Chapter 3 is an excellent overview of some of the current issues in the study of categories. One of the theoretical controversies in this domain concerns the prototype vs. exemplar issue, that is, whether a summary of all examplars is stored or each exemplar is stored seperately. Weaver handily resolves this issue with respect to connectionist models. He quickly follows with a strong argument for the existence of statistical categories based on sets of correlated features.

A number of topics are discussed in Chapter 4. There are two of primary interest, however. The first is whether/when categories of world objects are based on functional attributes (e.g., good to eat) or perceptual attributes (e.g., red and spherical). The second is the role of surpervision (i.e., clear, explicit feedback) in learning categories — what form it might take and indeed if it is necessary.

While reading Weaver, it is useful to keep in mind that the prototype theory and statistical categories of Chapter 3 along with the perceptual attributes of Chapter 4 are strongly interrelated concepts. Comparably, theory-based categories (Ch. 3) and functional attributes (Ch. 4) are also closely related.

In this selection McCloud does a nice job making the case that much of what we perceive as reality is in fact filled in by our minds. The perceptual model we will develop in this class is called an active symbol representation and here McCloud shows just how active our symbols can be.

This is our first direct exposure to Hebb. He is widely considered to be the father of modern neural network theory and his ideas find their way into nearly every aspect of this course. This chapter is so chock full of important ideas that we will break it up over the course of two sessions. For this time read up to the section "Cell-assemblies: The basis of thought."

Pay particular attention to the section "Synaptic Changes in Learning," in it Hebb discusses his famous learning rule. As you read this chapter keep in mind the other readings in this selection and try to put them into the context of Hebb’s theory.