References to Baars and 'Global Workspace'

from:

Facing Up to the Problem of Consciousness

David J. Chalmers

Department of Philosophy
University of California
Santa Cruz, CA 95064

chalmers@paradox.ucsc.edu

[This appeared in the Journal of Consciousness Studies in 1995.]

1 Introduction

Consciousness poses the most baffling problems in the science of the mind. There is nothing that we know more intimately than conscious experience, but there is nothing that is harder to explain. All sorts of mental phenomena have yielded to scientific investigation in recent years, but consciousness has stubbornly resisted. Many have tried to explain it, but the explanations always seem to fall short of the target. Some have been led to suppose that the problem is intractable, and that no good explanation can be given.

To make progress on the problem of consciousness, we have to confront it directly. In this paper, I first isolate the truly hard part of the problem, separating it from more tractable parts and giving an account of why it is so difficult to explain. I critique some recent work that uses reductive methods to address consciousness, and argue that such methods inevitably fail to come to grips with the hardest part of the problem. Once this failure is recognized, the door to further progress is opened. In the second half of the paper, I argue that if we move to a new kind of nonreductive explanation, a naturalistic account of consciousness can be given. I put forward my own candidate for such an account: a nonreductive theory based on principles of structural coherence and organizational invariance and a double-aspect view of information.

...(snipped)...

4 Some case-studies

In the last few years, a number of works have addressed the problems of consciousness within the framework of cognitive science and neuroscience. This might suggest that the analysis above is faulty, but in fact a close examination of the relevant work only lends the analysis further support. When we investigate just which aspects of consciousness these studies are aimed at, and which aspects they end up explaining, we find that the ultimate target of explanation is always one of the easy problems. I will illustrate this with two representative examples.

The first is the "neurobiological theory of consciousness" outlined by Crick and Koch (1990; see also Crick 1994) ...

The second example is an approach at the level of cognitive psychology. This is Baars' global workspace theory of consciousness, presented in his book A Cognitive Theory of Consciousness. According to this theory, the contents of consciousness are contained in a global workspace, a central processor used to mediate communication between a host of specialized nonconscious processors. When these specialized processors need to broadcast information to the rest of the system, they do so by sending this information to the workspace, which acts as a kind of communal blackboard for the rest of the system, accessible to all the other processors.

Baars uses this model to address many aspects of human cognition, and to explain a number of contrasts between conscious and unconscious cognitive functioning. Ultimately, however, it is a theory of cognitive accessibility, explaining how it is that certain information contents are widely accessible within a system, as well as a theory of informational integration and reportability. The theory shows promise as a theory of awareness, the functional correlate of conscious experience, but an explanation of experience itself is not on offer.

One might suppose that according to this theory, the contents of experience are precisely the contents of the workspace. But even if this is so, nothing internal to the theory explains why the information within the global workspace is experienced. The best the theory can do is to say that the information is experienced because it is globally accessible. But now the question arises in a different form: why should global accessibility give rise to conscious experience?

....(general text continued)....

The principle of structural coherence. This is a principle of coherence between the structure of consciousness and the structure of awareness. Recall that "awareness" was used earlier to refer to the various functional phenomena that are associated with consciousness. I am now using it to refer to a somewhat more specific process in the cognitive underpinnings of experience. In particular, the contents of awareness are to be understood as those information contents that are accessible to central systems, and brought to bear in a widespread way in the control of behavior. Briefly put, we can think of awareness as direct availability for global control. To a first approximation, the contents of awareness are the contents that are directly accessible and potentially reportable, at least in a language-using system.

Awareness is a purely functional notion, but it is nevertheless intimately linked to conscious experience. In familiar cases, wherever we find consciousness, we find awareness. Wherever there is conscious experience, there is some corresponding information in the cognitive system that is available in the control of behavior, and available for verbal report. Conversely, it seems that whenever information is available for report and for global control, there is a corresponding conscious experience. Thus, there is a direct correspondence between consciousness and awareness.

..... (snip).....

It is this isomorphism between the structures of consciousness and awareness that constitutes the principle of structural coherence. This principle reflects the central fact that even though cognitive processes do not conceptually entail facts about conscious experience, consciousness and cognition do not float free of one another but cohere in an intimate way.

....(snip)....

The principle of structural coherence allows for a very useful kind of indirect explanation of experience in terms of physical processes.

.....(snip)....

The coherence between consciousness and awareness also allows a natural interpretation of work in neuroscience directed at isolating the substrate (or the neural correlate) of consciousness. ..... If we accept the principle of coherence, the most direct physical correlate of consciousness is awareness: the process whereby information is made directly available for global control. The different specific hypotheses can be interpreted as empirical suggestions about how awareness might be achieved. ....    The same applies to other suggested correlates such as the "global workspace" of Baars (1988), the "high-quality representations" of Farah (1994), and the "selector inputs to action systems" of Shallice (1972). All these can be seen as hypotheses about the mechanisms of awareness: the mechanisms that perform the function of making information directly available for global control.

Given the coherence between consciousness and awareness, it follows that a mechanism of awareness will itself be a correlate of conscious experience. The question of just which mechanisms in the brain govern global availability is an empirical one; perhaps there are many such mechanisms. But if we accept the coherence principle, we have reason to believe that the processes that explain awareness will at the same time be part of the basis of consciousness.

...(general text to completion)....

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