Semantic Cognition: Its Nature, Its Development, and Its Neural Basis

Abstract

We consider parallels in the development of conceptual knowledge and its disintegration in a neurological disorder. During development, children's concepts become more differentiated. Developing children make striking errors, attributing properties to objects that they do not have and over-extending frequent category labels to other objects. Patients with semantic dementia (SD), a progressive condition affecting the anterior temporal lobes, show a loss of differentiation of concepts. Like developing children, they attribute properties to objects that they do not have and over-extend frequent category labels. Such patients may draw four legs on a duck, or call an elephant a horse. We present a theoretical framework and computational models that explain these parallel phenomena. We also consider the disintegration of lexical knowledge, which parallels the deterioration of semantics in SD patients. We present a model that simulates these findings within a single system that processes and represents both lexical and semantic information.