Effects of Age on the Contingent Negative Variation and Preparatory Set in a Reaction-Time Task

Age differences in preparatory set, as inferred from simple reaction time performance in trial series with constant or variable foreperiod duration, were related to the contingent negative variation (CNV), since this electrocortical potential seems to reflect the time-course of preparation. The CNV appeared not be be a unitary potential, but to consist of an orienting response following the warning signal, and an anticipatory response preceding the imperative signal when this is predictable in time. Elderly subjects failed to show an anticipatory response when the foreperiod was long. This suggests that their poor performance with long constant foreperiods results not from impaired ability to sustain preparation but from difficulty in controlling a sequence of operations so as to initiate preparation at an appropriate time.