Although the mechanics of how the eye works are well understood, debate still exists as to how the complex machinery of the brain interprets neural impulses...

There are two concepts of consciousness that are easy to confuse with one another, access-consciousness and phenomenal consciousness. However, just as the concepts of water and H 2 O are different concepts of the same thing, so the two concepts of consciousness may come to the same thing in the brain. The focus of this paper is on the problems that arise when these two concepts of consciousness are conflated. I will argue that John Searle's reasoning about the function of (...) consciousness goes wrong because he conflates the two senses. And Francis Crick and Christof Koch fall afoul of the ambiguity in arguing that visual area V1 is not part of the neural correlate of consciousness. Crick and Koch's work raises issues that suggest that these two concepts of consciousness may have different neural correlates – despite Crick and Koch's implicit rejection of this idea. (shrink)

Consciousness is a mongrel concept: there are a number of very different "consciousnesses." Phenomenal consciousness is experience; the phenomenally conscious aspect of a state is what it is like to be in that state. The mark of access-consciousness, by contrast, is availability for use in reasoning and rationally guiding speech and action. These concepts are often partly or totally conflated, with bad results. This target article uses as an example a form of reasoning about a function of "consciousness" based on (...) the phenomenon of blindsight. Some information about stimuli in the blind field is represented in the brains of blindsight patients, as shown by their correct "guesses," but they cannot harness this information in the service of action, and this is said to show that a function of phenomenal consciousness is somehow to enable information represented in the brain to guide action. But stimuli in the blind field are BOTH access-unconscious and phenomenally unconscious. The fallacy is: an obvious function of the machinery of access-consciousness is illicitly transferred to phenomenal consciousness. (shrink)

The distinction between phenomenal (P) and access (A) consciousness arises from the battle between biological and computational approaches to the mind. If P = A, the computationalists are right; but if not, the biological nature of P yields its scientific nature.

First published in 1995, The Visual Brain in Action remains a seminal publication in the cognitive sciences. It presents a model for understanding the visual processing underlying perception and action, proposing a broad distinction within the brain between two kinds of vision: conscious perception and unconscious 'online' vision. It argues that each kind of vision can occur quasi-independently of the other, and is separately handled by a quite different processing system. In the 11 years since publication, the book has provoked (...) considerable interest and debate - throughout both cognitive neuroscience and philosophy, while the field has continued to flourish and develop. -/- For this new edition, the text from the original edition has been left untouched, standing as a coherent statement of the authors' position. However, a very substantial epilogue has been added to the book in which Milner and Goodale review some of the key developments that support or challenge the views that were put forward in the first edition. The new chapter summarizes developments in various relevant areas of psychology, neuroscience and behaviour. It notably supplements the main text by updating the reader on the contributions that have emerged from the use of functional neuroimaging, which was in its infancy when the first edition was written. Neuroimaging, and functional MRI in particular, has revolutionized the field over the past 11 years by allowing investigators to plot in detail the patterns of activity within the visual brains of behaving and perceiving humans. The authors show how its use now allows scientists to test and confirm their proposals, based as they then were largely on evidence accrued from primate neuroscience in conjunction with studies of neurological patients. (shrink)

Do studies of perception without awareness and studies of perception without attention address a similar underlying concept of awareness? To answer this question, we compared qualitative differences in performance across variations in stimulus quality with qualitative differences in performance across variations in the direction of attention . The qualitative differences were based on three different phenomena: Stroop priming, false recognition, and exclusion failure. In all cases, variations in stimulus quality and variations in the direction of attention led to parallel findings. (...) These results suggest that perception with and without awareness and perception with and without attention are equivalent ways of describing the same underlying process distinction. (shrink)

This paper develops an empirically motivated theory of visual consciousness. It begins by outlining neuropsychological support for Jackendoff's (1987) hypothesis that visual consciousness involves mental representations at an intermediate level of processing. It then supplements that hypothesis with the further requirement that attention, which can come under the direction of high level representations, is also necessary for consciousness. The resulting theory is shown to have a number of philosophical consequences. If correct, higher-order thought accounts, the multiple drafts account, and the (...) widely held belief that sensation precedes perception will all be found wanting. The theory will also be used to illustrate and defend a methodology that fills the gulf between functionalists who ignore the brain and neural reductionists who repudiate functionalism. (shrink)