[This is an excerpt from Part II of my latest book On Consciousness: Science & Subjectivity.]
In Book VII of Plato’s Republic (Plato, 1956) we find the following allegory:
Imagine mankind as dwelling in an underground cave with necks and legs fettered, so they have to stay where they are. They cannot move their heads round because of the fetters, and they can only look forward, but light comes to them from fire burning behind them … What do you think such people would have seen of themselves and each other except their shadows, which the fire cast on the opposite side of the cave? (p. 312).
Plato’s famous Allegory of the Cave has odd and unexpected resonances down the ages, and indeed in Asian philosophy as well. Remarkably, two and a half millennia later another observer wrote:
A common metaphor is that of a “spotlight” of visual attention. Inside the spotlight the information is processed in some special way. This makes us see the attended object or event more accurately and more quickly and also makes it easier to remember. Outside the “spotlight” the visual information is processed less, or differently, or not at all (Crick, 1993, p. 62).
Plato’s point was the fallibility of conscious perception compared to the eternal verities of philosophy, while Francis Crick was aiming to understand the relationship between the brain structure called the thalamus and the great cerebral cortex, both necessary for consciousness.
What is the difference between Plato’s fire-cast shadows and Francis Crick’s thalamic spotlight?
I feel moved as much by the similarities as the differences: both are unifying conceptions of human consciousness. In fact, both seem to reflect the same underlying metaphor of our personal experience, the theater metaphor.
Plato’s Allegory of the Cave may be more elaborate, but Crick’s spotlight has a more solid basis in brain anatomy and physiology. A number of cognitive and brain scientists have suggested versions of the theater metaphor, and in ancient times the same theme was sounded in Vedanta philosophy, at various points in Western thought, and surely by poets and philosophers in many other times and places.
Daniel Dennett and Marcel Kinsbourne have criticized one theater model, the Cartesian Theater in which conscious experience comes together in a single point in the brain, much as René Descartes thought consciousness might be located in the tiny pineal gland. Descartes was looking for just one dimensionless point where the singular soul might connect with the brain.
Dennett and Kinsbourne claim the Cartesian Theater cannot work, and I believe they are right. It makes no sense. There is no single point in the brain where “it all comes together.” But no one in science today suggests a Cartesian Theater. Certainly none of the cognitive theaters models that have been proposed since the 1950s suffer from these defects. Nor do movie theaters converge on a single dimensionless point. Theaters work just fine in the real world, and provide helpful metaphors for exploring human experience. If such a metaphor becomes misleading at some point, we should simply walk away from it and look for something better.
The Wide Use of Theater Models
As it happens, all of our unified models of mental functioning today are theater metaphors; it is essentially all we have. Cognitive architectures developed by Alan Newell, Herbert A. Simon, John R. Anderson and others resemble theaters. All are equipped with working memories that are limited in capacity. All involve active elements, much like the conscious elements of working memory, though without using the word “consciousness.” And all have large sets of unconscious mechanisms, whether they are called productions, long-term memory, or procedural memory (Newell, 1990; Anderson, 1983).
These theories have been developed over the last forty years based on a vast range of evidence, from studies of chess players to arithmetic problem-solving, mental rotation of visual images to action skills. A remarkable group of distinguished scientists have devoted careers to these integrative conceptions of human cognition.
The theater of consciousness is simple in concept. Imagine a stage, with an attentional spotlight shining on the stage, actors to represent the contents of conscious experience, an audience, and a few invisible people behind the scenes, who exercise great influence on whatever becomes visible on stage. The stage receives sensory and abstract information, but only events in the spotlight shining on the stage are completely conscious. The actor in the spotlight frets and struts his hour upon the stage, directed by the playwright and director, against a background created by scene setters. These behind-the-scenes influences are frame stacks (context operators),unconscious systems that shape conscious events. The spotlight selects the most significant actors on stage, and once lit up, their messages are distributed to an audience consisting of all the unconscious routines and knowledge sources — the vast array of unconscious tools we use to adapt to the world.
Here is perhaps the most important point:
Scientific metaphors
Metaphors have a long history in science to help us make the leap from the known to the unknown. The clockwork metaphor of the solar system helped astronomers in the 16th century understand the interplay of the planets. William Harvey’s discovery that the heart pushed blood through the veins and arteries, much like a pump, has been a useful metaphor for several centuries and it is still used today. Physicists about 1900 found the image of the atom as a tiny solar system a helpful starting point for under‐ standing subatomic structure. Many scientific theories begin as humble metaphors.
Obviously we don’t expect to find tiny theaters in the brain. We may, however, be able to find structures that display and disseminate conscious contents. The conscious parts of the brain seem to include the sensory areas of the cortex, perhaps some surrounding areas, supported by a few subcortical structures; and fleetingly, perhaps, amodal cortex, which does not give rise to sensory qualities. Together they may provide the stage for the unconscious audience in the rest of the brain. The theater concept helps us to think about brain functioning in an interesting way.
Metaphors must be used with care. They are always partly wrong, and we should keep an eye out for occasions when they break down. Yet they often provide the best starting point we can find.
. . .
Global Workspace Theory (GWT) began with this question: “How does a serial, integrated and very limited stream of consciousness emerge from a nervous system that is mostly unconscious, distributed, parallel and of enormous capacity?”
GWT is a widely used framework for the role of conscious and unconscious experiences in the functioning of the brain, as Baars first suggested in 1983.
A set of explicit assumptions that can be tested, as many of them have been. These updated works by Bernie Baars, the recipient of the 2019 Hermann von Helmholtz Life Contribution Award by International Neural Network Society form a coherent effort to organize a large and growing body of scientific evidence about conscious brains.
