Characteristics of Visual Target Influence Detection of Change in Naturalistic Scenes in Alzheimer Disease

Abstract

To examine the role of visual characteristics of the target on Alzheimer disease (AD) patients' ability to detect change in naturalistic scenes. AD patients exhibit impairments in detecting changes in the visual environment. Unexamined to date is the influence of visual characteristics of the target on this ability. The change-detection experiment used 36 pairs of photographs of naturalistic scenes. Each pair was identical except for one target that differed in color, gray-scale, or presence/absence. Scene complexity also varied. The task was to locate the target; reaction times (RTs) were recorded. RTs increased as scene complexity increased. AD patients exhibited slower RTs than elderly adult controls (ECs), who were slower than young adults (N = 14/group). AD patients were unable to locate the target in 33.3% to 61.9% of the complex gray-scale trials, compared with 4.8% to 38.1% in the EC group. Performance on color and presence/absence trials was relatively good for all groups. The ability of AD patients to detect change in simulated real-world scenes is influenced by visual characteristics of the target and by scene complexity.