Between- and within-individual effects of visual contrast sensitivity on perceptual matching, processing speed, and associative memory in older adults

Background: Although cross-sectional studies have demonstrated associations between visual contrast sensitivity and cognitive test performance, it remains unclear whether peripheral visual or perceptual factors explain the association. Objective: We aimed at determining whether reducing static contrast of the study stimuli would simulate the performance deficits on measures of processing speed and associative memory that are associated with aging. Methods: We investigated the mechanism by which vision and memory are associated in a sample of 91 volunteers aged 60 - 87 years. In tests of perceptual matching, digit-symbol matching, and associative memory, the level of static contrast of the stimuli was manipulated, with three contrast levels. The duration of stimuli presentation was also manipulated in the associative memory task in a full-factorial experimental design. Accuracy and response latencies ( for correct trials) were measured. Results: Experimental results showed that within subjects, lower contrast was associated with longer latencies, indicating an effect on information processing speed. Regression analyses replicated previous findings of a moderate to strong association between visual contrast sensitivity and cognitive performance in cross- sectional studies. Conclusion: These results provide support for a theory in which visual aging is associated with slower encoding of information as well as being involved at a more central level. Copyright (c) 2006 S. Karger AG, Basel.