back in depth in some sense presents a changing, elliptical shape. How are we to understand such (in this case) ‘appearances of ellipticality’? How is the experiential sense of such shifting shape appearances related to the experiential sense of enduring shape definitive of perceived shape constancy? Is the experiential recovery of surface shape based on the prior (perhaps more fundamental) recovery of point or element 3D spatial locations?—or is the perception of shape a largely independent perceptual achievement? Do we gain access to enduring shape properties by first detecting and working from ‘shape appearances’? These are some of the topics taken up in this paper.

Berkeley thinks that we only see the size, shape, location, and orientation of objects in virtue of the correlation between sight and touch. Shadows have all of these spatial properties and yet are intangible. In Seeing Dark Things (2008), Roy Sorensen argues that shadows provide a counterexample to Berkeley's theory of vision and, consequently, to his idealism. This paper shows that Berkeley can accept both that shadows are intangible and that they have spatial properties.

Converging psychophysical evidence suggests that the human visual system parses shapes into component parts for the purposes of object recognition. We examine the Schyns et al. claim of “creation” of features in light of recent work on part-based representations of visual shape, particularly the perceptual rules that human vision uses to parse shapes.

profile deforms as we move about it. As perceivers we are masters of the patterns of sensorimotor contingency that shape our perceptual interaction with the world. We expect changes in such things as apparent size, shape and color to occur as we actively explore the environment. In encountering perspective-dependent changes of this sort, we learn how things are quite apart form our particular perspective. Our possession of these skills is constitutive of our ability to see (and generally to perceive). This is confirmed by the fact that we can disrupt a person.

In an article in Mind (Vol. 73, No. 291, July 1964) I tried to show that there is a fundamental difference between primary and secondary qualities. The present analysis of perceived size of an object and its relation to the size of the 'objective' and the 'real' object reveals that my thesis 1 regarding visual primary qualities, viz. size and shape, while true so far as shape is concerned, has to be modified in regard to size. After having criticized the usual view of size constancy, I show by means of a diagram how we may determine the location in physical space of a percept of an object. This diagram reveals at the same time how perceived size decreases gradually with increasing distance of the object from the percipient, but at a much smaller rate than the retinal image of the object. By means of the diagram I show furthermore how the perceived size may in theory vary from person to person. In conclusion a modification of my thesis 1 is suggested.

We are accustomed to thinking that a primrose is "concrete" and a prime number is "abstract," that "roundness" is more abstract than "round," and that "property" is more abstract than "roundness." In reality, the relation between "abstract" and "concrete" is more like the (non)relation between "abstract" and "concave," "concrete" being a sensory term [about what something feels like] and "abstract" being a functional term (about what the sensorimotor system is doing with its input in order to produce its output): Feelings and things are correlated, but otherwise incommensurable. Everything that any sensorimotor system such as ourselves manages to categorize successfully is based on abstracting sensorimotor "affordances" (invariant features). The rest is merely a question of what inputs we can and do categorize, and what we must abstract from the particulars of each sensorimotor interaction in order to be able to categorize them correctly. To categorize, in other words, is to abstract. And not to categorize is merely to experience. Borges's Funes the Memorious, with his infinite, infallible rote memory, is a fictional hint at what it would be like not to be able to categorize, not to be able to selectively forget and ignore most of our input by abstracting only its reliably recurrent invariants. But a sensorimotor system like Funes would not really be viable, for if something along those lines did exist, it could not categorize recurrent objects, events or states, hence it could have no language, private or public, and could at most only feel, not function adaptively (hence survive). Luria's "S" in "The Mind of a Mnemonist" is a real-life approximation whose difficulties in conceptualizing were directly proportional to his difficulties in selectively forgetting and ignoring. Watanabe's "Ugly Duckling Theorem" shows how, if we did not selectively weight some properties more heavily than others, everything would be equally (and infinitely and indifferently) similar to everything else. Miller's "Magical Number Seven Plus or Minus Two" shows that there are (and must be) limitations on our capacity to process and remember information, both in our capacity to discriminate relatively (detect sameness/difference, degree-of-similarity) and in our capacity to discriminate absolutely (identify, categorize, name), The phenomenon of categorical perception shows how selective feature-detection puts a Whorfian "warp" on our feelings of similarity in the service of categorization, compressing within-category similarities and expanding between-category differences by abstracting and selectively filtering inputs through their invariant features, thereby allowing us to sort and name things reliably. Language does allow us to acquire categories indirectly through symbolic description....

This commentary focuses on shape constancy in vision and its relation to sensorimotor knowledge. I contrast “Protean” and “Constancian” views about how to describe perspectival changes in the appearance of an object’s shape. For the Protean, these amount to changes in apparent shape; for Constance, things are not merely judged, but literally appear constant in shape. I give reasons in favor of the latter view, and argue that Noë’s attempt to combine aspects of both views in a “dual aspect” account does not manage to avoid an unacceptable attribution of contradictory content to visual appearance. I argue also that my position here actually fits better with Noë’s critique of a “snapshot” conception of visual appearance than his own interpretation of visual constancy, and better supports his claim that experiential content is constituted by the exercise of sensorimotor understanding.