Exploring interhemispheric collaboration in older compared to younger adults

Physical and Name Identity letter-matching tasks were used to explore differences in interhemispheric collaboration in younger and older adults. To determine whether other factors might also be related to across/within-hemisphere processing or visual field asymmetries, neuropsychological tests measuring frontal/executive functioning were administered, and comparisons were made for participants split into low and high efficiency groups based on performance on the letter-matching tasks. A Task by Across/Within interaction was found for both groups, but with a stronger within-hemisphere advantage for the Physical Task and a weaker across-hemisphere advantage for the Name Task for older participants. More efficient groups and better performers on several neuropsychological tasks showed a reduced across-hemisphere advantage for the Name Identity task. Findings suggest that computational complexity, specific task demands, and perhaps trade-offs between age-related changes in gray and white matter all contribute to whether processing loads are distributed across or within hemispheres as we age.