(Download) "Visual Perception in Normal Aging and Alzheimer's Disease" by Judith Ann Turner * Book PDF Kindle ePub Free
eBook details
- Title: Visual Perception in Normal Aging and Alzheimer's Disease
- Author : Judith Ann Turner
- Release Date : January 19, 2013
- Genre: Medical,Books,Professional & Technical,
- Pages : * pages
- Size : 8012 KB
Description
Perceptual influences on naming and recognition of picture stimuli were assessed for a sample of 20 nondemented elderly and 20 Alzheimer's disease patients. Subjects were shown three sets of 32 pictures to name and recognize. One set was presented without perceptual alteration. For the other two sets, a filter was applied to the spatial frequency magnitude spectra of the images to minimize (by degradation or enhancement) the perceptual effects of differences in spatial frequency contrast sensitivity between nondemented and Alzheimer subjects. Naming and recognition accuracy and latency were analyzed as a function of several stimulus variables (e.g. visual complexity and word frequency), in conjunction with filter condition. Overall, both groups performed ably on naming and recognition tasks. Findings indicated that alterations of spatial frequency amplitude influenced naming performance. Both subject groups were less accurate in naming enhanced images relative to nonfiltered stimuli. The accuracy of Alzheimer patients also suffered under degraded conditions relative to nonfiltered stimuli. Both groups were significantly slower in responding to degraded images, relative to nonfiltered and enhanced pictures. Word frequency was found t o interact with perceptual filtering. When low frequency words were shown in the enhanced condition, naming accuracy was diminished relative for nonfiltered stimuli for both groups. The accuracy of Alzheimerpatients was also diminished when stimuli were degraded. Naming latency for nondemented subjects was not influenced by word frequency. For Alzheimer patients, however, naming latency was significantly decreased for high frequency, enhanced pictures. Recognition (forced-choice, two alternative) accuracy and latency were not found to vary as a function of filter condition or word frequency for either group. Correlational analyses suggested that image familiarity was significantly related to performance on naming tasks. This has not been recognized previously as an important variable. Implications of these findings and suggestions for future research are discussed.