Context-updating processes facilitate response reprogramming in younger but not older adults.

The current study used concurrent acquisition of motion capture and event-related potential (ERP) data to test the prediction that response reprogramming relies on context-updating processes, and that age differences in conflicting-response performance are related to context-updating deficits in the elderly. Participants performed a motor sequencing task that included prepotent pairs of key presses, and conflicting pairs that started with the same first key press of the prepotent pair, but ended in an unexpected alternate response. ERP analyses were used to measure the P3b component as an electrophysiological correlate of context updating. The results revealed an age-related reduction in the ability to reprogram a response as younger, but not older, adults exhibited a negative correlation between planning and execution time for conflicting responses, such that shortened execution time led to better performance by the younger group. Both age groups demonstrated a large P3b component following conflicting, but not prepotent stimuli. The peak of this P3b was delayed, and its amplitude reduced in the older, compared with younger, adults. Noteworthy was that conflicting responses with faster execution time were associated with a larger P3b component than responses with slower execution time in younger, but not older, adults, suggesting that better context updating led to more efficient response reprogramming. These findings are novel in showing that context updating is associated with adjustments in response execution, and that older adults were less able to use these context-updating processes to support successful movement reprogramming.