Global
Workspace

A Theory of
Consciousness

Bernard J. Baars and Katherine McGovern

(revised November 5, 1997)

Global Workspace theory is a simple cognitive architecture that has been
developed to account qualitatively for a large set of matched pairs of conscious
and unconscious processes (Baars, 1983, 1988, 1993, 1997). Such matched
contrastive pairs of phenomena can be either psychological or neural.
Psychological phenomena include subliminal priming, automaticity with
practice,  selective attention, and many others. Neural examples include
coma and blindsight.   Like other cognitive architectures (Newell,
1990), GW theory may be seen in terms of a theater metaphor of mental
functioning.  Consciousness resembles a bright spot on the theater stage of
Working Memory (WM), directed there by a spotlight of attention,  under
executive guidance (Baddeley, 1992). The rest of the theater is dark and
unconscious. "Behind the scenes" are contextual systems, which shape conscious
contents without ever becoming conscious, such as the dorsal cortical stream of
the visual system.

This architectural approach leads to specific neural hypotheses.  For
sensory consciousness the bright spot on stage is likely to require the
corresponding sensory projection areas of the cortex. Sensory consciousness in
different modalities may be mutually inhibitory, within approximately 100-ms
time steps.

Sensory cortex can be activated internally as well as externally, resulting
in conscious inner speech and imagery.  Once a conscious sensory content is
established, it is broadcast widely to a distributed "audience" of expert
networks sitting in the darkened theater, using corticocortical and
corticothalamic fibers. Among the experts behind the scenes are "self-systems,"
viewed as contextual data structures that both shape and receive information
from the bright spot; they include parts of prefrontal cortex, but may range
posteriorly as far as parietal cortex for visual orientation.

The primary functional role of consciousness is to allow a "blackboard"
architecture to operate in the brain, in order to integrate, provide access, and
coordinate the functioning of very large numbers of special- ized networks that
otherwise operate autonomously (Mountcastle, 1978). All the elements of GW
theory have reasonable brain interpretations, allowing us to generate a set of
specific, testable brain hypotheses about consciousness and its many roles in
the brain.  This approach is compatible with a number of other proposals
(Crick, 1984; Crick & Koch, 1990; Damasio, 1989; LaBerge, 1997; Gazzaniga,
1996; Ramachandran, 1995; Edelman, 1989; Llinas & Ribary, 1992; Newman &
Baars, 1993; Shallice, 1976; Posner, 1992).

Bernard J. Baars and Katherine McGovern
The Wright Institute

Berkeley, California

2003 Update

See Baars, Bernard J. (2003). The global brainweb: An update on global
workspace theory. Guest editorial, Science and Consciousness Review,
October 2003. Full
text.

Bibliography (revised 10 August 2004)

Baars, Bernard
J. (1983). Conscious contents provide the nervous system with coherent, global
information.  In R.J. Davidson, G.E. Schwartz & D. Shapiro (Eds.).
Consciousness & Self- regulation. New York, NY: Plenum Press.

Baars, Bernard J. (1988). A Cognitive Theory of Consciousness. New
York: Cambridge University Press. Preface and first
chapter.

Bridgeman, Bruce (1996). What We Really Know About Consciousness.
Review of A Cognitive Theory of Consciousness by Bernard Baars.
Psyche 2. 30. Full
text (external).
Baars, Bernard J. (1996). Understanding
Subjectivity: Global Workspace Theory and the Resurrection of the Observing
Self. Journal of Consciousness
Studies 3. 3: 211-16.

Baars, B. (1997). In the theater of
consciousness: The workspace of the mind. New York: Oxford University
Press.

Baars, Bernard J. (1997). In the Theatre of Consciousness: Global
Workspace Theory, A Rigorous Scientific Theory of Consciousness. Journal of
Consciousness Studies 4. 4: 292-309. Full text
(external pdf). Full issue with
peer commentary (external).

Baars, Bernard, James Newman, and John Taylor (1998) Neuronal mechanisms
of consciousness: A Relational Global Workspace framework. In Hameroff,
Stuart and Kaszniak, Al and Laukes, James, Eds. Toward a Science of
Consciousness II: The second Tucson discussions and debates., chapter 24,
pages pp. 269-278. MIT Press. Abstract with link to
full text (CogPrints; external).

Baars, B.J. (2002) The conscious access hypothesis: Origins and recent
evidence. Trends in Cognitive Science 6. 1: 47-52.

Baars, Bernard J., William P. Banks, and James B. Newman (eds) (2003).
Essential Sources in the Scientific Study of Consciousness. MIT Press. Publisher's
abstract.

Crick, F., Koch, K. (2003). A Framework for Consciousness. Nature
Neuroscience 6. 2.

Damasio, A.R. (1989). Time-locked multiregional retroactivation: A
systems-level proposal for the neural substrates of recall and recognition.
Cognition 33. 1-2:25-62.

DeHaene, Stanislas & Lionel Naccache (2001). Toward a cognitive
neuroscience of consciousness: basic evidence and a workspace framework.
Cognition 79: 1-37.

Dennett, Daniel (2001). Are we explaining consciousness yet? Cognition
79: 221-237.
Dretske, F. (1995). Naturalizing the Mind. Cambridge, MA:
MIT Press.

Edelman, Gerald M. (1989). Neural Darwinism. New York:
Basic Books.

Edelman, Gerald M. & Tononi, G. (2000). A universe of
consciousness. How matter become imagination. New York: Basic Books.

Humphrey, N. (2000). How to solve the mind-body problem. Journal of
Consciousness Studies 7. 4: 5-20.

John, E.R. (2000). Consciousness & Cognition 10.
2.

Kanwisher, N.  (2001). Neural events and perceptual awareness.
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Llinas, R., Ribary, U., Contreras, D.,
Pedroarena, C. (1998). The neuronal basis for consciousness. Philos Trans R
Soc Lond B Biol Sci 353. 1377: 1841-9

Metzinger, T. (ed) (2000). Neural Correlates of Consciousness: Empirical
and Conceptual Questions. Cambridge, MA: MIT Press.

Metzinger, T. (2003). Being No One: The Self-model Theory of
Subjectivity. Cambridge, MA: MIT Press.

Revonsuo, A. (2000). Prospects for a scientific research program on
consciousness. In Metzinger (2000), 41-56.

Taylor,J.G. (2003). The missing self, or: 10 ways to be a zombie,” Science
and Consciousness Review, http://psych.pomona.edu/scr/editorials/20030203.html.

Tye, M. (1995). Ten Problems of Consciousness: A Representational Theory
of the Phenomenal Mind. Cambridge, MA: MIT Press.

Varela, F., J.-P. Lachaux, E. Rodriguez, J. Martinerie (2001). The brainweb:
Phase synchronization and large-scale integration. Nature Reviews -
Neuroscience 2 (April): 237.

Critiques of Global Workspace Theory

Blackmore, Susan (2002). There is no stream of consciousness.
Journal of Consciousness Studies 9. 5-6. Full text
(external).

Blackmore, Susan (2004).
Why Global Workspace Theory cannot explain consciousness. Presentation.
Toward a Science
of Consciousness 2004. Abstract
(external).

See also the peer commentary (external) to
the target article Baars (1997). In the Theatre of Consciousness: Global
Workspace Theory.

Gamma & Kiper's course on
Consciousness at the University of Zurich, 2003-4.

Next: Dynamics of
Brain Processes

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Francis F. Steen,
Communication Studies, University of California, Los
Angeles