Attribute Verification in Dementia of Alzheimer Type: Evidence for the Preservation of Distributed Concept Knowledge

Abstract

This study reports on a group of patients with dementia of Alzheimer's type DAT who were selected on the basis that they all made similar semantic paraphasias in a word-to-picture matching test. Using knowledge probe questions, it was shown that these patients were more accurate at verifying properties shared by many exemplars in a category i.e. superordinate knowledge, than properties specific to few exemplars in the category i.e. item-specific knowledge. Differences in level of cognitive effort could not explain this effect. Furthermore, it was shown that although concept familiarity correlated with performance on item-specific probes it did not correlate with performance on superordinate probes. It is argued that these results support the predictions of neural network models of semantic memory in which a concept is represented by a distributed pattern of activity across a set of features. In such models, there is noexplicitdistinctionbetween basic level, subordinatelevel, andsuperordinate level features, but rather, features vary in the number of times they occur within the training set.

Ähnliche Arbeiten