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P1‐473: Face, scene and object perception in posterior cortical atrophy
Author(s) -
Shakespeare Tim,
Crutch Sebastian,
Warrington Elizabeth
Publication year - 2011
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2011.05.756
Subject(s) - posterior cortical atrophy , psychology , categorization , audiology , perception , context (archaeology) , neuropsychology , cognitive psychology , medicine , cognition , artificial intelligence , disease , neuroscience , pathology , dementia , computer science , paleontology , biology
Background: Posterior cortical atrophy (PCA) is a degenerative condition characterised by progressive visual dysfunction and atrophy of the parietal and occipital lobes, most commonly due to Alzheimer’s disease (Lehmann et al., 2009, Tang-Wai et al., 2004). Experiments investigating PCA typically use pencil and paper tests, where the connection between test results and real world ability is unclear. The present experiment aimed to improve our understanding of patients’ visual deficits in a more naturalistic context using pictures of faces, scenes and objects. The use of color as a cue was also assessed as this can be relatively spared in PCA (Lehmann et al, in press). Methods: Participants were 20 patients with a clinical diagnosis of PCA due to probable Alzheimer’s disease. A background neuropsychological battery including tests of memory, visual acuity and color perception was completed. Three types of stimuli were chosen; faces (Minear & Park, 2004, Tottenham et al., 2009), scenes and objects (see Figure 1a). Each had two categories, and each category had three forced choice options. For example in the aged faces category, the choices were ‘young’ ’middle aged’ or ‘old’. Participants responded verbally. Reaction time data was used only when accuracy was greater than 80%, and included correct trials only. Results: Pilot data has been collected from four participants; we hope to complete data collection by April 2011. Average categorization performance was more accurate for color than grayscale images (color: 89.7%, RT 3.1s; grayscale 84.7%, 4.1s). However, for some individuals the magnitude and direction of the color effect differed between stimulus categories. Whilst the majority of patients showed equivalent deficits, some patients showed greater deficits in certain categories (see Figure 1b). Conclusions: The results demonstrate a difference in performance between colour and grayscale conditions, particularly in the object and scene categories where colour contains strong cues. This study demonstrates heterogeneity in the face, object and scene perception abilities of PCA patients. Dissociations in performance between categories and colour/grayscale conditions are likely to reflect variation in the loci of greatest atrophy. This has implications for management of visual deficits in PCA and the design of visual aids to improve everyday functional ability. P1-474 RELATING MEMORY TO FUNCTIONAL CAPACITY FROM NORMAL AGING TO DEMENTIA USING HIERARCHICAL BAYESIAN COGNITIVE PROCESSING MODELS William Shankle, James Pooley, Mark Steyvers, Junko Hara, Barry Reisberg, Michael Lee, Medical Care Corporation, Newport Beach, California, United States; 2 University of California, Irvine, Irvine, California, United States; Shankle Clinic, Newport Beach, California, United States; New York University, New York, New York, United States.