Online research in philosophy

Motor imagery typically involves an experience as of moving a body part. Recent studies reveal close parallels between the constraints on motor imagery and those on actual motor performance. How are these parallels to be explained? We advance a simulative theory of motor imagery, modeled on the idea that we predict and explain the decisions of others by simulating their decision-making processes. By proposing that motor imagery is essentially off-line motor action, we explain the tendency of motor imagery to mimic motor performance. We close by arguing that a simulative theory of motor imagery gives (modest) support to and illumination of the simulative theory of decision-prediction.

6. Seeing With the Mind’s Eye 1: The Puzzle of Mental Imagery .................................................6-1 6.1 What is the puzzle about mental imagery?..............................................................................6-1 6.2 Content, form and substance of representations ......................................................................6-6 6.3 What is responsible for the pattern of results obtained in imagery studies?.................................6-8..

It is clear that visual imagery is somehow significantly visual. Some theorists, like Kosslyn, claim that the visual nature of visualisations derives from features of the neural processes which underlie those episodes. Pylyshyn claims, however, that it may merely reflect special features of the contents which we grasp when we visualise things. This paper discusses and rejects Pylyshyn's own attempts to identify the respects in which the contents of visualisations are notably visual. It then offers a novel and very different account of what is distinctively sensory about the contents of sensory images. The paper's alternative account is used in explaining various pieces of phenomenological and behavioural data concerning visualisation. Finally, it is tentatively suggested that the proposed account of the contents of sensory images may also shed light upon some of the neurological data involving visualisation and sensory imagery more generally.

Observations on patients who lost visual imagery after brain damage call into question the notion that the knowledge subserving visual imagery is “tacit.” Dissociations between deficient imagery and preserved recognition of objects suggest that imagery is exclusively based on explicit knowledge, whereas retrieval of “tacit” visual knowledge is bound to the presence of the object and the task of recognizing it.

Defining Imagery: Experience or Representation?
Historical Development of Ideas about Imagery
Subjective Individual Differences in Imagery Experience
Theories of Imagery, and their Implications for Consciousness
Picture theory
Description theory
Enactive theory.

The imagery debate re-enacts controversies persisting since Descartes. The controversy remains important less for what we can learn about visual imagery than about cognitive science itself. In the tradition of Arnauld, Reid, Bartlett, Austin and Ryle, Pylyshyn’s critique exposes notorious mistakes being unwittingly rehearsed not only regarding imagery but also in several independent domains of research in modern cognitive science.

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.

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.

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.

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?