Identity negative priming in older adults and individuals with dementia of the Alzheimer type.

Abstract

This study addressed the question of whether dementia of the Alzheimer type (DAT) produces a breakdown in aspects of the inhibitory component underlying selective attention. Two measures of identity negative priming and 2 measures of distractor interference were obtained. In Experiment 1, participants were presented with overlapping picture stimuli, and in Experiment 2, participants were presented with overlapping written word stimuli. The results of both experiments produced reliable and similar size negative priming in young and old adults, but there was no evidence of negative priming in the individuals with DAT. In contrast, the naming latencies of all 3 groups showed a reliable and similar size distractor interference effect. These results suggest that although the inhibitory component underlying selective attention is impaired in individuals with DAT, the ability to differentiate a target from a distractor may be preserved under certain task conditions. In the natural environment, we are confronted with multiple sources of information. One function of attention is to select some subset of this information for further processing. Many current theories of selective attention are based on the assumption that the selected or goal-relevant information is facilitated while the ignored or irrelevant information is actively inhibited (Dalrymple-Alford & Budayr, 1966; Neill, 1977; Tipper, 1985). In the present experiments, we investigate the inhibitory aspect of selective attention in healthy old adults and in individuals with dementia of the Alzheimer type (DAT). In pursuit of this goal, we first review the literature on inhibitory processes in healthy old adults and then turn to a review of the corresponding literature on individuals with DAT.