When we consider the closing of circuits (or completion of cycles) which embody the meaning cycle in an individual brain, we are obviously dealing with a microscopic time scale – but exactly how microscopic? And are we talking about a single loop or many going on simultaneously? Baars and Franklin give a fairly typical set of answers to these questions, analyzing the iterations of a cycle into nine steps.
Our picture is of cognition as a continuing stream of cognitive cycles, overlapping so as to act somewhat in parallel. Because any single cognitive cycle can only become conscious at any given instant, their parallelism is constrained in such as way as to maintain the seriality of consciousness. We conjecture that a full cognitive cycle might take a minimum of 200 ms. But because of overlapping and automaticity, which shortens the cycle … as many as twenty cycles could be running per second. Working-memory tasks occur on the order of seconds, indicating that several cognitive cycles may be needed for any given WM task, especially if it has conscious components such as mental rehearsal.
Although we describe an iterating cycle from step 1 to step 9, in many tasks the cycle might begin with step 8, starting from an action that will enable some particular perception. That is because human beings are active, curious, and exploratory creatures, in which much input is interpreted in the context of ongoing activities.
— Baars and Franklin (2003, 169)
The 9-step cycle proposed by Baars and Franklin is only one variation on the cyclic theme represented in our meaning cycle diagram and the Rosen diagram. Freeman (1999b, 150), Edelman (2004, 79, Figure 10) and many others include such diagrams which are topologically similar, varying mostly in the number, arrangement and labelling of subloops. Freeman’s diagram of the action-perception cycle features a brain-body loop within it, and within that, reafference, control and spacetime loops.
Edelman’s diagram of ‘causal chains in the world, body, and brain’ (2004, 79, Figure 10) is also cognate to the Rosen diagram. It shows brain and body acting into the world, causing ‘world signals’ which interact with ‘self signals’ in the ‘dynamic core,’ enabling ‘higher-order distinctions or discriminations’; this neural activity then modifies our action patterns. Since ‘the world is causally closed,’ consciousness itself does not cause anything to happen, but is entailed by the distinction-making neural activity, as ‘the entailed phenomenal transform with its qualia consists of those distinctions’ (2004, 78-9).
Both Freeman and Edelman quote the remark of William James (1879) that consciousness appears to be ‘an organ added for the sake of steering a nervous system grown too complex to regulate itself’ (Freeman 1999b, 155-6; Edelman 2004, 84). But as Freeman points out, ‘consciousness is not provided by another “organ” (an add-on part of the human brain) but by a new hierarchical level of organization of brain dynamics’ (156). In his model, the nervous system does regulate itself, by means of circular causality, which works both bottom-up and top-down. Consciousness does not initiate any impulses toward action, but as these arise from the microscopic neural activity, the higher-level ‘global operator’ takes advantage of the delay introduced by the complexity of cortical functioning to damp most of these impulses and amplify a selected few, and thus it constrains the very microscopic processes that constitute it.
Both Freeman and Edelman emphasize the variability of this process: unlike a computer, a human brain does not reliably produce the same ‘output’ when given the same ‘input.’ Edelman remarks that the ‘very richness of core states provides the grounds for new matches to the vicissitudes of the environment. Those matches are stabilized through the workings of the brain as a complex system’ (2004, 85). The richness (variability) of the ‘core states’ underlying consciousness provide the same service for the organism that ‘overhead’ provides for an ecosystem in the Ulanowicz model – or that ‘prophecy’ and creative imagination provide for a culture.