Gabora's target article presents an engaging scenario of the evolutionary origins of culture in the streams of consciousness of early human beings. Her thesis is grounded in a model of episodic memory and its representation in the brain. The present commentary explores questions concerning the role of consciousness in ongoing mental processes, as well as issues concerning memory and the brain. It examines the association of consciousness with brain activity in abstract and creative thinking, and reviews contemporary theories of memory in the brain. The present commentator prefers a holistic approach to memory using, for example, a dynamical representation, or a holonomic one.
2. To begin, the idea that the various elements of our day to day stream of consciousness, memes included, are self-organizing seems well founded. Indeed, a detailed examination of the process nature of human experience supports the notion that many elements of experience such as thoughts, memories, emotions, and perceptions combine and recombine dynamically in ways that are mutually supportive -- or to be more accurate, actually self-creating -- so that the overall fabric of experience is autopoietic, creating itself anew in each moment (Combs, 1996a, 1996b). Gabora describes this process as autocatalytic, analogous to complex self-sustaining chemical reactions, as suggested by Kauffman (1993), or similarly complex algorithmic interactions such as those developed by Fontana and Buss (1996). Reflection on this approach leads directly to the core question of whether the mind, and thus the brain, operates in a logical, computational mode (e.g., Fodor, 1995), or in some other way. My own inclination is toward dynamical processes in the brain, and thus in the mind. Although the latter can be shown to be formally equivalent to the former (Kampis, 1991), it is becoming increasingly apparent that the brain operates in terms of activity in large neural networks that can best be characterized by dynamical models. For an interesting twist on this whole issue, however, note Dennett's (1991) proposal that logical thought is made possible by neural networks that mount a simulated von Neumann architecture, reminiscent of the inverse and commonly used simulation of neural network architectures run on traditional Turing machines.
3. The target paper also addresses the importance of consciousness in the thinking process. Although Gabora gives it a central role, it is not obvious why her basic idea would not be as valid without the continuous light of consciousness. Indeed, it is not known at this time just how important consciousness is to the thinking process at all. An excellent case can be made that consciousness is incidental and often even absent for many of the mental processes ordinarily associated with thinking and intelligence, including linguistic ones (e.g., Baars, 1997; Gazzaniga, 1998). There is a related question of whether conscious experience is continuous. Despite William James's (1890/1981) observation that thought is sensibly continuous (p. 221), many contemporary theorists of consciousness question this (e.g., Dennett, 1991). The matter is yet to be settled.
4. Looking into this question a bit more deeply, however, we note that Gabora's discussion turns critically on the ability of early humans to make connections in time not only between sensory experiences and drive states, but between abstractions. It seems reasonable to suspect that abstract ideas require conscious participation to a degree beyond that needed for more basic or automatic mentation, especially if the former involves novelty. There is strong evidence that novelty in thought and action requires considerably more from the brain than do routine tasks, not only metabolically but also in terms of the range of structures activated (e.g., Baars, 1997; Posner & Raichle, 1994). This is further supported by literature suggesting that unconscious cognition is more habit-bound and rigid than what is associated with consciousness (Reber, 1992). All this is favors the idea that, while conscious experience may not be continuous in the strict Jamesian sense, the connection of abstract ideas into an increasingly large and fluid body of knowledge -- knowledge of the sort that might undergird human culture -- might have originated from higher-order conscious brain processes, in other words, conscious creative thought, conjoining the past to the present and the future in a continuous arc.
5. Much of Gabora's target article concerns the distribution of memories in the brain. This has been one of the most intriguing and enigmatic problems in the history of brain science. Gabora suggests that memory storage must, among other things, be distributed, content addressable, and modular, all of which seem to be true in the literature, at least in broad terms. An important question concerns whether memory storage is best understood on the scale of circuitry and neuronal activity, or on the smaller scale of synaptic interactions and the complex interference patterns typical of local dendritic fields (e.g., Alkon et al., 1996; Pribram, in press). While the former is most widely accepted at this time, the present commentator favors the latter for a number of reasons (Combs, in press). Whatever the form of the engram, it must, according to the conditions of the target article, be readily accessible for easy elicitation of episodic memory associations. Complex neural networks would in general seem well suited to this end, since the dynamical processes they tend to support could, given the right architecture, flow easily from one attractor basin (memory) to another. An explicit physiological version of this idea is seen in Freeman & Berrie's (1994) model of perception and memory, both represented by attractor patterns in the cortex that are constantly altered by experience. Pribram's (1991) holonomic model also postulates memory at the level of the cortex as a dynamic attractor. The latter approach has the advantage of explicitly positing a multidimensional process in which multiple memory images can be elicited simultaneously. One memory could directly activate another, much as either of the interference beams that create a hologram can (re)activate the other.
6. The above issues only circle around the central thesis of the target article, namely, that the evolution of culture required a fluid conscious process that has easy spontaneous use of episodic memories and the creation of abstractions. Without ready access to memories of past experiences, human intelligence (let alone the evolution of cultures) could hardly have come about. In this, Gabora's thinking is based explicitly on the work of Donald (1991), who argues that among primates only humans have the ability to spontaneously draw on episodic memories to weave new tapestries of complex ideas. Donald's argument is attractive, and hints at a fundamental difference between the human and non-human brain. It would be rewarding to see more research aimed directly at this hypothetical difference. One hopes that over the next few decades research in anthropology, paleoneurology, and careful thinking about the evolution of intelligence and culture by theorists like Donald, Mithen (1996), and Gabora will provide nourishing fare for those of us interested in the origins and nature of the human being.
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