Effects of ageing on cognitive task preparation as reflected by event-related potentials

The anticipation of complex cognitive tasks involves effortful preparation being reflected in the contingent negative variation (CNV) of the event-related potential. In the literature there are contradictory results concerning the effect of age on this potential. We wanted to investigate effects of age, time-on-task, and task difficulty on the CNV.

Young and middle-aged participants performed a visual search and a non-search task during an early and a late phase of a 6-h session.

Performance data revealed increased response times and error rates for middle-aged vs. young participants. Most importantly, an increased frontal CNV amplitude was found for the older participants, especially pronounced in the search task. A late positivity which was elicited to the offset of the preceding stimulus was increased for the middle-aged vs. young group in the visual search task only. There was no effect of time-on-task on performance, but the CNV became larger with time-on-task in the search task while it became smaller in the non-search task.

The results suggest an enhancement of effortful task preparation for middle-aged participants especially when the task is difficult.

This underlines the role of the CNV as a neurophysiological indicator for effortful cognitive preparation.