Influence of aging on visual attention and peripheral perception.

Abstract

During visual search, our attention extends around each fixation. It has been suggested that, in aging, there is a reduced attentional field, leading to visual function declines. To investigate the attentional field, 30 younger and 20 older adults performed a pop-out visual search task. We estimated each participant's attentional field size based on their search times in the presence of different sizes of gaze-contingent visible windows (25°, 20°, and 15° around fixation). Further, we tested whether performance in the visual search task was related to peripheral visual function. Participants performed a contrast discrimination task and two motion perception tasks (local and global motion perception). In these tasks, stimuli were presented at two different peripheral eccentricities (5° and 10°). Overall, older adults took longer than younger adults to report the presence of the target in the control full-view pop-out search task. Compared to younger participants, they also had a significantly smaller attentional field. In addition, irrespective of eccentricity, older adults had higher peripheral contrast discrimination thresholds and a higher threshold in global motion perception, but not local. We also found negative correlations between attentional field size and thresholds for contrast discrimination and for global motion perception for older adults. In conclusion, we observed reduced attentional fields in aging, which were associated with lowered contrast and lowered global motion perception. These results highlight the importance of spatial covert attention in peripheral visual function and support the notion of a decline in the functions of the dorsal visual network in aging.