The Dual Mechanism Model posits two different cognitive mechanisms for morphologically complex word forms: decomposition of regulars into stems and exponents, and full-form storage for irregulars. Most of the research in this framework has focused on contrasts between productive and non-productive inflection. In this paper, we extend the model to derivational morphology. Our studies indicate that productive derivation shows affinities with both productive and non-productive inflection. We argue that these results support the linguistic distinction between derivation and inflection, particularly as it is represented in realization-based models of morphology
