COMPETING FOR CONSCIOUSNESS: How Subconscious Thoughts Cook on the Backburner
A Talk with William H. Calvin

Francis Crick likes to observe that people once worried about the boundary between the living and the nonliving. Today, the boundary seems meaningless; we instead talk about all the varied aspects of molecular biology. Today's brain researchers think it likely that much of the present scientific and philosophical concern about consciousness will soon become equally obsolete, that we will simply come to talk of the various physiological processes involved with attention and creative problem-solving. Dan Dennett called consciousness "the last surviving mystery." A mystery, Dennett said, "is a phenomenon that people don't know how to think about - yet." Here I will attempt to clarify the appropriate levels of explanation and then propose a candidate mechanism, a Darwin Machine¹ that seems, because its circuitry is found in many parts of neocortex, capable of encompassing the higher intellectual function aspects of consciousness as well as some of the attentional aspects.

Consciousness is the tip of the iceberg, in the sense that many other things are going on in the brain at the same time, hidden from view. There are subconscious trains of thought that vie for "attention." Though the obvious analogy is to the television viewer who surfs the channels (and our nighttime dreams often seem like switching between soap operas in progress), there need not be a central place where choices are viewed. The "best" channel need only temporarily win out over the others in the battle for access to output pathways such as speech and other body movements. Soon, another channel comes to dominate and we speak of "our attention shifting" - but there need not be an agent which makes the decision or performs the action. There is nothing in this overview that demands a central place: the "center of consciousness" could, instead, shift from moment to moment: from language to nonlanguage areas, from frontal to parietal lobe, from left to right hemisphere, and maybe even from cortical to subcortical structures - anywhere, I suspect, with the potential for generating novel patterns of movement. Routine tasks can be handled on the back burner but dealing with ambiguity, groping around, generating creative choices, and performing precision movements may temporarily require substantial allocations of neocortex.

Rather than place, I think that we need to concern ourselves with levels - levels of mechanism from the subsynaptic to the metaphorical - and how new levels can be temporarily formed as we think about what to say next. What's missing from most discussions of consciousness is, surprisingly, the whole concept that there are levels of mechanism, or levels of explanation. Douglas Hofstadter² gives a nice example of levels when he points out that the cause of a traffic jam is not to be found within a single car or its elements. Traffic jams are an example of self-organization, more easily recognized when stop-and-go achieves an extreme form of quasi-stability - the crystallization known as gridlock. An occasional traffic jam may be due to component failure, but faulty spark plugs aren't a very illuminating level of analysis-- not when compared to merging traffic, comfortable car spacing, driver reaction times, traffic signal settings, and the failure of drivers to accelerate for hills. -----

The more elementary levels of explanation are largely irrelevant to traffic jams. Such decoupling was emphasized by the physicist Heinz Pagels³, who noted:

"Causal decoupling" between the levels of the world implies that to understand the material basis of certain rules I must go to the next level down; but the rules can be applied with confidence without any reference to the more basic level. Interestingly, the division of natural sciences reflects this causal decoupling. Nuclear physics, atomic physics, chemistry, molecular biology, biochemistry, and genetics are each independent disciplines valid in their own right, a consequence of the causal decoupling between them.... Such a series of "causal decouplings" may be extraordinarily complex, intricate beyond our current imaginings. Yet finally what we may arrive at is a theory of the mind and consciousness - a mind so decoupled from its material support systems that it seems to be independent of them - and "forgot" how we got to it.... The biological phenomenon of a self-reflexive consciousness is simply the last of a long and complex series of "causal decouplings" from the world of matter.

Closely related is the notion of emergent properties: traffic jams and crystals emerge from combinations, and we expect emergence to play a large role in the transient levels of organization involved with higher intellectual function (language, planning, games, etc.). In our search for a level corresponding to consciousness, it is well to recall that levels arise from what Jacob Bronowski called stratified stability:

Nature works by steps. The atoms form molecules, the molecules form bases, the bases direct the formation of amino acids, the amino acids form proteins, and proteins work in cells. The cells make up first of all the simple animals, and then the sophisticated ones, climbing step by step. The stable units that compose one level or stratum are the raw material for random encounters which produce higher configurations, some of which will chance to be stable.... Evolution is the climbing of a ladder from simple to complex by steps, each of which is stable in itself.

The tumult of random combinations occasionally produces a new form of organization. Some forms, such as the hexagonal cells that appear in the cooking porridge if you forget to stir it, are ephemeral (as, indeed, are the contents of our consciousness). Other forms may have a "ratchet" that prevents backsliding once some new order is achieved. Crystals are the best known of these quasi-stable forms.