Online research in philosophy

Tye argues that visual mental images have their contents encoded in topographically organized regions of the visual cortex, which support depictive representations; therefore, visual mental images rely at least in part on depictive representations. This argument, I contend, does not support its conclusion. I propose that we divide the problem about the depictive nature of mental imagery into two parts: one concerns the format of image representation and the other the conditions by virtue of which a representation becomes a depictive representation. Regarding the first part of the question, I argue that there exists a topographic format in the brain but that does not imply that there exists a depictive format of image representation. My answer to the second part of the question is that one needs a content analysis of a certain sort of topographic representations i n order to make sense of depictive mental representations, and a topographic representation becomes a depictive representation by virtue of its content rather than its form.

Is mental imagery pictorial? In Pylyshyn's view no empirical data provides convincing support to the “pictorial” hypothesis of mental imagery. Phenomenology, Pylyshyn says, is deeply deceiving and offers no explanation of why and how mental imagery occurs. We suggest that Pylyshyn mistakes phenomenology for what it never pretended to be. Phenomenological evidence, if properly considered, shows that mental imagery may indeed be pictorial, though not in the way that mimics visual perception. Moreover, Pylyshyn claims that the “pictorial hypothesis” is flawed because the interpretation of “picture-like” objects in mental imagery takes a homunculus. However, the same point can be objected to Pylyshyn's own conclusion: if imagistic reasoning involves the same mechanisms and the same forms of representation as those that are involved in general reasoning, if they operate on symbol-based representations of the kind recommended by Pylyshyn (1984) and Fodor (1975), don't we need a phenomenological homunculus to tell an imagined bear from the real one?

Pylyshyn provides sound arguments against the dominant picture theory of mental imagery. However, we claim that mental imagery is intrinsically dynamic and that the very nature of mental imagery will not be uncovered by studying static pictures. Understanding mental imagery of motor actions reveals that any theory of mental imagery should start off with the temporal nature of real-life experiences.

Mental imagery (varieties of which are sometimes colloquially refered to as “visualizing,” “seeing in the mind's eye,” “hearing in the head,” “imagining the feel of,” etc.) is quasi-perceptual experience; it resembles perceptual experience, but occurs in the absence of the appropriate external stimuli. It is also generally understood to bear intentionality (i.e., mental images are always images of something or other), and thereby to function as a form of mental representation. Traditionally, visual mental imagery, the most discussed variety, was thought to be caused by the presence of picturelike representations (mental images) in the mind, soul, or brain, but this is no longer universally accepted.

In the imagery debate, a key question concerns the inherent spatial nature of mental images. What do we mean by spatial representation? We explore a new idea that suggests that motion is instrumental in the coding of visual space. How is the imagery debate informed by the representation of space being determined by visual motion?

The relationship between mental representation and consciousness is considered. What it means to 'represent', and several types of representation (e.g., analogue, digital, spatial, linguistic, mathematical), are described. Concepts relevant to mental representation in general (e.g., multiple levels of processing, structure/process differences, mapping) and in specific domains (e.g., mental imagery, linguistic/propositional theories, production systems, connectionism, dynamics) are discussed. Similarities (e.g., using distinctions between different forms of representation to predict different forms of consciousness, parallels between digital architectures of the brain and connectionist models) and dissociations (e.g., insensitivity to gaps in subjective experience, explicit memory/implicit memory, automatic processing/controlled processing, blindsight, neglect, prediction/ explanation) of mental representation and consciousness are discussed. It is concluded that representational systems are separable from consciousness systems, and that mental representation appears necessary but not sufficient for consciousness. Considerations for future research on correspondences between representation and consciousness are suggested.

An introduction to the science and philosophy of mental imagery.

With admirable clarity, Pylyshyn shows that there is little evidence that mental imagery is strongly constrained to be analog. He urges that imagery must be considered part of a more general symbolic system. The ultimate solution to the challenges of image theory, however, rest on understanding the manner in which mental imagery is both a symbolic and an analog system.