Older adults tend to prioritize positive information more and negative information less than younger adults. This pattern, known as the positivity effect, was recently observed using an emotion-induced blindness task: task-irrelevant negative images distracted younger adults but less so older adults, whereas positive images distracted both groups. One possibility is that older adults simply fail to process the content of complex negative distractors. In the current study, we explored whether older adults were distracted by negative images when they had to report about them. Participants completed a modified emotion-induced blindness task whereby emotional distractors were either task-irrelevant (younger: n=49; older: n=46) or task-relevant (younger: n=46; older: n=44). The task-relevance of distractors made no difference, such that younger adults were distracted by negative images more than neutral images, but older adults were not, regardless of task-relevance. Such indicates that older adults saw but remained undistracted by the content of negative images.

The locus coeruleus (LC) regulates attention via the release of norepinephrine (NE), with levels of tonic LC activity constraining the intensity of phasic LC responses. In the current fMRI study, we used isometric handgrip to modulate tonic LC-NE activity in older women and in young women with different hormone statuses during the time period immediately after the handgrip. During this post-handgrip time, an oddball detection task was used to probe how changes in tonic arousal influenced functional coordination between the LC and a right frontoparietal network that supports attentional selectivity. As expected, the frontoparietal network responded more to infrequent target and novel sounds than to frequent sounds. Across participants, greater LC-frontoparietal functional connectivity, pupil dilation, and faster oddball detection were all positively associated with LC MRI structural contrast from a neuromelanin-sensitive scan. Thus, LC structure was related to LC functional dynamics and attentional performance during the oddball task. We also found that handgrip influenced pupil and attentional processing during a subsequent oddball task. Handgrip decreased subsequent tonic pupil size, increased phasic pupil responses to oddball sounds, speeded oddball detection speed, and increased frontoparietal network activation, suggesting that inducing strong LC activity benefits attentional performance in the next few minutes, potentially due to reduced tonic LC activity. In addition, older women showed a similar benefit of handgrip on frontoparietal network activation as younger women, despite showing lower frontoparietal network activation overall. Together these findings suggest that a simple exercise may improve selective attention in healthy aging, at least for several minutes afterwards.