Monday, March 23, 2009

TNP 10. Summary

The Network Phenomenon: Empiricism and the New Connectionism
Stephen Downes, 1990
(The whole document in MS-Word)


TNP Part IX Previous Post


Part X Summary

This concludes the presentation of the theory of learning and cognition which I wish to present. Before describing some of the further avenues of investigation I wish to pursue, let me summarize what I have asserted to this point in this paper.

I began by proposing a new theory of learning, connectionism, and described some prima facie objections to the theory. In order to respond to those objections, I argued that we need to reconsider some paradigms concerning rules and categories. Then I developed connectionism as an alternative theory of rules and categories. On this new theory, any concept is represented as a pattern of activations in a network of interconnected units. A category, on this view, is represented by a unit which can be actiuvated, and the members of the category are the concepts whose connections activate the unit which represents the category. Connectionist networks not only store categories in this manner, they can learn them on their own. In order to develop this idea further, I examined a number of objections to the concept of distributed representation. To meet these objections, I described how patterns are developed from perceptual input and described and defended the "picture" theory of representation.

I then turned to considering detailed objections to associationism and connectionism. These divided into problems concerning distributed representation, problems concerning perception, and problems concerning associative mechanisms in general. In order to defend against problems of distributed representation, three types of patterns of connectivity were identified and the concept of similarity was defined in terms of activation vectors. In order to develop a theory of perception, I defined perception as input activations and two types of perception, conscious and real perception, were identified. This successfully explained theory-ladeness and the development of three-dimensional representations without the requirement of a priori or innate knowledge. Finally, a number of arguments against associationism were considered. In order to show that associationist and connectionist systems can perform higher level cognitive functions, I argued that a two-stage process is employed. First, prototypical representations are constructed, and then second, these are used to support inference by analogy or metaphor. This is in turn supported by the observation that such process [can] be viewed as operations. Finally, I considered the problem of the evaluation of models and inferences in connectionist systems, and argued that we should employ the concept of relevant similarity.


TNP Part XI Previous Post

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