Multilevel category structure in the ART-2 network

Multilevel categorization is investigated within the context of analog activity patterns on the output layer of an ART 2 network. The ART 2 network parameters are analyzed in terms of stable category formation and in terms of the number of nodes in the output layer that can become most active. The resulting activity patterns on the output layer demonstrate a multilevel category structure based on the relative differences between patterns that exist for many different values of the vigilance parameter. We have shown that the information contained in the output analog patterns can be interpreted in several different ways, which is not possible when the category is represented by a single winning node. Also, favorable comparisons are also demonstrated between the category structure emerging from the set of category patterns and principles of categorization in psychology and neurobiology.