Abstract
Objective: The purpose of this control study was to assess how visual information interacts with the cognitive processes involved in naming. The impact of subtle alterations in the visual-perceptual integrity of target stimuli on naming was investigated. Methods: Stimuli consisted of 150 black and white line drawings of everyday objects (75 living & 75 non-living). Manipulations of contrast and spatial frequency were made independently during one of two experimental sessions. Session A investigated the effects of 5 levels of contrast (i.e., 1.25%, 2.5%, 5%, 10%, and 20%) on naming. Session B investigated the effects of 6 spatial frequency bandpass filters (i.e., 0.25–0.5; 0.5–01; 1–2; 2–4; 4–8; 8–16 c/deg) on naming. Two neurologically normal adults participated in Session A, two neurologically normal adults participated in Session B, and one neurologically normal adult participated in both (age range = 35–60 years). Results: Significant differences were found between level 1 and levels 3-6 of spatial frequency for latency to name, and differences were found between the lowest two levels and all subsequent levels for accuracy to name. For contrast, there were significant differences between 1.25% contrast and the higher levels (10% & 20%, latency data; 5% & 20%, accuracy data). Discussion: The long-term trajectory of this study is to develop an object naming test for the detection of incipient Alzheimer's disease. In order to achieve this goal, it is important to understand what elements of visual processing are most important in naming in general. This study investigated the influence of spatial frequency and contrast on naming in normal subjects. These pilot data suggest that there is no statistically significant improvement in accuracy and latency to name obtained above and beyond 1–2 c/deg of spatial frequency. The results for the contrast sessions were more ambiguous, and additional data is needed in order to make any conclusions.