A Non-Symbolic Theory of Conscious Content- Imagery and Activity
Nigel J.T. Thomas
Page 4
Source: http://www.imagery-imagination.com/nonsym.htm
From this point of view, any robot or organism capable of a rich behavioral repertoire in a complex environment will need to have a large number of perceptual instruments at its disposal, even though it may not need many types of actual sensor (five should be about enough!). But with large numbers of instruments, coordinating their use becomes an important issue. A sensor employed in making one sort of test may not always be simultaneously available for making another, and each instrument also draws on a necessarily limited pool of computational resources for control and analysis functions. It becomes important to deploy them strategically, using each instrument when and where its deployment is most likely to bring in currently useful information. Thus some sort of overall control program for the perceptual apparatus as a whole will be required. In a robot or organism capable of learning to improve its functioning in the environment this control system will need to be modifiable in the light of experience, revising its strategic plans for the deployment of perceptual instruments according to whether or not particular strategies have proved efficient or have led to desirable outcomes in the past. In a sense, then, the control system can be said to embody expectations about the world, but expectations that are constantly modified in the light of actual findings. Following Neisser (1976), I call such a self-modifying control structure a schema.
Note, however, that the schema is not to be identified with the conscious percept. Although it may be being constantly updated from perceptual input, its job is not to represent the world to us (to our selves, our consciousness, "higher level systems," our Cartesian minds, whatever), but to control the effective deployment of our perceptual instruments. This is the behavior that needs to be got right for perceptual consciousness to arise. For present purposes it hardly matters how this control function is realized or explained: whether in terms of dynamical systems theory, neural networks, "traditional" symbolic programming, or whatever. That is pragmatic issue for engineers or biologists. The only caveat is that it is important not to think of any computational symbols involved in the workings of the schema as being the mental representations of thought itself. The suggestion is that perceptual consciousness consists not in the internal presence of any sort of model of the outside world, but in the complex process of interaction between the schema, the array of perceptual instruments, and the environment itself.
The general form of such a schema controlled perceptual system is shown in figure 1. The two-headed dotted arrows toward the right represent the perceptual tests that can be made upon the perceived object itself, or its correlated causal products, querying the environment and returning results. The ongoing cyclical interaction between the schema, the array of instruments, and the environment is intended as equivalent to the "perceptual cycle" of Neisser (1976), and is hypothesized to be the material basis of conscious experience. The schema is responsible for sending out the orders, as it were, for the making of particular perceptual tests. However, it seems plausible that it might be possible for this process sometimes to become decoupled from actual perceptual testing. If the operation of the perceptual instruments were inhibited, or if their actual output were ignored (or partially ignored) in favor of the expectations embodied in the schema, then the cyclical process could become decoupled from the current environment, and the experience it produced would reflect memories previously laid down in the schema rather than the structure of the current environment. This, I suggest, is the material basis of imagery experience. If the schema is busily sending out orders to make the tests that would confirm the presence of a cat, no confirmatory results come back to it, yet it continues sending out cat-relevant orders anyway, then we are imagining a cat. Such activity has intentionality because it is directed at an object type (cats), and explaining such intrinsic intentionality is at least the first step to explaining consciousness. There will, of course, be a considerable (although never complete) degree of overlap between the physiological processes involved in this imagery and those involved in actually perceiving a cat, so it should be no surprise that the experiences are also significantly similar.
Provided this decoupled perceptual activity is not confused with actual perception, it can serve a very useful cognitive function. It makes it possible to be conscious of, to think about, things that are not actually present to sense. It makes it possible to imagine, to daydream, to plan: it is the substrate of conscious thought (Ellis, 1995). In language using creatures, imagined speech provides an especially powerful medium for complex and wide ranging thinking. But all this imagining is ultimately a form of behavior, albeit highly complex and largely covert behavior. If this paper is on the right track then filling in the details of this story and explaining how the relevant behavior is controlled and coordinated remains a large task for cognitive science. However, it is a task that seems likely to be amenable to the sorts of intellectual and experimental tools that cognitive scientists have already developed. Despite what some people may think, cognitive science may yet have the resources to explain the conscious mind.
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