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Helen Payne, Harriet Allen; Neural mechanisms underlying active ignoring in the ageing brain. Journal of Vision 2010;10(7):1279. doi: 10.1167/10.7.1279.
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There is evidence to suggest that we actively ignore information that is irrelevant to our current goals. This is demonstrated using the preview search paradigm. Here half of the distracters in a visual search task are presented briefly before the addition of the remaining distracters (and target) to the display. Results for young adults show that the time taken to find the target in these “Preview” trials is reduced in comparison to a “Full” condition where all distracters are presented simultaneously. This preview benefit suggests that observers exclude the previewed distracter items from search. fMRI studies reveal enhanced neural activation in posterior parietal cortex in response to preview trials, reflecting a distinct active ignoring process.
Ageing is associated with various cognitive costs including the ability to inhibit processing. Thus, older adults may show less preview benefit because they are unable to ignore the previewed items. There is some evidence that older adults do not benefit from the preview display in a similar manner to young adults. A key aim of our study was to compare neural activation during active ignoring between old and young participant groups to investigate how ageing affects ignoring. We found that old (M = 71.8 years) and young adults (M = 21.8 years) who demonstrated a clear behavioural preview benefit showed similar areas of neural activation to each other. Contrasting preview trials against full trials revealed activation in the precuneus and superior parietal lobule (SPL), areas consistently activated in previous fMRI studies with young adults. Furthermore, activity in the SPL was significantly greater for older adults. These results show that 1) older adults are able to ignore previewed distracter items and, 2) the function of the posterior parietal cortex, an area implicated with distracter suppression, can be retained in older adults.
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