Bernard Baars’s Global Workspace Model of Consciousness
Another researcher from within the cognitive science tradition is Bernard Baars (1946—). He models the mind as a system of nonconscious information-processing modules that communicate through a global workspace. Baars’s model is based on research in symbolic artificial intelligence (AI) in so-called blackboard models. In his book “A Cognitive Theory of Consciousness” (Baars 1988, p. 87), he refers the reader to an article by AI researchers Lee Erman and Victor Lesser, titled “A Multilevel Organization for Problem Solving” (Erman and Lesser 1975). The abstract of that paper begins:
An organization is presented for implementing solutions to knowledge-based AI problems.
Erman and Lesser describe their blackboard architecture as a globally available memory storage area:
A uniform and integrated multi-level structure, the blackboard, holds the current state of the system. Knowledge sources cooperate by creating, accessing, and modifying elements in the blackboard. (Erman and Lesser 1975)
Baars finds blackboard models appealing, as they allow him to think of the brain as a distributed cognitive system with a central information exchange:
The nervous system does have components that act as executives. But these executives operate in a fundamentally decentralized environment, much as a government may operate to regulate a market economy, which is still fundamentally decentralized. But even without a true executive, a distributed collection of processors still needs some central facility through which the specialists can communicate with each other. This kind of central information exchange has been called a “global workspace,” “blackboard,” or “bulletin board”
. . . (Baars 1988, p. 87)
As in Erman and Lesser’s system, the information interchange is globally available symbolic memory:
A “workspace” is just a memory in which different systems can perform operations, and the word “global” implies that symbols in this memory are distributed across a variety of processors. (Baars 1988, p. 87)
Baars’s blackboard approach to consciousness involves a global workspace of conscious action and experience. We are to think of consciousness as information processing in a global workspace—metaphorically, a stage where conscious processes are part of a theatrical performance. Baars motivates his theater model through an appeal to Plato:
This idea is sometimes called “the screen of consciousness.” An early version may be found in Plato’s classic Allegory of the Cave. Plato compared ordinary perception to the plight of bound prisoners in a cave, who can see only the cave wall with the shadows projected on it of people moving about in front of a fire. The people projecting the shadows are themselves invisible; they cannot be seen directly. We humans, according to Plato, are like those prisoners—we only see the shadows of reality. Modern versions of the Theater Hypothesis may be found in Lindsay and Norman (1977); Crick (1984)—and throughout this book. (Baars 1988, p. 31)
In Baars’s version, consciousness is in the spotlight, and as its intensity diminishes, so does awareness until we reach its fringe. Backstage, actors are getting ready to go onstage—they are changing costumes, stagehands are running around rigging things, the director might be talking to actors, props are being moved around, and so on.
Baars’s backstage work is a metaphor for processing prior to conscious experience—sense data are processed, objects are being discriminated and identified, memories are retrieved and formed, new associations are made, and so on. Backstage work makes it possible for things to appear in consciousness, in the spotlight of the theater—the light of consciousness.
Baars supports his theater model by noting that we cannot hold many things simultaneously in working memory. When someone gives you their phone number and you rehearse it before writing it down, you put each digit into consciousness, one at a time (onstage). Evolution appears to have given us consciousness as a focused information-processing space, which we are to understand through his theater model.