Online research in philosophy

In his target article, Barsalou cites current work on emotion theory but does not explore its relevance for this project. The connection is worth pursuing, since there is a plausible case to be made that emotions form a distinct symbolic information processing system of their own. On some views, that system is argued to be perceptual: a direct connection with Barsalou's perceptual symbol systems theory. Also relevant is the hypothesis that there may be different modular subsystems within emotion and the perennial tension between cognitive and perceptual theories of emotion.

Abstract This paper studies Olivi's account of perceptual representation. It addresses two main questions: (1) how do perceptual representations originate? and (2) how do they represent their objects? Regarding (1), it is well known that Olivi emphasizes the activity of the soul in the production of perceptual representations. Yet it is sometimes argued that he overstresses the activity of the soul in a way that yields a philosophically problematic result. I argue that Olivi was well aware of the problem that could be raised for his theory and that he sought to cope with it. Regarding (2), Pasnau argues that for Olivi, causal relationships with external objects determine the content of perceptual representations. I argue that, rather, perceptual representations are about their objects because they are their similitudes. This makes him an internalist about representational content.

Supposing the symbol system postulated by Barsalou is perceptual through and through -- what then? The target article outlines an intriguing and exciting theory of cognition in which (1) wellspecified, event- or object-linked percepts assume the role traditionally allotted to abstract and arbitrary symbols, and (2) perceptual simulation is substituted for processes traditionally believed to require symbol manipulation, such as deductive reasoning. We take a more extreme stance on the role of perception (in particular, vision) in shaping cognition, and propose, in addition to Barsalou's postulates, that (3) spatial frames, endowed with a perceptual structure not unlike that of the retinotopic space, pervade all sensory modalities and are used to support compositionality.

It is very tempting to try to reconcile perception and cognition perceptual symbol systems may be a good way to achieve this; but is there actually a perception-cognition continuum? We offer several arguments for and against the existence of such a continuum and in favor of the choice of perceptual symbol systems. One of these arguments is purely theoretical, some are based on PET-scan observations and others are based on research with handicapped subjects who have communication problems associated with cerebral lesions. These arguments suggest that modal perceptual symbols do indeed exist and that perception and cognition might have a common neuronal basis; but perceptual and cognitive activities require the activation of different neuronal structures.

Barsalou proposes (sect. 4.1.6) that perceptual symbols play a role in language processing. Data from our laboratory document this role and suggest the sorts of constraints used by simulators during language comprehension.

Various defenses of amodal symbol systems are addressed, including amodal symbols in sensory-motor areas, the causal theory of concepts, supramodal concepts, latent semantic analysis, and abstracted amodal symbols. Various aspects of perceptual symbol systems are clarified and developed, including perception, features, simulators, category structure, frames, analogy, introspection, situated action, and development. Particular attention is given to abstract concepts, language, and computational mechanisms.

The perceptual symbol approach to knowledge representation combines structured frames and dynamic imagery. The perceptual symbol approach provides a good account of the representation of scientific models, of some types of naive theories held by children and adults, and of certain reconstructive memory phenomena. The ontological status of perceptual symbols is unclear and this form of representation does not succeed in accounting for all forms of human knowledge.

Many recent cognitive studies reveal that human cognition is inherently perceptual, sharing systems with perception at both the conceptual and the neural levels. This paper introduces Barsalou's theory of perceptual symbols and explores its implications for philosophy of science. If perceptual symbols lie in the heart of conceptual processing, the process of attribute selection during concept representation, which is critical for defining similarity and thus for comparing taxonomies, can no longer be determined solely by background beliefs. The analogous nature of perceptual symbols and the spatial nature of intraconceptual relations impose new constraints on attribute selection. These constraints help people with different background beliefs select compatible attributes, which constitute a common "platform" for taxonomy comparison.

Although Barsalou is right in identifying the importance of perceptual symbols as a means of carrying certain kinds of content, he is wrong in playing down the inferential resources available to amodal symbols. I argue that the case for perceptual symbol systems amounts to a false dichotomy and that it is feasible to help oneself to both kinds of content as extreme ends on a content continuum. The continuum thesis I advance argues for the inferential content at one end and perceptual content at the other. In between the extremes, symbols might have aspects that are either perceptual or propositional-linguistic in character. I argue that this way of characterising the issue preserves the good sense of Barsalou's recognition of perceptual representations and yet avoids the tendency to minimise the gains won with symbolic representations vital to contemporary cognitive science.

Barsalou's theory rightly emphasizes the perceptual basis of cognition. However, the perceptual symbols that he proposes seem ill suited to carry the representational burden entailed by the architecture in which they function, given that Barsalou accepts the requirement for productivity. A more radical proposal is needed in which symbols are largely external to the cognizer and linked to internal states via perception.