Aging and visual crowding.

OBJECTIVES The ability to perceive high spatial frequencies (i.e., fine detail) is impaired when contours are placed near the detail to be resolved (Bouma, H. [1970]. Interaction effects in parafoveal letter recognition. Nature, 226, 177-178. doi:10.1038/226177a0; Flom, M. C., Weymouth, F. W., & Kahneman, D. [1963]. Visual resolution and contour interaction. Journal of the Optical Society of America A, 53, 1026-1032. doi:10.1364/JOSA.53.001026.). This visual crowding is more pronounced outside of central vision and may be more pronounced in older adults. Thus, the motivation for the present study. METHOD Younger (M = 20.95 years) and older adults (M = 70.32 years) detected gap orientation in a Landolt C presented at 3° or 6° either alone or flanked by bars of the same spatial scale. RESULTS Both age groups demonstrated a visual crowding effect, in that acuity deteriorated in the flanking condition, an effect that grew with eccentricity. Older adults exhibited a larger crowding effect, particularly at 6°. Younger adults tested at reduced illumination did not show the crowding effect of older adults. Thus, age differences do not appear to result from reduced retinal illumination. When the crowding effect was operationalized as the ratio of crowded to uncrowded acuity, age differences were eliminated at both 3° and 6°. DISCUSSION These data have implications for understanding age differences in functional vision, including reading and visual search.