Aging effects on the identification of digitally blurred text,scenes and faces: Evidence for optical compensation on everyday tasks in the senescent eye

When older observers are defocused optically to the same reduced acuity levels as their younger adult counterparts they are better able to read distant text. This study sought to determine if this ability extended to intrinsically blurred (i.e., image-processed) stimuli of different types. Such an outcome suggests an explanation based on older persons’ greater experience with blurred stimuli; otherwise, one attributable to compensatory changes in the optic media of the older eye would be favored. Twelve young and 12 old healthy community-resident adult observers with excellent acuity were compared on their ability to identify low-pass filtered real words, nonsense words, scenes, and faces arranged in a sequence of decreasingly blurred images. Young observers were able to identify the images correctly earlier in the blur sequence than older adult observers, significantly so for both real and nonsense words. This finding suggests that compensatory changes in the eye’s optical media rather than older observers’ greater experience with blur accounts for their superior legibility performance with optically defocused text. While the image-enhancing effects of the age-related decline in pupil size (senile miosis) may be involved, further research is needed to clarify the mechanism(s) underlying this ability. Paul Bartel received his B.Sc. (Honours) in Psychology (Vision and Aging Lab) and the Bachelor of Social Work degrees from the University of Calgary. He is currently the Director of Community Programs at the North Central Community Resource Centre in Calgary. Donald W. Kline is a professor of psychology and the Director of the Vision and Aging Lab (PACE Program) at the University of Calgary. His research interests include the neural and optical mechanisms of visual aging, visual human factors, and visual health, eye surgery and quality of life. This research was supported by a grant to D. Kline (No. OGP0046593) from the Natural Sciences and Engineering Research Council of Canada (NSERC).