title: Effects of graded levels of physical similarity and density on visual selective attention in patients with Alzheimer's disease.
abstract: A multitarget visual cancellation test was administered to patients with Alzheimer's disease (AD) and age-matched healthy controls (HC). Attentional loads--physical similarity (number of features shared by target and distractors; 3 levels) and density (number of items per page; 3 levels)--were varied systematically. As physical similarity increased, both groups slowed their search, but whereas the HC group maintained accuracy, the AD group increased commission errors and tended to miss more targets. Increased density yielded slower search and more target omissions in the AD group. Commission errors are additional indicators of higher order attentional deficits, especially in early disease. The findings suggest that patients with AD may rely increasingly on physical features of stimuli during a search, leading to inefficient bottom-up processing strategies.
authors.affiliation: Department of Psychology, Queens College and The Graduate Center, City University of New York, Flushing, NY 11367, USA. nsfoldi@qc.edu
authors.forename: Nancy S
authors.initials: NS
authors.lastname: Foldi
authors.forename: Lynn A
authors.initials: LA
authors.lastname: Schaefer
authors.forename: Richard E C
authors.initials: RE
authors.lastname: White
authors.forename: Ray
authors.initials: R
authors.lastname: Johnson
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Berger
authors.forename: Maria T
authors.initials: MT
authors.lastname: Carney
authors.forename: Lucy O
authors.initials: LO
authors.lastname: Macina
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000503:physiopathology*; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000503:physiopathology*; D003710:Demography; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D015203:Reproducibility of Results; D014794:Visual Fields / Q000502:physiology*