Analysis of the conceptual structure of natural and artifactual categories in Alzheimer's disease patients

This work has two goals, the first one is to study in detail the conceptual structure of some natural and artifactual categories, by using multidimensional scaling (MDS). According to our theoretical approximation, conceptual structure is composed of semantic features, and these features have different entities and nature. As an index of relevance in mental representation of semantic categories, we took the frequency of production of semantic features on a free verbal production task. Our second goal was to compare the structure of conceptual representations in two populations, healthy elderly and Alzheimer's disease (AD) patients, assuming that conceptual representation is impaired in this last population. We assume that the impairment in the conceptual representations of AD patients will show, when the disease reaches a determined level, loosing specific features. This impairment will have serious consequences in the whole conceptual structure.