0 Self-Organization of Object Categories in a Cortical Artificial Model Alessio Plebe Department of Cognitive Science, University of Messina Italy 1. Introduction Explaining the human capacity to construct mental categories is a central question in cognitive science, yet how reality is perceived and compartmentalized by our mind has puzzled philosophers since Aristotle. Today, categorization is believed to be a strategy humans have in common with many animals. In most species, individuals have the opportunity to directly experience only a tiny fraction of the entities, objects, features and events offered by their environments. By relying on categorization, organisms become able to determine which things in the world belong together or are alike in some way, therefore reacting in an appropriate manner, thanks to the previous experiences had with other instances of the same category. The purpose of this chapter is to investigate computational models that can simulate mechanisms underlying the ability to develop categories. We argue that a neural mechanism for detecting and coding recurrent coincidences in stimuli could be the key component in our brain’s ability to build the categories it uses to organize reality. The mathematical framework that has given the best interpretation so far on how signals with high levels of autocorrelation affect networks of neurons with local coincidence detection and coding abilities, is the one referred to as self-organization. Being categorization a phenomena appearing at so many different cognitive levels, and that is pervasive in so many different modalities, we doubt that it could rely upon a single mechanism. Moreover, we believe that humans unlike any other animal reshape their categories and build new ones, by virtue of the information provided to them by language as soon as they have developed the most rudimentary understanding of it. Nevertheless, we do not see reasons for posing that the pre-linguistic development of categories in infants should happen as a result of mechanisms different from those found in other species. Even if we are convinced that different mechanisms might contribute, the basic mechanism briefly discussed is one we consider to play a key role. 1.1 The problem of mental categories The research on categorization in humans can be traced back to traditional domains. In philosophy the objective of epistemology has included explaining the acquisition of knowledge, with empiricists attempting to formulate explanations in terms of mental mechanisms (Locke, 1690; Hume, 1739). It was within the field of psychology, however, that the search for this sort of mechanism became a central issue, employing the strategy of experimental analysis of the ontogenesis of categories in infants. While holding in high regard 33