Linguistic or systematic research of irregularity is a comparatively new area of concern in the last 20 years. In addition to the description of regulars and irregulars, close attention began to be shifted to these aspects: What is the interaction between storage and computation in language processing? What is the psychological status of grammatical rules? What are the relative strengths of connectionist and symbolic models of cognition? How do the components of language implemented in the brain? The English past tense has served as an arena for debates on these issues.