Purpose. Older adults commonly report thai they experience difficulties in locating objects, especially in scenes that are novel or visually cluttered. The useful field of view (UFOV) provides a useful index of such impairments. The current experiments assess UFOV task performance throughout the life span, and attempt to determine the factors that underlie age related performance differences. Method. Experiment 1: 176 observers aged 16 to 84 completed a central letter identification task, a peripheral target localization task, and then both tasks concurrently. In all conditions, stimuli were presented for 67 msec at 30% contrast. Experiment 2: 24 young subjects repeated the UFOV task from Experiment 1 under conditions of varying task difficulty. For half the subjects, stimulus duration varied from 27 msec to 67 msec. For the remaining subjects," stimulus contrast varied from 6% to 30%. Results. Experiment]: Central task performance did not change significantly from the separate to the concurrent condition. In contrast, regardless of age, peripheral task performance decreased from the separate to the concurrent condition. The decrease was significantly greater for older observers. Additionally, absolute levels of performance on each task alone decreased as a function of increasing age. Experiment 2: Younger observers performed like older observers when stimulus contrast decreased but not when stimulus duration decreased. Conclusions, These findings suggest that task difficulty per se does not determine the pattern of results on a UFOV task. The results do not lend strong support to the general slowing hypothesis of aging. Instead, under divided attention conditions, the stimuli seem to have a functionally lower effective contrast for older observers than younger observers. Supported by the Ontario Ministry of Transportation and NSERC grants OGP01Ü5494 & OGP0042133.