Constraining Theories of Semantic Memory Processing: Evidence from Dementia

Abstract

In this paper we analyse the performance of ten patients with Dementia of the Alzheimer’s Type (D.A.T.) who show a pattern of performance suggesting a deficit at the level of semantic memory in the face of normal visual perceptual processing. We use the results of their performance on probe questions for pictures and words to evaluate several hypotheses arising from recent theories concerning semantic memory. We assess whether these patients demonstrate better performance on pictures than words (they do), and whether this can be explained away as a by-product of the perceptual nature of the items tested; pictures whose items have many discernible object parts would tend to contact more residual information in semantic memory, thus producing apparent superior performance from pictures. In fact, we find no support for this explanation. Rather, we are able to demonstrate, in the semantic category of animals, that it is only the items that are correctly identified (as a whole) that will give rise to evidence of better performance on pictures. © 1992, Taylor & Francis Group, LLC. All rights reserved.