Attentional Effects of Hand Proximity Occur Later in Older Adults: Evidence From Event-Related Potentials

Research with young adults has shown hand proximity biases attention both early (by the time stimuli are categorized as relevant for action) and later, selectively for goal-relevant-stimuli. We examined agerelated changes in this multisensory integration of vision and proprioception by comparing behavior and event-related potentials (ERPs) between younger and older adults. In a visual detection task, the hand was placed near or kept far from target and nontarget stimuli matched for frequency and visual features. Although a behavioral hand proximity effect-faster response times for stimuli appearing near the hand-was found for both age groups, a proportionately larger effect was found for younger adults. ERPs revealed age-related differences in the time course of the hand's effect on visual processing. Younger adults showed selective increases in contralateral N1 and parietal P3 amplitudes for targets near the hand, but older adults only showed hand effects at the P3 which were accompanied by concurrent neural activity in bilateral frontal regions. This neural pattern suggests that compared with younger adults, older adults may produce the behavioral hand proximity effect by integrating hand position and visual inputs relying more on later, task-related, frontal attentional mechanisms and less on early, posterior, multisensory integration.